# MELF diode package

Cylindrical surface-mount diode packages: MELF (DO-213AB, plastic), MiniMELF (SOD-80, glass) and MicroMELF (glass), as Vishay draws them. The package lies on the XY plane (the board) with its axis along X, centred on the origin in X and Y. It is the body between two metal end caps, with the cathode band on the body at the -X end. Each end cap is its own solid.

## Source

Vishay Semiconductors, "Package Dimensions for ESD-, Zener-, Small Signal Switching-, and Schottky Diodes", document number 80128, revision 1.4, 11-Oct-2022, <https://www.vishay.com/docs/80128/package_information.pdf>. Each page is "PACKAGE DIMENSIONS in millimeters (inches)":

- MELF DO-213AB (PLASTIC): page 33, drawing S8-V-3453.03-001, 13 May 2009. The same drawing is in Vishay's GL41 data sheet, document 88546, revision 18-May-2021.
- MiniMELF (SOD-80): page 37, drawing 6.560-5005.01-4, rev. 8, 07 Jun 2006.
- MicroMELF: page 35, drawing 6.560-5007.01-4, rev. 13, 07 Jun 2006.

| Package | Length | End cap diameter | End cap length | Body |
|---|---|---|---|---|
| MELF | 4.7–5.2 | D2 = D1 + 0 to 0.2 | 0.46–0.56 | D1 = 2.41–2.67 |
| MiniMELF | 3.3–3.7 | 1.4–1.6 | 0.47 max. | not given |
| MicroMELF | 1.8–2.0 | 1.1–1.2 | 0.15–0.25 | glass: 0.6 from the axis to its flat sides; under 1.35 across the corners |

The model uses the middle of each range. MELF's end caps are 0.1 larger than its body, the middle of D1 + 0 to 0.2. MiniMELF's end cap length is given only as 0.47 max., so 0.47 is used. MicroMELF's glass is a square 1.2 across its flat sides with its corners rounded to 1.35 across, the limit given; the drawing's sides bulge slightly (radius over 2.5), and they are modelled flat. MicroMELF rests on its glass's flat side, the others on their end caps.

**Proportions, stated plainly.** The drawings show these but don't dimension them:

- MiniMELF's glass body is 0.92 of its end caps' diameter. The drawing shows it a little smaller than the caps.
- The cathode band is flush with the body. It runs from the -X end cap 0.2 of the way along the body. The drawings place it near that end cap but don't dimension it.
- The body runs from end cap to end cap. The small gap the glass drawings show at one end isn't modelled.

**Materials and mass.** MELF's body is moulded epoxy over a glass body (Vishay's GL41 data sheet). It is ptfe (2.07), the nearest in the material list to a silica-filled epoxy (about 1.9 to 2.0). MiniMELF's and MicroMELF's bodies are glass, soda-lime glass. The end caps are plated metal, shown as copper. The band is marking ink, shown in ptfe. Vishay's data sheets give each package's weight:

| Package | Model | Vishay's weight | Data sheet |
|---|---|---|---|
| MELF | 91 mg | 0.114 g | GL41, document 88546, revision 18-May-2021 (vishay.com) |
| MiniMELF | 25 mg | approx. 31 mg | LL4148-M, document 81162, rev. 1.4, 25-Jun-2024 (vishay.com) |
| MicroMELF | 9 mg | approx. 12 mg | MCL4151, document 85567, rev. 2.2, 25-Jun-2024 (vishay.com) |

The models come out lighter than stated, because the metal slugs and the die inside the body aren't modelled.

## Catalogue models

The old catalogue's `D_MELF`, `D_MiniMELF` and `D_MicroMELF` entries have no models to measure. Each names its package, and each maps to Vishay's drawing of that package. MELF is DO-213AB, and its plastic drawing is used, which is the one that dimensions the body. Vishay also draws a glass DO-213AB, 2.4 to 2.6 across, which isn't offered.

The family is shared with `do214-diode` (SMA, SMB and SMC). The other surface-mount diode packages in it aren't read here; see `COVERAGE.md`.