Drogheda/03-Architecture-Hardware/2026-10-13_Drogheda_EinarBoard-V5.6_Audit-Michelle-Pass_NOT-READY_EN.md

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EinarBoard HBOX V5.6 — Purchase-readiness audit of Michelle's pass (kicad d71098d, 13-Oct-2026)

!!! warning "Designators from before 22-Oct (T43)" This document keeps the designators the board had on its date. Since 22-Oct (T43) the V5.6, V5.7 and v6 carry new ones, and several old names now belong to another part: on the V5.6 and V5.7 the LTC4040 is now U14 (was U6) and J7 is the DFU USB-C (was J11). To read it against today's board, use the old → new table (in Spanish); parts already gone by 22-Oct are not in it.

!!! warning "Superada el 16-oct" Sustituida por la auditoría de producción del 16-oct (V5.6, V5.7 y v6) y las correcciones de la pasada 3. Se conserva como histórico.

Verdict: NOT READY — one more layout pass. Independent review agent (59 checks, files only: PCB d71098d vs b508a2c, schematic, KiCad XML netlist, kicad-cli DRC JSON). Cross-checked by Claude's own pad-level parity run (0 differences). Michelle's correction list (ES): 2026-10-13_Drogheda_Instrucciones-Michelle_V5.6-Pasada-2_ES.md.


Reviewer: independent (files only, no prior knowledge of the board). Date: 2026-10-13. Inputs: hbox-watchdog-v5.kicad_pcb (after layout pass, 13-Oct), pcb_pre_michelle_b508a2c.kicad_pcb (12-Oct, before the pass), hbox-watchdog-v5.kicad_sch, v56-netlist-1013.xml, v56-drc-1013-nofill.json. Analysis with Python 3 stdlib on the s-expression trees (pad positions = footprint at + rotated pad at; connectivity by true copper-shape overlap incl. zone fills; IPC-2221 with k=0.048 external / 0.024 internal, 1 oz outer = 35 µm, 0.5 oz inner = 17.5 µm as specified for the JLCPCB 4-layer stackup).

1. Verdict

NOT READY. Do not order this revision. The layout pass introduced a battery-path regression that would act as a fuse (0.5 mm trace on the In1 GND-plane layer carrying up to 2–4 A), moved six edge connectors and 12 other parts that were explicitly frozen, failed to do items 4 and 5 of the brief, and placed U26 and its decoupling away from the requested location/distances. Independently of this pass, the pre-existing board carries three more power paths through undersized inner-layer traces (MAIN5V, SYS5V, U7 switch node) that must also be corrected before any order. Pad-level schematic parity, zone fills, and DRC clearance are otherwise clean.

2. Findings, ranked

BLOCKER

B1. /BAT_PLUS from P4.1 now runs 10.7 mm on In1.Cu at 0.5 mm width, then through a single 0.3 mm-drill via — in series with the whole battery current. Path P4.1 (165.10, 44.88) → In1.Cu 0.5 mm: (165.10,44.88)→(165.10,52.70)→(165.85,53.45)→(165.85,55.25) [10.69 mm] → via 0.8/0.3 at (165.85,55.25) → B.Cu 1.0 mm, 52.9 mm → via (180.12,100.81) → In2 1.5 mm 9.6 mm → via (179.96,109.61) → F.Cu 1.0 mm → L6.2. Every element listed is a single-point series element (removing it disconnects P4 from L6/U6/C35; there is no zone or parallel copper on this net). IPC-2221, 0.5 mm × 17.5 µm internal: 0.44 A at ΔT=10 °C, 0.59 A at 20 °C, 0.71 A at 30 °C. At the 1.4 A charge current the formula extrapolates to ≈140 °C rise; at 2 A ≈300 °C; 4 A peaks are not survivable — the trace is a buried fuse under the connector row, and it also slots the GND plane right where P4.2 returns the same current. Even if JLCPCB inner copper were 1 oz, capacity is only 0.72 A at 10 °C. Before the pass: P4.1 (190.2,44.64) → B.Cu 1.5 mm for 63.8 mm → via (180.12,100.81) → In2 1.5 mm 9.6 mm → via → F.Cu 1.0 → L6.2; narrowest element 1.5 mm/B.Cu = 3.21 A @10 °C (the pre-existing In2 1.5 mm/0.5 oz stretch = 0.97 A @10 °C, see M3). Trunk resistance ≈27 mΩ before vs ≈53 mΩ now (In1 0.5 mm alone ≈21 mΩ → 0.34 W at 4 A). Fix: route P4.1 → U6/L6 entirely on outer copper at ≥1.5 mm (2.0 mm preferred for 4 A peaks), no inner-layer segments, ≥2 vias (0.5 mm drill) wherever a layer change is unavoidable. Instruction 7 ("do not change track widths") was also violated: the trunk went 1.5 → 1.0 mm on B.Cu.

B2. Six edge connectors and 12 other components were moved although instruction 7 froze everything except the U26 block. P4 (battery) −25.1 mm in x (190.2 → 165.1), P6 −17.7, P8 −17.4, P2 −12.6, P11 −12.1, P10 −11.1 mm, all along the top edge; plus F1, JP1, D1, D6, R3, Q2, Rgs1, Rigb1, Rled1, R112, TP6, TP7 (table §4.3). The whole top connector row was compacted leftwards to make room for U26/C126–C128/TP6/TP7 at x≈88–101. Any enclosure cut-outs, panel labels, harness lengths or test fixtures referenced to the previous connector positions are now wrong. The move is also what forced the BAT_PLUS re-route (B1) and the NTC/LED/FAN/SYS5V/MAIN5V/VEH5V re-routes (457 segments and 85 vias changed in total). Fix: revert all 18 non-U26 footprints and their routing to b508a2c unless Leo explicitly approves the new connector positions.

