EPCOS Capacitor Guide: Power & Film Solutions for Industrial and Automotive Electronics

If you’ve been designing power electronics for more than a few years, you’ve worked with an EPCOS capacitor at some point — probably without realizing it. EPCOS is the brand name under which TDK Electronics sells its power and film capacitors globally, following TDK’s acquisition of EPCOS AG in 2009. Today, EPCOS and TDK capacitors coexist as sister brands within TDK Electronics, with EPCOS specifically associated with aluminum electrolytic capacitors, film capacitors (MKP and MKT), EMI suppression X/Y safety capacitors, and large power capacitors for industrial applications. Understanding which product families live under the EPCOS brand — and which design tools TDK provides for them — is practical knowledge that saves real sourcing and design validation time.

This guide covers the EPCOS capacitor portfolio from a working PCB and power electronics perspective: the key product families, the B-series part numbering that organizes the catalog, where each technology is most appropriate, and the free simulation tools TDK provides that most engineers underuse.

EPCOS and TDK: Understanding the Brand Structure

EPCOS was founded in 1999 as a spin-off from Siemens AG to commercialize passive electronic components. TDK acquired EPCOS in 2009, creating TDK Electronics, and has since operated EPCOS as a product brand within that structure. When you’re searching for an EPCOS capacitor by part number — something starting with B25, B32, B33, B41, or B43 — you’re navigating a catalog that is now officially part of TDK Electronics but retains EPCOS brand identity and B-series part numbering for continuity.

The practical takeaway: shop for EPCOS capacitors on TDK Electronics’ product portal (tdk-electronics.tdk.com) or TDK Product Center (product.tdk.com). Distributor listings at DigiKey and Mouser typically show “EPCOS / TDK” or “EPCOS – TDK Electronics” as the manufacturer name, and all technical support flows through TDK’s engineering team and their online design tools.

EPCOS Capacitor Product Families: The B-Series Overview

EPCOS organizes its capacitor portfolio using a B-series numbering system. Once you understand the basic groupings, navigating the catalog becomes straightforward.

B-Series Range	Product Family	Technology	Typical Application
B32xxx	Film capacitors	MKP (PP), MKT (PET), EMI X/Y	AC mains filtering, DC coupling, EMI suppression
B33xxx	AC film capacitors	MKP polypropylene	Motor run, power factor correction
B25xxx	Power capacitors	MKP, large format	Industrial inverters, wind/solar, traction
B40xxx	Hybrid aluminum electrolytic	Polymer/liquid hybrid	Power supplies, high-frequency ripple
B41xxx	Aluminum electrolytic, large size	Wet aluminum	Industrial drives, UPS, screw terminal
B43xxx	Aluminum electrolytic, snap-in	Wet aluminum	Frequency converters, SMPS, OBC

This table is not exhaustive — EPCOS produces several dozen distinct sub-series within each B-series group — but it gives you the orientation most engineers need to stop guessing and start searching efficiently.

EPCOS Film Capacitors: MKP and MKT Series

Film capacitors are EPCOS’s deepest product category and the area where their engineering heritage is strongest. The two core dielectric technologies are metallized polypropylene (MKP) and metallized polyester / polyethylene terephthalate (MKT). Each has a fundamentally different performance profile, and choosing the wrong one for your circuit position is a common mistake.

## MKP (Metallized Polypropylene) Film Capacitors

Polypropylene is the premium dielectric for film capacitors. It delivers the lowest dissipation factor (tan δ) of any standard film dielectric — typically 0.0001 to 0.0005 at 1 kHz, orders of magnitude lower than polyester. That matters in three specific circuit positions: snubber networks where heat dissipation in the capacitor body directly affects system efficiency, resonant circuits where capacitor losses degrade Q factor, and high-frequency DC bus filtering where ESR-generated heat limits ripple current handling.

