The Kynix Blog

Executive Summary: What is a Phototransistor?A phototransistor is a light-sensitive semiconductor device that converts incident light into electric current while providing internal gain amplification. Unlike simple photodiodes, phototransistors utilize a bipolar junction structure (NPN or PNP) to amplify the signal, making them highly effective for optical switching, object detection, and encoding systems in modern 2026 electronics.Ⅰ Introduction to PhototransistorsThe phototransistor is a specialized semiconductor device engineered to detect light levels and modulate the current flowing between the emitter and collector based on the photon intensity it receives.While both phototransistors and photodiodes serve as optical sensors, the phototransistor distinguishes itself through high sensitivity attributed to the internal gain of its bipolar transistor architecture. As of 2026, this intrinsic amplification makes phototransistors the preferred choice for applications requiring robust signal detection without complex external amplification circuitry.Ⅱ Video Tutorial: How Phototransistors WorkVisual learners can understand the practical operation of light detection in the following tutorial.Phototransistor Tutorial Phototransistor Video Description:A comprehensive tutorial demonstrating how to utilize phototransistors for precise light detection in circuit design.  Ⅲ What Is a Phototransistor?A phototransistor is an electronic switching and current amplification component that operates by converting photon energy into electrical signals. When light strikes the exposed base-collector junction, a reverse current flows proportional to the luminance intensity.Widely used to convert light pulses into digital electrical signals, these components are powered by light interactions rather than solely electrical bias at the base. They offer high gain and low cost, making them ubiquitous in 2026 consumer electronics. Figure 1: Phototransistor SymbolFunctionally, phototransistors share similarities with photoresistors (LDRs), but with a key distinction: phototransistors generate current and voltage through the photovoltaic effect and amplification, whereas LDRs only change resistance.Transistors with the base terminal exposed are chemically doped to maximize light sensitivity. Photons striking the depletion layer generate electron-hole pairs, activating the transistor just as a base current would in a standard BJT. Silicon-based photosensors typically respond to visible and near-infrared radiation (approx. 400nm to 1100nm). Ⅳ How are Phototransistors Constructed?The phototransistor's structure is specifically optimized for photo-applications by maximizing the area of the base-collector junction. While ordinary bipolar transistors exhibit some photosensitivity, phototransistors feature significantly larger base and collector areas to capture maximum light flux.Figure 2: Construction of a PhototransistorⅤ Semiconductor Material EvolutionHistorical phototransistors utilized a homo-junction structure, fabricated entirely from germanium or silicon. In contrast, modern 2026 phototransistors often employ type III-V semiconductor materials, such as gallium arsenide (GaAs), to target specific wavelengths and increase efficiency.Key structural variations include:NPN Topology: The most popular configuration due to the higher mobility of electrons compared to holes.Heterostructures: Utilizing different materials on either side of the PN junction to enhance conversion efficiency.Mesa Structure: A common physical layout for optimized light absorption.Schottky Junctions: Occasionally used for the collector to improve switching speeds.To ensure optimal sensitivity, the emitter contact is frequently offset, preventing it from blocking light from reaching the active region. Ⅵ How Does a Phototransistor Work?A phototransistor operates by using light to control the flow of current, effectively replacing the base current of a standard transistor with photon energy.Biasing: The collector is biased positively relative to the emitter (in NPN), creating a reverse-biased Base-Collector (B-C) junction.Injection: Light strikes the B-C junction, generating electron-hole pairs.Amplification: The movement of these carriers constitutes a base current, which the transistor amplifies by its gain factor (hFE).Typically, the physical base terminal is left unconnected (floating), as the device is controlled entirely by incident light. Ⅶ Key Electrical CharacteristicsSince phototransistors are essentially Bipolar NPN Transistors with an exposed junction, their V-I characteristics resemble a standard BJT family of curves, but with Light Intensity (mW/cm²) replacing Base Current (IB).Dark Current: When no light is present, a minuscule leakage current flows from collector to emitter. In high-precision applications, minimizing this Dark Current is crucial.Light Current: As light intensity increases, the base current rises, triggering the amplification process. Figure 3: Reverse Bias Configuration The collector current characteristics curve below demonstrates the linear relationship between light intensity and output current in the active region.Figure 4: Collector Current vs. Irradiance Ⅷ Selection Criteria & PropertiesWhen selecting a component for 2026 designs, engineers must evaluate specific properties to ensure the device matches the optical environment.Critical Datasheet Properties:Peak Wavelength: The specific color of light (e.g., 850nm IR vs. 560nm Visible) the device is most sensitive to.Linearity: How accurately the output follows the input light intensity.Sensitivity: The ratio of output current to incident light power.Response Time: The rise and fall time, which determines the maximum data rate (typically slower than photodiodes).Acceptance Angle: The field of view from which the sensor can detect light. Ⅸ Common Types: BJT vs. FETPhototransistors are primarily categorized by their internal transistor architecture:BJT Phototransistor: The standard type. In darkness, it leaks only ~100 nA. Under illumination, it can conduct up to 50mA. This high current handling capability distinguishes it from photodiodes.Photo-FET (Field Effect Transistor): Utilizes light to generate a gate voltage that controls the drain-source current. Photo-FETs offer extremely high input impedance and are more sensitive to weak light signals, though they are less common in general switching applications. Ⅹ Practical Circuit Examples (2026 Applications)The primary goal of phototransistor circuits is to generate a usable output voltage from light-induced current. Unlike photodiodes which often require Transimpedance Amplifiers (TIA), phototransistors have built-in gain, allowing for simpler circuit designs.Common Configurations:Common-Emitter (Inverting): Output voltage drops as light increases.Common-Collector (Non-Inverting): Output voltage rises as light increases.Figure 5: Basic Amplifier Configurations 10.1 Step-by-Step Circuit Implementations 1. Light Operated Relay (Automatic Day Switch)Mechanism: When light strikes phototransistor Q1, it conducts, supplying base current to the driver transistor Q2. Q2 then activates the mechanical relay, turning on the connected load. 2. Darkness Operated Relay (Night Light)Mechanism: By inverting the logic, the relay activates only when light is absent. In darkness, the phototransistor turns off (high resistance), allowing the bias resistor to trigger Q2. 3. Light Interruption Alarm (Security System)Mechanism: This circuit functions as a tripwire. Under normal conditions (laser/light hitting sensor), the phototransistor pulls the SCR gate LOW (off). When the beam is broken by an intruder, the gate voltage rises, latching the SCR and sounding the alarm until manually reset. Ⅺ Datasheet Specifications to WatchTo ensure system reliability, consult the following parameters in manufacturer datasheets:Collector Current (IC): Maximum current the device can handle (typically 1mA - 50mA).Dark Current (ID): Leakage current in total darkness (lower is better for precision).Peak Wavelength (λp): The wavelength of maximum sensitivity.VCE(sat): Collector-Emitter saturation voltage.Rise/Fall Time (tr/tf): Critical for optical data transmission applications.Power Dissipation (Ptot): Thermal limits of the package. ⅻ Pros and Cons AnalysisSelecting the right optical sensor requires balancing sensitivity, speed, and cost.AdvantagesDisadvantagesHigh Gain: Produces higher current output than photodiodes, reducing the need for external amplifiers.Limited Voltage: Cannot withstand high voltages compared to Thyristors or Triacs.Cost-Effective: Inexpensive to manufacture and integrate into ICs.Slower Speed: Slower response time (lower bandwidth) compared to PIN photodiodes.Simplicity: Can drive small relays or logic gates directly in simple circuits.Temperature Sensitivity: Dark current increases significantly with temperature fluctuations. XIII Modern Applications in 2026Due to their versatility, phototransistors are integral to many modern technologies:Optocouplers (Optoisolators): Protecting low-voltage logic circuits from high-voltage spikes in power supplies.Optical Encoders: Used in robotics and motors to detect position and speed.Object Detection: Proximity sensors in smartphones and automated manufacturing lines.Safety Systems: Smoke detectors and light curtain barriers for industrial machinery.Remote Control Receivers: IR detection for consumer electronics (though often integrated with demodulators). XIV Comparison: Photodiode vs. PhototransistorWhile both detect light, their use cases differ based on speed and sensitivity needs.FeaturePhotodiodePhototransistorOutputLow Current (µA)High Current (mA) - AmplifiedResponse SpeedVery Fast (Nanoseconds)Moderate (Microseconds)ApplicationsFiber Optics, High-Speed DataRemote Controls, Light Switches, EncodersNoiseLow NoiseHigher Noise levels XV Frequently Asked Questions1. What type of device is a phototransistor?A phototransistor is a bipolar semiconductor device. It functions as a transistor where the base current is generated by incident photons striking the exposed semiconductor junction, rather than an electrical connection.2. What is the main difference between a standard transistor and a phototransistor?Physically, the primary difference is the packaging. A phototransistor has a transparent lens or window to allow light to reach the junction, and it often lacks an external base pin. Electrically, it is controlled by light intensity rather than input current.3. Is a phototransistor considered a sensor?Yes, it is a discrete photosensor. It detects the presence and intensity of light and converts it into a measurable electrical signal.4. How do you test if a phototransistor is working?You can test it using a multimeter or a simple circuit:Connect the phototransistor in series with a resistor and LED to a power source (checking polarity).Expose the sensor to light; the LED should brighten.Cover the sensor; the LED should dim or turn off.5. Which is better: Photodiode or Phototransistor?Neither is universally "better"; it depends on the application. For high-speed data (like fiber optics), a photodiode is superior. For switching and sensing without extra amplifiers, a phototransistor is more efficient due to its internal gain.{ "@context": "https://schema.org", "@graph": [ { "@type": "Article", "headline": "Phototransistors: The Ultimate 2026 Guide", "datePublished": "2021-12-02", "dateModified": "2026-01-07", "description": "A comprehensive guide to phototransistors, covering construction, working principles, circuit diagrams, and 2026 applications.", "image": "https://www.kynix.com/editor_u/image/20211202/2021120216390176.jpg", "author": { "@type": "Organization", "name": "Kynix Electronics" } }, { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What type of device is a phototransistor?", "acceptedAnswer": { "@type": "Answer", "text": "A phototransistor is a bipolar semiconductor device where the base current is generated by incident photons striking the exposed junction." } }, { "@type": "Question", "name": "What is the difference between a transistor and a phototransistor?", "acceptedAnswer": { "@type": "Answer", "text": "The main difference is that a phototransistor has an exposed optical window and is controlled by light intensity, whereas a standard transistor is controlled by electrical current at the base pin." } }, { "@type": "Question", "name": "Is a phototransistor a sensor?", "acceptedAnswer": { "@type": "Answer", "text": "Yes, a phototransistor is a discrete photosensor that converts light intensity into an electrical signal." } }, { "@type": "Question", "name": "Which is better: Photodiode or Phototransistor?", "acceptedAnswer": { "@type": "Answer", "text": "Photodiodes are better for high-speed data applications, while phototransistors are better for switching and sensing applications requiring higher sensitivity and gain." } } ] }, { "@type": "HowTo", "name": "How to Build a Simple Light Interruption Alarm", "step": [ { "@type": "HowToStep", "name": "Setup the Phototransistor", "text": "Connect the phototransistor to a pull-down resistor to create a voltage divider." }, { "@type": "HowToStep", "name": "Connect the SCR", "text": "Connect the output of the phototransistor junction to the Gate of an SCR (Silicon Controlled Rectifier)." }, { "@type": "HowToStep", "name": "Align the Light Source", "text": "Point a laser or light beam directly at the phototransistor. This keeps the SCR gate low (Off)." }, { "@type": "HowToStep", "name": "Trigger the Alarm", "text": "Interrupt the light beam. The phototransistor turns off, voltage spikes at the SCR gate, latching the alarm on." } ] } ]}