MUST-FIX-BEFORE-ORDER

M1 (pre-existing). /MAIN5V: U6.1/24 (VSYS, boost output up to 2.5 A in backup) leaves the IC through a 0.3 mm × 1.05 mm F.Cu neck → one 0.3 mm via (153.19,110.88) → In1.Cu 1.0 mm, 15.1 mm (153.20,110.89)→(160.79,110.89)→(166.09,116.19) → one 0.3 mm via → F.Cu. All series for every MAIN5V load (P11, JP6, Q7). In1 1.0 mm/0.5 oz = 0.72 A @10 °C; 2.5 A → ≈170 °C rise (≈55 °C even at 1 oz inner). Present identically in b508a2c — not introduced by the pass, but it is the backup-power path and must be fixed: bring VSYS out on F.Cu/B.Cu ≥1.5 mm with 2+ vias, no In1 segment.

M2 (pre-existing). /SYS5V: the only path from P11.2/JP6.2 to U7.2 (modem buck VIN, ≈1.4–2 A) and U12.2 is K1.2 → B.Cu 1.0 → via 0.6/0.3 (158.60,57.92) → In2.Cu 0.5 mm, 9.1 mm (158.64,57.95)→(156.47,57.95)→(154.19,60.23)→(154.19,63.06)→(153.57,63.69) → via 0.8/0.3 → F.Cu 0.75/0.5 mm. In2 0.5 mm/0.5 oz = 0.44 A @10 °C; 1.5 A → ≈160 °C rise. Also 31 mm of 0.5 mm F.Cu (1.45 A @10 °C) in series on the way to U7. Fix: 1.0–1.5 mm outer-layer route P11 → U7/U12 input caps, 2 vias per transition.

M3 (pre-existing). Inner-layer 1.5 mm segments in the battery trunk and BAT pin path at 0.5 oz: In2 1.5 mm, 9.6 mm (178.77,102.17)→(179.94,109.59) in series to L6.2 (0.97 A @10 °C; 2 A → ≈52 °C), and In1 1.5 mm, 21.7 mm (156.18,99.89)→(172.75,106.28) to U6.23/C35. Two 0.3 mm-drill vias in series carry the full battery current (≈1.8 A @10 °C each by annular-ring area). Fix together with B1: outer layers only, 2× vias ≥0.5 mm drill.

M4 (pre-existing). /SW3_NODE (U7 pin 8 switch node → L7.1) runs 12.85 mm on In1.Cu at 0.5 mm through two 0.3 mm vias ((136.0,105.0)→(142.68,111.68)→(142.68,115.08)). 0.44 A @10 °C for a node carrying the full inductor current (2 A peaks), and a high-dv/dt switching node slotted into the GND reference plane under the modem supply. Fix: SW node on F.Cu only, short and wide (≥1.0 mm), L7 adjacent to U7.

M5. Instruction 5 not done: title blocks still read Rev "3.0". PCB title block: date 2026-08-12, rev 3.0 (unchanged pre→cur). Schematic: date 2026-07-07, rev 3.0. Silkscreen "HBOX v5.6 - 2026-10" / "EINARBoard 5.6" is present (it already was in b508a2c). Fabrication drawings/Gerber job file will carry the wrong revision.

M6. Instruction 4 not done, and reversed: In1 (GND plane) gained 90 mm of new signal routing. The two /NTC_CELL In1 segments (114.4,52.2)→(119.2,52.2)→(123.0,56.0) are still on In1.Cu (ADC input to U16 pin 25). New on In1: /I2C_SDA 30.7 mm, /I2C_SCL 28.9 mm, /ACC_INT1 29.6 mm, all 0.25 mm, running x≈109–125, y≈51–75, i.e. straight under the MCU (In1 signal copper inside the U16 13×13 mm courtyard went 45.4 → 56.0 mm). Plus the /BAT_PLUS 0.5 mm slot (B1). In1 totals: 917 → 985 mm of non-GND tracks, 27 → 28 nets.

M7. U26 block placed away from the request and decoupling out of spec. U26 at (93.2, 44.68) instead of (124.5, 84.5) — 3.4 mm from the top board edge, 30 mm from U16. C126.1 → U26.7 (VDD) = 3.43 mm, C127.1 → U26.3 (VDDIO) = 3.06 mm (spec ≤2 mm); both caps sit on the left of the part while VDD/VDDIO pins are on the right. C128 (10 µF) courtyard is 0.50 mm from the board edge (pad edge ≈0.85 mm) — below JLCPCB's ≥1 mm component-to-edge guidance. An 0.8 mm GND via sits dead-centre under the LGA body at (93.2,44.6) (tented per (tenting (front yes)), acceptable but unnecessary). Pad nets are correct (1 GND/SDO, 2 SDA, 3 VDDIO, 5 INT1→U16.62 PB9, 7 VDD, 8/9 GND, 10 CS→3V3, 12 SCL; 4/6/11 unconnected), pin-1 marker coincides with pad 1 (bottom-left, CCW numbering, LGA top view). Routing to U16: ACC_INT1 19.3 mm F.Cu + 29.6 mm In1; SDA/SCL ≈19–22 mm F.Cu + ≈30 mm In1 each (see M6).

M8. BOM hygiene for SMT order. 14 non-DNP symbols carry no LCSC code and are not marked exclude-from-BOM: JP1–JP6 (solder jumpers), TP1–TP7 (test points), MOD1 (header outline) — JLCPCB's BOM import will flag them; set exclude_from_bom/DNP or add codes. LCSC C5126709 (U26 SC7A20TR) showed "out of stock" on LCSC at review time and is an Extended part — confirm stock before ordering. 10 nF 0603 uses two different codes (C57112 and C1589) — consolidate. DNP: Dbk2 (SS34), R109 (10k). No empty footprints. 20 through-hole footprints (connectors, K1, SW1/SW2, H4, MOD1) are hand-assembly or JLC TH-assembly items.