EPCOS MKP film capacitors also exhibit self-healing behavior — when a localized dielectric breakdown occurs from a voltage spike, the thin metallized electrode vaporizes around the fault site and the capacitor continues functioning with a minor capacitance loss. This safe-fail property is essential in power electronics where transient overvoltages are routine.

Key EPCOS MKP series for general power electronics (B32674, B32676, B32678 and the B327xx DC link family) cover voltage ratings from 250V DC to 1,200V DC and capacitance values up to several hundred microfarads in the larger can sizes. The B32671P, B32672P, B32673P series (low-profile MKP) are specifically designed for applications where board height is constrained — power supplies and frequency converters with tight Z-height requirements.

EPCOS also introduced the B3271xP series DC link film capacitors in 2025, specifically targeting high-temperature automotive and industrial applications. This series offers a maximum operating temperature of +125°C with no power derating up to +105°C — a meaningful advance for xEV traction inverters, on-board chargers, and DC-DC converters where elevated ambient temperatures and continuous ripple loads are common. Capacitance values cover 0.47 µF to 110 µF at rated DC voltages from 600V to 1,200V.

## MKT (Metallized Polyester) Film Capacitors

Polyester film capacitors trade the low-loss performance of polypropylene for higher capacitance per unit volume and lower cost. MKT is the right choice for general-purpose DC coupling, bypass in signal-path circuits, timing capacitors in lower-frequency applications, and any position where the capacitor sees no significant AC ripple or pulse current.

EPCOS MKT series B32520 through B32529 cover standard pitch through-hole configurations from 5mm to 27.5mm lead spacing, with voltage ratings from 50V DC to 630V DC and capacitance from 1nF to 10µF. The B32560/B32561 series covers compact 10mm pitch MKT for space-constrained PCB designs.

Do not use MKT in snubber or motor run positions. The higher dissipation factor generates heat under ripple current that polyester dielectric cannot handle as reliably as polypropylene. That’s not opinion — it’s a direct consequence of the dielectric material properties.

## MMKP Series: Double-Metallized Polypropylene

The EPCOS MMKP series uses a film that is metallized on both sides — a construction that allows exceptionally compact body dimensions for a given capacitance and voltage rating. These parts target applications where board space is the primary constraint and polypropylene dielectric performance is still required, such as compact SMPS output filtering and small inverter snubber positions.

EPCOS EMI Suppression Capacitors: X2 and Y2 Safety Classes

EMI suppression capacitors are a large and technically specific product segment within the EPCOS catalog. The distinction between X-class and Y-class capacitors is not just a specification difference — it has direct implications for product safety certification and regulatory compliance.

## X2 Safety Capacitors: Across-the-Line Applications

X-class capacitors are connected directly across the AC mains line (line to line) to suppress differential-mode interference. The safety requirement is that an X-class capacitor must fail safely — on failure, it must not create a fire hazard or electric shock risk. X2-rated capacitors are approved for applications with peak impulse voltages up to 2.5 kV and rated voltages up to 305 VAC (X1 class goes to 4 kV impulse for higher-voltage mains).

EPCOS B32921 through B32928 are the standard X2 MKP series, covering capacitance from 0.001 µF to 15 µF with lead spacings from 10mm to 37.5mm. The key specification is maximum operating temperature: standard X2 series is rated to +110°C, while the B3292xP/Q series (high-temperature X2) extends this to +125°C. In motor drives, HVAC equipment, EV on-board chargers, and solar microinverters where ambient temperatures near the mains input filter can exceed standard limits, the +125°C X2 series is the correct specification. These parts carry AEC-Q200D qualification, making them suitable for automotive EMI filter applications as well.

TDK extended its X2 safety film capacitor portfolio in 2025 with the B3292xU/V series, rated at 350V AC — an increase from the standard 305V rating — covering compact lead spacings of 15mm and 22.5mm. This 350V rating addresses interference suppression in demanding industrial and automotive environments where mains line voltages can exceed 305V nominal, including OBC applications, EV charging systems, and PV inverters.

