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This technical guide evaluates soft-termination multilayer ceramic chip capacitors (MLCCs), mechanical board flexure failure mechanisms, and design-for-manufacturability (DFM) controls for printed circuit board (PCB), component, and reliability engineers. Mechanical stress during assembly and operation remains one of the primary causes of latent electrical failures in surface-mount ceramic capacitors.Standard Class II MLCCs, particularly in package sizes of 0805 and larger, risk brittle fracture under printed circuit board assembly (PCBA) deflections as low as 2 mm during qualification testing and dynamic handling strains exceeding 700 to 1,000 με. Soft-termination MLCCs introduce an elastic, metal-filled conductive resin layer between the inner copper termination and outer nickel/tin plating, raising the guaranteed deflection threshold to 3 mm to 5 mm under AEC-Q200-005 test standards[2]. Furthermore, this architecture shifts the failure mode from an internal inter-electrode dead short to a benign external peel-off (fail-open). However, soft termination does not replace proper layout: excessive solder fillet height (>75% of chip thickness) forms a rigid metallic bridge that completely bypasses the polymer cushion, causing ceramic fracture regardless of the termination rating.The Mechanics of MLCC Flex Cracking and Latent Field FailuresTensile Stress Concentration and the 45-Degree Ceramic Shear CrackCeramic dielectric materials, such as barium titanate (BaTiO3), exhibit high compressive strength but poor tensile strength. When a printed circuit board bends, convex deflection stretches the outer surface of the laminate. This elongation transmits mechanical strain through the copper solder pad and the rigid solder fillet directly into the lower margin of the capacitor's termination cap.Because the solder fillet adheres tightly to the outer metallization, tensile bending moments concentrate at the junction where the rigid metal termination ends and the bare ceramic body begins. When local tensile stress exceeds the fracture modulus of the ceramic matrix—typically 150 to 200 MPa for standard ferroelectric formulations—the material shears, as documented in evaluations of ceramic capacitor cracking[8]. The fracture follows the principal stress plane, propagating inward and upward at an angle of roughly 45 degrees. This diagonal crack slices through the active interleaved internal electrode layers, mechanically rupturing the sub-micron dielectric barrier separating opposing polarities.Latent Failure Dynamics: From Micro-Crack to Insulation Resistance BreakdownThe primary engineering challenge of flex cracking is its latent behavior. A 45-degree micro-crack rarely severs continuity across the entire component immediately. At the factory gate, the cracked capacitor typically retains sufficient dielectric integrity to pass automated optical inspection (AOI), in-circuit testing (ICT), and functional end-of-line verification.Field failure develops progressively through environmental exposure and electrical bias:Moisture Ingress: Ambient atmospheric humidity enters the microscopic ceramic fissure via capillary action.Electrochemical Dissolution: Under continuous operating DC voltage bias, local electric fields across the narrow crack reach tens of kilovolts per millimeter. Metal ions from internal electrode layers (typically nickel in Base Metal Electrode systems) dissolve into the moisture film.Dendritic Migration: Metal dendrites grow along the crack interface between opposing electrode margins.Dielectric Collapse: Insulation resistance (IR) drops exponentially from gigohms to milliohms. Localized leakage current generates focal I2R heating, triggering thermal runaway that culminates in an unrecoverable dead short, component incineration, or PCB carbonization.Package Size Scaling: Why 0805 and Larger Cases Bear Elevated RiskMechanical strain transferred into a surface-mount capacitor scales directly with component body length (L) and the span between solder fillets.Miniature packages such as 0201 (0603 metric) and 0402 (1005 metric) possess short geometric spans. Under typical handling flexure, the differential deflection between their two termination pads is negligible; consequently, they rarely experience sufficient tensile bending moment to cause fracture.Conversely, packages of 0805 (2012 metric), 1206 (3216 metric), and 1210 (3225 metric) span substantial board distances. In dynamic strain evaluations, 1206 ceramic capacitors on standard FR4 substrates fail at board strains between 1,700 με and 2,500 με, with fracture occurring at deflections under 2 mm to 3 mm. As component thickness and length increase, the mechanical lever arm amplifies stress at the ceramic margin, making large MLCCs vulnerable to minor assembly flexure.Standard vs. Soft Termination: Internal Architecture and Failure ModesLayered Construction: Integrating the Conductive Polymer BufferStandard MLCC end terminations consist of three primary layers:An inner thick-film copper (Cu) electrode bonded directly to the ceramic and the internal nickel electrodes.An electroplated nickel (Ni) barrier layer to resist solder leaching.A matte tin (Sn) outer finish for solderability.All three layers consist of rigid metals with high elastic moduli (E>100 GPa). When the board deflects, this rigid stack transmits strain straight into the brittle ceramic.Soft-termination (flexible or resin-electrode) capacitors modify this stack by interposing a conductive polymer matrix between the inner copper electrode and the nickel plating layer, as detailed in the Murata GCJ Series documentation[5] and KYOCERA AVX FLEXITERM technical analysis[6]. This buffer layer consists of an epoxy or polymer matrix heavily doped with conductive metal particles (typically silver or copper). The polymer matrix features a low elastic modulus (E≈2 to 5 GPa), providing mechanical compliance. When substrate bending induces shear forces across the solder joint, the polymer layer deforms elastically and plastically, absorbing strain energy and dampening stress concentrations before they reach the ceramic body.Qualification Benchmarks: AEC-Q200-005 Standard Deflection vs. Soft-Termination GuaranteesThe automotive standard for assessing capacitor flex resistance is AEC-Q200-005 (Substrate Bending Test), part of the broader AEC-Q200 passive component qualification suite[1]. The test geometry is strictly standardized:Support Span: 90 mm between cylindrical support rollers.PCB Substrate: 1.6 mm thick FR4 board (100 mm×40 mm).Actuator Speed: 1.0 mm/second applied at the center of the board.Duration: Deflection held for 60 seconds (+5 seconds).Under AEC-Q200-005, standard Class II ceramic capacitors (e.g., X7R, X8R) require a baseline qualification deflection of only 2 mm without mechanical fracture or capacitance shift outside specification limits.By contrast, tier-1 automotive soft-termination MLCCs guarantee 