SHOULD-FIX

S1. Dangling copper (DRC warnings, all in the changed area): /BAT_PLUS B.Cu 1.5 mm stub (181.53,100.79)→(180.13,100.79), 1.40 mm — remnant of the old right-edge trunk; /3V3_ETH In2 spur (105.16,47.89)→(104.72,48.32), 0.61 mm; /24V via at (181.04,64.075) connected on F.Cu only — the "stray via" at (182.92,60.325) from instruction 2 was removed but a new dangling one was created when the C22 stub was re-drawn. S2. Silkscreen regressions from the moves: Rig1 reference text over Rigb1 pad 2 (GND) at (131.6,50.6); Rled1 reference text over D5 pad 1 (/3V3) at (121.6,50.7); silk-overlap pairs U7/Cbst2 (pre-existing), Rig1/Rigb1, D5/Rled1. S3 (pre-existing). /SW_IN (F1 PPTC 4 A → Q1 → MOD1 5 V) runs 85.3 mm on In2.Cu at 1.0 mm (0.72 A @10 °C), lengthened from 74.6 mm by the pass. Either the PPTC rating or the trace is wrong; move to outer layer ≥1.5 mm or document the real MOD1 current. S4 (pre-existing). /3V3_MODEM L7.2 → J7.1: 54 mm of 0.5 mm F.Cu in series (1.45 A @10 °C; ≈54 mΩ → ≈110 mV drop at 2 A modem peaks). Widen to ≥1.0 mm. S5 (pre-existing). U6 EP DFM: 6 paste windows 0.95×0.85 mm = 4.84 mm² of 9.67 mm² EP (50 %) and 3 GND vias 0.6/0.3 in the EP — as per the standing rule — but two of the vias ((155.74,111.92) and (157.13,111.88)) are centred inside paste windows (155.79,111.9)/(157.11,111.9): paste printed over an open via barrel wicks solder and is a known cause of EP voids/solder balls. Recommend shifting those two vias into the gaps between windows (or specify plugged vias) while keeping the 50 % rule. U6 footprint is byte-identical pre→cur (rule respected by the pass). S6 (pre-existing). /VEH5V trunk P2.1 → RS1.1 is 122.8 mm of 1.0 mm B.Cu (2.39 A @10 °C; ≈61 mΩ → ≈150 mV at 2.5 A) — marginal for the 2.5 A rating; 1.5 mm recommended. Lengthened by 11.8 mm by the connector move. S7 (pre-existing). No mounting holes anywhere on the 140×100 mm board (no MH*/NPTH footprints, no Edge.Cuts circles). Confirm the enclosure retains the board by other means before ordering. S8. Stackup declared in KiCad does not match the JLCPCB order: all four copper layers are 0.035 mm in (stackup), dielectrics 0.48/0.48/0.48 mm. JLCPCB 4-layer uses 0.5 oz inner copper (and ≈0.21/1.06/0.21 mm dielectrics). This is probably why inner traces were sized as if they were 1 oz; fix the stackup so the current-capacity tooling tells the truth.

NOTE

N1. Pad-level parity is clean: 813/835 netlist nodes match exactly; 9 differ only by the /→{slash} encoding of unconnected pin names on U10; 13 are PWR_FLAG PF* nodes (no footprint, expected). No footprint without a symbol, no footprint-name or value mismatch. N2. DRC: 0 errors, 0 unconnected, 13 parity items (all PF* missing footprints), 97 warnings = 85 lib_footprint_mismatch (library drift, noise), 2 silk_edge_clearance (MOD1 outline past the left edge, noise), 5 silk_overlap, 2 silk_over_copper (S2), 2 track_dangling + 1 via_dangling (S1). Ignored checks: missing_courtyard, track_not_centered_on_via, tuning_profile, footprint_filters, footprint_type. N3. Zones: all 4 copper zones carry filled_polygons and the fills are fresh (no foreign copper inside any fill; the pre-pass file had U26 pads inside the F.Cu pour, so the refill was done). P3V3_PLANE_IN2: 1 polygon, 11 563 mm² (one piece ✓). GND_PLANE_IN1: 4 polygons — main 11 796 mm² (84 % of board area) + islands 28.1, 11.3, 0.8 mm²; the plane is not fragmented into islands but it is heavily slotted (see M6; largest In1 signal runs: /IGN_IN 116 mm @1.0 mm, /MODEM_LED_MCU 89 mm, /I2C_SDA 76 mm, /RTCM_TAP 74 mm, /MODEM_RST_MCU 69 mm, /I2C_SCL 66 mm, 4× /BATLED 44–61 mm). MAGJACK_NO_POUR is a keep-out (no fill, correct). N4. /24V Q10.3 → U2.7 runs 47 mm on In2 at 1.0 mm (0.72 A @10 °C) for ≈0.7 A — acceptable (~10 °C). /3V3_ETH 27.9 mm on In2 at 1.0 mm (different 3.3 V rail cutting the 3V3 plane) — acceptable. N5. U26 pin 4 is left unconnected; the SC7A20 datasheet names it NC but its connection table lists GND in all modes — harmless to tie to GND in the next schematic touch. I²C pull-ups R30/R31 present; address 0x18 (SDO=GND) and CS=3V3 (I²C mode) are correct. Footprint pad arrangement (4-2-4-2, CCW from pad 1 bottom-left) matches the "BL" LCSC-style footprint convention but could not be checked against the datasheet figure from text — verify against the JLCPCB/EasyEDA footprint for C5126709 before first build. N6. Courtyards: 4 overlaps, all pre-existing (C35/U6, C3/C123, C3/JP5, C32/D19); none introduced. No copper within 0.5 mm of the board edge (closest: /3V3_ETH 1.0 mm tracks at y=41.40, 0.58 mm). No acute (<45°) track junctions; 2 exact duplicate segments (GND F.Cu at (125.33,75.86), /CHRG_EN at (148.0,108.0), pre-existing). N7. /SW_BAT (L6.1 → U6.21/22) is 11 mm at 1.0 mm plus a 0.75 mm neck on F.Cu (1.94 A @10 °C neck) — acceptable for short peaks, but 1.5 mm would match the BAT trunk. N8. C35 (the only BAT_PLUS capacitor) is 20 mm from L6.2 and reached through two vias and the In1 1.5 mm run (M3); the charger's output ripple loop is long. Consider a second 22 µF at L6.2. N9. Items of instruction 2 that were done: the old /24V via at (182.92,60.325) is gone; no P12/R42/C24 copper remains near (181,45) (nothing dangles there). K1 only had the uuid of its reference text regenerated (harmless).