## Y2 Safety Capacitors: Line-to-Ground Applications

Y-class capacitors are connected from line to earth ground (or neutral to ground) for common-mode noise suppression. Y2-class parts are rated for peak impulse voltages of 5 kV and must pass stringent insulation resistance and high-voltage tests because a Y-capacitor failure that results in ground isolation loss creates a shock hazard.

EPCOS MKP-Y2 series (B32021 through B32026) cover capacitance from 1nF to 1µF at 300 VAC, in standard lead spacings from 10mm to 37.5mm. Like the X2 high-temperature series, EPCOS also offers a B3202xH/J Y2 series rated to +125°C for automotive and high-temperature industrial applications, also AEC-Q200D qualified. All EPCOS X/Y safety capacitors are certified to IEC 60384-14, UL, EN (ENEC), and CQC standards — the complete set of safety approvals needed for major markets.

Safety Class	Connection	Impulse Voltage	Max VAC	EPCOS Series	Max Temp
X1	Line to line	4 kV	305 / 400	B81123	+110°C
X2	Line to line	2.5 kV	305	B32921–B32928	+110°C
X2 High-Temp	Line to line	2.5 kV	305	B3292xP/Q	+125°C
X2 High-Voltage	Line to line	2.5 kV	350	B3292xU/V	+125°C
Y2	Line to earth	5 kV	300	B32021–B32026	+110°C
Y2 High-Temp	Line to earth	5 kV	300	B3202xH/J	+125°C

A common design mistake: using an X2 capacitor in a Y-position because it was already in the BOM. These are not interchangeable — X and Y classes have different failure mode requirements enforced through different construction and test standards. Mixing them in a design creates a certification problem that will not survive safety agency review.

EPCOS Aluminum Electrolytic Capacitors: Snap-In, Screw Terminal, and Large Size

The EPCOS aluminum electrolytic capacitor line covers everything from compact PCB-mount snap-in parts for SMPS and industrial frequency converters, through screw-terminal DC link capacitors for large inverters, to giant can formats for three-phase power factor correction banks.

## Snap-In Series: B43xxx for Power Electronics

The B43xxx snap-in series is the mainstream EPCOS aluminum electrolytic offering for power electronics applications — frequency converters, industrial power supplies, UPS systems, medical equipment, PV inverters, and EV on-board chargers.

Key recent series in the B43xxx family include:

Series	Voltage Range	Capacitance	Max Temp	Key Feature
B43548	400–500V	68–820 µF	105°C	High ripple up to 9.80A, fast charge/discharge
B43647	450V	120–1,000 µF	105°C	High CV product, compact case
B43657	450–475V	120–1,250 µF	105°C	Extremely high capacitance density
B43658	Various	Various	105°C	Ultra-compact design, -40 to +105°C
B43659	Various	Various	105°C	High reliability, high ripple, -40 to +105°C
B43655/B43656	400/450V	Various	105°C	AEC-Q200 Rev.E, OBC-optimized DC link

The B43655 and B43656 series (February 2026 release) are specifically designed for on-board chargers in electric vehicles, with AEC-Q200 Rev.E qualification and optimized thermal performance for OBC topologies. The B43655 delivers useful life of more than 3,000 hours at +105°C, with ripple current capability up to 3.29A at +105°C and ESR values down to 100 mΩ. The B43656 at 450V handles up to 4.42A at +105°C for higher-power OBC designs. These are the most current-optimized standard snap-in parts in the EPCOS OBC portfolio.

For all B43xxx snap-in parts, EPCOS provides the AlCap online lifetime calculation tool — described in detail in the design tools section below. Specifying an aluminum electrolytic capacitor without running its actual operating conditions through AlCap is leaving reliability verification on the table.

## Large-Size and Screw-Terminal Series: B41xxx

The B41xxx series covers large-can aluminum electrolytic capacitors with screw-terminal or multi-pin connections for industrial drive systems, large UPS, wind turbines, and railway traction electronics. B41231 (snap-in, large size) reaches capacitance values up to 22,000 µF at 35V DC — the kind of bulk energy storage that feeds large motor drive input stages. B41605 represents the large-size screw-terminal category, used in three-phase inverters and large DC power supplies where capacitor banks provide the DC bus energy storage.

