imrishabh18/rp2040-motor-controller

engineering/imported-driver-thermal-vias.md

# Imported DRV8825 thermal vias — v1.0.36

DRV8825PWPR / JLCPCB C81582 now uses the exact imported EasyEDA footprint, including its twelve plated thermal vias. The previous ten manually positioned in-pad vias and six manually positioned perimeter vias are removed. Driver current settings and component population are unchanged.

The supplier geometry is preserved: approximately 0.300025 mm drills, 0.500024 mm copper diameters, and a three-column/four-row array inside the exposed pad. One center-column via is slightly offset in the supplier drawing; the import keeps that offset. The regression compares the placed geometry against the original EasyEDA VIA records, rather than assuming a regular grid.

Import provenance:

- Command: `tsci import C81582 --jlcpcb --use-exact-footprint`
- Component UUID: `d345a5568656bb8892b39dc79df37b70`
- Package UUID: `26071c9fef5e4e48bd9ebf04133c5d9d`
- Package: `HTSSOP-28_L9.7-W4.4-P0.65-LS6.4-BL-EP`
- Imported geometry: `imports/jlc/DRV8825PWPR.tsx`
- Original via records: `tests/fixtures/C81582-thermal-vias.json`

The wrapper adds electrical connections to pin 29 (EP/GND) and bottom tenting. It does not define or override via positions or diameters. Explicit EP connections are needed because the pinned core version misses automatic pad-containment association for some of the rotated imported vias. The top mask remains open over the solderable exposed pad; the bottom is tented, not specified as filled or capped.

The supplier courtyard is also retained. C_PD_VBUS moves 0.10 mm upward, R_MCU_ENABLE_PD rotates 90 degrees, and R_STATUS_B moves slightly left and 1.45 mm downward to clear it. Tracks are rerouted around the imported via locations. Inner ground patches are widened to maintain solid copper around the outer columns after the pour clearance inset. Motor-current paths remain on top/bottom copper, with the separate Kelvin sense branches retained.

See `revision-checks.json` for the built circuit and Gerber hashes and validation results. Fabrication checks cover routed DRC, all-layer Gerber shorts, physical connectivity, drill clearance, the twelve plated holes, exposed-pad mask opening, bottom tenting and solid ground around each thermal-via annulus. These geometry checks are not thermal measurements on hardware.