# MELF resistor

Vishay Beyschlag's thin film MELF resistors: MMU 0102 (MicroMELF), MMA 0204 (MiniMELF) and MMB 0207 (MELF). The resistor lies on the XY plane (the board) with its axis along X, centred on the origin in X and Y. It is the coated ceramic body between two metal end caps, and each end cap is its own solid. The resistance and tolerance set the colour rings on the body (IEC 60062), read from the -X end.

## Parameters

- `size`: `MMU0102`, `MMA0204` or `MMB0207`.
- `resistance` in Ω, and `tolerance`: B 0.1 %, C 0.25 %, D 0.5 %, F 1 %, G 2 % or J 5 %. Only the combinations the sheet lists are accepted (table below). ± 5 % and ± 2 % carry two digit rings, and the closer tolerances three. Then come the multiplier ring and the tolerance ring.

## Source

Vishay Beyschlag, "MMU 0102, MMA 0204, MMB 0207 - Thin Film MELF Resistors", document number 28963, revision 02-Jun-2026, <https://www.vishay.com/doc?28963>.

Page 13, "DIMENSIONS AND MASS" (mm):

| Size | L | D (end caps) | D1 (body) | L1 min. | K (end cap length) | Mass |
|---|---|---|---|---|---|---|
| MMU 0102 | 2.2 + 0 / - 0.1 | 1.1 + 0 / - 0.1 | D + 0 / - 0.1 | 1.2 | 0.4 + 0.1 / - 0.05 | 8 mg |
| MMA 0204 | 3.6 + 0 / - 0.2 | 1.4 + 0 / - 0.1 | D + 0 / - 0.15 | 1.8 | 0.75 ± 0.1 | 22 mg |
| MMB 0207 | 5.8 + 0 / - 0.15 | 2.2 + 0 / - 0.2 | D + 0 / - 0.2 | 3.2 | 1.15 ± 0.1 | 80 mg |

The model uses the middle of each range. The body between the end caps is L - 2K long, which is more than L1 min. for every size.

Pages 2 and 3, "TEMPERATURE COEFFICIENT AND RESISTANCE RANGE": the resistance ranges by tolerance, every temperature coefficient's rows taken together. Jumpers aren't offered.

| Size | B 0.1 % | C 0.25 % | D 0.5 % | F 1 % | G 2 % | J 5 % |
|---|---|---|---|---|---|---|
| MMU 0102 | 100 Ω to 221 kΩ | 47 Ω to 332 kΩ | 10 Ω to 221 kΩ | 10 Ω to 2.21 MΩ | 1 Ω to 9.1 Ω | 0.22 Ω to 0.91 Ω |
| MMA 0204 | 10 Ω to 5.11 MΩ | 10 Ω to 5.11 MΩ | 10 Ω to 2.21 MΩ | 0.22 Ω to 0.91 Ω, 1 Ω to 10 MΩ | – | 0.22 Ω to 0.91 Ω |
| MMB 0207 | 20 Ω to 10 MΩ | 15 Ω to 10 MΩ | 10 Ω to 1 MΩ | 0.22 Ω to 0.91 Ω, 1 Ω to 15 MΩ | 0.1 Ω to 0.2 Ω, 0.22 Ω to 0.91 Ω | 0.1 Ω to 0.2 Ω, 0.22 Ω to 0.91 Ω |

Page 5: "Four (E24 series) or five (E96 and E192 series) color code rings designate the resistance value and tolerance in accordance with IEC 60062". Page 13: "The last color band for tolerance is approximately 50 % wider than the other bands."

**Proportions, stated plainly.** The sheet shows the rings but doesn't dimension them. Each ring is 0.1 of the body's length between the end caps wide, and the tolerance ring is 1.5 times that. The gaps between the rings and at their ends are equal. The rings are flush with the body.

**Materials and mass.** Page 5 says "a high grade ceramic body (Al2O3)", "Nickel plated steel termination caps" and "a final pure matte tin on nickel plating". The body is alumina and the end caps are steel. The sheet doesn't name the coating's colour; the light blue is for looks only. The model weighs about 10 mg (MMU 0102), 27 mg (MMA 0204) and 105 mg (MMB 0207), against the sheet's 8, 22 and 80 mg. It is heavier because the end caps are modelled solid steel, where the real caps are pressed over the ceramic rod's ends.

## Catalogue models

The old catalogue's `R_MicroMELF_MMU-0102`, `R_MiniMELF_MMA-0204` and `R_MELF_MMB-0207` entries have no models to measure. Each names the Vishay series and size, and each maps to it. Each preset is 10 kΩ at 1 %.

The family is shared with `chip-resistor`. The other resistors in it (arrays, shunts and the chip sizes Vishay's D/CRCW e3 doesn't have) aren't read here; see `COVERAGE.md`.