Summary: Film capacitors are the preferred choice for reliability, audio clarity, and long service life across consumer electronics, automotive, and industrial applications. The global film capacitor market reached approximately USD 4.2 billion in 2024 and is projected to grow at a 4.2% CAGR through 2034, driven by electric vehicles, renewable energy, and 5G infrastructure. Top brands including Panasonic, Nichicon, WIMA, and Vishay consistently earn high marks from engineers and audiophiles alike.When you look for the best film capacitors, you want brands that users trust for solid reliability and great performance. Many people praise these capacitors for their low ESR, long life, and steady operation even when things heat up. You can count on top brands because they focus on quality and real-world results. Users often share stories about how a good brand makes all the difference in their projects.Film Capacitors OverviewKey FeaturesFilm capacitors stand out for their strong performance and long service life, making them a reliable choice across a wide range of electronic devices — from power tools and automotive inverters to high-fidelity audio gear. They handle high temperatures and demanding conditions without degradation, and because they are non-polarized, you can use them freely in both AC and DC circuits.Here are some important features you will find in film capacitors:Capacitance tells you how much energy the part can store.Rated voltage shows how much voltage it can safely handle.High insulation resistance means less energy leaks out.Breakdown strength lets it survive voltage spikes.Rated current shows how much current it can take during use.Low loss means it does not waste much energy as heat.Capacitance stays steady, even when things get hot.Fewer failures and longer life because of the stable plastic film inside.No change in performance when the voltage changes.Polypropylene types give you the best voltage strength and lowest loss.Tip: Always check the markings on your film capacitors. You will see the rated capacitance, voltage, and other details right on the part.You can see how film capacitors lead the market in the table below:AspectStatistic / ResultDescription / Technical AdvantageElectronic Circuits Segment25.1% market share, 4.1% CAGR (2025–2037)High reliability and long life, great for automotive and high-temp uses.AC Segment54.7% market share, 3.4% CAGR (2025–2037)Used in power transmission, industrial drives, and motors.Plastic Film Capacitors72.7% revenue share; polypropylene holds 65.55% of that segmentPopular in electronics, cars, and green energy.Market SizeUSD 4.2B (2024) to USD 6.34B (2034), 4.2% CAGRDriven by EVs, renewable energy, and 5G infrastructure build-out.Automotive Segment34.8% end-use share; automotive demand alone worth USD 793.5M in 2026EV traction inverters and onboard chargers are the primary growth driver.Product Development HighlightsNew high-current, high-voltage, and miniaturized models (e.g., KEMET R41P, 40% smaller than predecessor)Support for green energy, EVs, and space-efficient electronics.User BenefitsYou get a lot of value when you pick film capacitors for your projects. They last a long time and rarely fail, so you do not have to worry about replacing them often. Their steady performance means your devices work better and stay safe, even if the temperature goes up.You can use them in both AC and DC circuits.They keep their capacitance steady, so your sound or signal stays clear.They resist heat and voltage spikes, which protects your gear.You will find them in everything from smartphones to electric cars.They help save energy because they do not waste much as heat.You can trust them for both simple DIY projects and high-end electronics.If you want a part that gives you peace of mind and strong results, film capacitors are a smart choice.What Should You Prioritize When Choosing Film Capacitors?ReliabilityReliability is the top priority for most engineers and hobbyists — a film capacitor that handles heat, voltage stress, and humidity outperforms alternatives in virtually every demanding application. Film capacitors stand out because they handle these conditions better than most other types.Polyester film capacitors stay stable up to 125°C and have low ESR, so they work well in tough spots.Polypropylene types keep their value steady, even when things get hot or the voltage changes.Metalized film capacitors can fix small problems inside themselves, which helps them last longer.Tests show that film capacitors can survive high temperatures and humidity. In one study, experts put them through harsh conditions — over 120°C and high humidity. They found that the best ones kept working, even when other parts failed. You can trust these capacitors in cars, power supplies, and even aerospace gear.Note: Most users and engineers say that longevity and reliability are the top reasons they choose film capacitors for important jobs.Sound QualityFor audio applications, polypropylene and polystyrene film capacitors are the go-to choice because they keep distortion extremely low and capacitance stable across temperature and frequency ranges. Polypropylene and polystyrene types are favorites for audio fans, and their behavior closely approaches that of a theoretically ideal capacitor.Polypropylene capacitors have tight tolerances and low distortion.Polystyrene types are stable and do not leak, which helps with clean sound.Many people in forums and reviews say that switching to good film capacitors makes their speakers or amps sound better. You might notice less noise and more detail in your music.ValueThe best value depends on your application: polyester film capacitors cost less and work well for most general-purpose uses, while polypropylene types cost more but deliver superior performance under stress. Polyester film capacitors cost less and work well for most uses. Polypropylene types cost more but last longer and handle stress better.TypeCostBest UsePolyesterLowGeneral, affordablePolypropyleneMediumHigh power, precision, audioPTFE (Teflon)HighExtreme environments, ultra-low distortion audioMost people look for a balance. In Asia-Pacific, many choose polyester for the price. In Europe, users often pay more for eco-friendly polypropylene. No matter where you live, you want a part that fits your needs and budget.Brand ComparisonImage Source: pexelsJapanese BrandsJapanese brands are consistently the first choice for engineers who need film capacitors that deliver long-term reliability without compromise. You see names like Panasonic, Nichicon, Rubycon, and Nippon Chemicon in many trusted projects. People who build and repair electronics say these brands last a long time and rarely fail. You can spot their parts in everything from audio gear to industrial machines.Here’s what makes these brands stand out:They have low ESR, which means less heat and better efficiency.Their lifespan is high, even when you use them in hot places.They handle ripple current well, so they work in tough power circuits.They keep working even if the temperature swings from freezing to very hot.BrandESRLifespanTemp RangeRipple CurrentBest UseRubyconLow-MediumHigh-55°C to +150°CMed-HighIndustrial, AudioNichiconLow-MediumHigh-55°C to +150°CMed-HighIndustrial, AudioPanasonicLow-MediumHigh-55°C to +135°CMed-HighIndustrial, ConsumerTDKLow-HighMed-High-40°C to +125°CMediumPower, AutomotiveIf you want a part that keeps your project running for years, you can trust these Japanese brands. Many users say they never worry about failures when they use them.Japanese brands also fight against fake parts by using strict quality checks. You get real, reliable film capacitors that match the specs on the datasheet.European BrandsEuropean brands have a strong reputation for premium materials and exacting quality standards, particularly in high-end audio and industrial applications. You might see names like WIMA, Vishay, and Epcos (TDK Europe) in high-end audio and industrial gear. These brands focus on quality and often use advanced materials.WIMA is famous for its red box capacitors. Many audio fans love them for clear sound.Vishay offers a wide range, from general use to special high-voltage types. In November 2025, Vishay acquired Birkelbach Kondensatortechnik GmbH, strengthening its capacitor film manufacturing capabilities.Epcos makes parts for both power and signal circuits.European brands often use polypropylene film, which gives you stable performance and low loss. You will find their film capacitors in audio equipment, power supplies, and even electric cars.BrandKnown ForUser FeedbackTypical ApplicationWIMAAudio clarity"Clean, detailed sound"Audio, Hi-Fi, Pro GearVishayWide selection"Reliable, consistent"Industrial, PowerEpcosPower handling"Great for tough jobs"Automotive, PowerMany users in forums say European brands give them peace of mind, especially when they want the best sound or need to meet strict safety rules.Boutique OptionsIf you want something special, boutique brands offer film capacitors made for top audio and custom projects. These brands include Auricap, Mundorf, and Jensen. They use premium materials and hand-check each part.Auricap uses special film and foil for pure sound.Mundorf makes capacitors for high-end speakers and amps.Jensen uses oil-filled designs for smooth, warm audio.Boutique capacitors cost more, and the measured electrical differences versus quality commercial polypropylene types are typically very small. That said, many audiophiles report subjectively hearing more detail, less noise, and a richer tone — particularly in highly sensitive signal-path applications. Whether those differences justify the cost is ultimately a personal decision.BrandSpecialtyUser CommentsTypical UseAuricapPure audio"Open, natural sound"Hi-Fi, Studio GearMundorfHigh-end builds"Big, clear soundstage"Speakers, AmpsJensenOil-filled, warm"Smooth, vintage tone"Vintage Audio, Hi-FiIf you build or upgrade audio gear, boutique film capacitors can give your project a unique sound. Many users say these brands make their music come alive.What to AvoidMost users agree you should be cautious with unbranded or unknown-origin film capacitors, particularly those sold without datasheets or clear markings, as these parts often fail early or do not meet their stated specs. SMD film capacitors are also generally avoided in audio signal paths, where through-hole types deliver better performance and longevity. You want to stick with trusted names for important projects.Tip: Always buy from a trusted supplier. This helps you avoid fake or low-quality parts.Technology and MaterialsEach brand uses different materials and designs. Japanese and European brands often use polypropylene or polyester film for