3. Instruction-by-instruction status

# Instruction Status Evidence
1 Update PCB from schematic (add U26, C126–C128; remove P12, R42, C24) Already done in b508a2c (pre-pass board has all four, none of the three) — nothing further required; parity clean §4.1
2 Remove P12/R42/C24 leftovers near (181,45) and stray /24V via (182.9,60.3) Partly: old via removed, no leftovers near (181,45); but a new dangling /24V via at (181.04,64.08) and a dangling /BAT_PLUS stub at (181.5,100.8) were left S1
3 Place U26 near (124.5,84.5); C126/C127 ≤2 mm from pins 7/3; route SDA/SCL/3V3/GND/INT1→PB9; 4/6/11 NC Done differently: U26 at (93.2,44.68); caps 3.43 / 3.06 mm; nets and connectivity correct; INT1→U16.62 ✓ M7
4 Move /NTC_CELL In1 segments to B.Cu so In1 has no tracks under the MCU Not done; /NTC_CELL still on In1 and 90 mm of new In1 signal tracks added under/near U16 M6
5 Silkscreen v5.6 texts; title block Rev 5.6 + date on PCB and schematic Silk texts present (pre-existing); title blocks NOT updated (PCB rev 3.0 / 2026-08-12, SCH rev 3.0 / 2026-07-07) M5
6 Refill zones; DRC: 0 unconnected, 0 parity, 0 dangling; In2 plane one piece Zones refilled ✓; 0 unconnected ✓; parity = 13 PF* only ✓; 3 dangling items ✗; In2 plane 1 polygon ✓ N2, N3, S1
7 Do not move other parts, change widths, touch U6 paste, use bottom side Violated: 18 non-U26 footprints moved (6 connectors), BAT_PLUS trunk 1.5→1.0 mm plus a 0.5 mm In1 run; U6 untouched ✓; no bottom-side components added ✓ (B.Cu tracks were already in use) B1, B2, §4.3

4. Raw tables

4.1 Parity (netlist v56-netlist-1013.xml vs current PCB)

Quantity Value
Netlist components 253 (incl. 13 PWR_FLAG PF*, 2 DNP: Dbk2, R109)
PCB footprints 240 (pre-pass also 240)
In netlist, no footprint 13 — PF1, PF2, PF4–PF14 (PWR_FLAG, expected)
On PCB, not in netlist 0 (no MH* exist)
Footprint-name mismatches / value mismatches 0 / 0
Netlist (ref,pin) nodes 835
Exact net match on PCB pad 813
Name-encoding-only differences 9 (U10 pins 12,18–21,25–28: / vs {slash} in unconnected-net names)
PWR_FLAG nodes (no pad) 13
Real mismatches / missing pads / extra-net pads 0 / 0 / 0
Pads on unconnected-* nets 76 (77 no-connects in schematic)
Track/via nets not in netlist 0

4.2 DRC classification (v56-drc-1013-nofill.json, KiCad 10.0.4, severities error/warning/exclusion)

Type Count Class
errors (any) 0 —
unconnected_items 0 —
schematic_parity: missing_footprint PF1…PF14 13 expected noise (PWR_FLAG)
lib_footprint_mismatch 85 library drift, noise (C80–C118, R80–R97, D14–D18, U3/U6/U10–U17, Y1–Y4, P1/P4/P8/P10/P14–16, JP5, H4, MOD1)
silk_edge_clearance (MOD1 outline at x=56–62) 2 expected noise
silk_overlap 5 2 pre-existing (U7/Cbst2), 3 new (Rig1/Rigb1, D5/Rled1 ×2)
silk_over_copper 2 new (Rig1 ref on Rigb1 pad; Rled1 ref on D5 pad)
track_dangling 2 /3V3_ETH In2 (105.155,47.89) 0.61 mm; /BAT_PLUS B.Cu (181.525,100.79) 1.40 mm
via_dangling 1 /24V via (181.04,64.075), F.Cu only