The AEC-Q200 qualified large-size series within B41xxx targets industrial and automotive applications with formal qualification requirements. EPCOS notes that large-size aluminum electrolytic capacitors qualified based on AEC-Q200 are particularly suitable for on-board charger applications due to their compact design and high ripple current capability.

## B40xxx Hybrid Polymer Aluminum Electrolytic Capacitors

The B40xxx hybrid series is EPCOS’s answer to the performance gap between standard wet aluminum electrolytics and full polymer capacitors. Hybrid construction combines a liquid aluminum electrolyte (providing stable long-term capacitance) with a polymer layer (providing dramatically lower ESR and better high-frequency performance than liquid-only construction).

Series	Rated Temp	Life at Max Temp	Key Feature
B40910	135°C	4,000 h	Ultra-high temperature, miniaturized
B40930	125°C	—	Hybrid polymer, compact
B40950	105°C	10,000 h	Long life, low impedance, miniaturized

The B40950 is particularly notable — 10,000 hours at +105°C exceeds the typical wet electrolytic life spec (2,000–5,000 hours) by a factor of two or more. For industrial infrastructure applications where capacitor replacement is impractical or impossible, that additional life margin directly reduces total cost of ownership.

EPCOS Power Capacitors: B25xxx for Industrial Inverters and Renewable Energy

The B25xxx series represents EPCOS’s large-format, high-power film capacitors for industrial-scale power electronics. These are not PCB-mount components — they’re large cylindrical or box-format parts for DC link filtering in megawatt-class drives, wind turbine converters, solar central inverters, and railway traction equipment.

Key product families include B25655, B25620, B25623, B25640, B25650, and B25750, covering capacitances from tens of microfarads up to thousands of microfarads at DC voltages from 700V to over 1,500V depending on the series. These parts use polypropylene (MKP) film dielectric for its low dissipation factor and self-healing properties.

The most recent addition to the B25xxx family relevant to advanced power systems is the ModCap UHP series (B25648). ModCap UHP uses a BOEPN (biaxially oriented ethylene-naphthalate) dielectric film that enables operation at higher temperatures and current densities without derating, compared to the standard BOPP film used in ModCap HF (B25647). ModCap UHP targets energy storage systems, central solar inverters, electrolyzers, high-power DC-DC converters, and auxiliary drives using SiC semiconductors. The dielectric film is ISCC-certified bio-circular BOPP, addressing sustainability requirements increasingly included in procurement specifications.

ModCap’s cubic design simplifies busbar integration, increasing power density in compact converters and reducing the need for additional snubber capacitors. TDK provides SPICE model libraries and the web-based CAP Thermal simulation tool for thermal performance analysis of ModCap products under real operating conditions.

EPCOS Capacitor Part Number Structure: Reading the B-Series Code

EPCOS part numbers follow a consistent structure that encodes type, voltage, and capacitance once you know the pattern. Taking a concrete example: B32922C3474K000

Position	Value	Meaning
B	Product brand	EPCOS (formerly B-series)
32	Technology group	Film capacitor
9	Sub-family	MKP EMI suppression
22	Product series	X2, 305VAC rated
C	Design variant	Specific construction/approval variant
3	Voltage multiplier prefix	—
474	Capacitance code	47 × 10⁴ pF = 470 nF
K	Capacitance tolerance	±10%
000	Packaging and terminal variant	Standard bulk

The capacitance code uses the standard three-digit EIA system: the first two digits are significant figures, the third is the power of ten in picofarads. So 474 = 47 × 10⁴ pF = 470 nF. Tolerance codes follow IEC standard: J = ±5%, K = ±10%, M = ±20%.

For aluminum electrolytics (B4xxxx), the structure is different — the middle digits encode voltage and capacitance in a proprietary code that requires the datasheet table for decoding. When in doubt with an EPCOS aluminum electrolytic part number, the TDK Product Center parametric search is faster than manual decode.