stability and low loss. Boutique brands may use foil, oil, or even silver for the best sound. You can pick the right film capacitor by looking at your needs—whether you want long life, top sound, or the best value.Film Capacitors in AudioWhen you build or upgrade audio equipment, the type of capacitor you choose can shape the way your music sounds. Many people in the audio world talk about film capacitors because they help keep your sound clear and true. You will often see two main types in audio gear: polyester (Mylar) and polypropylene. Each has its own strengths and fans.Polyester (Mylar) TypesPolyester film capacitors are a practical entry point for audio upgrades — they offer a meaningful step up from ceramic types at a low cost, making them a solid choice for midrange and bass crossover sections. You will find these in many affordable audio devices. People often say that polyester is the minimum quality you should use for audio. If you want a basic upgrade from ceramic capacitors, polyester is a good place to start.Polyester capacitors are easy to find and cost less than other types.They work well in many audio circuits, like crossovers and signal paths.You get steady performance across a wide temperature range, usually from -40°C to 105°C.Many users share their experiences with polyester capacitors in online forums. They say these capacitors sound better than ceramics, but not as clear as higher-end types. Most of the feedback comes from listening tests, not scientific studies. People trust their ears and often notice a warmer, fuller sound after swapping in polyester capacitors.Some hobbyists mention that Mylar capacitors can sound a bit "soft" or "rounded" compared to other film types. Still, if you want a reliable and affordable choice, polyester is a solid pick for most audio projects.Polypropylene TypesPolypropylene film capacitors are the top choice for audio applications because they combine extremely low distortion, stable capacitance under varying temperature and voltage, and tight tolerances — all critical for accurate signal reproduction. You will see them in high-end amplifiers, preamps, and even studio gear. These capacitors use a special plastic film that keeps distortion and energy loss very low.Polypropylene capacitors hold their value steady, even when the temperature or voltage changes.They have tight tolerances, which means you get more accurate sound.You will notice less noise and more detail in your music.In hybrid crossover designs, DIYers commonly use polypropylene in tweeter sections for clarity while placing polyester in bass/mid sections for cost efficiency.Engineers and audiophiles often point out that polypropylene capacitors behave almost like perfect capacitors. They have lower resistance and inductance, so they do not mess with your signal. When you use them in places like passive crossovers or signal coupling, you get a cleaner, more open sound.Experts say that the biggest factor in sound quality is the actual capacitance value. If you match the values closely, you may not hear much difference between brands or types. Still, many people prefer polypropylene because it gives them peace of mind and a sense of sonic transparency.Some tests use double-blind listening to check if people can hear a difference between polypropylene and other film capacitors. When the capacitance is matched, most listeners cannot tell them apart. However, in real-world use, polypropylene types often win praise for their clarity and reliability.Standard vs. Boutique CapacitorsYou might wonder if boutique capacitors really sound better than standard ones. Boutique brands use special materials and hand-check each part. Some listeners say they hear more detail or a bigger soundstage. Others think the differences are small, especially if you use good standard polypropylene capacitors.TypeCostSound QualityBest UseStandard PolyesterLowWarm, basicEntry-level audioStandard PolypropyleneMediumClear, accurateHi-Fi, Pro AudioBoutique PolypropyleneHighSubtle, refinedHigh-end, Studio GearTip: If you want the best value, start with standard polypropylene capacitors. Try boutique brands if you want to experiment with your sound.What the Pros and Audiophiles SayProfessional reviews and audiophile forums often highlight the benefits of film capacitors in audio. People love their long life, stable performance, and ability to keep music sounding natural. You will see them recommended for everything from headphone amps to big home theater systems.Film capacitors use premium materials like polypropylene and foil, which help reduce distortion.They keep your sound clear, even as your gear ages.You get better high-frequency response and less noise, especially in sensitive circuits.If you want to upgrade your audio gear, film capacitors are a smart choice. They give you reliability, great sound, and peace of mind.Community InsightsEnthusiast FeedbackYou can learn a lot from people who build and fix things at home. Many DIYers and hobbyists share their stories on forums like DIYAudio and Reddit. They talk about what works and what does not. You might see someone say,"I swapped out the old caps in my amp for WIMA and the sound opened up right away!"Others warn you about cheap parts. One user wrote,"I tried some no-name caps from an online auction. They failed after a few months. Stick with trusted brands."Here are some tips you will see again and again:Always check the specs before you buy.Buy from a reliable store or supplier.Avoid parts that look fake or have no clear markings.Test new capacitors before you install them.Many enthusiasts also share photos of their projects. You can spot neat soldering and careful layouts. They say this helps with both sound and reliability.Professional OpinionsAudio engineers and manufacturers have their own advice. They test parts in labs and real products. You will often hear them say,"Choose the right type for your job. Polypropylene is best for audio, polyester works for general use."Professionals also warn about common mistakes. They see people use the wrong voltage rating or mix up the polarity. This can cause problems later.Here is a quick table of best practices from the pros:TipWhy It MattersMatch voltage ratingPrevents breakdownUse trusted brandsEnsures long lifeCheck for fakesAvoids early failureSolder carefullyKeeps connections strongYou can trust these tips. They come from years of experience and lots of testing. If you follow them, your projects will last longer and sound better.VerdictsBest OverallYou want a capacitor that works well in almost any project. After looking at expert reviews and user feedback, Panasonic stands out as the best overall choice. You get strong reliability, steady performance, and a wide range of options. Panasonic capacitors show up in many top-rated devices, from power supplies to audio gear.Experts use different ways to compare brands. They look at things like expert scoring, the Analytic Hierarchy Process (AHP), and objective methods such as entropy weight and CRITIC. Here’s a quick look at how these methods help pick the winner:MethodTypeAdvantageDisadvantageExpert scoringSubjectiveFast and simpleCan be biasedAHPSubjectiveSystematic, practicalNeeds careful math, possible biasEntropy weightObjectiveNo expert bias, uses real dataSensitive to errorsCRITICObjectiveConsiders data changes and linksNeeds lots of dataVariation coefficientObjectiveEasy to use, clear differencesLimits on what you can compareThese methods help make sure the verdict is fair and based on real facts.Best for AudioIf you care about sound, you want the best clarity and detail. Listening tests and technical checks put Jupiter Cosmos at the top for audio. You get a big soundstage, clear highs, and no harshness. Elna Silmic II also scores high, giving you great sound without breaking the bank.RankBrandListening NotesSJupiter CosmosBest clarity, wide sound, smooth trebleSElna Silmic IIClear, budget-friendly, no harsh highsAAudio Note KaiseiGood, just below top picksANichicon FGGood, just below top picksTests show that these brands keep distortion low and sound stable, even as the temperature changes. You will notice more detail and less noise in your music.Tip: For the best sound, match the right value and type to your audio gear.Best ValueYou want good performance without spending too much. Nichicon and WIMA give you the best value. They offer solid quality, long life, and fair prices. Many users trust these brands for both DIY and pro projects.Nichicon: Great for general use, easy to find, lasts long.WIMA: Known for clear sound in audio, also works well in power circuits.You can count on these brands to deliver strong results without costing a fortune.You have many great choices when picking film capacitors. If you want top reliability, Panasonic and Nichicon stand out. For audio, Jupiter Cosmos and Elna Silmic II get high marks. WIMA and Nichicon offer the best value for your money. Experts and users agree that brands like Murata, Cornell Dubilier, and Vishay lead with strong innovation and trusted products.Think about what matters most to you—sound, price, or long life. Share your own picks or questions below. Your experience helps everyone!Frequently Asked QuestionsWhat makes film capacitors better than electrolytic capacitors?Film capacitors last longer and handle heat better. You get more stable performance and less risk of leaks. Many users pick them for audio and power circuits because they sound cleaner and fail less often.Can I mix different brands of film capacitors in one project?Yes, you can mix brands. Just match the values and voltage ratings. Most people do this when upgrading or repairing gear. You might notice small sound changes, but your project will still work well.How do I spot a fake film capacitor?Look for clear markings and check the brand logo. Buy from trusted stores. If the price seems too low, it could be fake. Many users share photos online to help you compare real and fake parts.Are SMD film capacitors reliable for audio projects?Most users avoid SMD film capacitors in audio signal paths. Standard polypropylene SMD types can melt during soldering, limiting material choices, and through-hole polypropylene or polystyrene parts typically deliver better distortion performance and longevity. Stick with trusted through-hole brands for critical audio applications.Do boutique film capacitors really improve sound quality?Some people hear a difference with boutique brands. You might notice more detail or a richer tone. Others say standard polypropylene types sound just as good. Try both if you want to see what works best for your ears.Which film capacitor types are best for EV and renewable energy applications?High-voltage polypropylene film capacitors in the 400–800 V range are the standard for EV traction inverters and solar converters. Automotive demand alone accounts for over 30% of the film capacitor market as of 2025, with each EV inverter typically requiring multiple film capacitor banks to handle ripple currents up to 600 A.{ "@context": "https://schema.org", "@graph": [ { "@type": "Article", "headline": "Best Film Capacitor Brands: Top Picks for Audio & Electronics", "dateModified": "2026-03-25", "author": { "@type": "Organization", "name": "Site Author" }, "publisher": { "@type": "Organization", "name": "Site Publisher" }, "description": "A comprehensive comparison of the best film capacitor brands for 2026, covering Japanese, European, and boutique options for audio, industrial, and EV applications, with updated market statistics and expert guidance." }, { "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "What makes film capacitors better than electrolytic capacitors?", "acceptedAnswer": { "@type": "Answer", "text": "Film capacitors last longer and handle heat better. You get more stable performance and less risk of leaks. Many users pick them for audio and power circuits because they sound cleaner and fail less often." } }, { "@type": "Question", "name": "Can I mix different brands of film capacitors in one project?", "acceptedAnswer": { "@type": "Answer", "text": "Yes, you can mix brands. Just match the values and voltage ratings. Most people do this when upgrading or repairing gear. You might notice small sound changes, but your project will still work well." } }, { "@type": "Question", "name": "How do I spot a fake film capacitor?", "acceptedAnswer": { "@type": "Answer", "text": "Look for clear markings and check the brand logo. Buy from trusted stores. If the price seems too low, it could be fake. Many users share photos online to help you compare real and fake parts." } }, { "@type": "Question", "name": "Are SMD film capacitors reliable for audio projects?", "acceptedAnswer": { "@type": "Answer", "text": "Most users avoid SMD film capacitors in audio signal paths. Standard polypropylene SMD types can melt during soldering, limiting material choices, and through-hole polypropylene or polystyrene parts typically deliver better distortion performance and longevity. Stick with trusted through-hole brands for critical audio applications." } }, { "@type": "Question", "name": "Do boutique film capacitors really improve sound quality?", "acceptedAnswer": { "@type": "Answer", "text": "Some people hear a difference with boutique brands. You might notice more detail or a richer tone. Others say standard polypropylene types sound just as good. Try both if you want to see what works best for your ears." } }, { "@type": "Question", "name": "Which film capacitor types are best for EV and renewable energy applications?", "acceptedAnswer": { "@type": "Answer", "text": "High-voltage polypropylene film capacitors in the 400–800 V range are the standard for EV traction inverters and solar converters. Automotive demand alone accounts for over 30% of the film capacitor market as of 2025, with each EV inverter typically requiring multiple film capacitor banks to handle ripple currents up to 600 A." } } ] } ]}