3 mm to 5 mm of continuous deflection under identical test conditions. In destructive testing where boards are bent until failure occurs, soft-termination capacitors routinely withstand deflections up to 8 mm to 10 mm before electrical disruption, providing substantial mechanical headroom over standard components.Failure Mode Transition: Catastrophic Short Circuit vs. Benign Fail-Open (Peel-Off)The critical reliability distinction between standard and soft-termination capacitors lies in the ultimate failure mode under extreme over-stress:Standard Termination: When board bending exceeds mechanical limits, tensile stress fractures the ceramic body across the active electrode region. The end-state failure mode is an internal inter-electrode dead short, creating a direct conductive path across power rails.Soft Termination: Under extreme deflection exceeding the elastic absorption capability of the polymer (>5 mm to 8 mm), stress resolves through adhesive failure at the metal-polymer interface. The outer nickel/tin termination peels cleanly away from the conductive resin buffer (termination peel-off). The underlying ceramic body remains structurally intact, leaving the component in a benign open-circuit state (Fail-Open).While an open circuit interrupts circuit functionality, it prevents catastrophic thermal runaway, short-circuit fire hazards, and localized board destruction.Parasitic and Thermal Trade-Offs: Addressing ESR Penalties and Asymmetric TerminationsEngineers frequently hesitate to specify soft-termination MLCCs on power conversion rails due to potential parasitic penalties. In conventional full-wrap soft termination, the conductive resin completely encloses the terminal cap. Because conductive epoxy exhibits lower bulk conductivity than pure copper, full-wrap parts introduce a small increase in equivalent series resistance (ESR) and equivalent series inductance (ESL). On high-ripple DC-DC output stages and 48 V automotive domains, this added resistance can lead to higher I2R internal heating.To resolve this trade-off, manufacturers have developed asymmetric terminal structures, such as the TDK MLCC solution guide architecture[4]. In visual stress tests and 3D architectural renders of advanced configurations (such as TDK's CNC series), the conductive soft resin layer is restricted solely to the bottom-side mounting pad beneath the outer metal plating, leaving the vertical end faces and top edge with standard low-resistance metal plating.CNC Series: Low Resistance Soft Termination MLCC | Datasheet PreviewExperts point out that by placing the resin exclusively on the bottom plane where board-flex shear forces enter the component, the high-frequency current loop traversing the vertical terminal walls bypasses the polymer layer entirely. This maintains low ESR and low ESL characteristics while preserving mechanical compliance.From a thermal endurance standpoint, the polymer buffer also relieves internal stress driven by coefficient of thermal expansion (CTE) mismatches between the ceramic body (≈9.5 to 11.5 ppm/∘C) and the FR4 substrate (≈14 to 17 ppm/∘C). Consequently, tier-1 soft-termination series routinely achieve qualification across >3,000 thermal shock cycles (−55∘C to +125∘C/+150∘C), triple the standard AEC-Q200 baseline requirement of 1,000 cycles.Manufacturing Stress Hotspots: Depaneling, Fastening, and InterconnectsEven components that satisfy qualification benchmarks will fail if PCBA manufacturing processes generate excessive mechanical strain. Under IPC/JEDEC-9704A strain measurement guidelines[3], dynamic strain must be monitored across transient assembly operations using triaxial rosette strain gauges. Allowable dynamic microstrain (με) depends directly on board thickness and strain rate:Max Allowable Strain=2.35PWB Thickness×[1900−300×log10(Strain Rate)]During high-velocity operations, allowable transient limits frequently drop below 700 to 1,000 με. Three primary manufacturing operations routinely exceed these safe limits.Depaneling Operations: V-Cut Scoring vs. Router Milling MechanicsDepaneling is the single largest contributor to MLCC flex cracking in production:V-Cut Scoring: Breaking panels along V-grooves using circular blades ("pizza cutters") or manual snapping generates high out-of-plane torsional flexure and local shear stress. As the blade wedges into the score line, localized board deflection easily induces strains from 1,500 to over 3,000 με, fracturing adjacent MLCCs oriented perpendicular to the cut.Router Milling: High-speed mechanical spindle routing dramatically reduces transient panel flexure compared to V-scoring. However, stress transfers to the break-out tabs ("mouse bites"). Cutting these retention tabs with manual nibbling tools or punch dies without underside mechanical backing fixtures generates severe localized bending moments.Hardware Fastening: Screw Boss Warpage and Torque-Induced StrainSecuring a populated circuit board into a chassis with threaded fasteners introduces severe static strain:Uneven Boss Heights: If cast aluminum or molded plastic standoffs deviate in planar height by as little as 0.2 mm, torquing a screw pulls the semi-rigid FR4 laminate into severe dish or saddle warpage.Torque Transfer: Without counter-torque fixtures, screw head friction twists the local board area around the mounting hole. This locks static tensile stress permanently into adjacent solder joints, lowering the margin required for subsequent thermal cycles to initiate cracking.Dynamic Assembly Stress: Connector Mating and In-Circuit Test FixturesConnector Insertion: Pressing large multi-pin wire harnesses or automotive header connectors into unsupported circuit boards creates significant downward flexure. Manual insertion forces reaching 50 to 100 N across an unsupported span can generate board deflections exceeding 4 mm.ICT Bed-of-Nails Pressing: In-circuit test fixtures utilize spring-loaded pogo pins that press upward against the PCBA while mechanical push-rods press downward from above. If push-rods and backup pins are misaligned or spaced too far apart, the compressive force bends the board locally during test actuation, cracking components situated near test pads.Field Observations: Perspectives from Assembly and Reliability EngineersEngineering discussions on technical forums and failure analysis reports highlight recurring operational patterns regarding MLCC cracking:The "Zero-Defect" Illusion at EOL: Assembly engineers frequently note that lots experiencing severe depaneling stress often pass initial factory testing with 100% yields. Failures only appear 3 to 12 months later following humidity exposure in the field, often misleading teams into blaming component quality rather than depaneling fixtures.The Manual Handling Risk: Technicians handling large panel arrays before separation frequently flex the board during transport. Panel flexure caused by picking up unsupported boards with one hand generates sufficient flexure to