# MEF/CL21 Series Metallized Polyester Film Capacitors

> General-purpose epoxy-dipped metallized polyester (PET) film capacitors for bypass, blocking, coupling and filtering. 100–630 VDC, 10 nF–10 µF.

- Series code: MEF/CL21
- Product line: [Film capacitors](https://www.songtian-ste.com/en/products/film-capacitors/) › Metallized polyester (PET) film capacitors
- Part numbers: 788 · [part list (JSON)](https://www.songtian-ste.com/data/parts/cl21.json)
- Page: https://www.songtian-ste.com/en/products/film-capacitors/cl21/
- Chinese version: https://www.songtian-ste.com/zh/products/film-capacitors/cl21/
- [Ask AI about this series](https://www.songtian-ste.com/en/products/film-capacitors/cl21/?ask=Help%20me%20choose%20a%20part%20from%20the%20STE%20MEF%2FCL21%20series.)

## Key specifications

| Parameter | Value |
| --- | --- |
| Rated voltage | 100 / 250 / 400 / 630 VDC |
| Capacitance | 10 nF–10 µF |
| Operating temperature | −40 °C to +125 °C |
| Dielectric | Metallized PET |
| Tolerance | ±5% / ±10% |
| Lead spacing | 7.5–27.5 mm |

## Engineering details

### Overview

Metallized polyester (PET) film capacitors with a non-inductive, self-healing winding and epoxy-resin dip coating, for bypass, blocking, coupling, filtering and low-pulse circuits. Rated 100, 250, 400 and 630 VDC, 10 nF–10 µF, J ±5% or K ±10%. Lead spacing 7.5–27.5 mm. Operating temperature −40 °C to +125 °C, with voltage derating above +105 °C.

#### Series features

- Metallized PET film, non-inductive winding, epoxy-dipped radial body
- Rated 100 / 250 / 400 / 630 VDC; 10 nF to 10 µF
- Self-healing; operating temperature −40 °C to +125 °C
- Six lead spacings from 7.5 to 27.5 mm

#### Typical applications

- General-purpose bypass, blocking, coupling and filtering in DC circuits
- Low-pulse circuits; validate dV/dt, peak current and temperature rise
- Electronic ballasts and energy-saving lamps at high temperature; apply voltage derating and check the mission profile
- Dense radial-lead PCB assemblies; check body, leads, packing and soldering per part number

### Specifications

|   |   |
| --- | --- |
| Product type | General-purpose metallized polyester DC film capacitor for bypass, blocking, coupling, filtering and low-pulse circuits; not a safety capacitor, not for reflow soldering |
| Construction | Metallized polyethylene terephthalate (PET) film · non-inductive winding · epoxy-resin dipped radial body |
| Self-healing | Yes |
| Rated DC voltage | 100 · 250 · 400 · 630 VDC |
| Capacitance range | 100 VDC: 10 nF–10 µF · 250 VDC: 10 nF–4.7 µF · 400 VDC: 10 nF–3.3 µF · 630 VDC: 10 nF–1.5 µF |
| Capacitance tolerance | J ±5% · K ±10% |
| Operating temperature | −40 °C to +125 °C |
| Voltage derating above +105 °C | 1.25% of UR per °C from +105 °C to +125 °C; 75% of UR at +125 °C when applied linearly. Derating curve on request. |
| Climatic category | 40/100/21 |
| Storage temperature | +15 °C to +35 °C |
| Dissipation factor | tan δ ≤1.0% at 1 kHz, 1.0 Vrms, 20 °C |
| Insulation resistance, UR >100 V, C ≤0.33 µF | ≥30,000 MΩ at 100 VDC, 60 s, 20 °C |
| Insulation resistance, UR >100 V, C >0.33 µF | Time constant IR × C ≥10,000 s at 100 VDC, 60 s, 20 °C |
| Insulation resistance, UR ≤100 V, C ≤0.33 µF | ≥15,000 MΩ at 100 VDC, 60 s, 20 °C |
| Insulation resistance, UR ≤100 V, C >0.33 µF | Time constant IR × C ≥5,000 s at 100 VDC, 60 s, 20 °C |
| Voltage proof, terminal to terminal | 1.6 × UR for 5 s |
| Pulse ratings | Designed for low-pulse duty |
| AC operation | DC-rated only; do not use in AC, resonant or capacitive-dropper circuits without frequency, current and lifetime data from STE |
| Safety class | No X/Y class and no agency approval; do not use across the line or line to earth |
| Coating | Epoxy resin |
| Body dimensions | W 10–31 · H 8–23 · T 4.5–13.5 mm, depending on voltage and capacitance |
| Lead spacing | 7.5 · 10 · 15 · 20 · 22.5 · 27.5 mm, ±1.0 mm |
| Lead diameter | 0.6 ±0.05 mm at 7.5 / 10 mm spacing · 0.8 ±0.05 mm at 15–27.5 mm spacing |
| Lead forms and packing | Long straight · inner-bent · straight taped · bent taped |
| Taping | Tape dimensions specified for 7.5, 10, 15 and 20–22.5 mm lead spacing; 27.5 mm packing on request |
| Soldering profile, PP | Preheat ≤110 °C · soldering ≤120 °C · ≤15 s |
| Soldering profile, PE | Preheat ≤125 °C · soldering ≤160 °C · ≤15 s |
| Hand soldering | 350 °C max. · 3 s max. · ≥2 mm from the coating |
| Reflow soldering | Not permitted; film shrinkage can degrade performance |
| Environmental compliance | RoHS and REACH compliant; bromine-free and halogen-free. Material declarations on request. |
| Further data | On request: clearing energy, capacitance loss and end-of-life limits · storage humidity and shelf life · dV/dt, K0, peak and repetitive current, pulse energy and repetition rate · ESR, ESL, impedance, self-resonant frequency, permissible voltage and current versus frequency, thermal resistance and temperature rise · capacitance and dissipation factor versus temperature and frequency, dielectric absorption, drift and DC-bias curves · UL 94 class · loaded-life, high-temperature endurance, pulse-life, damp-heat, overload, thermal-cycle, vibration and lead-strength test results |