Ⅰ Introduction A Bluetooth transmitter is a device that sends data between two Bluetooth devices. A Bluetooth transmitter operates by decoding the source file into a format that is then transferred via radio waves to the Bluetooth device. Bluetooth transmitters may now connect to a broad variety of devices, including headphones and speakers. this video shows some basic information about bluetooth transmitter Bluetooth is not supported by all gadgets. A Bluetooth transmitter would be required to make one compatible. This is a gadget that allows televisions and home theater systems to broadcast high-definition audio to headphones and speakers. In other words, a transmitter sends out a Bluetooth signal that may be controlled by a compatible device, such as a smartphone or tablet. It operates by connecting to a device's digital or analog output and transmitting a signal to specific Bluetooth devices. It's fantastic for listening to your favorite movies or TV shows without bothering those around you. Because you can wirelessly connect your headphones to the television, you can roam around your house while still watching the show. CatalogⅠ IntroductionⅡ Types of Bluetooth Transmitters2.1 Wired Bluetooth Transmitters2.2 Wireless Bluetooth TransmittersⅢ Bluetooth Transmitter VS Bluetooth Receiver3.1 The Range of a Receiver and Transmitter3.2 Do Receivers and Transmitters Distort Sound Quality?3.3 Do Receivers and Transmitters Interfere With Other Devices?3.4 Which Is Better: Bluetooth Receiver or Transmitter?Ⅳ Consider These Factors When Purchasing a Bluetooth Transmitter4.1 Dual Function Technology4.2 Battery Life4.3 Controls4.4 Sound Output4.5 Device Pairing Capabilities4.6 Transmission Range4.7 Ease of ConnectionⅤ Applications and Usages of Bluetooth Transmitter5.1 Bluetooth Transmitter for Car5.2 Bluetooth Transmitter for TV5.3 Bluetooth Transmitter for PCⅥ Frequently Asked Questions About Bluetooth Transmitter Ⅱ Types of Bluetooth Transmitters2.1 Wired Bluetooth TransmittersThis sort of transmitter, as the name implies, employs a wire to connect two devices. While they are simple to connect, having a device-compatible adaptor is required. Wired Bluetooth transmitters are likewise less popular than wireless Bluetooth transmitters. 2.2 Wireless Bluetooth TransmittersWireless Bluetooth transmitters, on the other hand, are more advanced. Some variants include antennae for wireless data transmission. Others are pocket-sized, which means they are more convenient. They can connect to devices without the use of adapters, making them many people's first pick. Ⅲ Bluetooth Transmitter VS Bluetooth ReceiverA receiver receives a Bluetooth signal and uses it to stream audio from an existing non-compliant Bluetooth device. A Bluetooth receiver can be connected to your preferred analog or digital audio system, allowing you to stream music and podcasts from your phone to the speaker. this video shows the difference of bluetooth transmitter and receiver This can turn any audio system wireless, transforming it into a Bluetooth-controllable device. This means that you can obtain the high-quality sound you want from digital or analog systems while still reaping the benefits of wireless communication. 3.1 The Range of a Receiver and TransmitterThe early Bluetooth devices could only send signals within a 10-meter (32-foot) range. When you consider that walls and obstructions can reduce this signal, it suggests you didn't have a lot of movement. However, as newer versions of Bluetooth were released, it became easier to carry audio signals across longer distances. Most wireless receivers and transmitters currently have a range of 30 meters, or around 100 feet. This allows you to listen to music or watch TV from a room or two down the corridor. 3.2 Do Receivers and Transmitters Distort Sound Quality?Since its inception in the late 1990s, Bluetooth has come a long way. Audio data can now stream further and quicker than ever before thanks to the most recent update. However, when employing receivers or transmitters, the sound characteristics can alter as a result of the use of a secondary source. One of the most common problems with Bluetooth receivers is that the music is delayed from its source. While this isn't generally evident when listening to music, it can be annoying when watching a movie or television show. This is due to the fact that the characters' lips frequently appear to be out of sync with their conversation. It is critical to purchase a receiver or transmitter that employs low latency technology, as this reduces the length of time it takes for the signal to reach the device. Standard Bluetooth audio takes 170-270 ms, therefore you'll want a device that just takes 30-40 ms to avoid synchronization troubles. Furthermore, as compared to corded headphones, Bluetooth headphones can have inferior sound quality. Consider using a Bluetooth amplifier to maintain wired quality while also delivering the convenience of Bluetooth. With LDAC audio coding technology, this can convert any wired headset into a Bluetooth compatible device while also improving the original audio quality. 3.3 Do Receivers and Transmitters Interfere With Other Devices?Some Bluetooth receivers and transmitters may lose signal or cross signals with other Bluetooth devices in the proximity. Wi-Fi can potentially interfere with the strength of your Bluetooth signal. If you're looking for one of these devices, make sure it has a high interference tolerance. This is often accomplished with a chip set that supports 24-bit audio and employs aptX HD, as this provides a considerably more steady signal, particularly in places with a lot of interference. 3.4 Which Is Better: Bluetooth Receiver or Transmitter?It's less a matter of which is better in general and more about which works best for you. Both of these goods offer incredible features that will be extremely useful in your daily routines. If you have an antique stereo system that you adore for its design or sound quality, a Bluetooth receiver is the way to go. This is one of the finest ways to make any wired stereo Bluetooth compatible, so you can listen to music from Spotify or Apple Music on a stereo that ordinarily only accepts tapes or LPs. If you wish to stream sound from a device that isn't Bluetooth compatible, such as your television, you'll need to get a Bluetooth transmitter. This is ideal if you recently purchased a high-end wireless speaker system but require a way to stream sound from your television. It's also ideal if you prefer listening to music using headphones. Receivers and transmitters are essential tools for Bluetooth technology, and much more so for audiophiles who appreciate high-quality sound. While there are some parallels between the two, the fundamental difference is that a receiver receives Bluetooth signals while a transmitter sends them out. Receivers are ideal for streaming music to your favorite wired audio system, while transmitters are ideal for transferring Bluetooth sound from a television to wireless audio devices. You might also purchase an amplifier to enhance the audio quality of corded headphones. Regardless of which product you choose, you will have an unrivaled enjoyment of your favorite media. Ⅳ Consider These Factors When Purchasing a Bluetooth TransmitterThere are numerous Bluetooth transmitters available on the market. Here are the precise factors to consider when purchasing a Bluetooth transmitter to assist you choose the ones that best suit your needs. 4.1 Dual Function TechnologyWhen purchasing a Bluetooth transmitter, the first thing to consider is its functioning. Many Bluetooth transmitters can also function as Bluetooth receivers (we'll go through transmitters and receivers in more detail later). While all Bluetooth transmitters can send music to your headphones or speakers, some may also receive audio from your device and send it to your headphones or speakers. 4.2 Battery LifeThis section only relates to Bluetooth transmitters that are cordless or portable. Lengthy battery life means you'll be able to use the transmitters on long excursions or for days without needing to charge them constantly. This also means that the transmitter will most likely be available whenever you need it. A Bluetooth transmitter with a long battery life can last for at least 8 hours. Anything less than that may not be ideal, especially if the transmitter must be used outside. 4.3 ControlsBluetooth transmitters are simple devices, although the controls differ greatly between types. Some transmitters have only one universal button and light, whilst others have several buttons and lights. Contrary to popular assumption, those with several buttons and lights are less difficult to use because they do not confuse you. 4.4 Sound OutputAlthough Bluetooth transmitters can transport information, they are most typically used to link audio devices such as headphones and speakers. Given this, it's critical that you listen to the transmitter's audio output. Unfortunately, some Bluetooth transmitters limit sound volume or quality. To test the sound output of a transmitter, the volume control (if present) must first be adjusted to maximum. You can then compare its sound to that of your headphone set or speaker when connected by wire or another Bluetooth transmitter. 4.5 Device Pairing CapabilitiesSome Bluetooth transmitters can only send data to one device at a time. Others, on the other hand, can connect to numerous devices at the same time (for example, your headphones and your roommates'). Bluetooth transmitters that can connect to numerous devices are clearly superior than those that can only connect to one device. They can help you save money because you won't have to buy a Bluetooth transmitter for every non-Bluetooth gadget you own. 4.6 Transmission RangeThe transmission range is the maximum distance a Bluetooth transmitter can work if there are no objects interfering with the signal. Bluetooth transmitters are categorized based on their broadcast range. Class 1 has a range of roughly 100 meters, whereas Class 2 has a range of up to 10 meters. Class 2 is the most prevalent class on the market, and it is adequate for residential use. However, if you want a longer transmission range, investing a few dollars more with a Class 1 transmission is worthwhile. 