induce micro-cracks in 1206 capacitors near the center of the panel.Bypassing the Upgrade: Quality teams reporting component failures after upgrading to soft-termination parts regularly find that SMT solder paste volumes were left unadjusted. The resulting excessive solder fillets bridged over the flexible polymer layer, nullifying the upgrade.PCB Layout DFM and Assembly Process Controls: Preventing the Solder Bypass TrapComponent-level upgrades cannot compensate for poor physical layout or out-of-spec soldering processes. Mitigating flex cracking requires a multi-layered design defense.Component Orientation: Mitigating Strain through Geometric AlignmentThe orientation of an MLCC relative to the board's primary bend axis dictates the magnitude of tensile stress transmitted into the ceramic body.Perpendicular Placement (High Risk): When the longitudinal axis of the capacitor sits perpendicular to the bend axis (e.g., perpendicular to a V-cut line or board edge), board deflection pulls the two solder fillets apart. This maximizes the tensile bending moment across the ceramic body.Parallel Placement (Low Risk): Aligning the capacitor's longitudinal axis parallel to the bend axis ensures that both terminals experience uniform deflection simultaneously. Empirical strain gauge evaluations and finite element analysis (FEA) show that parallel orientation reduces mechanical tensile stress across the termination by up to 50% compared to perpendicular placement under identical deflection levels.Mechanical Keep-Out Distances for High-Risk Board FeaturesLayout designers must enforce strict mechanical clearance zones around manufacturing stress concentrators.Stress FeatureMinimum Clearance (0402 / 0603)Mandatory Clearance (0805 / 1206 / 1210)Recommended OrientationV-Cut Score Line≥3.0 mm≥5.0 mmStrictly ParallelRouted Edge / Break-Out Tab≥1.5 mm≥3.0 mmParallel to tab edgeScrew Mounting HoleWasher Radius +3.0 mmWasher Radius +5.0 mmCircumferential (Tangential)Heavy Connector Boundary≥2.0 mm≥4.0 mmParallel to insertion axisICT Fixture Support Pins≥2.5 mm≥4.0 mmNon-criticalThe Solder Fillet Bypass Risk: Why Excess Solder Paste Negates Soft TerminationThe most common implementation failure involving soft-termination MLCCs occurs on the surface-mount technology (SMT) assembly line.Soft-termination capacitors rely on the exposed, compliant resin band situated between the inner electrode and the rigid outer plating to absorb shear stress. According to tier-1 manufacturer mounting guidelines (including Murata and Knowles Syfer), the solder fillet height (h) must remain between 1/3 and 2/3 (33% to 66%) of the component's total thickness (T), with an absolute maximum allowable limit of <75% of T.If stencil apertures deposit excessive solder paste, surface tension pulls molten solder up the termination during reflow. When the solidified solder fillet exceeds 75% of the component's thickness, the metallic solder forms a rigid bridge directly from the PCB landing pad to the upper ceramic body, completely spanning past the soft polymer resin band.This rigid bridge physically couples the board's tensile deflection directly into the brittle ceramic. Under mechanical flexure, the capacitor cracks at the standard 45-degree angle, rendering the soft-termination design ineffective. Stencil apertures for soft-termination parts must be reduced by 10% to 20% relative to standard pad sizes to control paste volume.Capacitor Architecture Selection FrameworkHardware and component engineers must match capacitor architecture to the specific mechanical and electrical criticality of each net.Structural Comparisons: Soft-Termination vs. Open-Mode vs. Floating-Electrode DesignsWhen evaluating crack-resistant and fail-safe capacitors, three primary internal architectures exist:Soft Termination (External Mechanical Cushion): Adds an external conductive polymer resin buffer. It acts externally to dissipate mechanical strain and prevent ceramic cracking up to 5 mm of deflection, converting over-stress failures into external terminal peel-off.Open-Mode Design (Internal Margin Defense): Standard termination externally, but internal electrode prints are set back away from the capacitor end caps. If a 45-degree shear crack forms across the terminal corner due to mechanical bending, the fracture plane passes through an inactive ceramic zone without intersecting overlapping opposing electrode plates. Capacitance drops slightly, but an internal short circuit is avoided.Floating-Electrode / Serial Design (Internal Redundancy): Divides the internal dielectric array into two capacitive elements connected in series within a single ceramic block. If board flexure cracks one side of the capacitor and shorts that section, the opposing intact serial capacitor maintains basic dielectric isolation, preventing power rail collapse.Automotive Rail Requirements and Critical System Standards (VW 80808-2)In safety-critical applications, such as automotive electronics, regulatory and OEM specifications dictate fail-safe strategies. The Volkswagen Group standard VW 80808-2 failsafe MLCC specification[7] establishes strict criteria for ceramic capacitors connected directly to unswitched power networks:Scope: Applies to any circuit where an MLCC short-circuit could disable critical vehicle safety functions or generate a localized power dissipation exceeding 2.5 W.Direct Battery Rails (Terminal 30 / KL30): Because Terminal 30 connects directly to the vehicle battery without switched ignition isolation, a short circuit presents a fire hazard. VW 80808-2 mandates capacitors qualified to 5 mm deflection (soft termination) combined with open-mode internal geometries, or the use of two standard capacitors placed in mutually orthogonal series layouts.Engineering Selection Matrix: Matching Architecture to Risk VectorOperating / Layout ConditionRecommended Capacitor ArchitectureTarget Package SizesAEC-Q200-005 Deflection LimitPrimary Failure Mode Under Severe StressTypical Circuit ApplicationsLow-Risk Core Zones(>10 mm from edges/screws; flat substrate)Standard Class I / Class II Termination0201, 0402, 06032 mmCatastrophic internal dead short (45° shear crack)High-speed digital decoupling, RF matching, precision analog filteringModerate-Risk Zones(3–5 mm from V-cut; near connectors; package ≥0805)Soft Termination (Conductive Resin Layer)0805, 1206, 12103 mm to 5 mmBenign external open circuit (terminal peel-off)Intermediate buck/boost stages, general industrial I/O, ECU power suppliesHigh-Ripple Power Paths(High-flex zone + strict ESR/thermal limits)Asymmetric Soft Termination (Bottom-Only Resin)0805, 12063 mm to 5 mmBenign external open circuit (terminal peel-off)DC-DC converter output filters, point-of-load regulators, battery charge pathsDirect Battery Lines (Fail-Safe)(Unfused Terminal 30 / KL30 automotive nets)Dual Protection (Soft Termination + Open-Mode / Serial)0805, 1206, 12105 mmFail-open / intact secondary series dielectric marginAutomotive 12V/48V