### Variants

Ranges by dielectric, package and lead style within this series.

| Variant | Body dimensions | Rated voltage / capacitance | Dielectric / tolerance | Lead / land pattern | Notes |
| --- | --- | --- | --- | --- | --- |
| J · 7.5 mm | W 10 · H 8–10.5 · T 4.5–6.5 mm | 100 VDC: 10–100 nF · 250 VDC: 10–68 nF · 400 VDC: 10–15 nF | Metallized PET · J/K | P 7.5 ±1.0 · d 0.6 ±0.05 mm | Smallest body; 5 mm lead spacing on request. |
| N · 10 mm | W 13 · H 9–13 · T 5–7.5 mm | 100 VDC: 150–680 nF · 250 VDC: 100–220 nF · 400 VDC: 22–150 nF · 630 VDC: 10–68 nF | Metallized PET · J/K | P 10 ±1.0 · d 0.6 ±0.05 mm | Compact size; check frequency loss and temperature rise for the actual waveform. |
| Q · 15 mm | W 18 · H 11.5–16 · T 6–9 mm | 100 VDC: 1–2.2 µF · 250 VDC: 330 nF–1 µF · 400 VDC: 220–680 nF · 630 VDC: 100–330 nF | Metallized PET · J/K | P 15 ±1.0 · d 0.8 ±0.05 mm | Mid-range values for filtering and coupling; validate PET loss, drift and ripple current. |
| S · 20 mm | W 23 · H 15.5–20 · T 8.5–10.5 mm | 100 VDC: 3.3–4.7 µF · 250 VDC: 1.2–2.2 µF · 400 VDC: 1–1.2 µF · 630 VDC: 470–680 nF | Metallized PET · J/K | P 20 ±1.0 · d 0.8 ±0.05 mm | Higher capacitance; check temperature, ripple current and lead support. |
| T · 22.5 mm | W 25 · H 18–21 · T 11.5–12 mm | 100 VDC: 6.8 µF · 250 VDC: 3.3 µF · 400 VDC: 1.5 µF · 630 VDC: 1 µF | Metallized PET · J/K | P 22.5 ±1.0 · d 0.8 ±0.05 mm | Tape dimensions specified; verify case temperature and vibration support. |
| V · 27.5 mm | W 31 · H 19–23 · T 11.5–13.5 mm | 100 VDC: 10 µF · 250 VDC: 4.7 µF · 400 VDC: 2.2–3.3 µF · 630 VDC: 1.2–1.5 µF | Metallized PET · J/K | P 27.5 ±1.0 · d 0.8 ±0.05 mm | Largest body; packing on request. Support the body mechanically. |

### Selection guide

Start with the duty (signal, filtering or low pulse) and whether PET suits it. Then check DC voltage, capacitance, frequency loss, pulse current, derating above +105 °C, dielectric drift, lifetime and dimensions.