4.3 Footprints moved in the pass (22 of 240; none added/removed; no footprint-name/value/pad-net changes)

Ref Value Before (x,y,rot) After (x,y,rot) Shift mm Classification
C126 100nF (116.62,95.105,0) (89.8,44.4,180) 57.4 required (U26 block)
C127 100nF (116.62,97.615,0) (89.8,46.6,180) 57.6 required (U26 block)
C128 10uF (116.84,92.345,0) (89.6,41.8,180) 57.4 required (U26 block)
U26 SC7A20TR (120.445,95.54,0) (93.2,44.68,0) 57.7 required (but not at requested 124.5,84.5)
D1 LED (176.37,43.645,90) (159.8,43.6,90) 16.6 NOT requested (instr. 7)
D6 1N4148W (152.24,48.2675,90) (152.2,52.6,90) 4.3 NOT requested (instr. 7)
F1 PPTC 4A/8A 12V 1812 (147.2,43.91,180) (132.4,43.8,180) 14.8 NOT requested (instr. 7)
JP1 0R (154.26,44.05,180) (137.6,44.4,180) 16.7 NOT requested (instr. 7)
P10 RESET-EXT (116.655,44.655,0) (105.55,44.6,0) 11.1 NOT requested (instr. 7) - connector
P11 CUTOFF-SW (135.8,44.755,0) (123.7,44.6,0) 12.1 NOT requested (instr. 7) - connector
P2 5V-IN-SD15B05 (127.2,44.795,0) (114.6,44.6,0) 12.6 NOT requested (instr. 7) - connector
P4 BATT-1S4P+NTC (190.2,44.64,0) (165.1,44.875,0) 25.1 NOT requested (instr. 7) - connector
P6 FAN 2-pin (160.41,44.755,0) (142.7,44.755,0) 17.7 NOT requested (instr. 7) - connector
P8 PANEL_LED (169.3,44.755,0) (151.9,44.8,0) 17.4 NOT requested (instr. 7) - connector
Q2 AO3400A (145.8,49.0,0) (149.0,50.4,0) 3.5 NOT requested (instr. 7)
R112 4.7k (98.2,48.4,0) (101.8,50.4,0) 4.1 NOT requested (instr. 7)
R3 120R (170.25,50.47,0) (159.2,46.4,180) 11.8 NOT requested (instr. 7)
Rgs1 100k (142.8,48.8,-90) (146.0,50.4,-90) 3.6 NOT requested (instr. 7)
Rigb1 3.3k (128.585,49.575,0) (130.6,50.4,0) 2.2 NOT requested (instr. 7)
Rled1 10k (123.145,45.65,90) (121.4,52.625,90) 7.2 NOT requested (instr. 7)
TP6 GND (107.38,42.14,0) (97.8,42.6,0) 9.6 NOT requested (instr. 7)
TP7 3V3 (110.465,42.23,0) (100.6,42.6,0) 9.9 NOT requested (instr. 7)

Pass totals: segments 2102 → 2139 (210 removed, 247 added), vias 343 → 352 (38 removed, 47 added), zones 5 → 5 (refilled), gr_text unchanged (21). Nets with changed routing (bbox of change): /24V, /3V3, /3V3_ETH, /5V_FAN, /ACC_INT1 (new), /BASE_LS, /BAT_PLUS, /BOOT0, /BYP_CTRL, /ETH_ACT_A, /ETH_LNK_A, /ETH_PMODE, /ETH_RST, /EXT_LED, /FAN_GATE, /FAN_RET, /I2C_SCL, /I2C_SDA, /IGN_SENSE, /KCOIL, /LED_A, /LED_K, /MAIN5V, /MODEM_EN, /NRST, /NTC, /SWCLK, /SW_IN, /SYS5V, /USART1_RX, /VEH5V, GND.

4.4 IPC-2221 reference (A, ΔT = 10 / 20 / 30 °C)

Width F/B.Cu 1 oz (35 µm) In1/In2 0.5 oz (17.5 µm) inner if 1 oz
0.25 mm 0.88 / 1.19 / 1.42 0.26 / 0.36 / 0.43 0.44 / 0.59 / 0.71
0.3 mm 1.00 / 1.36 / 1.62 0.30 / 0.41 / 0.49 0.50 / 0.68 / 0.81
0.5 mm 1.45 / 1.96 / 2.35 0.44 / 0.59 / 0.71 0.72 / 0.98 / 1.17
0.75 mm 1.94 / 2.63 / 3.15 — —
1.0 mm 2.39 / 3.24 / 3.88 0.72 / 0.98 / 1.17 1.20 / 1.62 / 1.94
1.5 mm 3.21 / 4.35 / 5.20 0.97 / 1.32 / 1.57 1.60 / 2.18 / 2.60
2.0 mm 3.95 / 5.36 / 6.41 1.20 / 1.62 / 1.94 1.98 / 2.68 / 3.21
via 0.3 drill, 25 µm plating 1.80 / 2.44 / 2.91
via 0.4 drill 2.21 / 3.00 / 3.59

Temperature rise at rated current, worst series element: BAT_PLUS In1 0.5 mm @0.5 oz: 1.4 A → ≈140 °C, 2 A → ≈316 °C, 4 A → off-scale; In1 0.5 mm even at 1 oz: 2 A → ≈100 °C. B.Cu 1.0 mm: 2 A → 7 °C, 4 A → 32 °C (was 3 / 17 °C at 1.5 mm). Inner 1.5 mm @0.5 oz: 2 A → 52 °C. MAIN5V In1 1.0 mm: 2.5 A → ≈170 °C. SYS5V In2 0.5 mm: 1.5 A → ≈160 °C.