KL30 power inputs, safety-critical aerospace busesSevere Mechanical Deflection(Board flex >5 mm; high CTE thermal mismatch)Metal Lead-Frame Capacitors (Megacap / Lead-Frame)1812, 2220, stacked arrays>6 mm to 10 mmElastic lead-frame deformation; ceramic isolated from boardHeavy industrial motor drives, high-voltage EV traction inverters, resonant tanksPractical Reliability Checklist and Implementation WorkflowReliability in high-stress environments depends on integrating component selection with layout and process audits. Engineering teams should review this verification checklist prior to tape-out and production ramp.PCBA Mechanical Stress Audit & DFM Verification Checklist1. Schematic and Net Criticality ReviewIdentify all capacitors tied directly to unswitched DC battery rails (KL30 / Terminal 30) or power buses where short-circuit dissipation can exceed 2.5 W.Mandate dual-protection capacitors (soft termination combined with open-mode or serial internal structure) for all safety-critical nets per VW 80808-2.Review decoupling positions on high-ripple power rails: specify asymmetric bottom-resin soft termination if ripple currents demand minimal ESR and ESL.2. Layout Geometry and Keep-Out AuditVerify that all MLCCs in package sizes ≥0805 are oriented parallel to adjacent board edges, V-cut score lines, and break-out tabs.Verify a minimum keep-out distance of ≥5.0 mm between 0805+ MLCCs and V-cut breakout lines.Verify a minimum clearance of screw head/washer radius +3.0 mm (preferably +5.0 mm) for all mounting holes.Verify that no MLCCs are placed directly beneath or immediately adjacent to large through-hole connectors subject to manual mating forces.3. SMT Stencil and Assembly Process VerificationInspect SMT stencil aperture designs for MLCC footprints: ensure aperture volumes are scaled to yield a solder fillet height between 33% and 66% (strictly <75%) of chip thickness (T).Verify that pick-and-place nozzle placement forces do not exceed manufacturer limits to prevent micro-cracking during component centering and placement.Perform dynamic strain gauge testing per IPC/JEDEC-9704A on prototype assemblies during depaneling, ICT bed-of-nails pressing, and connector insertion, ensuring transient microstrain remains below safe limits (<700 to 1,000 με).Frequently Asked QuestionsHow much more PCB deflection can soft-termination MLCCs handle compared to standard parts?Under the standardized AEC-Q200-005 test method (90 mm support span on a 1.6 mm FR4 board held for 60 seconds), standard Class II MLCCs (such as X7R) require a baseline qualification deflection of only 2 mm. Tier-1 automotive soft-termination MLCCs guarantee 3 mm to 5 mm of deflection without mechanical fracture or insulation degradation. Under destructive over-stress evaluations, soft-termination capacitors routinely withstand 8 mm to 10 mm of deflection before mechanical disruption occurs.Will a soft-termination MLCC short circuit if board bending exceeds its maximum deflection threshold?No. Standard MLCCs crack across the active internal electrodes, creating an inter-electrode breach that results in a catastrophic short circuit. Soft-termination MLCCs are engineered to exhibit a fail-open mechanism: when deflection exceeds material absorption limits (>5 mm to 8 mm), shear stress triggers an adhesive separation at the polymer interface, causing the terminal to peel away from the component (termination peel-off). The ceramic body remains intact, interrupting the circuit path and preventing thermal runaway.Why does excessive solder fillet height negate the advantages of soft termination?Soft termination functions because the exposed, compliant conductive polymer band absorbs shear strain transmitted from the solder joint. If stencil paste deposits are excessive and the solder fillet climbs beyond 75% of the capacitor's total thickness (T), the solder forms a continuous, rigid metallic bridge from the PCB land to the upper ceramic body. This bypasses the flexible resin layer entirely, routing raw tensile stress directly into the ceramic and causing standard 45-degree flex cracking.Does soft termination increase equivalent series resistance (ESR) or high-frequency losses?Conventional soft termination introduces a minor increase in ESR and ESL because the conductive polymer matrix has lower bulk conductivity than pure copper. While negligible for standard low-frequency decoupling and filtering, this added resistance can impact high-ripple power rails. Modern asymmetric soft-termination designs resolve this by restricting the conductive resin strictly to the bottom mounting face while keeping the vertical end faces standard metal plating. This provides mechanical strain absorption while preserving low ESR and ESL across high-frequency switching loops.Can soft-termination MLCCs substitute for proper PCB layout keep-out zones and depaneling support?No. Soft-termination components provide an essential safety margin against unforeseen mechanical flexure, but they are not a substitute for proper DFM practices. Severe manufacturing operations, such as manual panel snapping or driving screws into unlevel standoffs, can generate local strains exceeding 2,500 to 3,500 με. Strains of this magnitude exceed the absorption capability of any surface-mount passive component. Soft termination must be deployed as the final layer of a defense-in-depth strategy alongside parallel orientation, proper keep-out distances, and controlled solder paste volume.ReferencesAEC-Q200 REV D: Stress Test Qualification for Passive Components — Automotive Electronics CouncilAEC-Q200-005 REV A: Board Flex Test — Automotive Electronics CouncilIPC/JEDEC-9704A: Printed Circuit Assembly Strain Gage Test Guideline — IPC / JEDEC Solid State Technology AssociationFlex Crack Countermeasures in MLCCs: High-Reliability Series Solution Guide — TDK CorporationGCJ Series Soft Termination Chip Multilayer Ceramic Capacitors Product Documentation — Murata Manufacturing Co., Ltd.AVX MLCC FlexiTerm: Guarding Against Capacitor Crack Failures — KYOCERA AVX Components CorporationMLCC Failsafe Strategy: Future-proof products for demanding Automotive Applications (VW 80808-2) — Samsung Electro-MechanicsCracking Problems and Mechanical Characteristics of PME and BME Ceramic Capacitors — NASA Electronic Parts and Packaging (NEPP) Program