4.7 Ease of ConnectionTrying out a Bluetooth transmitter, or any device for that matter, is essential before purchasing. Of course, you must first link it with the devices you use the most regularly. Some Bluetooth transmitters, according to my experience, instantaneously couple with devices, while others do not (even after repeated attempts). Although Bluetooth pairing can be difficult at times, you need a Bluetooth transmitter that can couple with your devices consistently and smoothly. Ⅴ Applications and Usages of Bluetooth Transmitter5.1 Bluetooth Transmitter for CarIf you wish to utilize a Bluetooth transmitter to connect your car's music system to your smartphone, follow these instructions. 1)As with TVs, you must first locate a Bluetooth FM transmitter compatible with your car's audio system.2)Connect the Bluetooth transmitter to your vehicle to activate it.3)Enable Bluetooth on your smartphone and pair it with the transmitter.4)You must next adjust your car's radio to an empty FM frequency. This is necessary since a radio station's channel may interfere with your phone calls.5)On the Bluetooth transmitter, select the same empty channel. That's all. You can now listen to music or make phone calls using your car's audio system. 5.2 Bluetooth Transmitter for TVIf you wish to utilize a Bluetooth transmitter to link your TV to your wireless headphones or speaker, follow these steps. 1)You may wish to begin by purchasing a Bluetooth transmitter that is compatible with your television.2)To switch on the Bluetooth transmitter, connect it to a power supply. If it has its own battery, all you have to do is switch it on.3)After turning on the transmitter, connect it to the audio output of your television.4)After that, you must pair your Bluetooth-enabled device with the transmitter. It's best if you can get close to the transmitter while doing this to ensure a smooth connection.5)There you have it. Once associated, you can use your Bluetooth device to listen to your TV. 5.3 Bluetooth Transmitter for PCIf you wish to utilize a Bluetooth transmitter to link your PC to your smartphone, speakers, or headphones, follow these steps. Bluetooth is built into the majority of PCs. It is the older ones who aren't. First, ensure that your PC does not have Bluetooth. 1)As with the previous gadgets, you must first locate a Bluetooth transmitter that is compatible with your computer. 2)Connect your Bluetooth transmitter to your PC.3)Install the transmitter after connecting it to your PC. Typically, an installer will appear on your screen. When the installer appears, run it. 4)Connect your Bluetooth device to the Bluetooth transmitter.5)There you have it. After you've associated your Bluetooth headphones or speakers, you're ready to transfer files to or from your PC, watch videos, or listen to music. Ⅵ Frequently Asked Questions About Bluetooth Transmitter1. How Does a Bluetooth Transmitter Work?They convert wired audio signals to wireless audio signals, which they then "transmit" to your Bluetooth headphones or speakers. To put it another way, they "add" Bluetooth audio capability to non-Bluetooth devices. 2.Can a Bluetooth transmitter connect to a Bluetooth receiver?Simply connect your Bluetooth-enabled phone, PC, or tablet to the receiver, the transmitter unit to Bluetooth headphones or speakers, and the 3.5mm cable to both the transmitter and receiver. This extends the reach of your music across your home. 3.How do I reset my Bluetooth transmitter?Transmitter/Receiver Device Reset:1)Ensure that the device is turned off.2)Switch the TX/RX switch to the opposite position.3)Power on the device.4)When the device begins to flash red and blue, switch it off.5)Return the switch to its original TX or RX position. 4.Why is my Bluetooth transmitter not connecting?Previous linked devices can be remembered by the Bluetooth transmitter. If the transmitter is unable to couple with your Bluetooth device, delete the pairing history by pushing the Power Button twice while the transmitter is turned on until the LED indicator alternately flashes red and blue. The transmitter should then be restarted to couple again. 5.Do I need a transmitter for wireless headphones?If you have Bluetooth headphones, all you truly need is a Bluetooth transmitter. Transmitters can be purchased for as little as $15 online or at your local electronics store. Essentially, it converts the 3.5mm or RCA output from your television into a Bluetooth signal. 

 CatalogIntroductionRelated VideoStructureOperation of USB HubTypes of USB HubWhen Do You Need a USB Hub?Pros and ConsFAQIntroductionA USB hub is a convenient way to add more USB ports to a device. When using USB hubs, all devices must share bandwidth and power supply from the computer's USB port. No matter how many devices are connected, the bandwidth and power from the computer's port remain constant. However, the USB hub has its limitations.  For example, connecting devices that consume too much power can increase their instability, requiring users to read the instructions before using them properly.  When users want to connect to common electronics such as phones, mice and keyboards to power them, the USB hub can meet these basic needs.   Related VideoVideo: What is the difference between a USB hub and a USB charging station?Video Description:In this video, I explain the difference between a USB hub and a USB charging station, and let you know which one you should choose for your needs, depending on whether you are looking to simply charge your USB devices, or also connect them to your PC, Mac, iPhone or iPad. StructureA USB interface can be split into multiple working USB interfaces.It uses a USB HUB controller from the second generation.It is simple to use and can be directly connected to the computer without the need for an external power supply.It is installed as soon as the computer recognizes it, and no driver is required. You can freely plug and play it.It supports USB2.0 at speeds of up to 480Mbps and is backwards compatible with USB1.1.It also includes a current protection device.It is compatible with Windows 95/98/Me/2000/XP, Linux 2.4, and Mac OS 8.5 or later. Operation of USB HubA USB hub has one 'upstream port,' which connects to the host, and several 'downstream ports,' which connect to other hubs or peripheral devices / connections. Most systems operate with hubs that are transparent and do not appear on any system visible mapping. Data received from the upstream port, i.e. the host, is broadcast to all devices connected to the downstream ports, whereas data received from the downstream port is routed only to the upstream port and the host. With the introduction of USB 3, a Point to Point routing capability was introduced, in which a routing string sent in the data packet header allows the host to direct the data to a single destination port. This reduces the amount of data on the USB'network' while also lowering power consumption. Another advantage of using a USB hub is that it can provide a system length increase. For low-speed USB 1.1 devices, for example, USB cables are limited to 3 metres. A hub can be used as an active USB repeater to increase cable length by up to 5 meters at a time. Types of USB HubPowered USB Hub & Unpowered USB HubPowered USB HubPowered or active USB hubs use an external power source to raise the energy level of each hub port to that of an on-system port. Active USB hubs are typically powered by a wall outlet. While active USB hubs are not required to distribute power to all connected devices, the hub does distribute data bandwidth to all connected devices. In brief, the USB ports on your computer generate a small amount of power. When you "split" a port (by plugging in a hub), the power is also split among the additional ports. And, depending on the devices you plug into the hub, there may not be enough power for everything.That is why choosing a powered hub with its own AC adapter is critical. You can fill every port with power-hungry devices without fear of limited amps causing operational problems. Unpowered USB HubUnpowered USB hubs lack an external power source and rely solely on the computer's USB port for power. Unpowered hubs have compatibility issues with devices that require more power than the hub can supply. A USB flash drive, for example, may work perfectly fine when connected to the computer's USB port or an active hub, but it may not power on when connected to a passive hub. The USB 3.0 standard improves on previous versions' power management capabilities and may be able to use higher power devices that hubs running older standards cannot. When Do You Need a USB Hub?Now you might think about some essential factors when you want to purchase a USB hub. Check the connection options first. Users can choose to connect four or five ports.   The second step is to check the cable connection to the main device to determine if the appropriate hub has been purchased.   Third, you should buy a USB device with the latest connection protocol, because older devices have slow transfers or are incompatible.  Finally, you should purchase USB devices that are suitable for the user's daily use situation, including size, portability, etc.   Pros and ConsPowered USB HubPros:Make their own powerCan provide power to high-voltage devicesCan power multiple devices at the same time Cons:Unpowered USB hubs are typically more expensive.Need access to a power outlet. Unpowered USB HubPros:Small and portableless expensive than powered USB hubsThere is no need to look for a power outlet. Cons:High-voltage devices cannot be powered without causing performance issues.Struggle to power multiple devices at the same time. FAQ1.What is a USB hub used for?A USB hub functions as an extension cord for USB devices. It connects to your computer and allows you to connect more devices than your current USB ports allow. Some USB hubs are powered, while others are not. 2.Is it OK to use USB hub?USB hubs are the ideal companion for anyone who has a large number of power-hungry USB devices. A USB hub can meet the needs of any device that requires USB power, from phones to tablets to desk gadgets. It's also convenient because you don't have to look for a spare power plug; simply plug everything into the same hub. 3.Can you plug a USB hub into a wall charger?Yes. You can charge your iPad/iPhone by connecting it to a wall charger with a USB connector, just like any other Apple wall charger. It will work with any other device as long as the power source to which the hub is connected can charge your devices. 4.Can I charge my phone through A USB hub?While non-powered hubs must be plugged into a host system to charge your devices, powered hubs can charge your devices even when those systems are not available. Because they come with their own AC adapter, these USB hubs require access to an electrical outlet or power strip. 5.Can I use USB hub for power?When using power adapters for USB peripherals, the USB ports on the hub are only used for data transfer and do not draw power from the hub. Low-power USB peripherals (such as keyboards and mice) can be used on hubs without a power adapter in conjunction with other low-power USB peripherals. 6.What is the purpose of USB hub?This port hub is remarkably small, but its specs are impressive:1.Connects to your computer via USB 3.02.4 USB 3.0 ports (backwards compatible with USB 2.0 and USB 1.1)3.Data transfer rate up to 5 Gbps4.Supports hot swapping 7.What is 4 port USB hub?The USB splitter expands one usb port to 4 Ports USB3.0 , connects your PC or Laptop with hard drives,USB headphone, speakers, memory cards, mouse, keyboards, USB flash drives, printers ,etc. 8.How to identify USB ports on your computer?Quick Navigation :Method 1. Check Port's Color and LogoMethod 2. Check the USB ControllerMethod 3. Check Pins' NumberUser Comments 9.How to create a programmatically switchable USB hub?1.USB device manufacturing2.USB device validation and development3.Plug/unplug cycle testing4.Functional testing5.Battery charging6.USB device resets7.USB power monitoring8.Controlling USB device enumeration sequence 10.Where is the USB hub port?USB hubs are small devices with a few USB ports that connect to your computer or a power source via a single port. USB hubs expand your capacity for connected USB devices in the same way that a power strip allows multiple appliances to plug in for electricity. 

