# Land pattern check: C1812C124J1GACTU

The footprint on this page is KiCad's standard library footprint `Capacitor_SMD:C_1812_4532Metric`, renamed to
`C_1812_4532Metric_C1812C124J1GACTU` so it can sit beside other parts in one library folder. The copper is unchanged; only the name and
the 3D model path (`${KIPRJMOD}/C1812C124J1GACTU.step`) differ from upstream. This page compares it with the land pattern KEMET
recommends for 1812 parts in datasheet C1003_C0G (2/20/2025), page 12, Table 3 (IPC-7351).

![KiCad pads (teal) over KEMET's density level B land (amber dashed), true scale](land-pattern.png)

## KEMET's three density levels for 1812 (mm)

| Level | C (centre to land centre) | Y (land length) | X (land width) | V1 x V2 (courtyard) |
|---|---|---|---|---|
| A, maximum protrusion | 2.15 | 1.60 | 3.60 | 6.90 x 4.60 |
| B, median (nominal) | 2.05 | 1.40 | 3.50 | 6.00 x 4.00 |
| C, minimum protrusion | 1.95 | 1.20 | 3.40 | 5.30 x 3.70 |

KEMET's drawing (p.12) gives C from the part centre to each land centre, so the gap between the lands is 2C - Y and the
overall length is 2C + Y. KEMET describes level B as "a robust solder attachment condition for reflow solder processes".

## KiCad pads against level B

| Dimension | KiCad C_1812_4532Metric (used) | KEMET density level B | Difference |
|---|---|---|---|
| gap between lands | 2.70 mm | 2.70 mm | +0.00 mm |
| land length | 1.40 mm | 1.40 mm | +0.00 mm |
| land width | 3.40 mm | 3.50 mm | -0.10 mm |
| overall length | 5.50 mm | 5.50 mm | +0.00 mm |

## Result

KiCad's footprint is IPC-7351 nominal, the same rule as KEMET's level B: land centres, land length, gap and overall length
are identical. The only difference is the land width: KiCad's pads are 3.40 mm wide, KEMET's level B lands
3.50 mm (0.10 mm narrower, 0.05 mm per side; level C uses 3.40 mm). The KiCad pads have rounded corners
(roundrect ratio 0.18); KEMET draws plain rectangles. KiCad's courtyard is 6.00 x 3.90 mm, KEMET's V1 x V2 6.00 x 4.00 mm.
Both cover the full printed body width (3.20 +/-0.30 mm). This page keeps the KiCad pads. A design that wants KEMET's
level B exactly should widen each pad to 3.50 mm.

KEMET lists the 1812 case as reflow only (datasheet p.3 and p.13).

The drawing and [land-check.json](land-check.json) come from `provenance/tools/landcheck.py`.