IntroductionCeramic capacitors are the most used components in the electronics industry, as they are loved for their versatility, reliability, and affordability. However, these components are not limited to such narrow applications, but they play a very important role, from non-critical reductions of noise in consumer electronics to very critical in power supply circuits or communications. This article discusses the fundamentals of ceramic capacitors, their types, and applications, as well as the considerations you must take in mind before using them. Understanding Ceramic CapacitorsCeramic capacitors are passive electronic components made of two conductive plates separated by a dielectric material. The dielectric compound is a ceramic material approached mainly with barium titanate, titanium dioxide or a combination of such and other ceramic products. Through the stuffing in the capacitor, the ceramic material is capable of cyclically attracting and releasing electrical charge, which makes the device work. It consists of repeatedly alternate conductive and dielectric layers, ultimately creating a solid compact structure made of many thin layers. In this way, not only does the construction withstand high values fixed in small areas, but it also achieves the following performance criteria. Types of Ceramic CapacitorsCeramic capacitors are broadly categorized into two main types based on their construction and electrical properties: Multilayer Ceramic Capacitors (MLCCs) and Ceramic Disc Capacitors. Multilayer Ceramic Capacitors (MLCCs): Now, MLCCs are built by the vertical stacking of the ceramic dielectric and metal electrodes, which is repeated thousands of times in a single capacitor. Hence, the capacitors of this design can support high capacitance values in relatively small physical sizes. Accordingly, multilayer ceramic capacitors (MLCCs) are the most popular ceramic capacitors used worldwide in today's electronics industry. Ceramic Disc Capacitors: These supercapacitors involve coating a ceramic disc with two metallic electrodes. While their low capacitance value compared to MLCC (multilayer ceramic capacitor) is their disadvantage, ceramic disc capacitors are still highly prized for their stability and reliability in high-voltage applications. Ceramic Capacitors Dielectric ClassesThe ceramic capacitors' dielectric classes help in selecting the capacitors based on their usage.  Class 1 Ceramic Capacitor DielectricThey offer the ability to achieve the best results regarding stability and output, respectively.These two applications provide low-loss oscillators and filters.It is used for high-tolerance capacitors for its stable temperature coefficient.The ceramic capacitor dielectric can be characterized by three components: temperature coefficient, absolute value of capacitance changes at higher temperatures, and relative permittivity.The number that indicates the amount of multiplication is the second character numeric value.The third character is a letter that exhibits the maximum error in the ppm/C.  Class 2 Ceramic Capacitor DielectricThe capacitance behaves like a variable capacitor whose value is dependent on the applied voltage.Class-2 dielectric materials present with non-linear temperature coefficients.Coupling and decoupling utilize these. They help in the assembly operation.The event is equally drawn from the same three elements. The first parameter is the letter, which indicates the very low temperature of this type.The second element clarifies numerically the highest operating temperature.The third character is a letter, and it depicts capacitance variation with regard to temperature.  Class 3 Ceramic Capacitor DielectricIn addition, the permittivity values of class 3 dielectrics are very high, up to 50000 times higher than those of class 2 dielectrics.They entail heavy losses of current and display voltage-dependent capacitance behaviour.The most important technology that has emerged during a Class 4 Ceramic Capacitor Dielectric is digitalization.They are also known as input capacitors to them. Applications and Uses of Ceramic CapacitorsA Brief Explanation of the Applications and Utility of Ceramic Capacitors The applications of ceramic capacitors include:Transmitter stationsInduction furnacesHigh-power monolithic capacitors.Power circuit breakersHigh-density applicationsPrinted circuit boards These capacitors are additionally rechargeable and are also used as general-purpose capacitors across the brushes of the DC motors in order to suppress the RF noise. Advantages of Ceramic CapacitorsCeramic capacitors offer several advantages that make them a preferred choice in many electronic applications: Compact Size:First of all, ceramic capacitors have a very small footprint compared to other capacitors because of their small size. In contrast to traditional capacitors that have bulky outer cases, these small nano-capacitors have tiny packages. Thus, they can be used for small and cramped spaces and electronic devices with small dimensions. High Reliability:Ceramic capacitors are famous for their extreme reliability and superior solidity. They are characterized by fault-tolerance, which is resistance to climatic conditions, including high temperatures, vibrations, and shock, and they can support applications with heavy loads. Low Inductance:Overall, ceramic capacitors can be appreciated for their large construction, which accounts for low inductance, which is valuable for high-frequency applications and EMI (electromagnetic interference) minimization. Wide Capacitance Range:Ceramic capacitors can be procured in a wide range of values from pico- to microfarads; therefore, designers could select the optimal capacitance for a given circuit by coming for the right capacitance value. Cost-Effective:Ceramic capacitors are definitely a cheaper option than other types of capacitors, specifically for high-volume applications, which has given them the nickname of a pocket-friendly option for many electronics. Selecting the Right Ceramic CapacitorWhen choosing a ceramic capacitor for a particular application, several factors must be considered to ensure optimal performance and reliability: Capacitance Value:The right choice of the capacitance value has a major role in the correct operation of the circuit. The designers should perform careful calculations of the needed capacitance depending on the working frequency, voltage, and other related parameters. Voltage Rating:Capacitors made with ceramic can withstand different voltage ratings, and it is highly important to use one with a higher blocking voltage rating than the circuit's maximum operating voltage to prevent breakdown and maintain circuit safety. Temperature Characteristics:Ceramic capacitors inherently show the different reactions created by the temperature that moves. Choose the proper theses property, for example, for those which are not very much affected by wide workman's temperature.Mounting Style:Given the application, designers should understand both types of mounting methods well and make a final selection between surface mount and through-hole, considering that there are board space, assembly process, and environmental influences issues. Dielectric Material:Generally, the capacitance of ceramic capacitors depends on the dielectric material. A capacitor is also affected by resistance to current flow (power factor or dissipation factor) and how stable its structure is in the long run (dielectric stabilization). Particularly critical in selecting the dielectric material is achieving all the desired application requirements. Considering