Adom Fields

adom-fields 0.10.8: a leaded hot part's watts land in the drill void of large through-hole pins (+1064 C on an XT90)

fields.rs (heat sources): a hot part with no tabNet ("leads") spreads its watts over its pads by area, each into a disk of radius 1.2 mm around the pad centre (rad = 1.2 / d), on F.Cu. On a through-hole pin with a drill larger than 2.4 mm (XT90 contacts, 3.9 mm drill; AS150 5.2 mm) that whole disk is inside the drill hole, which is a copper void on every layer, so the heat has no copper path and the part reads +589 to +1064 C in still air. No-net plated pegs of the same footprint also take a share of the watts into isolated copper.

packageCooling cannot work around it: a board link must sit exactly on the pad centre ((p.x - link.at[0]).abs() < 1e-6), which is the same void.

Seen on a 4-layer power board (biped PDB): J2 XT90PW-F 3.92 W contact loss -> +1064 C, J3 +710 C, J1 AS150 +589 C. Modelling each connector's pins as solids bodies on their pads (heatOf, boardContactM2kW) gives a plausible result.

Suggested fix: for leaded parts, inject on the pad's copper annulus (cells with copper within the pad polygon), skip no-net pads, and let packageCooling links name a pad and be placed on its copper ring.