EPCOS Capacitor Selection by Application

Application	Recommended EPCOS Series	Key Selection Criterion
AC mains EMI filtering (standard)	B32921–B32928 (X2 MKP)	Safety approval, 305VAC rating
AC mains EMI, 125°C or automotive	B3292xP/Q (X2 high-temp)	AEC-Q200D, +125°C
AC mains 350VAC environments	B3292xU/V (X2 350V)	Higher impulse voltage rating
Line-to-ground EMI suppression	B32021–B32026 (Y2 MKP)	Y2 class safety approval
DC coupling / general bypass	B32520–B32529 (MKT)	Cost-effective, standard DC use
Snubber / resonant / motor run	B32674 / B32676 (MKP)	Low dissipation factor PP dielectric
Compact MKP for tight height	B32671P–B32673P (low-profile MKP)	Z-height constrained designs
DC link, standard industrial	B327xx / B32671–B32678 (MKP)	High voltage, self-healing, ripple
DC link, high-temp +125°C	B3271xP (MKP high-temp)	No derating to +105°C
Large-scale industrial DC link	B25xxx ModCap (power caps)	kW-to-MW class inverters
SMPS bulk decoupling (PCB)	B43xxx snap-in aluminum	Snap-in, high CV, ripple capability
OBC DC link (automotive)	B43655 / B43656	AEC-Q200 Rev.E, OBC thermal profile
Industrial drive large DC bus	B41xxx screw/large-size	High voltage, large capacitance
SMPS with high-freq ripple	B40950 hybrid polymer	Low ESR, 10,000h life at 105°C
High-temp automotive power	B40910 hybrid polymer	4,000h at 135°C

EPCOS Design Tools: AlCap, CLARA, FilmCap, and CAP Thermal

TDK/EPCOS provides some of the most capable free design tools in the passive component industry. For power electronics designs, not using them is a genuine mistake.

AlCap (Online Aluminum Electrolytic Capacitor Useful Life Calculation Tool) — AlCap calculates useful life for a selected EPCOS aluminum electrolytic capacitor under application-specific load conditions. It covers all high-voltage capacitors (>150V DC) with screw, snap-in, and solder pin connections, and allows up to 15 simultaneous load profiles for capacitor bank designs. Beyond lifetime, it outputs hot-spot temperature, power dissipation, and related thermal data. For custom types, entering the CSC code from the datasheet triggers calculation for that specific capacitor. Any power supply, inverter, or drive design using EPCOS aluminum electrolytics should have its DC link capacitor validated in AlCap before finalizing the BOM.

CLARA (Capacitor Life And Rating Application) — CLARA is TDK’s simulation tool for EPCOS and TDK film capacitors for PCB mounting. It provides parametric search across capacitance, voltage, RMS and peak current, temperature, dimensions, approvals, and typical applications, with simulation of up to four capacitors simultaneously under application conditions. CLARA generates operating temperature, DC voltage, AC voltage, peak current, and expected service life for each candidate part side by side. STEP files and SPICE simulation data are available for the majority of capacitors within CLARA. Access it at tdk-electronics.tdk.com/clara.

FilmCap Service Life Calculation Tool — The FilmCap tool specifically covers EPCOS film capacitors for DC link circuits of inverters (B3267x and B3277x series, approximately 250 standard types). Like AlCap, it accepts up to 15 load profiles simultaneously and supports CSC code entry for custom types. The integrated smart search feature lets engineers enter key load parameters (voltage, current, temperature, frequency) to identify suitable part numbers — a particularly useful starting-point when you don’t yet have a specific series in mind.

CAP Thermal — TDK’s CAP Thermal simulation tool calculates the thermal performance and lifetime of power capacitors (B25xxx ModCap and large-format series) under real operating conditions. For inverter and drive designers working with large-format film capacitors, thermal validation is as important as electrical specification — a capacitor operating at its thermal limit will fail early regardless of whether its electrical ratings are met on paper.