Ⅰ IntroductionThe usage of modular electrical connectors has contributed to the global growth of communication and data services. The RJ45 connector is one of the most extensively used varieties in the modular family of devices. AT&T created the modular connector system in the 1960s and 1970s to replace large phone connectors  and their labor-intensive installation. This novel connector system provided a simple, quick, and convenient setup  that could be adjusted on-site by a specialist or installed at home by the user. Over the years, the line has evolved to include data communication stalwarts like as the RJ45, which was designed for computer networking. In fact, RJ45 connectors are often known as Ethernet connectors. CatalogⅠ IntroductionⅡ What is an RJ45 Connector?Ⅲ Types of RJ45 ConnectorsⅣ Applications of RJ45 Connectors Ⅴ Cat5 VS Cat6 CablingⅥ Wiring Pinouts of RJ45 ConnectorsⅦ RJ45 VS EthernetⅧ Things to Consider When Choosing an RJ45 ConnectorⅨ Frequently Asked Questions About RJ45 Connectors Ⅱ What is an RJ45 Connector?RJ45, modular plug, 8P8C, end, connection... they are all interchangeable words. All of these terms refer to the portion attached to the end of an Ethernet cable that plugs into your TV, computer, router, and so on. An RJ45 connector is a ubiquitous modular connecting device that, when paired with a cable, provides data communication service to a variety of electronic devices and systems. The FCC classified the numerous connectors produced using this technique into the Registered Jack (RJ) system in 1976, giving rise  to the RJ label. This was done to verify that phone company hardware and consumer equipment were compatible. The RJ system specifies the physical connector, wiring layouts, and signal characteristics. Metal contacts are separated by insulating plastic channels in RJ45 devices, as in all modular connectors. The channels slide into a matching socket, and the connections lock in place with a tab, making them both secure and detachable. RJ45 devices have 8 pins and 8 wire locations used to handle signals or power, allowing them to accept 4 twisted wire pairs. This RJ45 connector's 8-pin layout is identical to that of 8P8C connections, however true RJ45 connectors also feature a tab that only allows the device to be inserted in one orientation with a corresponding socket to avoid an incorrect wiring connection. As a result, an RJ45 connector is one type of 8P8C connector. However, most 8P8C connectors are commonly referred to as RJ45, which is not entirely correct. 8P8C connectors can be plugged into RJ45 sockets, but not the other way around. Ⅲ Types of RJ45 Connectorsthis video shows 3 types of RJ45 connectors Depending on the application, different types of RJ45 connections are available. These are some examples:1)Standard - 8 position, 8 connector, unshielded.2)Ruggedized - consists of several external elements that protect the gadget from hard situations. Also known as Hi-Rel, which stands for high-reliability.3)Shielded-internally shielded connections with a link to shielded cables. RJ48 is another name for RJ45.4)Miniaturized - RJ45 with a smaller footprint than conventional RJ45.5)10 Pin RJ45 - A 10 pin connector that is utilized when all serial lines are required, such as with a T1 line. Ⅳ Applications of RJ45 Connectors RJ45 connectors are primarily used to connect an internet-enabled device (such as a PC) to another network device such as a server, router, modem, smart TV.  gaming console, and other Ethernet  -enabled devices. Ethernet networks are widely used in both professional and home settings. Hardwiring with RJ45 devices offers faster data transfer while maintaining stability and security, making them appealing for usage in industry and on the factory floor. Ruggedized RJ45 technology is also being used more frequently in data transmission applications that expose system components to moisture, dust, vibration, chemicals, or mechanical stress. Various connector features, such as boots and strain reliefs, enable for the performance required to survive in these situations. When designing Ethernet capabilities into a system, the usual solution for connectivity in networks, peripherals, and telecommunications is to use RJ45 connectors with Cat5 or Cat6 cabling. The expansion of features and capabilities to the RJ45 product range, such as greater speed and ruggedness, has also made this connector method useful for usage outside than office or home networking. The advent of the EtherCAT protocol has resulted in increased use on the production floor and elsewhere. Some of the more recent applications that make use of RJ45 technology are:1)Automation in the Factory 2)Industrial Robotics (manufacturing and assembly) 3)Industrial Process Control4)Quality Assurance Systems5)Network Devices for the Internet of Things(IOT)6)Testing and Measuring Systems7)Systems and Devices for Voice Over Internet Protocol(VOIP) Ⅴ Cat5 VS Cat6 CablingThere are several variants of Ethernet and EtherCAT wiring available. Both Cat5 and Cat6 cables are used to connect computers in a network, but their performance is vastly different. Cat5 cable is constructed of four twisted pairs of wire and, while formerly commonly used, is becoming obsolete owing to the Cat5e cable. Cat5e, which is likewise constructed of four twisted pairs of wire, is up to ten times quicker than Cat5 and has improved resilience to crosstalk or interference due to design improvements. Cat6 is likewise composed of four twisted pairs, but it is quicker than Cat5e, has more bandwidth capacity and functionality, eliminates crosstalk or interference by shielding, and is backwards compatible with Cat5 and Cat5e. Cat6 cable is commonly used in network setups capable of reaching Gigabit speeds. The newer Cat6a cable has thicker plastic housing to decrease crosstalk even further and can be utilized for longer cable runs (up to 328 feet). Cat7 cable gradually increases bandwidth. Cable TypeMaximum BandwidthMaximum SpeedCat 5100 MHz100 MbpsCat 5e100 MHz1,000 MbpsCat 6250 MHz1,000 MbpsCat 6a500 MHz10,000 MbpsCat 7600 MHz10,000 MbpsCat 7a1,000 MHz10,000 Mbps Remember that each of these cable designs uses four twisted pairs, or eight wires, necessitating the use of RJ45 connectors with eight pins to link all of those wires. The identical RJ45 connectors are used by all Cat5, Cat5e, Cat6, Cat6a, Cat7, and Cat7a cables. Ⅵ Wiring Pinouts of RJ45 ConnectorsThe T568A and T568B standards outline the layout of the individual eight wires required for adding connectors to a cable. Both adhere to a standard of covering individual wires in one of five colors (brown, green, orange, blue, or white) with various stripe and solid combinations. When building your own wires, it is critical to adhere to either the T568A or T568B conventions to ensure electrical compatibility with other devices. If you don't make your own cables, you merely need to ensure that the standard is compatible with your equipment. T568B is the more common standard due to historical reasons, however T568A is used in some residences. The color coding of the wires in the connectors is summarized in the table below. PinT568AT568B1white with green stripewhite with orange stripe2greenorange3white with orange stripewhite with green stripe4blueblue5white with blue stripewhite with blue stripe6orangegreen7white with brown stripewhite with brown stripe8brownbrown Several different types of connections are similar to RJ45 and can be readily confused with one another. RJ11 connectors, for example, are slightly narrower than RJ45 connectors because they use six-position connectors rather than eight-position connectors. Aside from that, they appear to be identical. Ⅶ RJ45 VS EthernetEthernet is basically a method of linking computers and other devices that are located in the same physical space. It allows data to be transmitted via a Local Area Network (LAN) or a Wide Area Network(WAN) and links them through cable, letting them to communicate with one another. The Ethernet standard (IEEE 802.3) was developed in the 1980s by the Institute of Electrical and Electronic Engineers(IEEE) and is now the most widely used LAN technology globally. It specifies the criteria for constructing an Ethernet network (connections), the number of conductors needed for a connection, the expected performance, and a data transmission framework. Ethernet technology's widespread appeal can be attributed to the balance it provides between ease of installation, speed, cost, and extensive network protocol support. RJ45 connectors are the most common devices used in network configuration. Ⅷ Things to Consider When Choosing an RJ45 ConnectorThere are a plethora of RJ45 Connectors available on the market. Here are the precise elements to consider when purchasing an RJ45 Connector to assist you choose the ones that best suit your needs.1)Will shielded connectors be required for the system?2)How long will the cables have to be?3)Will the product or system be subjected to high EMI or ESD levels?4)Will we be using integrated magnetics or board-mounted modules?5)Do we need robust or high-reliability devices?6)Which pinout protocol is most suited to the design?7)Will the device or system support Power over Ethernet (PoE)?8)How much bandwidth is required?9)How fast must data be transferred? Ⅸ Frequently Asked Questions About RJ45 Connectors1.What is the difference between RJ11 and RJ45 connectors?RJ45 connectors are typically used to connect to Cat5 and Cat6 cables, whereas RJ11 connects to a telephone cable. RJ45 connectors can connect to a variety of devices in a copper cable network, including switches, cables, computers, routers, and so on. Switches with RJ11 connectors typically include two sockets for a two-line phone system. 2.Is RJ45 same as CAT6?RJ45 is a connector, and CAT6 is a cable, both of which are used in Ethernet networks. RJ45 has eight pins, four of which are visible colors while the other four are striped, four of which are exclusively used for Ethernet. CAT6 has six pins of various colors that link Ethernet networking. 3.How do I identify my RJ45 connector?Examine an RJ45 connector on a cable while holding the flat underside toward you. Pin 1 is on the left. In TIA-568B configuration, the straight through configuration is what you're likely to see for Ethernet use: Striped orange. 4.How do I choose a RJ45 connector?When purchasing cable and connectors from several sources, aim towards the center! For example, if your Ethernet cable has a stated insulated conductor diameter of 1.00mm, choose an RJ45 plug with a 0.95 to 1.05mm insulated conductor range. 5.What are the three types of commonly used RJ45 cabling?Coaxial, twisted pair, and fiber-optic cabling are the three most popular cable types used for Ethernet cabling. 6.Can I use an RJ45 for phone?If you have a two-line phone, you can connect it to a T568A wired jack and both lines will function. The smaller RJ11/12 connectors can be inserted straight into an RJ45 jack. It's not ideal because you risk damaging the other pins, but it's designed to function that way. 7.Can I connect RJ11 to RJ45?Caution: Do not connect an RJ11 plug to an RJ45 socket.RJ11 plugs have the potential to irreversibly damage your RJ45 socket. RJ45 connections are commonly used in data cabling systems. An RJ11 to RJ45 converter is the proper technique to use an RJ11 connector in a data cabling system. 8.Which is better RJ45 or Cat6?Cat5e RJ45 cable offers a lower degree of transmission performance, but Cat6 RJ45 cable has a 250MHz bandwidth, better data throughput, and greater resistance to crosstalk and noise. 9.How does a RJ45 connector work?RJ45 plugs have eight pins that electrically link with the wire strands of a cable. Individual wires are placed into each plug's eight positions, which are spaced roughly 1 mm apart, using special cable crimping equipment. This type of connector is known in the industry as an 8P8C connector, which stands for eight position, eight contact. 10.What is another name for an RJ45 connector?RJ45 is a cable termination specification that specifies physical male and female connectors as well as the pin assignments of wires in telephone lines and other networks that employ RJ45 connections. RJ45 connections are also referred to as data jacks. 11.What is one aspect of the proliferation of communication and data services?Modular electrical connectors. 12.What connector is one of the most widely used varieties in the modular family of devices?RJ45. 13.What was the RJ45 designed for?Computer networking. 14.What are RJ45 connectors often known as?Ethernet connectors. 15.What is an RJ45 connector paired with?A cable. 16.What was the purpose of the RJ label?Verify that phone company hardware and customer equipment worked together. 17.How many pins do RJ45 devices have on the inside to handle signals and power?Eight pins and eight wire locations. 18.What does RJ45 connectors have that only allows the device to be inserted in one orientation with a corresponding socket?Tab. 19.What are most 8P8C connectors referred to as in general usage?RJ45. 20.What can be plugged into RJ45 sockets?8P8C connectors. 