these factors and communicating with capacitor manufacturers or technical advice are important steps for the design of the circuits where the ceramic capacitors are supposed to be embedded, making such an effort will ensure the best application of such capacitors in electronics. Proper Installation and HandlingThe right method is a must for the installation and handling of ceramic capacitors for good results and increasing lifespan. The correct board layout, component placement, and soldering ensure that physical stress is kept at a minimum and avoid any possible failures. Furthermore, taking actions such as electrostatic discharge (ESD) protection measures during assembly and handling must be the preventive measure to keep these components from damage. ConclusionIn conclusion, ceramic capacitors are not replaceable in the electronic devices industry because of their efficient combination of characteristics such as working range, reliability, and prices. Their generic system capabilities are used for all kinds of applications, from as simple as noise reduction to the more critical roles of ensuring safety and communication systems. Discovering and knowing the kinds, areas of utilization, and rules that can be faced in the use of ceramic capacitors can help engineers and designers make the best use of them for their particular circuits that prioritize stability, efficiency, and cost-reduction in their designs.

Overview: The article discusses the importance of maintenance in ensuring the reliability and safety of power electronic systems. It outlines the steps involved in maintenance, including condition observation, anomaly identification, defect diagnosis, and remaining useful life prediction. Power electronic systems are subject to a variety of risks, including catastrophic failures, despite the careful consideration of dependability characteristics during design and control. This is because of the complex and demanding operating settings of power electronic systems. For field applications, power electronic components, converters, and systems must be extremely reliable and safe. What are the steps in maintenance to make the power electronic system more reliable?Preventive maintenance systems are useful ways to guarantee that planned functions are carried out as intended. The steps in maintenance of power electronic system includesCondition observationIdentification of anomaliesDiagnosing defectsRemaining Use Life (RUL) predictionThe above actions coincide with the IEEE standard framework of prognostics and health management for electronic systems. Condition ObservationPower electronics condition observation consists ofIdentification of system parametersPreprocessing dataMining featuresThe data from the condition observation is used to discover informative and hidden patterns that form the foundation for the prognostic and health management applications that follow. Identification of System ParametersIdentification of system parameters involves the gathering of data for important components.Characteristics of power electronic systems includesExtremely small space inside a power moduleExtremely fast switching frequencyRelatively insignificant parameter changes in terms of aging, etc.Because of these characteristics, developing specific hardware for parameter identification is quite a challenging task.A noninvasive approach that uses existing physical signals to indirectly get information or estimate relevant information without the need for additional hardware implementation is one of the more promising methods.Therefore, a sensorless and cost-effective option can be used for condition monitoring, which is good for people who work in industry. In general, there are two types of methods for identifying system parameters:Model-freeModel-based. Preprocessing data and Mining featuresThe goal of data preprocessing and feature mining is to improve the quality of the raw data so that it can be used for applications like problem diagnostics.Improving the quality of data involves the following steps to make it more organized. The steps are as followsData cleaning to minimize noiseData clustering is used to find groups of related data pointsDensity estimation is used to determine the distribution of the dataData compression to reduce the number of features by projecting large-sized data to small-sized dataData fusion to combine various information sources, and moreWhen data preparation and feature mining are done correctly, the performance of the ensuing prognostics and health management applications—such as diagnostic accuracy—can usually be greatly enhanced. Identification of Anomalies and Diagnosing DefectsThe anomaly detection process focuses on identifying unusual patterns and making a binary decision. When the nominal parameters or rated system characteristics exceed the predetermined safety range, it gives an indication.The fault diagnosis finds and identifies the specific failure modes after the unusual changes happen.The classification, regression, or clustering tasks are essentially anomaly detection and fault diagnosis. When a new fault signature arrives, it identifies the fault label based on the learned relationship from the training stage.Anomaly detection and fault diagnosis techniques fall into two categories:Supervised learningUnsupervised learning Remaining Useful Life (RUL) PredictionIn the design phase, lifetime prediction serves to support the characteristics of a population of units known as the ‘Design for Reliability’. It is one of the crucial components of prognostics and health management.The purpose of the estimation of RUL is not to accurately predict the lifespan of a population of units. Based on condition monitoring data, it predicts the remaining lifespan of each single unit in operation. For applications where availability, safety, or reliability are crucial, RUL prediction is used as an extra tool to lower uncertainty.The lifetime estimate is subject to several challenges, such asInaccuracies in model calibrationManufacturing tolerancesDifferences in operational environments and workloadWhen a particular unit is operated in the field, these uncertainties lead to inaccurate reliability estimations. The following areas require greater attention in order to improve the practicality of AI-based RUL prediction techniques for field applications. Quantification of uncertaintyFor RUL prediction, being able to measure uncertainty is more important than for other regression-related tasks, like control functions. Since the RUL is a random variable, quantifying the confidence interval is crucial for making the best decisions.All of these uncertainties—due to population heterogeneity, measurement noise, various operating settings, etc.