# Chip fuse

Vishay's MFU series of thin film chip fuses, in sizes 0402, 0603, 0805 and 1206. The fuse is centred on the origin, lying on the XY plane with its length along X. It is the substrate, the protective coat on top between the terminations, and a wrap-around termination at each end. Each is its own solid.

## Source

Vishay Beyschlag, "MFU Series, Thin Film Chip Fuses", document 28747, revision 11-Mar-13, <https://www.vishay.com/doc?28747>, page 3, "DIMENSIONS - Chip fuse types, mass and relevant physical dimensions":

| Size | H | L | W | WT | T1 (top) | T2 (bottom) | Mass |
|---|---|---|---|---|---|---|---|
| 0402 | 0.32 ± 0.07 | 1.0 ± 0.05 | 0.5 ± 0.05 | > 75 % of W | 0.2 +0.1/-0.15 | 0.2 ± 0.1 | 0.65 mg |
| 0603 | 0.45 +0.1/-0.05 | 1.55 ± 0.05 | 0.85 ± 0.1 | > 75 % of W | 0.3 +0.15/-0.2 | 0.3 +0.15/-0.2 | 1.9 mg |
| 0805 | 0.45 +0.1/-0.05 | 2.0 ± 0.1 | 1.25 ± 0.15 | > 75 % of W | 0.4 +0.1/-0.2 | 0.4 +0.1/-0.2 | 4.7 mg |
| 1206 | 0.55 ± 0.1 | 3.2 +0.1/-0.2 | 1.6 ± 0.15 | > 75 % of W | 0.5 ± 0.25 | 0.5 ± 0.25 | 9.5 mg |

The model uses the nominal values.

**Proportions, stated plainly.** The sheet doesn't dimension these:

- The terminations and the coat are 0.1 times H thick. The coat stands 0.03 (0402: 0.016) below the terminations' top bands so their edges show.
- The terminations run the full width. The sheet gives their width only as more than 75 % of W.

**Materials and mass.** The sheet names no materials. The substrate is shown as alumina, the coat as ptfe and the terminations as tin, as for the library's chip resistor. With those densities (3.95, 2.2 and 7.3), the model's mass against the sheet's is 0.64 against 0.65 mg (0402), 2.34 against 1.9 (0603), 4.4 against 4.7 (0805) and 10.7 against 9.5 (1206).

## Catalogue models

The old catalogue's `Fuse_0402_1005Metric`, `Fuse_0603_1608Metric`, `Fuse_0805_2012Metric` and `Fuse_1206_3216Metric` have no reference models. Each names an EIA chip size, and each maps to the MFU of that size. `Fuse_1210_3225Metric` is left out, because the MFU series has no 1210. The family's Bel Fuse PTC fuses are the radial-ptc-fuse part's, and its fuse holders are left with their reasons in `COVERAGE.md`.