How do I start selecting a TDK EPCOS aluminum capacitor?

Fix the voltage class from your bus with margin, size the capacitance for the ripple and hold-up, then check the ripple current rating and the case size. Finally confirm the lifetime at the expected case temperature. Those decisions narrow the range quickly.

Screw-terminal or snap-in?

Use a screw-terminal capacitor for the main high-voltage DC link, where the current and the capacitance are large and a busbar connection is needed. Use a snap-in capacitor for the auxiliary and control rails and for dense boards, where it mounts directly on the PCB. Many designs use both.

How do I size the ripple current?

The capacitor carries the pulsed current of the switching stage, so check the ripple against the rating at your case temperature and frequency. Paralleling shares the ripple, so the bank rating is the sum of the individual ratings provided the sharing is even. Our FAE team can check the ripple margin.

How do I estimate the lifetime?

Aluminum electrolytic lifetime roughly doubles for every 10 °C reduction in core temperature, so estimate the core temperature from the case temperature and the ripple heating, then use the datasheet endurance and the rule. Our FAE team can run the lifetime estimate for you.

How do I start selecting a DC-link film capacitor?

Fix the voltage class from your bus with margin, size the capacitance for the ripple and hold-up, then check the current, the dV/dt and the self-inductance for your switching speed. Finally confirm the case and terminal fit. Those decisions narrow the range quickly.

When do I choose film over aluminum electrolytic?

A film capacitor does not dry out and handles high ripple and fast dV/dt with low self-inductance, so it suits long-life, high-frequency and high-reliability designs. An electrolytic offers more capacitance per volume and cost at lower frequency. Many designs combine both. Our FAE team can help partition the DC link.

Why does self-inductance matter?

At high switching speed the self-inductance of the capacitor and its busbar sets the voltage overshoot across the switches. A low-inductance film capacitor in the nanohenry range keeps the overshoot small and helps the EMC of the converter. Plan the busbar layout with the capacitor.

How do I size the DC-link capacitance?

Size the capacitance for the acceptable bus ripple and the required hold-up, then check the RMS current and the dV/dt against the capacitor rating. The energy density of the MKP DC series keeps the case small while meeting the requirement. Our FAE team can run the sizing.

How do I start selecting a snubber capacitor?

Fix the voltage class from the DC link, size the capacitance for the energy you need to absorb, then choose the lowest ESL you can and match the terminal configuration to the IGBT module. Finally plan the layout. Those decisions narrow the range quickly.

Why does ESL matter so much in a snubber?

The snubber must absorb the commutation-loop energy within a fast switching edge, so its equivalent series inductance sets how quickly it responds. Lower ESL means the snubber acts sooner and the overshoot is smaller, which is why TDK EPCOS offers parts in the single-digit nanohenry range. Keep the snubber loop short for the best result.

How do I match the terminal configuration?

The snubber is mounted directly across the IGBT module, so the terminal configuration, the hole spacing and the height must match the module. TDK EPCOS offers many configurations with hole spacings from 19.5 mm to 63 mm so a capacitor can be matched to common modules. Our FAE team can confirm the configuration for your module.

How do I size the snubber capacitance?

Size the capacitance to absorb the energy stored in the commutation-loop inductance at the current you switch, so the resulting voltage rise stays within the IGBT rating. The exact value depends on the loop inductance and the switching current, and our FAE team can help. Validate the overshoot reduction on the bench.

How do ESR and ESL affect my capacitor choice?

ESR converts ripple current into heat, so it drives the temperature rise and the life; ESL sets the high-frequency impedance and, for a DC-link or snubber, the voltage overshoot. A film capacitor has low ESR and low ESL, which suits high frequency, while an electrolytic has higher ESR but more capacitance per volume. Match the part to the frequency content of your ripple.

How do I combine film and electrolytic capacitors?

Use the electrolytic for the bulk energy and the low-frequency ripple, and add a film capacitor in parallel for the high-frequency ripple and the low-inductance path. The film part handles the fast content and the electrolytic handles the energy, which gives the best combination of density and performance. Our FAE team can size the split.

How do I lay out the capacitor bank?

Keep the commutation loop small for the film capacitors, place the electrolytics for airflow and away from heat sources, and keep the connections low-inductance. A tight layout reduces the voltage overshoot and the EMI, and a cooler layout extends the life of the electrolytics. Request a layout review.

My capacitor has lost capacitance. Why?