—should be considered in a workable practical solution. Quantifying the uncertainty using AI algorithms is quite difficult.A few practical options areThe use of particle filters in neural networks (NNs)Bayesian-based artificial intelligence techniques (e.g., Gaussian process, RVM)Monte Carlo methodsStochastic data-drivenStochastic, data-driven approaches are an interesting option to explore. These approaches can naturally yield the probability density function of the RUL for the purpose of computing the confidence interval. Adaptive capabilityThis is the crucial stage for real-world applications and is related to the model parameter tuning layer in Fig. 1 that connects the offline and online models. If an AI approach lacks adaptive flexibility, its use is limited.Power electronics have difficulties because the operational conditions of the training dataset, which is often acquired through accelerated testing trials, differ significantly from those of the in-situ system (i.e., the test data). Most of the research makes the assumption that the in-situ system's operational parameters are the same as those of the training dataset, which could not be the case in real-world applications.Therefore, the AI-based RUL prediction method's adaptability is essential for bridging the gap between research in academia and practical implementations in industry.Detailed mapping relationship derivations and transfer learning of degradation characteristics under different operating settings (temperature, voltage, humidity, etc.) are also interesting ways to tune model parameters. This means that system models need to be studied in great detail.Fig. 1 shows a methodical flowchart of power electronic system maintenance tasks. It typically comprises the three elements listed below.             Summarizing the Key PointsMaintenance of power electronic systems involves condition observation, anomaly identification, defect diagnosis, and remaining useful life prediction to ensure reliability and safety.The IEEE standard framework for prognostics and health management is applicable to power electronic systems, emphasizing the importance of a comprehensive maintenance approach.Data preprocessing and feature mining are crucial for improving the quality of raw data, enhancing the performance of prognostics and health management applications.AI-based remaining use life prediction techniques face challenges in real-world applications, requiring quantification of uncertainty and adaptability.Power electronic systems require an adaptive maintenance strategy to bridge the gap between research and practical implementation in industry, addressing operational parameter variations. ReferenceZhao, Shuai, Frede Blaabjerg, and Huai Wang. “An Overview of Artificial Intelligence Applications for Power Electronics.” IEEE Transactions on Power Electronics 36, no. 4 (April 2021): 4633–58. https://doi.org/10.1109/tpel.2020.3024914.

Power grids are becoming more decentralized as renewable energy sources take over as the dominant factor. These cutting-edge technological advancements, while providing opportunities for greater productivity.Why is a new reliability framework necessary?The new components of today's power systems bring up novel difficulties that necessitate a new reliability framework, which has recently been implemented. Assessing the reliability of modern power systems necessitates not only assessing various electro-magnetic and mechanical stability difficulties but also introducing new ideas related to local reliability.New Reliability ConceptA new methodology for reliability analysis in contemporary power systems should be established in order to address the issues brought on by new power system technology. It could keep the main ideas of adequacy and security while also taking into account the effects of grid modernization.Modern Power System Adequacy AssessmentThe cyber-physical structure of the current power system, which consists of three layers—power, communication, coupling, and decision—explains the adequate nature of this system. The proposed adequacy assessment framework is depicted in Fig. 1 in order to address all the drawbacks of reliability evaluation methodologies.Fig. 1. Framework for modern power system adequacy assessment. Source: IEEE Open Journal of Power Electronics As illustrated in Fig. 1, the suggested framework allows for the evaluation of the cyber-physical power system's suitability at three hierarchical levels: generation, generation-transmission, and distribution.GenerationFirst and foremost, sufficient generation system capacity is needed to meet system demand as a whole. As a result, the generating sufficiency in HL I can be assessed similarly to the sufficiency of the traditional power system, as illustrated in Fig. 2(a).Fig. 2. Conventional framework for adequacy assessment. Source: IEEE Open Journal of Power ElectronicsCyber-Physical Generation-Transmission SystemTo make sure that the cyber-physical generation-transmission system in HL II is good enough, the effects of the cyber-layers and the effects of distribution generation must be modeled. Large-scale generation units and distribution networks based on microgrids are shown in simplified form in Fig. 3(a). The microgrids are modeled as a specific node at a Point of Common Coupling (PCC), which is depicted in Fig. 3(b), in order to assess the adequacy of these systems. Fig. 3. Scalable framework for modern power system adequacy: a) main structure as a simplified grid; b) equivalent model of microgrids from distribution systems; c) local adequacy for each microgrid. Source: IEEE Open Journal of Power Electronics Depending on the topology and accompanying power management technique inside each microgrid, this special PCC node may be a load or a generation unit for each microgrid in a distribution network. For example, in the substation microgrid comprising medium-scale generators to provide its load, the equivalent load (which is equal to the generation minus the load) can be taken into account at the PCC in Fig. 3(b). Additionally, the equivalent generation can be assumed at the PCC in Fig. 3(b) if the substation microgrid's generation is greater than its load. The substation's internal generation unit availability, load power, and upstream switch reliability all have an impact on this equivalent generation unit's availability. The MV distribution networks can therefore be characterized for transmission system analysis as equivalent loads or generations. The cyber-physical availability model, as shown in Fig. 2(b), can therefore be used for modeling the reliability of the cyber-physical transmission system.Cyber-Physical Distribution SystemThe reliability of cyber-physical distribution networks can be modeled in HL III for each microgrid based on its structure in HL III-A and for the distribution network in HL III-B, as illustrated in Fig. 1. In distribution networks, there are four different types of microgrid structures: single-customer, partial feeder, full feeder, and substation microgrid. The single customer microgrid's adequacy can be modeled by simplifying its structure, as seen in Fig. 3(c). The distribution network outside of the