These four tools represent a complete validation workflow: CLARA for film capacitor selection and life estimation on PCB-mounted parts, FilmCap for DC link film capacitors, AlCap for aluminum electrolytics, and CAP Thermal for large power capacitors.

Useful Resources for EPCOS Capacitors

Official TDK / EPCOS Product Portals and Catalogs

• TDK Electronics Film Capacitor Catalog — Complete EPCOS film capacitor product catalog with parametric search
• TDK Electronics Aluminum Electrolytic Capacitor Search — Parametric search for all EPCOS aluminum electrolytic series
• TDK Power Capacitors (B25xxx) — ModCap and large-format industrial power capacitor catalog
• TDK Snap-In Capacitor Product Page — B43xxx series with full specs, AEC-Q200 status, and newest OBC-optimized series

Design Tools (Free)

• CLARA Film Capacitor Design Tool — Life simulation and selection for EPCOS/TDK PCB film capacitors
• AlCap Aluminum Electrolytic Life Calculator — Online useful life calculation for EPCOS aluminum electrolytics
• TDK Electronics Design Tools Overview — Complete index of tools including FilmCap, CAP Thermal, Snubber Cap Finder

Key Datasheets and Application Documents

• EPCOS X2 MKP B32921–B32928 Datasheet — Safety certifications, humidity performance, application position guide
• EPCOS MKP-X2 High-Temperature Series Overview (DigiKey) — B3292xP/Q series, 125°C rating, AEC-Q200D qualification details
• EPCOS Y2 High-Temperature Series Overview (DigiKey) — B3202xH/J series, 125°C Y2, AEC-Q200D details
• EPCOS Film Capacitors Overview (DigiKey) — Self-healing, current capability, and series comparison overview

Distributor Parametric Search

• Mouser EPCOS/TDK Aluminum Electrolytics — Full lineup with newest B43xxx OBC series and hybrid B40xxx
• DigiKey EPCOS/TDK Capacitors — Full portfolio search with live inventory and datasheet links

5 Frequently Asked Questions About EPCOS Capacitors

Q1: What is the difference between EPCOS X2 and Y2 capacitors, and can I use them interchangeably?

X2 and Y2 capacitors are fundamentally different safety classes and cannot be used interchangeably. X-class (X1, X2) capacitors are connected across the AC line — between live and neutral — to suppress differential-mode interference. On failure, they must be designed not to ignite or cause electric shock. Y-class (Y1, Y2) capacitors are connected from live or neutral to protective earth ground to suppress common-mode interference. Y-class failure requirements are more stringent because a Y capacitor fault that breaks ground isolation creates a direct shock hazard. Safety agencies test and certify each class separately — a product with an X2 capacitor placed in a Y circuit position will fail safety certification regardless of its electrical performance. Always confirm the safety class matches the circuit position during design review, and verify the safety approval marks (IEC 60384-14, UL, ENEC) on the specific part you’re specifying.

Q2: How do I select between EPCOS MKP and MKT film capacitors for a power supply filter position?

The decision comes down to the AC ripple current the capacitor sees and the required dissipation factor. MKT (polyester) is appropriate for pure DC coupling, signal path blocking, and bypass positions where the capacitor sees no significant ripple current. It offers higher capacitance per unit volume and lower cost than MKP. MKP (polypropylene) is required for any position with meaningful AC ripple — snubber networks, resonant circuits, motor run, and DC bus filtering in switching power supplies and inverters. Polypropylene’s dissipation factor is 10–100× lower than polyester, so under ripple current conditions, an MKT capacitor will heat significantly more than an MKP of identical rating. That self-heating accelerates aging and ultimately reduces service life. If there’s any doubt about the AC current content at a given circuit node, use MKP. The cost difference rarely justifies the reliability risk from using MKT in a current-stressed position.

Q3: When should I use the EPCOS B40xxx hybrid polymer aluminum electrolytic series instead of standard B43xxx wet electrolytics?

