ULX3S 3V3 rail: Fix before you build

5 pass, 1 with one change, 1 failing, 1 not assessed, 3 coming.

ULX3S 3V3 rail top copper with every via ringed green or amber

Top copper: every via ringed green (keeps its Class 3 ring) or amber (widen this pad), with the spacing and ampacity checks marked.

UL 796 construction Pass

UL 796

meets the fab's UL-recognized construction

ULX3S on JLCPCB meets the fab's UL-recognized construction (UL 796 design check).

FabJLCPCB
Conductors checked4811
Findings0
Board thickness1.6 mm
ULX3S top copper: the narrowest conductor UL 796 checked

Method: Construction rules checked against the fab's published UL 796 capabilities

IPC-6012 Class 2 Pass

IPC-6012 Class 2

Class 2: 100% via ring retention under the fab drill tolerance

ULX3S is IPC-6012 Class 2 ready (100% via ring retention under the fab's drill tolerance).

Vias554
Ring retention100%
Nominal ringsPass
Aspect ratio (max)7.9
Monte Carlo boards1000
ULX3S top copper: every via keeps its Class 2 ring as drawn

Method: Monte Carlo of every via over the fab drill and layer-registration tolerance

IPC-6012 Class 3 One change

IPC-6012 Class 3

Class 3: 77.9% ring retention as drawn, 100% with the pad change

Vias554
Ring retention77.9%
Nominal ringsPass
Aspect ratio (max)7.9
Monte Carlo boards1000
Ring retention with the change100%

Findings and the one change that fixes each

ULX3S top copper: the vias that lose their Class 3 ring as drawn, ringed amber
400 simulated drill hits on a Ø0.2 mm via; each circle is the drill, the shaded band is the 50 µm Class 3 ring it must not touchAs drawn0.419 mm pad75.2% keep the ring102 of 400 hits in the band2 break out of the padWith the change0.55 mm pad100% keep the ring0 of 400 hits in the band0 break out of the pad
Smallest annular ring per simulated drill hit, weighted to the board's 554 viasAs drawn: 77.9% keep the ringWith the change: 100%Class 3 min 50 µm050100150200+smallest ring, µm (left of line = lost)vias

Method: Monte Carlo of every via over the fab drill and layer-registration tolerance

Coupon predictions Pass

IPC-6012 coupons

9 via structures predicted to pass solder float, 6x reflow and IST; fewest IST cycles 1424 against 1000 required

PTH Ø0.2/0.419 F.Cu→B.Cu x488IST 1424 / 1000, float pass, reflow pass
PTH Ø0.25/0.5 F.Cu→B.Cu x5IST 1478 / 1000, float pass, reflow pass
PTH Ø0.254/0.454 F.Cu→B.Cu x1IST 1482 / 1000, float pass, reflow pass
PTH Ø0.254/0.5 F.Cu→B.Cu x3IST 1482 / 1000, float pass, reflow pass
PTH Ø0.3/0.6 F.Cu→B.Cu x13IST 1529 / 1000, float pass, reflow pass
PTH Ø0.35/0.7 F.Cu→B.Cu x2IST 1578 / 1000, float pass, reflow pass
ULX3S top copper: one via of each structure the coupon tests cover
PTH Ø0.2/0.419 F.Cu→B.Cu: 1424 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.2/0.419488 vias1424PTH Ø0.25/0.5 F.Cu→B.Cu: 1478 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.25/0.55 vias1478PTH Ø0.254/0.454 F.Cu→B.Cu: 1482 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.254/0.4541 via1482PTH Ø0.254/0.5 F.Cu→B.Cu: 1482 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.254/0.53 vias1482PTH Ø0.3/0.6 F.Cu→B.Cu: 1529 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.3/0.613 vias1529PTH Ø0.35/0.7 F.Cu→B.Cu: 1578 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.35/0.72 vias1578PTH Ø0.4/0.8 F.Cu→B.Cu: 1625 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.4/0.89 vias1625PTH Ø0.5/1 F.Cu→B.Cu: 1713 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.5/132 vias1713PTH Ø0.6/1 F.Cu→B.Cu: 1793 IST cycles available, 1000 required; solder float pass, 6x reflow passØ0.6/11 via17931000 cycles required