single-customer microgrid is represented in this form as an equivalent generation unit. The local adequacy of the microgrid must be met depending on the application of the single-customer microgrid, such as household load, hospital load, etc. The partial or full feeder microgrid's adequacy can be evaluated similarly to the single-customer microgrid by treating the single-customer microgrids inside it as a specific equivalent node at PCC, which can be a load or generator. Additionally, by modeling the feeder microgrids as special nodes at PCC, the substation microgrid's adequacy is assessed. The distribution network adequacy assessment's primary focus is on the accessibility as well as the availability of energy sources in each sub-grid. This may necessitate restrictions across sub-grids, particularly for single customers who may wish to be islanded during grid outages in order to retain their adequate supply despite the upstream microgrid's declining adequacy. A distribution network consists of numerous substations, which are connected to the high-voltage grid and to one another by MVAC or MVDC transmission systems. Thus, by modeling each substation microgrid as a particular node at their PCC, be it a load or a generator, which is connected to the main grid, it is possible to assess the adequateness of the cyber-physical distribution systems. Due to the presence of DGs and DESS, distribution system reliability, unlike traditional power systems, necessitates local adequacy assessment. The suggested scalable reliability modeling for distribution networks' microgrids ensures each microgrid's adequate suitability.Modern Power System Security AssessmentIn addition to being adequate, modern power systems also need to be secure due to the various sources of uncertainty they include. Similar to conventional power systems, security can be characterized as a system's capacity to tolerate unforeseen events. As indicated in Fig. 4, the security of modern power systems can be examined in three domains: static, dynamic, and cyber. Fig. 4. Framework for security assessment in modern power systems. Source: IEEE Open Journal of Power ElectronicsStatic SecurityThe steady-state operation of the system following any unforeseen event is referred to as static security. The system frequency, bus voltages, and temperature limits of the equipment must therefore remain within a reasonable range. In contrast to traditional power systems, converters specifically for HV and MV transmission lines require appropriate analysis of their thermal limits due to their restricted overloading capacity. Therefore, corrective measures must be taken to maintain system security because any contingency could lead to link overload. Additionally, after any contingency that results in the islanding of the microgrids, the distribution networks must guarantee that the power quality standards are met in addition to the voltage limitations. This is because the power quality requirements for various applications cannot be the same. Therefore, after islanding the microgrids, active and passive filters must be properly relocated in distribution networks to fulfill static security.Dynamic SecurityIn addition, the power system needs to be dynamically secure in case of an emergency. Modern power systems heavily rely on fluctuating energy sources with low inertia; hence, dynamic security is crucial. It could cause problems with voltage and frequency stability in the power systems. Without the proper voltage regulators, intermittent output power or renewable resources may degrade the grid voltage, which may impact the stability of the voltage. Furthermore, the absence of inertia in more or full renewable energy supplies may have an impact on the stability of the grid's frequency. Intercommuting to nearby grids with HVDC systems and using energy storage systems are required to resolve the frequency stability difficulties in the grid. The overall system security can control the size and placement of renewable energy sources, as well as the connection points, capacity, and ancillary services of HVDC networks. Proper system design can guarantee the entire security of the power system. As a result, just like traditional power systems, power system security evaluation calls for an analysis of voltage, frequency, and angular stability. Additionally, due to the widespread use of power electronic converters, the EMM stability difficulties in modern power systems must be taken into account in security evaluation. Power systems and microgrids may experience serious stability problems as a result of EMM interactions. Due to the quick dynamics of converter control systems, the EMM stability assessment within contingency analysis may be a challenging and time-consuming operation. Therefore, adequate models and tools for EMM stability analysis for security evaluation in modern power systems should be established.Cyber SecurityModern power systems are vulnerable to cyber-security vulnerabilities in addition to static and dynamic security problems. Cyber problems may be connected to either the decision layer or the communication and coupling layer. The physical malfunction of monitoring and measurement devices, as well as the lack of data availability, can have an impact on the system's performance at the communication and coupling layers. Additionally, cyberattacks affecting sensors and shift measurements, as well as physical failure of decision equipment that results in false data being injected into communication links, can lead to poor decisions and malfunctions in power systems. The security of the power system must be ensured against physical failure, data loss, and cyberattacks. These issues could have a number of detrimental effects on the system, including angular and frequency stability due to poor decision-making and a change in the demand-generation balance, issues with islanding detection and grid separation, as well as effects from equipment overloading, all of which could jeopardize the security of the entire system. Therefore, in security evaluation and management, it is necessary to consider the cyber-security of modern power systems.Summarizing the Key PointsThe decentralization of power grids due to renewable energy sources requires a new approach to assessing their reliability. The cyber-physical structure of the current power system consists of three layers: power, communication and coupling, and decision. The main ideas of adequacy and security are taken into account in new reliability framework. The new framework can address all the drawbacks of reliability evaluation methodologies. The cyber-security of modern power systems is a crucial consideration in security evaluation and management.ReferencePeyghami, Saeed, Peter Palensky, and Frede Blaabjerg. “An Overview on the Reliability of Modern Power Electronic-Based Power Systems.” IEEE Open Journal of Power Electronics 1 (2020): 34–50 https://doi.org/10.1109/ojpel.2020.2973926.