4.5 High-current nets — total copper by layer/width and series-path analysis (pre vs cur)

Net Board Segments Vias Length by layer/width (mm)
/BAT_PLUS pre 40 6 B.Cu/0.3: 0.2, B.Cu/0.5: 33.2, B.Cu/1.5: 72.3, F.Cu/0.3: 1.5, F.Cu/0.5: 17.6, F.Cu/1.0: 2.5, F.Cu/1.5: 11.4, In1.Cu/1.5: 21.7, In2.Cu/0.5: 16.1, In2.Cu/1.0: 0.0, In2.Cu/1.5: 9.6
/BAT_PLUS cur 35 6 B.Cu/0.3: 0.2, B.Cu/0.5: 16.6, B.Cu/1.0: 52.9, B.Cu/1.5: 10.0, F.Cu/0.3: 1.5, F.Cu/0.5: 17.6, F.Cu/1.0: 2.5, F.Cu/1.5: 11.4, In1.Cu/0.5: 10.7, In1.Cu/1.5: 21.7, In2.Cu/1.0: 0.0, In2.Cu/1.5: 9.6
/SW_BAT pre 6 0 F.Cu/0.75: 3.1, F.Cu/1.0: 12.0
/SW_BAT cur 6 0 F.Cu/0.75: 3.1, F.Cu/1.0: 12.0
/VEH5V pre 46 4 B.Cu/0.5: 32.9, B.Cu/1.0: 111.0, F.Cu/0.25: 5.9, F.Cu/0.5: 7.6, F.Cu/1.0: 36.3
/VEH5V cur 46 4 B.Cu/0.5: 27.6, B.Cu/1.0: 122.8, F.Cu/0.25: 5.9, F.Cu/0.5: 8.0, F.Cu/1.0: 48.9
/MAIN5V pre 39 2 B.Cu/1.0: 95.3, F.Cu/0.25: 1.6, F.Cu/0.3: 1.6, F.Cu/1.0: 15.8, F.Cu/1.5: 25.7, In1.Cu/1.0: 15.1
/MAIN5V cur 40 2 B.Cu/1.0: 102.5, F.Cu/0.25: 1.6, F.Cu/0.3: 1.6, F.Cu/1.0: 25.8, F.Cu/1.5: 25.7, In1.Cu/1.0: 15.1
/SYS5V pre 72 5 B.Cu/0.75: 9.4, B.Cu/1.0: 4.6, F.Cu/0.5: 37.8, F.Cu/0.75: 79.7, F.Cu/1.0: 44.8, F.Cu/1.5: 28.4, In2.Cu/0.5: 9.1, In2.Cu/1.5: 20.2
/SYS5V cur 69 5 B.Cu/0.75: 9.4, B.Cu/1.0: 4.6, F.Cu/0.5: 37.8, F.Cu/0.75: 79.7, F.Cu/1.0: 43.8, F.Cu/1.5: 28.1, In2.Cu/0.5: 9.1, In2.Cu/1.5: 20.2
/24V pre 34 5 B.Cu/1.0: 13.9, F.Cu/0.5: 2.3, F.Cu/1.0: 47.6, In2.Cu/0.5: 5.3, In2.Cu/1.0: 47.2
/24V cur 30 5 B.Cu/1.0: 13.9, F.Cu/0.5: 2.3, F.Cu/1.0: 44.0, In2.Cu/0.5: 5.3, In2.Cu/1.0: 47.2
/24V_IN pre 11 1 B.Cu/1.0: 34.2, F.Cu/1.0: 15.3
/24V_IN cur 11 1 B.Cu/1.0: 34.2, F.Cu/1.0: 15.3
/SW_IN pre 14 2 F.Cu/1.0: 3.9, In2.Cu/1.0: 75.0
/SW_IN cur 13 2 F.Cu/1.0: 3.2, In2.Cu/1.0: 86.0
/SW_5V pre 13 0 F.Cu/1.0: 229.0
/SW_5V cur 13 0 F.Cu/1.0: 229.0
/3V3_MODEM pre 21 0 F.Cu/0.5: 93.7
/3V3_MODEM cur 21 0 F.Cu/0.5: 93.7
/SW3_NODE pre 10 2 F.Cu/0.5: 17.6, F.Cu/1.0: 0.5, In1.Cu/0.5: 12.8
/SW3_NODE cur 10 2 F.Cu/0.5: 17.6, F.Cu/1.0: 0.5, In1.Cu/0.5: 12.8
/5V_FAN pre 11 0 F.Cu/0.5: 5.7, F.Cu/1.0: 43.8
/5V_FAN cur 12 0 F.Cu/1.0: 65.2
/VIN_SW pre 5 0 F.Cu/0.25: 6.1, F.Cu/1.0: 8.5
/VIN_SW cur 5 0 F.Cu/0.25: 6.1, F.Cu/1.0: 8.5
Net Path Board Series min width (layer) IPC-2221 I @ΔT=10 °C (A) Series length by layer/width (mm) Series vias (drill)
/BAT_PLUS P4.1→L6.2 pre 1.5 mm (In2.Cu, 9.57 mm) 0.97 B.Cu/1.5: 63.8, F.Cu/1.0: 2.5, In2.Cu/1.5: 9.6 2: 0.3, 0.3
/BAT_PLUS P4.1→L6.2 cur 0.5 mm (In1.Cu, 10.69 mm) 0.44 B.Cu/1.0: 52.9, F.Cu/1.0: 2.5, In1.Cu/0.5: 10.7, In2.Cu/1.5: 9.6 3: 0.3, 0.3, 0.3
/BAT_PLUS P4.1→U6.23 pre 1.5 mm (In1.Cu, 21.69 mm) 0.97 B.Cu/1.5: 72.3, F.Cu/0.3: 1.5, F.Cu/1.5: 11.4, In1.Cu/1.5: 21.7, In2.Cu/1.5: 9.6 4: 0.3, 0.4, 0.3, 0.3
/BAT_PLUS P4.1→U6.23 cur 0.5 mm (In1.Cu, 10.69 mm) 0.44 B.Cu/1.0: 52.9, B.Cu/1.5: 8.6, F.Cu/0.3: 1.5, F.Cu/1.5: 11.4, In1.Cu/0.5: 10.7, In1.Cu/1.5: 21.7, In2.Cu/1.5: 9.6 5: 0.3, 0.3, 0.4, 0.3, 0.3
/SW_BAT L6.1→U6.21 pre 0.75 mm (F.Cu, 2.35 mm) 1.94 F.Cu/0.75: 2.3, F.Cu/1.0: 11.1 0:
/SW_BAT L6.1→U6.21 cur 0.75 mm (F.Cu, 2.35 mm) 1.94 F.Cu/0.75: 2.3, F.Cu/1.0: 11.1 0:
/VEH5V P2.1→U6.6 pre 0.25 mm (F.Cu, 3.94 mm) 0.88 B.Cu/1.0: 111.0, F.Cu/0.25: 3.9 1: 0.3
/VEH5V P2.1→U6.6 cur 0.25 mm (F.Cu, 3.94 mm) 0.88 B.Cu/1.0: 122.8, F.Cu/0.25: 3.9 1: 0.3