Catalog Introduction Design Flow of Chip Design Specification Development Design Details of the Chip Draw a Blueprint for the Plane About Wafer What Is a Wafer How to Make Single Crystal Wafer Metallurgical Purification Pulling the Crystal Design Flow of Chip Manufacture What Is an IC Chip Metal Sputtering Coating Photoresistance Etching Technology Photoresist Removal Nano-Process What Is the Nano-Process How Tiny Is the Nanometer Purpose of Reducing the Process Physical Limitations of Downsizing About Encapsulation Two Common Packages DIP Package BGA Package Two Ways to Reduce Size SoC SiP Introduction A chip is a silicon chip that contains an integrated circuit, so the chip is also called an integrated circuit. It may be only 2.5 centimeters in square size, but it contains tens of millions of transistors. Simpler processors, on the other hand, may have thousands of transistors engraved on chips which are a few millimeters in size. Chip is the most important part of electronic equipment, which undertakes the function of operation and storage. Design Flow of Chip The birth of a chip can be divided into two parts: design and manufacture. First, let's take a look at the complex and tedious chip design process. Fig 1. The process of making a chip is like building a house with Lego. First, the wafer is used as the foundation and the necessary IC chips can be produced after layers are stacked on top of each other. However, there is no use in having no amount of manufacturing capacity without a design drawing. Therefore, the role of an architect is very important. But who is the architect in IC's design? The next step is to introduce the IC design. In the IC production process, IC is mostly planned and designed by professional IC design companies, such as MediaTek, Qualcomm, Intel and other well-known large factories, all of which design their own IC chips to provide different specifications and efficiency chips for downstream manufacturers to choose from. Because IC is designed by the factories themselves, so IC design depends very much on the technology of engineers and the quality of engineers affects the value of an enterprise. But what are the steps engineers take to design an IC chip? The design process can be simply divided into the following steps. Design Specification Development In IC design, the most important step is specification development. This step is like deciding how many rooms, bathrooms, what building codes to comply with, and designing after all the features have been identified so that no additional time is spent on subsequent modifications. The IC design needs to go through similar steps to ensure that the chip is designed without any errors. The first step in specification development is to determine the purpose and effectiveness of IC and to set the general direction. The next step is to see what protocols to comply with, such as the wireless card chip needs to comply with IEEE 802.11 and other specifications. Otherwise, the chip will not be compatible with the products on the market, so that it will not be able to connect to other devices. Finally, the implementation method of this IC is established, different functions are allocated into different units, and the method of connecting different units is established, so that the specification can be completed. Design Details of the Chip After designing the specifications, it is followed by the details of the design chip. This step is like making a preliminary note of the planning of the building and depicting the overall outline for subsequent drawing. In IC chip, the hardware description language (HDL) is used to describe the circuit. The commonly used HDLs are Verilog, VHDL, and so on, which can easily express the function of a IC by code. This is followed by checking the correctness of the program's functionality and continuously modifying it until it meets the desired functionality. Fig 2. Verilog Example of 32 Bits Adder Draw a Blueprint for the Plane With a complete plan, the next step is to draw a blueprint for the plane. In IC design, the step of logic synthesis is to put the unmistakable HDL code into the electronic design automation tool (EDA tool), to let the computer convert HDL code into logic circuit, resulting in the following circuit diagram. After that, it is repeatedly determined whether the logic gate design conforms to the specification and is modified until the function is correct. Fig 3. The Result of the Synthesis of the Control Unit Finally, the synthesized code is put into another set of EDA tool for circuit layout and winding (Place And Route). After continuous detection, the following circuit diagram will be formed. You can see blue, red, green, yellow and other different colors, each of which represents a mask. As for the use of the mask, how should it be used? Fig 4. The Commonly Used Calculus Chip-FFT Chip, Which Completes the Circuit Layout and the Winding Result ——The chip is stacked by layers of masks. First of all, it is now known that an IC will produce multiple masks. These masks have the difference between the upper and lower layers and each layer has its own task. The following figure is a simple mask example. Taking the most basic element CMOS in the integrated circuit as an example, the full name of CMOS is complementary metal oxide semiconductor. That is, the combination of NMOS and PMOS to form CMOS. As for what is a metal oxide semiconductor (MOS)? This kind of component which is widely used in the chip is more difficult to explain, and it is more difficult for the general reader to figure it out, so there is no more detailed study here. In the following figure, on the left is the circuit diagram formed after the circuit layout and winding, and you have already known that each color represents a mask. On the right is the way each mask is spread out. Production is to start from the bottom, in accordance with the method proposed in the manufacture of the IC chip, layer by layer, and finally the desired chip will be produced. Fig 5.  At this point, you should have a preliminary understanding of the IC design. The overall view is very clear that IC design is a very complex major, but also thanks to the maturity of computer-aided software, so that IC design can be accelerated. The IC design relies heavily on the wisdom of engineers, and each of the steps described here has its own expertise and can be separated into multiple professional courses. For example, writing a hardware description language does not simply require familiarity with the programming language. You also need to understand how logic circuits work, how to convert the required algorithms into programs, and how synthetic software converts programs into logic gates. What Is a Wafer? In semiconductor news, it is always mentioned in the size of the wafer, such as 8-inch or 12-inch wafer. But what is the so-called wafer? What part of it is 8 inches? What is the difficulty of producing large wafers? Here is a step-by-step introduction to the most important foundation of semiconductors-what is a "wafer". Wafer is the basis for making all kinds of computer chips. We can compare chip manufacturing to building a house with Lego blocks and building the shape we want (that is, all kinds of chips) by stacking one layer after another. However, if there is no good foundation, the built house will be tilted back and forth, contrary to our wishes. In order to make the perfect house, we need a smooth substrate. For chip manufacturing, this substrate is the wafer that will be described next. First of all, think back to when you were a child playing with Lego blocks, there would be a small round bulge on the surface of the building blocks. With this structure, we can stack the two blocks firmly together without using glue. Chip manufacturing, also in a way like this, binds subsequent atoms to the substrate. Therefore, we need to find a substrate with a neat surface in order to meet the conditions needed for subsequent manufacturing. Fig 6. In solid materials, there is a special crystal structure. That is, single crystal (Monocrystalline). It has the characteristics of atoms one after another closely arranged together, which can form a flat atomic surface. Therefore, using single crystal to make wafer can meet the above needs. However, how to produce such a material? There are two main steps, respectively, purification and crystal pulling. After this, such a material can be completed. How to Make Single Crystal Wafer? Metallurgical Purification The purification is divided into two stages. The first step is metallurgical purification. During this process, we add carbon and convert silicon oxide into silicon with a purity of more than 98% in a redox manner. Most metals, such as iron or copper, are refined in this way to obtain sufficient purity of metal. However, 98% is still not enough for chip manufacturing and still needs to be further improved. Therefore, Siemens process will be used for purification, so that the high purity polysilicon needed for semiconductor process will be obtained. Fig 7. Silicon Column Manufacturing Process Pulling the Crystal Then there is the step of pulling the crystal. First, the high purity polysilicon obtained earlier is melted to form liquid silicon. After that, the single crystal silicon seed is in contact with the liquid surface and slowly pulls up as it rotates. As for why single crystal silicon is needed, that is because silicon atoms are arranged in the same way as people queue up. They will need to arrange the head so that later people can arrange it correctly. And silicon seed is an important row head, so that the later atoms know how to queue up. Finally, after the silicon atoms leaving the liquid surface solidify, the neatly arranged single crystal silicon columns are completed. Fig 8. Single Crystal Silicon Column But what do 8 inches and 12 inches stand for? It refers to the diameter of thin wafers being treated and sliced into，which is from the surface of the part of a crystal column that looks like a pencil rod. What is the difficulty of making large wafers? As mentioned earlier, the crystal column is made as if it were making marshmallows, rotating and forming at the same time. If you have made marshmallows, you should know that it is very difficult to make large and solid marshmallows, and the same is true of the crystal pulling process. The speed of rotation and the control of temperature will affect the quality of the crystal column. As a result, the larger the size, the higher the speed and temperature requirements are, so it is more difficult to make high-quality 12-inch wafers than 8-inch wafers. However, a whole silicon column cannot be made into a chip-making substrate. In order to produce a silicon wafer, the silicon column needs to be cut transversely into a wafer with a diamond knife, and the wafer can be polished to form the silicon wafer needed for chip manufacturing. After so many steps, the fabrication of the chip substrate is complete, and the next step is to stack the house, that is, chip manufacturing. So, how to make a chip? Manufacture ——Stacked chips After introducing what silicon wafers are, you also know that making IC chips is like building a house with Lego blocks, creating the shape you want by stacking layer after layer. However, there are quite a few steps to build a house, and so is IC manufacturing. What are the steps to make IC? Next, the process of IC chip manufacturing will be introduced. What Is an IC Chip? Before we begin, we need to know what an IC chip is. IC, which means integrated circuit (Integrated Circuit), is the design of the circuit that is in the form of stacking together. In this way, we can reduce the area required to connect the circuit. The following figure is a 3D diagram of the IC circuit, from which you can see that its structure is like the beams and columns of a house. It is done layer by layer and this is the reason why IC manufacturing is compared to building a house. Fig 9. 3D Profile of IC Chip From the 3D profile of the IC chip in the image above, the dark blue part at the bottom is the wafer introduced in the previous step. From this picture, we can see more clearly how important the wafer substrate plays in the chip. As for the red and khaki parts, they are the places to be completed when IC is made. First of all, the red part can be compared to the hall on the first floor of the building. The hall on the first floor is the door of a house because everyone and everything come in and out of here. It has more functionality under the control of traffic. Therefore, compared with other floors, the construction will be more complex and requires more steps. In IC circuit, this hall is the logic gate layer; it is the most important part of the whole IC by combining a variety of logic gates together and completes the fully functional IC chip. The yellow part is like a normal floor. Compared with the first floor, there will not be much complex structure, and each floor will not change much when it is built. The purpose of this layer is to connect the logic gates of the red part. The reason why so many layers are needed is that there are so many lines to be connected that a single layer cannot hold all the lines. So it is necessary to stack a few more layers to achieve this goal. Among them, the lines of different layers will be connected up and down to meet the needs of the wiring. ——Layered construction, layer by layer architecture Once you know the construction of IC, let's show you how to make it. Imagine that if we want to make a fine drawing with a paint spray tank, we need to cut out the cover plate of the figure and cover it on paper. Then spray the paint evenly on the paper and remove the mask when the paint is dry. After repeating this step over and over again, you can complete neat and complex graphics. IC is made in a similar way, by covering up a layer of stacking. Fig 10.  