Electrolytic, ceramic or tantalum?

Electrolytic vs ceramic (MLCC) vs tantalum capacitors: capacitance, polarity, ESR, lifespan, where each one goes, common mistakes and an ESR simulator.

Short answer

Use electrolytics for large, cheap storage, and ceramics for 100 nF decoupling next to supply pins and for high frequencies. Choose tantalum only when you need high capacitance in a small space, and leave twice the voltage margin.

Comparison

	Electrolytic (aluminium)	Ceramic (MLCC)	Tantalum
Capacitance range	1 µF – 10,000 µF and up	1 pF – a few tens of µF	0.1 µF – a few hundred µF
Polarity	Polarised (stripe on the negative side)	Non-polarised	Polarised (on SMD, the striped end is positive)
Voltage	6.3 – 450 V	6.3 V – kV range	Usually 4 – 50 V
ESR	High; rises with age	Very low	Low to medium
Lifespan and failure	Shortened by heat; dries out, bulges	Very long; can crack and short if the board flexes	Long; shorts under overvoltage and can burn
Size / cost	Large, cheap	Small, cheap	Small, more expensive
Typical use	Supply filtering, energy storage	Decoupling (100 nF), high frequency, timing	Tight spaces like laptop and phone boards

Choose electrolytic if…

✓You need hundreds of µF or more
✓You're building a post-rectifier filter or energy store
✓Cost comes first

Choose ceramic if…

✓You're decoupling every IC's supply pin (100 nF)
✓You need low ESR at high frequency or on an SMPS output
✓You want a non-polarised, long-lived part

Choose tantalum if…

✓You need high capacitance in a small space
✓You can leave at least twice the voltage margin
✓The board you're repairing already uses tantalum (replace like for like)

Common mistakes

!Fitting an electrolytic or tantalum backwards. Electrolytics bulge or burst; tantalums can catch fire.
!Leaving no voltage margin. Pick a part rated at least 1.5× the working voltage (2× for tantalum).
!Fitting an ordinary electrolytic on a switch-mode supply output. Use a low-ESR, 105 °C type; an ordinary part heats up and dries out quickly.
!Not knowing about DC bias on ceramics. In X5R/Y5V types, a 10 µF part can lose half its capacitance under voltage.
!Judging a bulging or old electrolytic healthy by measuring capacitance alone. The real failure is rising ESR; check it with an ESR meter.

Try it: what happens when ESR rises?

Increase the ESR of an ageing capacitor and watch the ripple grow.

Open the simulator full page →

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