Method: Plated-via fatigue model for each via structure

Creepage and clearance Pass

IPC-2221 spacing

+5V to GND: clearance 0.2 mm, 0.1 mm required

Clearance0.2 mm (need 0.1)
Surface path0.2 mm
Working voltage5 Vrms
ULX3S top copper: the closest +5V to GND copper

Method: Shortest air and surface paths between the nets

Trace ampacity Pass

IPC-2221 / IPC-2152 ampacity

vccio33 0.48 A: pass; core1v1 0.3 A: pass

vccio33 (+3V3)Peak current density, B.Cu 20.48 of 68.33 A/mm2; Busiest via current 0.48 of 1.25 A; Trace rise 0.02 of 10 K
core1v1 (+1V1)Peak current density, In1.Cu 14.29 of 34.17 A/mm2; Busiest via current 0.3 of 1.25 A; Trace rise 0.03 of 10 K
ULX3S top copper: the via that carries the whole 3.3 V rail current

Method: Current capacity per rail from the IPC-2221 / IPC-2152 charts

Vibration and drop Fails

Steinberg vibration fatigue / JESD22-B111 board-level drop

Steinberg: all 7 assessed parts within their allowable deflection, lowest margin 5.62x (U1); JESD22-B111 drop: U1 1927 microstrain over the 1500 microstrain limit

First mode1265 Hz, board edges simply supported
Random input8.9 Grms, flat 0.04 g^2/Hz from 20 to 2000 Hz
Drop input1500 g, 0.5 ms half-sine (condition B)
U1 BGA 18 x 18 mmvibration 0.040 of 0.224 mm (5.62x); drop 1927 of 1500 microstrain (0.78x)
U2 QFP 22.1 x 10.16 mmvibration 0.028 of 0.507 mm (18x); drop 1345 of 1500 microstrain (1.12x)
U8 LCC 5 x 5 mmvibration 0.010 of 0.658 mm (68x); drop 465 of 1500 microstrain (3.23x)
U7 QFP 4.9 x 3.9 mmvibration 0.017 of 1.495 mm (86x); drop 836 of 1500 microstrain (1.79x)
U10 QFP 4.9 x 3.9 mmvibration 0.026 of 1.157 mm (45x); drop 1252 of 1500 microstrain (1.2x)
U6 LCC 4 x 4 mmvibration 0.013 of 0.735 mm (56x); drop 635 of 1500 microstrain (2.36x)
U9 LCC 31.4 x 18 mmvibration 0.016 of 0.142 mm (9.12x); drop 752 of 1500 microstrain (1.99x)

Findings and the one change that fixes each

Method: Plate model of the board with edges simply supported, 7 IC bodies from the KiCad placement; Steinberg allowable deflection Z = 0.00022 B / (C h r sqrt L) against the 3-sigma deflection at each part; drop as the modal response to the half-sine. Part masses and the corner mounting holes are not modelled, and both raise deflection and strain

Solder joint fatigue Not assessed

IPC-9701 solder joint thermal-cycle fatigue

Not assessed: no cycles-to-failure is given for any part. This report has no solder-joint life model and no sourced package or laminate CTE to run one on, and it does not invent them

Profile to assess againstIPC-9701 TC1, 0 to 100 C (an input of this report)
BGA jointsU1 LFE5U-85F-6BG381C, 381 balls at 0.8 mm pitch, 18 x 18 mm body
Leaded jointsU2, U7, U10
Leadless jointsU8, U6, U9
Missing inputssolder-joint life model; package and laminate in-plane CTE; U1 ball standoff

Method: Parts taken from the KiCad placement (7 IC bodies). The ball-map adapter exists for flip-chip BGA builds; the Engelmaier life equation it feeds is not in the tree, so no part is assessed

Reflow warpage Coming

IPC-TM-650 warpage

Coming next

Conductive anodic filament Coming

IPC-TM-650 CAF

Coming next

FCC pre-compliance Coming

FCC 47 CFR 15.109

Coming next

Design-stage readiness report against the standards; not a certificate issued by any standards body.