When making IC, you can simply divide into the above four steps. Although the actual manufacturing steps will be different and the materials used will be different, but generally using a similar principle. This process is slightly different from painting: IC manufacturing is to paint first and then cover while painting is to cover and then paint. And the processes are described below. Metal sputtering:  Sprinkle the metal material which is to be used evenly on the wafer to form a thin film. Coating photoresistance:  First put the photoresist material on the wafer, and then hit the beam on the desired part through the mask to destroy the structure of the photoresist material. Next, use chemicals to wash away the damaged material. Etching technology:  The silicon wafer without photoresistance protection will be etched by ion beam. Photoresist removal:  Use the photoresist solution to dissolve the remaining photoresist, so that a process can be completed. Finally, a lot of IC chips will be completed on a whole wafer, and then as long as the completed square IC chips are cut off, they can be sent to the packaging factory for packaging. What is the packaging factory? We'll have to explain it later. Nano-Process What is the nano-process? Samsung and TSMC compete fiercely in advanced semiconductor processes because both of them want to take the lead in wafer contract manufacturing to win orders, which has almost become a battle between 14 nanometers and 16 nanometers. But what is the meaning of 14 nm and 16 nm, and where do they refer? What are the benefits and problems that will be brought about by the reduction of the process? Next we will give a brief description of the nano-process. How tiny is the nanometer? Before you start, you need to understand what nanometer really means. Mathematically, nanometers are 0.000000001 meters, but this is a pretty bad example. After all, we can only see a lot of zeros after the decimal point, but we don't actually feel it. If you compare it with the thickness of nail, it may be more obvious. If you actually measure it with a ruler, you can tell that the thickness of the nail is about 0.0001 meters (0.1mm), that is to say, try to cut the side of a nail into 100000 lines, each of which is about one nanometer. From this, we can slightly imagine how tiny a nanometer is. Purpose of Reducing the Process After knowing how small the nanometer is, it is necessary to understand the purpose of reducing the process. The main purpose of reducing the transistor is to insert more transistors into smaller chips so that the chip will not become larger as a result of technological advances; second, it can increase the computational efficiency of the processor; moreover, reducing the volume can also reduce the power consumption. Finally, after the chip size is reduced, it is easier to plug into the mobile device to meet the needs of thinness and lightness in the future. Come back to explore what the nano-process is and we will take 14 nm as an example. The process refers to the minimum size of 14 nm in the chip. The following figure shows the appearance of a traditional transistor, as an example. The main purpose of reducing transistor is to reduce power consumption, but which part needs to be reduced to achieve this goal? The L in the figure on the left is what we expect to shrink. By reducing the gate length, the current can be routed from the Drain side to the Source end in a shorter path (if you are interested, you can use Google to search for MOSFET, which will be explained in more detail). Fig 11. In addition, computers operate on 0 and 1. How can we use transistors to meet this purpose? The way to do this is to determine whether the transistor has current flow. When a voltage supply is made at the Gate (green square), the current will flow from the Drain to the Source, and if there is no supply voltage, the current will not flow, so that it can represent 1 and 0. (As to why 0 and 1 are used to judge, if you are interested, you can go to the Brin algebra. That is the way we use this method to make a computer.) Physical Limitations of Downsizing However, the process cannot be reduced indefinitely. When we narrow the transistor to about 20 nanometers, we will encounter problems in quantum physics, so that the transistor has a leakage phenomenon, offsetting the benefits of L. As a way to improve, the concept of FinFET (Tri-Gate) was imported, as shown in the figure above. The leakage caused by physical phenomena can be reduced by importing this technology. Fig 12. More importantly, this method can increase the contact area between the Gate end and the lower layer. In traditional practice (top left), the contact surface has only one plane, but with FinFET (Tri-Gate), the contact surface will become three-dimensional, and the contact area can be easily increased. This allows the Source-Drain side to be smaller while maintaining the same contact area, which is of considerable help in reducing the size. Finally, why would anyone say that it would be a pretty serious challenge for factories to enter the 10-nanometer process? It is mainly because the size of an atom is about 0.1 nanometers, and in the case of 10 nanometers, there are fewer than 100 atoms in a line. It is very difficult to make, and as long as there is an atomic defect, such as atoms falling out or impurities in the production process, there will be unknown phenomena, affecting the yield of the product. If you can't imagine the difficulty, you can do a small experiment. Line up a 10 × 10 square with 100 small beads on the table, cut a piece of paper to cover the beads, then brush off the beads next to it with a small brush, and finally make it form a 10 × 5 rectangle. In this way, we can know the difficulties faced by the major factories and how difficult it is to achieve this goal. Encapsulation After a long process, from design to manufacture, finally we got an IC chip. However, a chip is so small and thin that it can be easily scratched and damaged if it is not protected from the outside. In addition, because of the small size of the chip, if you do not use a larger size of the shell, it will not be easy to manually place on the circuit board. Therefore, the next step is to describe the encapsulation: Two Common Packages At present, there are two common packages; one is the DIP package, which is common in electric toys and looks like a centipede, the other is the BGA package, which is common when buying boxed CPU. As for other packaging methods, there are PGA (Pin Grid Array) used in the early CPU or an improved version of QFP (plastic square flat package) of DIP. Because there are so many packaging methods, only DIP and BGA encapsulation are described below: ——Enduring Traditional Packaging DIP Package The first thing to introduce is the Dual Inline Package (DIP), we can see from the following figure that the IC chip with this package will look like a black centipede at the foot of the dual inline connection and this is the earliest IC packaging technology. It has the advantage of low cost and is suitable for small chips without too many wires. However, because most of them are plastic, the heat dissipation effect is poor, which cannot meet the requirements of the current high-speed chips. Therefore, most of the chips using this package are durable chips, such as OP741 shown in the following figure or smaller IC chips with less speed requirements and fewer holes. Fig 13.  The IC chip shown on the left is a common voltage amplifier named OP741. On the right is its section. The package connects the chip to the leadframe with a gold wire. BGA Package As for spherical array (Ball Grid Array,BGA) packaging, compared with DIP, it is smaller and can be easily placed in smaller devices. In addition, because the pin is located under the chip, it can hold more metal pins than the DIP so it is Ideal for chips that require more contacts. However, the cost of this packaging method is high and the connection method is more complex, so it is mostly used in high unit price products. Fig 14.  On the left is a chip encapsulated in BGA. On the right is a schematic diagram of BGA using a cladding packaging. ——The rise of mobile devices and the emergence of new technologies on the stage Two Ways to Reduce Size However, the use of these packaging methods will cost a considerable amount of volume. For example, today's mobile devices, wearing devices, and so on, require quite a variety of components. If each component is packaged independently, it will cost a lot of space. Therefore, there are two ways to meet the requirements of reducing size. They are SoC (System On Chip) and SiP (System In Packet). SoC At the beginning of the rise of smart phones, the term SoC can be found in major financial magazines, but what is SoC? To put it simply, ICs with different functions are integrated into one chip. By this method, not only the volume can be reduced, but also the distance between different IC can be reduced, and the calculation speed of the chip can be improved. As for the manufacturing method, during the IC design phase, different ICs are put together and then a mask is made through the design process described earlier. However, SoC is not the only advantage; to design a SoC requires considerable technical cooperation. When IC chips are encapsulated, they have their own external protection, and the distance between IC and IC is long, so there is no interactive interference. But when all the ICs are wrapped together, it is the beginning of a nightmare. The IC design factory has to change from the original simple design IC, to the IC which requires them to understand and integrate the various functions. Therefore, it increase the workload of engineers. In addition, there will also be a lot of situations, such as the high-frequency signal of the communication chip may affect the IC of other functions and so on. In addition, SoC also needs to obtain IP (intellectual property) authorization from other vendors in order to put components designed by others into SoC. Because making SoC needs to obtain the design details of the whole IC in order to make a complete mask, which also increases the design cost of SoC. Some people may question why not just design one by yourself. That is because designing all kinds of IC requires a lot of knowledge related to the IC, only a rich enterprise like Apple can have a budget to poach top engineers from well-known enterprises. It's still a lot cheaper to design a whole new IC through collaborative licensing than to develop it by yourself. SiP As an alternative, SiP has leapt onto the stage of integrating chips. Unlike SoC, it buys IC from different enterprises and finishes the last step, which is to encapsulate the IC. In this way, the IP licensing step is eliminated and the design cost is significantly reduced. In addition, because they are independent ICs, the degree of interference with each other is greatly reduced. Fig 15. Apple Watch uses SiP technology to package the entire computer architecture into a chip, not only to meet the desired performance but also to reduce the size, so that the watch has more space for battery release. The most famous product using SiP technology is Apple Watch. Because the internal space of Watch is too small, it cannot use the traditional technology, the design cost of SoC is too high, SiP has become the first choice. With SiP technology, not only the volume can be reduced, but also the distance between each IC can be shortened, so SiP can be a feasible compromise. The following figure shows the structure of the Apple Watch chip, and you can see that quite a few IC are included in it. Fig 16. Internal configuration Diagram of S1 Chip encapsulated by SiP in Apple Watch After the packaging is completed, we will enter the testing stage. At this stage, it is necessary to confirm whether the encapsulated IC is functioning properly and that it can be shipped to the assembly plant after it is correct, so that the electronic products we can see can be made. So far, the semiconductor industry has completed the task of the whole production.