1. **Define electrical and environmental duty**
   Specify DC bias, AC ripple, frequency spectrum, peak voltage, rise and fall time, dV/dt, repetition rate, RMS current, abnormal transients, ambient and case temperature, cooling and required service hours.
2. **Select voltage, capacitance and lead spacing**
   The series covers 100–630 VDC, 10 nF–10 µF and 7.5–27.5 mm lead spacing. For other voltages, values below 10 nF, or 5 and 12.5 mm lead spacing, request the part specification.
3. **Check PET loss, drift and pulse stress**
   Use Ipk = C·dV/dt and the measured spectrum. Obtain dV/dt, repetitive current, ESR, impedance, self-resonance, temperature rise, dielectric absorption and capacitance and loss drift for the selected part number.
4. **Apply temperature derating and validate lifetime**
   Reduce the rated voltage by 1.25% per °C above +105 °C. Check the derating curve, maximum case or hot-spot temperature and loaded-life data against the actual waveform and target hours.
5. **Confirm dimensions and assembly**
   Match the part number to voltage, capacitance, tolerance, W/H/T, lead spacing, lead diameter and form, packing and soldering profile. Do not use reflow soldering; validate lead forming, cleaning, coating compatibility, vibration and thermal cycling.

### Design notes

#### Check that PET suits the duty

PET offers compact high capacitance, but its loss, dielectric absorption and temperature and frequency behavior differ from polypropylene. Validate the actual signal, ripple and drift requirements.

#### Quantify low-pulse duty

Low pulse is not a defined limit. Calculate I = C·dV/dt and obtain dV/dt, repetitive-current, ESR and temperature-rise limits for the part number.

#### Apply the right insulation-resistance limit

Select the limit by rated voltage and by capacitance above or below 0.33 µF. A single fixed resistance value does not apply across the whole capacitance range.

#### Derate above +105 °C and validate lifetime

Applied linearly, the 1.25%/°C derating reaches 75% of rated voltage at +125 °C. Obtain the derating curve and loaded-life data; the temperature rating alone does not prove service life.

#### Ratings outside the standard range

For voltages other than 100–630 VDC, values below 10 nF, or 5 and 12.5 mm lead spacing, request the construction, drawing, loss and current limits and qualification report.

#### Control solder heat and lead stress

Do not use reflow soldering. Apply the PP/PE soldering limits to the actual part, keep lead-forming stress away from the epoxy seal, and validate cleaning, coating, vibration and thermal cycling.

### Part numbering

Example ordering code. Not every combination is available.

`L2 · 2G · 104 · J · N · 1 · B0 · 130 · 105 · 055 · E · 0 · Z`

| Code | Meaning |
| --- | --- |
| L2 | Series code: MEF/CL21 |
| 2G | Rated voltage code: 2G = 400 VDC; 2A = 100 VDC, 2E = 250 VDC, 2J = 630 VDC |
| 104 | Capacitance code: 104 = 100 nF; maximum value depends on voltage |
| J | Capacitance tolerance: J = ±5%, K = ±10% |
| N | Lead spacing: N = 10 mm; J = 7.5, Q = 15, S = 20, T = 22.5, V = 27.5 mm |
| 1 | Lead form: 1 = long straight, 2 = inner-bent, 5 = straight taped, 6 = bent taped |
| B0 | Lead length code: B0 = 20.0 mm |
| 130 | Body width: 130 = 13.0 mm |
| 105 | Body height: 105 = 10.5 mm |
| 055 | Body thickness: 055 = 5.5 mm |
| E | Environmental code: E = RoHS, F = RoHS and halogen-free |
| 0 | STE internal control code, first field |
| Z | STE internal control code, second field |

## Datasheets & approval documents

- [Datasheet: MEF/CL21 series encapsulated metallized polyester (PET) film capacitors — short-form datasheet (2023-10)](https://www.songtian-ste.com/documents/source-cn/%E9%87%91%E5%B1%9E%E8%86%9C%E7%94%B5%E5%AE%B9%E5%99%A8%E7%B3%BB%E5%88%97%E4%BA%A7%E5%93%81%E8%A7%84%E6%A0%BC%E4%B9%A6/MPE%E8%81%9A%E8%84%82%E8%86%9C%E7%94%B5%E5%AE%B9%E5%99%A8/%E5%8C%85%E5%B0%81%E9%87%91%E5%B1%9E%E5%8C%96%E8%81%9A%E9%85%AF%E8%86%9C%E7%94%B5%E5%AE%B9%E5%99%A8%28MEF%20CL21%29%E7%AE%80%E7%89%88%E8%A7%84%E6%A0%BC%E4%B9%A6-202310.pdf) — PDF · Chinese · 2023-10 · 269 KB

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