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Adom Fields

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Adom Fields: where the current and the heat go on your board.

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Closed PR #13 released in 0.10.6 on 5 Nov 2026 bug report

solids: a body under the board only couples to B.Cu at z = -1.535 mm; at the reported board thickness (1.57) it silently takes 0 W

Glenn Jones · ·closed by Colby Knox

We kept a list of tool issues as we worked on a project, the 772 power module (LM251772), a 4-layer board built with AI Flow on the Fusion lane, and set them aside so they wouldn't slow the build down. Now that the project is finished, we're filing them together. Some were seen on earlier versions; where we could, we checked that they still apply.

Versions: adom-fields 0.10.3.

What happens: we modelled a carrier board as a solids block under the module. With its top face at z = -1.57 mm (fields.json board.thicknessMm = 1.57), the solve put 0 W into it, with no warning. At -1.535 mm (the sum of copper and dielectric thicknesses) it coupled to B.Cu and took heat as expected.

Expected: one board thickness used everywhere (or a tolerance when matching a body's face to the bottom copper), and a warning when a solids body touches no copper and carries 0 W.

No design files attached; happy to describe more on request.

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Colby Knox marked this in progress ·
Colby Knox mentioned this in pull request #13 ·
Colby Knox ·

Fixed in adom-fields 0.10.6. Upgrade with adom-wiki pkg install adom/adom-fields.

What changed

  • board.thicknessMm in fields.json (every dielectric and every copper layer) is now the one thickness the report, the viewer and the bodies use.
  • A body's top face couples to B.Cu within 0.05 mm of that thickness, which also takes a nominal 1.6 mm on a 1.57 mm stack. The old sum (-1.535 in your case) still works, so your existing spec gives the same result.
  • A new solid-uncoupled issue says when a body is left out:
    • high: boardContactM2kW is set but no face is on the copper. The message gives the z to use.
    • medium: the body has no heat of its own and no path to the board, so it carries 0 W.
  • fields.json solids.still now has onCopper for each body.
  • One related fix: a body larger than the board now keeps its top face in the air outside the outline. It used to lose that face altogether, so a large carrier ran a little warm, and your results for one may shift.

How it was tested A 4-layer test board with the same stack sums as yours (1.57 and 1.535 mm) and a carrier block under it:

Top face z 0.10.5 0.10.6
-1.57 0 W, no warning 0.537 W
-1.535 0.537 W 0.537 W
-1.6 0 W, no warning 0.537 W
-2.0 0 W, no warning 0 W, solid-uncoupled high

The same block with no boardContactM2kW raises solid-uncoupled medium. Fan levels and a transient also ran on the carrier.

Not tested: your 772 module and carrier themselves, since we don't have the files.

Colby Knox closed this ·

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