Essential Guide to MLCC Capacitors: Types, Benefits, and Applications

Key takeaways

  • MLCCs are compact, low-ESR capacitors built from stacked ceramic dielectrics and metal electrodes—ideal for decoupling, filtering, RF, and timing.
  • Pick Class I (C0G/NP0) for precision and stability, and Class II (X7R/X5R/Y5V) for higher capacitance density.
  • Apply DC-bias and temperature derating (often choose 2–4× the nominal value you need) and leave voltage margin.
  • Match the case size to your voltage, ripple/ESR, and mechanical-stress constraints. See the full MLCC size chart (1515–13060).

What is an MLCC?

A multilayer ceramic capacitor (MLCC) is a stack of alternating ceramic dielectric layers and metal electrodes, co-fired into a single SMD component (0402, 0603, 0805, 1206, etc.). Ceramic construction yields very low ESR/ESL, excellent high-frequency behavior, and a small footprint compared to film or electrolytic capacitors of the same value.

Why MLCCs are popular

  • Low ESR & ESL → great for high-frequency decoupling and filtering
  • Small footprint → dense layouts and mobile/IoT boards
  • Wide voltage range → from a few volts to hundreds (depends on size/dielectric)

MLCC dielectric classes (and when to use each)

Class I (e.g., C0G/NP0)

  • Stability: Excellent. Minimal change over temperature, voltage, or time
  • Losses: Very low (good Q), low microphonics
  • Capacitance range: Small (pF to low nF, sometimes tens of nF)
  • Best for: Precision/RF, timing, filters, resonant circuits, low drift

Class II (e.g., X7R, X5R, Y5V)

  • Stability: Moderate to poor vs Class I
  • Losses: Higher; microphonics possible (piezoelectric effect)
  • Capacitance range: Much higher (nF to tens of µF in SMD)
  • Best for: Bulk decoupling/bypass, general filtering where value drift is acceptable

Quick comparison (rule-of-thumb)

Property C0G/NP0 (Class I) X7R (Class II) X5R (Class II) Y5V (Class II)
Typical stability ★★★★★ ★★★☆☆ ★★★☆☆ ★☆☆☆☆
Capacitance density ★☆☆☆☆ ★★★☆☆ ★★★★☆ ★★★★★
Temp rating (typ.) 0±30 ppm/°C −55 to +125 °C −55 to +85 °C −30 to +85 °C
DC-bias sensitivity Very low Medium–High High Very high
Common uses RF, timing, precision Decoupling, general High-density decoupling Space-saving, non-critical

Always confirm exact specs in the manufacturer datasheet.

DC-bias derating (the pitfall everyone hits)

Class II MLCCs lose capacitance as DC voltage is applied. The smaller the case and the higher the dielectric constant (X7R/X5R), the more drop you’ll see.

Practical rule-of-thumb

  • If you need Crequired = 1 µF at 3.3 V in a small case (e.g., 0402 X5R), pick 2–4 µF nominal so that under bias and temperature, the effective capacitance stays ≥ 1 µF.
  • Prefer larger cases (0603/0805) for less bias loss at the same nominal value.

Tip: If the value is critical across voltage and temperature, step up to C0G/NP0 (accepting a lower nominal capacitance) or use multiple parts in parallel.

Voltage rating & headroom

  • Choose a voltage rating with ≥ 2× headroom over your maximum steady DC voltage.
  • For pulsed or surge environments, increase margin or consider soft-termination and surge-rated series.
  • Higher voltage parts often require larger case sizes (0805, 1206, 1210, etc.).

Case sizes & coding (0402–1210+)

Case size affects voltage capability, bias derating, ESR/ESL, and mechanical robustness. For full dimensions, thickness, and electrode band data, see the MLCC size chart (1515–13060).

General guidance

  • 0402/0603: Great near fast IC pins; watch DC-bias loss and handling damage.
  • 0805/1206: Better voltage margin and lower bias loss; more robust to flex.
  • Larger packages (1210/13060): Higher voltage or special apps; manage board stress.

Selection workflow (5 quick steps)

  1. Define the job: Decoupling, bulk energy storage, RF coupling, timing, or filter? Required frequency band?
  2. Set the effective C target: Determine C at operating voltage and temperature (not just nominal). Use datasheet DC-bias curves.
  3. Pick dielectric: Class I (C0G/NP0) for stability/precision; Class II (X7R/X5R) for density/decoupling.
  4. Choose voltage & case size: Apply ≥ 2× voltage margin, then pick a case that meets bias/ESR/ESL and mechanical needs.
  5. Check reliability & layout: Consider flex cracking risks, soft termination, pad design, and mounting location.

Common applications

High-speed digital decoupling

  • Place small case MLCCs (0402/0603) as close as possible to VDD/GND pins.
  • Use several values (e.g., 100 nF + 1 µF) to cover a broader frequency band.
  • Parallel parts reduce ESR/ESL further.

Power supply input/output filtering

  • Use larger case X7R/X5R for bulk energy; add a small C0G in parallel to catch HF ripple.
  • Verify ripple current and self-resonant frequency in your frequency range.

RF & precision networks

  • C0G/NP0 for VCOs, filters, oscillators, and precision timing where drift is unacceptable.

Automotive/harsh environments

  • Consider AEC-Q200 components, soft-termination, and derate aggressively for temperature and surge.

Reliability & failure modes

Flex cracking

  • MLCCs can crack from board bending or thermal/mechanical stress.
  • Mitigate with soft-termination, proper pad design, avoid corners/edge-mounting, and support panels during depanelization.

Dielectric breakdown / over-voltage

  • Respect the voltage rating and transients; add transient suppression if needed.

Microphonics (“singing”)

  • Class II ceramics are piezoelectric; electrical ripple can cause physical vibration.
  • Use C0G, change mounting/orientation, or damp mechanically if audible noise matters.

Soldering & handling guidelines (quick checklist)

  • Storage: Keep dry; follow MSL guidance where applicable.
  • Preheat: Limit thermal shock; follow reflow profile.
  • Placement: Keep away from board edges; add slots near connectors if flexing is expected.
  • Cleaning: Avoid residues that could lead to leakage paths.
  • Inspection: X-ray/optical on critical builds to detect cracks or tombstoning.

When not to use an MLCC (and what to use instead)

  • Need very high, stable capacitance with low bias sensitivity → consider film (stable, larger).
  • Need hundreds of µF in small form → polymer electrolytic or tantalum polymer (watch ripple/ESR limits).
  • Need ultra-low loss at audio or power frequencies with no piezo effects → film capacitors.

FAQ

Are MLCCs polarized?

No. MLCCs are non-polarized and can be installed either way. Always honor the voltage rating and derating guidance.

C0G/NP0 vs X7R: which should I choose?

Choose C0G/NP0 for stability/precision (RF, timing). Choose X7R/X5R for higher capacitance in tight spaces (decoupling, bulk bypass).

How much derating is enough?

A common starting point is 2–4× the required capacitance for Class II to cover DC-bias and temperature; verify against the datasheet’s curves.

0402 vs 0603 vs 0805—what changes?

Larger cases usually mean better voltage headroom, less bias loss, lower ESL, and better mechanical robustness, at the cost of board area.

Why do some MLCCs “sing”?

Class II ceramics are piezoelectric; ripple can cause audible vibration. Solutions: shift to C0G where feasible, alter mounting, or mechanically damp.