49 lines
2.2 KiB
Plaintext
49 lines
2.2 KiB
Plaintext
(version 1)
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# hbox-watchdog v4 — design rules
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#
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# Why three rules instead of one blanket minimum:
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#
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# The old file was a single unconditional (min 0.15mm). A custom rule outranks
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# the netclass table, and an unconditional rule matches EVERY pair on the board,
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# so it was silently overriding the HV24 netclass's 0.5 mm clearance everywhere.
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# The netclass said 0.5; DRC was only ever enforcing 0.15.
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#
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# These three are mutually exclusive on the case that matters, so they give the
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# same answer whether KiCad resolves by rule order or by specificity:
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#
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# 1. neither item is HV24 -> 0.15 mm (unchanged)
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# 2. either item is HV24 -> 0.50 mm
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# 3. except U2 pad-to-pad, its own land pattern -> 0.15 mm
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#
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# Rule 3 exists for exactly one pair. U2 is the MP1584EN buck (SOIC-8-EP):
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# pad 7 (24V, 1.95 x 0.6) to pad 9 (the 2.29 x 3.0 exposed thermal pad, GND) is
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# 0.355 mm, and that is the manufacturer's qualified land pattern — it is set by
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# the package, not by routing, so no amount of rerouting can open it. Scoping
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# the exception to Pad-to-Pad inside U2 keeps it from relaxing anything else:
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# measured on this board, U2's courtyard contains 9 pads and all 9 belong to U2,
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# so this condition cannot match a foreign pad. The tracks and vias that pass
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# through that courtyard are excluded by the A.Type/B.Type test and stay at the
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# full 0.5 mm.
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#
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# HV24 = /24V_IN, 24V, IGN_IN, Q10_GATE (netclass_patterns in the .kicad_pro)
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#
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# Note: raising HV24 to 0.5 mm also widens the copper pour pullback around those
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# nets, because a zone floods to max(its own clearance, the effective DRC
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# clearance) — 0.3 mm before, 0.5 mm now. Press B to refill before running DRC.
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(rule "Minimum clearance 1"
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(constraint clearance (min 0.15mm))
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(condition "A.NetClass != 'HV24' && B.NetClass != 'HV24'")
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)
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(rule "HV24 clearance"
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(constraint clearance (min 0.5mm))
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(condition "(A.NetClass == 'HV24' || B.NetClass == 'HV24') && !(A.Type == 'Pad' && B.Type == 'Pad' && A.memberOfFootprint('U2') && B.memberOfFootprint('U2'))")
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)
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(rule "HV24 exception: MP1584EN land pattern"
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(constraint clearance (min 0.15mm))
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(condition "A.Type == 'Pad' && B.Type == 'Pad' && A.memberOfFootprint('U2') && B.memberOfFootprint('U2')")
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)
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