Use the B40xxx hybrid series when you need lower ESR at high frequencies and better ripple current handling than wet aluminum electrolytics provide, without paying the full cost premium of pure polymer capacitors. The hybrid series maintains the stable long-term capacitance of wet electrolyte construction while the polymer layer dramatically reduces high-frequency ESR. For power supply designs operating at switching frequencies above 50–100 kHz where the bulk of ripple current is at those frequencies, standard wet electrolytics become inefficient — most of the ripple current generates heat rather than being filtered. The B40950’s rated life of 10,000 hours at +105°C is also a practical advantage for industrial equipment where access for capacitor replacement is difficult. The tradeoff is cost and reduced capacitance per unit volume compared to equivalent wet electrolytic parts. Use wet B43xxx for cost-sensitive designs with moderate ripple frequencies; use B40xxx hybrid where ripple frequencies are high, service life is critical, or ESR budget is tight.

Q4: How do I use the EPCOS AlCap tool to validate a snap-in capacitor for an industrial inverter DC link?

Start by identifying your operating conditions: DC bus voltage, ripple current waveform (frequency, amplitude, and waveform type), ambient temperature, and cooling method (free convection, forced air, or heatsink mount). Enter the EPCOS part number or CSC code from the datasheet into AlCap, then input your load profile. AlCap outputs the estimated hot-spot temperature, power dissipation, and expected useful life under those conditions. The key output to check is useful life — it should comfortably exceed your product’s target service interval. If it doesn’t, you have three options: select a higher-rated part (larger can or higher-rated series), reduce the ripple current (add more capacitance in parallel to share the load), or improve the thermal environment (better airflow or heat sink). AlCap also supports up to 15 simultaneous load profiles, which means you can simulate a capacitor bank rather than just a single part. For industrial drives and UPS systems, running the full bank configuration through AlCap before finalizing the design is standard practice.

Q5: What is the EPCOS B3271xP series and why was it developed for EV and industrial applications?

The B3271xP is a new DC link polypropylene film capacitor series from TDK/EPCOS developed specifically to address the thermal challenges of EV traction inverters, on-board chargers, and high-frequency industrial converters. Standard DC link film capacitors typically begin to derate — reducing their allowable ripple current — above +85°C. In tightly packed inverter enclosures, particularly EV underbody and underhood environments, ambient temperatures near the capacitor can regularly exceed this threshold. The B3271xP operates to a maximum of +125°C with no power derating up to +105°C, using a polypropylene dielectric construction optimized for this temperature range. Capacitance values from 0.47 µF to 110 µF at 600V to 1,200V DC cover the main DC link positions in 400V and 800V EV platforms. For thermal validation, TDK provides SPICE models and the CLARA tool. This series represents EPCOS’s direct product response to the temperature requirements imposed by silicon carbide (SiC) and gallium nitride (GaN) power stages that enable higher switching frequencies and more compact inverter packaging.

Putting EPCOS Capacitors to Work in Your Next Design

The mental model for working with EPCOS capacitors efficiently is to navigate by B-series technology group first, then by voltage class and temperature requirement. For film capacitors, the MKP vs MKT choice is fundamental and should be resolved before selecting a specific series. For aluminum electrolytics, running AlCap before finalizing BOM quantities is non-negotiable in any design where the capacitor’s service life matters.

TDK’s CLARA and FilmCap tools are genuinely strong, and the ability to simulate four competing film capacitor candidates side by side under your actual application conditions — outputting lifetime, operating temperature, and current margins simultaneously — is the kind of validation that distinguishes a design that survives its service life from one that generates field returns. Build them into your component selection workflow from the start.

EPCOS’s safety capacitor portfolio also deserves more attention than it typically gets during early design. Specifying the wrong safety class (X vs Y position mismatch) or the wrong temperature rating for the application environment are both mistakes that surface at certification, not during prototyping. Getting them right the first time saves weeks of redesign late in the project.