Multi-layer ceramic capacitor (MLCC) — Failure Modes & Failure Rate

Non-polarised, surface-mount capacitor used for decoupling and high-frequency filtering. Failure rate dominated by mechanical cracking from PCB flexure and thermal cycling — not by chemistry. Very low λ on a per-part basis, but high-volume use makes them a real contributor in dense designs.

λ typical

2.0×10-9 / h

Range

5.0×10-10 – 1.0×10-8

Source

SN 29500-3

Failure modes

Mechanical crack

Root causes: PCB flexure during depanelisation, mounting-screw torque, drop / shock; coefficient-of-thermal-expansion mismatch between component and PCB during reflow or thermal cycling.
Detection: Often invisible until the crack propagates and the part fails open or short. X-ray or cross-section can detect early.
Mitigation: Place sensitive MLCCs away from PCB edges and depanelisation rails; use flex-cracker resistant lead-frame or polymer-terminated parts; specify case sizes ≤1210 in flexure-prone areas; leave ≥5 mm clearance from breakaway tabs.

Short-circuit

Root causes: Crack propagating through the dielectric layers; silver-electrode migration under DC bias and humidity (older constructions); voltage transient exceeding withstand.
Detection: Excess current draw on the rail; localised heating; sometimes a visible burn mark.
Mitigation: Voltage derating to 50% of rated; transient protection upstream; specify Class I (NP0) over Class II (X7R/X5R) where DC-bias stability matters.

Capacitance drift

Root causes: Class II dielectrics (X7R, X5R, Y5V) lose capacitance with applied DC voltage and over time — the V-bias and ageing coefficients can each cost 20–80% of rated value.
Detection: In-circuit measurement at operating bias shows much less than the rated nameplate value.
Mitigation: For timing or filter applications, use Class I (NP0/C0G); when forced into Class II, design to the de-rated value, not the nameplate.

Typical applications

IC decoupling, EMI filtering, high-frequency bypass, snubbers, charge pumps. Every modern PCB carries dozens to hundreds. Dominates capacitor count in mobile and consumer electronics.

How to model in a fault tree

For typical decoupling bulk, individual MLCCs are usually modelled as a homogeneous group with a combined λ — the loss of any one decap rarely defeats a function. For specific safety-critical roles (timing reference, isolation barrier crossing, gate-drive bootstrap), model the specific MLCC as its own basic event and apply Beta-CCF if the role is duplicated across redundant channels using the same part type and orientation.