Capacitance loss is the normal aging of an aluminum electrolytic, and it accelerates with core temperature and ripple. If the loss is faster than expected, check the ripple margin and the case temperature, and verify the capacitor is not operating above its voltage or reverse-biased. Our FAE team can review the operating conditions.

My capacitor is running hot. What should I check?

Check the ripple current against the rating at the case temperature, the local ambient near the capacitor, and the airflow. A hot capacitor is usually carrying too much ripple, sitting near a heat source, or starved of airflow. Recheck the derating and the layout. Measure the case temperature at worst-case load.

The capacitor vented or failed. What caused it?

Venting usually follows an over-voltage, a reverse voltage, an over-temperature or excessive ripple that dried the electrolyte. Check the applied voltage against the rating with margin, confirm the polarity, and verify the ripple and temperature are within limits. A single failure often points to a bank imbalance.

The film capacitor shows high overshoot. What should I check?

Check the layout, not the capacitor. A film capacitor's benefit depends on a low-inductance loop, so a long busbar or a wide loop defeats it. Keep the commutation loop small and measure the overshoot at the switch terminals. Our FAE team can review the layout.

What is the standout feature of the TDK EPCOS range?

The standout feature is the breadth of the range across all four power-capacitor types: screw-terminal and snap-in aluminum electrolytics, low-inductance DC-link film capacitors and low-ESL snubbers, in a consistent quality and with good documentation. That lets one distributor cover the whole DC link and the snubber. The main design care points are ripple, temperature and layout.

How does film compare with electrolytic in practice?

In practice a film capacitor is chosen for the high-frequency bus and the snubber because it is low-ESL and does not dry out, while an electrolytic is chosen for the bulk energy because it offers more capacitance per volume and cost. Modern designs use both in the same DC link. Our FAE team can help partition the DC link.

Does the low-ESL snubber really reduce overshoot?

Yes, when it is mounted correctly. On the bench a low-ESL snubber with a tight loop reduced the IGBT turn-off overshoot by a significant margin, while the same capacitor with a long loop helped much less. The layout is part of the snubber. Measure the overshoot at the switch terminals.

Can I get samples to evaluate?

Yes. We provide samples of the TDK EPCOS capacitors for your own ripple, temperature and overshoot testing, with documentation included and FAE support during bring-up. Request a sample and we will confirm stock and lead time.

Technical Support | TDK Expertise | BeiLuo

Guides, application notes, troubleshooting and reviews from BeiLuo's FAE team covering TDK EPCOS aluminum electrolytic, DC-link film and snubber capacitors.

Guides 3 Application Notes 1 Troubleshooting 1 Reviews 1

How to Select a TDK EPCOS Aluminum Capacitor

2026-07-26 - Guides - By Zhang Wei Lin

Compare TDK EPCOS screw-terminal and snap-in aluminum electrolytic capacitors by voltage, capacitance, ripple, case size and lifetime for your design task.

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How to Select a DC-Link Film Capacitor

2026-07-21 - Guides - By Li Hao Chen

A practical method for selecting TDK EPCOS DC-link film capacitors by voltage, capacitance, self-inductance and current for inverter and converter power stages.

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How to Select an IGBT Snubber Capacitor

2026-07-16 - Guides - By Li Hao Chen

Choose TDK EPCOS low-inductance snubber capacitors by voltage, capacitance, ESL and terminal configuration to protect IGBT modules against overvoltage.

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TDK EPCOS Capacitor Application and ESR Notes

2026-07-11 - Application Notes - By Wang Yu Bo

Ripple, ESR, self-inductance and lifetime guidance for designing reliable TDK EPCOS aluminum electrolytic and film capacitor banks in power converters.

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Troubleshooting TDK EPCOS Capacitors: A Fault Guide

2026-07-04 - Troubleshooting - By Wang Yu Bo

A systematic method for diagnosing capacitance loss, overheating, venting, overvoltage and mounting problems in TDK EPCOS aluminum electrolytic and film capacitors.

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TDK EPCOS Power Capacitors: A Practical Review

2026-06-27 - Reviews - By Zhang Wei Lin

A hands-on review of TDK EPCOS aluminum electrolytic, DC-link film and snubber capacitors, covering ripple, lifetime, self-inductance and layout practice.

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Meet Our FAE Team

Zhang Wei Lin

Senior FAE Engineer, Power Capacitors

Screw TerminalRippleInverters

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Li Hao Chen

FAE Engineer, Film and Snubber

DC-Link FilmSnubberEMC

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Wang Yu Bo

FAE Engineer, Applications

LifetimeThermalReliability

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