/VEH5V P2.1→JP1.2 pre 0.5 mm (F.Cu, 1.88 mm) 1.45 B.Cu/0.5: 27.2, F.Cu/0.5: 1.9 1: 0.4
/VEH5V P2.1→JP1.2 cur 0.5 mm (F.Cu, 2.25 mm) 1.45 B.Cu/0.5: 22.9, F.Cu/0.5: 2.3 1: 0.3
/MAIN5V U6.1→P11.1 pre 1.0 mm (In1.Cu, 15.09 mm) 0.72 B.Cu/1.0: 93.8, F.Cu/0.3: 1.0, In1.Cu/1.0: 15.1 2: 0.3, 0.3
/MAIN5V U6.1→P11.1 cur 1.0 mm (In1.Cu, 15.09 mm) 0.72 B.Cu/1.0: 102.5, F.Cu/0.3: 1.0, In1.Cu/1.0: 15.1 2: 0.3, 0.3
/MAIN5V U6.1→JP6.1 pre 1.0 mm (In1.Cu, 15.09 mm) 0.72 B.Cu/1.0: 93.8, F.Cu/0.3: 1.0, F.Cu/1.0: 5.9, In1.Cu/1.0: 15.1 2: 0.3, 0.3
/MAIN5V U6.1→JP6.1 cur 1.0 mm (In1.Cu, 15.09 mm) 0.72 B.Cu/1.0: 102.5, F.Cu/0.3: 1.0, F.Cu/1.0: 15.9, In1.Cu/1.0: 15.1 2: 0.3, 0.3
/MAIN5V U6.1→Q7.5 pre 1.0 mm (In1.Cu, 15.09 mm) 0.72 F.Cu/0.3: 1.0, F.Cu/1.0: 3.7, F.Cu/1.5: 5.2, In1.Cu/1.0: 15.1 2: 0.3, 0.3
/MAIN5V U6.1→Q7.5 cur 1.0 mm (In1.Cu, 15.09 mm) 0.72 F.Cu/0.3: 1.0, F.Cu/1.0: 3.7, F.Cu/1.5: 5.2, In1.Cu/1.0: 15.1 2: 0.3, 0.3
/SYS5V P11.2→U7.2 pre 0.5 mm (In2.Cu, 9.11 mm) 0.44 B.Cu/1.0: 4.1, F.Cu/0.5: 31.0, F.Cu/0.75: 30.9, F.Cu/1.0: 27.9, In2.Cu/0.5: 9.1 2: 0.3, 0.3
/SYS5V P11.2→U7.2 cur 0.5 mm (In2.Cu, 9.11 mm) 0.44 B.Cu/1.0: 4.1, F.Cu/0.5: 31.0, F.Cu/0.75: 30.9, F.Cu/1.0: 32.2, In2.Cu/0.5: 9.1 2: 0.3, 0.3
/SYS5V P11.2→F1.1 pre 1.0 mm (F.Cu, 12.35 mm) 2.39 F.Cu/1.0: 12.4 0:
/SYS5V P11.2→F1.1 cur 1.0 mm (F.Cu, 11.66 mm) 2.39 F.Cu/1.0: 11.7 0:
/SYS5V P11.2→U12.2 pre 0.5 mm (In2.Cu, 9.11 mm) 0.44 B.Cu/0.75: 9.4, B.Cu/1.0: 4.1, F.Cu/0.75: 36.7, F.Cu/1.0: 27.9, In2.Cu/0.5: 9.1 4: 0.3, 0.3, 0.3, 0.3
/SYS5V P11.2→U12.2 cur 0.5 mm (In2.Cu, 9.11 mm) 0.44 B.Cu/0.75: 9.4, B.Cu/1.0: 4.1, F.Cu/0.75: 36.7, F.Cu/1.0: 32.2, In2.Cu/0.5: 9.1 4: 0.3, 0.3, 0.3, 0.3
/SYS5V JP6.2→U7.2 pre 0.5 mm (In2.Cu, 9.11 mm) 0.44 B.Cu/1.0: 4.1, F.Cu/0.5: 31.0, F.Cu/0.75: 30.9, F.Cu/1.0: 32.8, In2.Cu/0.5: 9.1 2: 0.3, 0.3
/SYS5V JP6.2→U7.2 cur 0.5 mm (In2.Cu, 9.11 mm) 0.44 B.Cu/1.0: 4.1, F.Cu/0.5: 31.0, F.Cu/0.75: 30.9, F.Cu/1.0: 17.8, In2.Cu/0.5: 9.1 2: 0.3, 0.3
/24V Q10.3→U2.7 pre 1.0 mm (In2.Cu, 47.2 mm) 0.72 B.Cu/1.0: 13.9, F.Cu/1.0: 9.4, In2.Cu/1.0: 47.2 3: 0.3, 0.3, 0.3
/24V Q10.3→U2.7 cur 1.0 mm (In2.Cu, 47.2 mm) 0.72 B.Cu/1.0: 13.9, F.Cu/1.0: 9.4, In2.Cu/1.0: 47.2 3: 0.3, 0.3, 0.3
/24V_IN P1.1→Q10.2 pre 1.0 mm (B.Cu, 33.33 mm) 2.39 B.Cu/1.0: 33.3 1: 0.4
/24V_IN P1.1→Q10.2 cur 1.0 mm (B.Cu, 33.33 mm) 2.39 B.Cu/1.0: 33.3 1: 0.4
/SW_IN F1.2→Q1.2 pre 1.0 mm (In2.Cu, 74.6 mm) 0.72 F.Cu/1.0: 1.3, In2.Cu/1.0: 74.6 2: 0.4, 0.3
/SW_IN F1.2→Q1.2 cur 1.0 mm (In2.Cu, 85.31 mm) 0.72 F.Cu/1.0: 1.7, In2.Cu/1.0: 85.3 2: 0.4, 0.3
/SW_5V Q1.3→MOD1.5 pre 1.0 mm (F.Cu, 178.55 mm) 2.39 F.Cu/1.0: 178.5 0:
/SW_5V Q1.3→MOD1.5 cur 1.0 mm (F.Cu, 178.55 mm) 2.39 F.Cu/1.0: 178.5 0:
/3V3_MODEM L7.2→J7.1 pre 0.5 mm (F.Cu, 54.15 mm) 1.45 F.Cu/0.5: 54.1 0:
/3V3_MODEM L7.2→J7.1 cur 0.5 mm (F.Cu, 54.15 mm) 1.45 F.Cu/0.5: 54.1 0:
/SW3_NODE U7.8→L7.1 pre 0.5 mm (In1.Cu, 12.85 mm) 0.44 F.Cu/0.5: 4.4, In1.Cu/0.5: 12.8 2: 0.3, 0.3
/SW3_NODE U7.8→L7.1 cur 0.5 mm (In1.Cu, 12.85 mm) 0.44 F.Cu/0.5: 4.4, In1.Cu/0.5: 12.8 2: 0.3, 0.3
/5V_FAN JP1.1→P6.1 pre 0.5 mm (F.Cu, 5.69 mm) 1.45 F.Cu/0.5: 5.7 0:
/5V_FAN JP1.1→P6.1 cur 1.0 mm (F.Cu, 4.09 mm) 2.39 F.Cu/1.0: 4.1 0:
/VIN_SW Q7.1→U6.7 pre 1.0 mm (F.Cu, 8.47 mm) 2.39 F.Cu/1.0: 8.5 0:
/VIN_SW Q7.1→U6.7 cur 1.0 mm (F.Cu, 8.47 mm) 2.39 F.Cu/1.0: 8.5 0:

Reading the series table: "series" elements are those whose removal disconnects the two pads (no parallel copper exists); the worst element is the one with the lowest IPC-2221 capacity. Branches to sense dividers (R5 on BAT_PLUS, R51/R55/R7 on VEH5V, U6.6 VIN pin neck 0.25 mm, U6.16 OVSNS) are 0.25–0.5 mm and are fine; they are listed only where a pair was explicitly requested.

4.6 Inner-layer signal routing (non-plane nets)

Layer Board Nets Segments Total length Largest
In1.Cu (GND plane) pre 27 143 917 mm /IGN_IN 116, /MODEM_LED_MCU 89, /RTCM_TAP 74, /MODEM_RST_MCU 69, /BATLED4 61
In1.Cu (GND plane) cur 28 157 985 mm + /I2C_SDA 76 (was 46), /I2C_SCL 66 (was 37), /ACC_INT1 30 (new), /BAT_PLUS 32 (was 22)
In2.Cu (3V3 plane) pre 28 198 1293 mm /SER_TXB 150, /SER_RXB 133, /NTC 99, /CHRG_FAULT 94, /CHRG_STAT 89, /SW_IN 75
In2.Cu (3V3 plane) cur 28 199 1258 mm /SW_IN 86 (+11), /NTC 80 (−19), /BAT_PLUS 9.6 (−16, R5 branch moved)
In1 non-GND copper inside U16 13×13 mm courtyard pre / cur 45.4 / 56.0 mm cur adds /ACC_INT1 10.1 mm, /I2C_SDA 0.5 mm; /NTC_CELL 10.2 mm sits just above the courtyard (y 52.2–56.0) on In1 in both

4.7 BOM / LCSC gaps (netlist fields; 238 active parts, 224 with LCSC)

Ref Value Footprint Issue
JP1, JP2, JP3, JP4, JP5, JP6 solder jumpers Jumper:SolderJumper-* / Drogheda:SolderJumper-3 no LCSC, not excluded from BOM
TP1–TP7 test points TestPoint:TestPoint_Pad_D1.5mm no LCSC, not excluded from BOM
MOD1 simpleRTK2B-Pro on UNO headers Module:Arduino_UNO_R3 (B.Cu, TH, net-connected pads) no LCSC, not excluded from BOM/POS
C? (10 nF 0603) 10nF C_0603 two codes in use: C57112, C1589
U26 SC7A20TR LGA-12 2×2 C5126709 Extended; LCSC page showed out of stock at review time
Dbk2, R109 SS34, 10k — DNP (correct)
C86817 (22uF vs 22uF/16V), C25803 (100k vs 100k/1%), C17700171 (10uH vs 10uH/2A), C158012 (5× JST XH 2p), C2925557, C7095263, C5160226, C83205 same code, cosmetic value-string differences only

4.8 Title blocks / silkscreen

Item Value
PCB title block (pre and cur) title "EINARBoard HBOX", date 2026-08-12, rev 3.0, company "Helgen Servicios Especializados", comment "Last Review: Dr. Leopoldo Rodriguez Salazar"
Schematic title block title "EINARBoard HBox", date 2026-07-07, rev 3.0 (A1 sheet, KiCad 10.0 format 20260306)
PCB silkscreen "EINARBoard 5.6" at (115.7,134.5); "HBOX v5.6 - 2026-10" at (112.8,136.6); "www.helgen.tech" at (112.8,138.3) — identical pre/cur
Schematic revision notes texts "V5.6 ECO (2026-09-28)…", "V5.6 add (2026-10-08): U26 SC7A20TR … INT1 -> PB9 EXTI9. C126/C127 100nF at VDD/VDDIO, C128 10 µF" present

4.9 U6 (LTC4040) DFM snapshot (identical pre/cur)

EP pad 25: 2.65 × 3.65 mm, layers F.Cu + F.Mask only (no paste), net GND. Paste: 6 unnumbered F.Paste-only pads 0.95 × 0.85 mm at x = 155.79 / 157.11, y = 111.90 / 113.12 / 114.34 → 4.84 mm² = 50.1 % of EP. Vias in EP: 3 × 0.6/0.3 GND at (155.74,111.92), (156.45,112.50), (157.13,111.88); the first and third are centred in paste windows (S5). No other thermal vias within 4 mm of U6. 24 signal pads 0.85 × 0.25 mm with F.Paste. No footprint- or pad-level paste margin overrides.