PCB Markings & Compliance
WTI400 v1.2 — In service on the test vessel. The silkscreen marks, fiducials, and stackup documented here are as-built on the V1.2 boards deployed on the test vessel. Compliance-mark content is locked (the marks correspond to the EU RED 2014/53/EU, FCC Part 15, UKCA, RoHS, and China EFUP regulatory frameworks the WTI400 is targeted at), but final compliance-test confirmation (the test report that authorises affixing the CE / UKCA / FCC marks) is itself a V1.3 milestone — see the V1.3 backlog below.
Overview
This page documents the PCB-level markings on pcb_markings.kicad_sch: the fiducial markers that support automated assembly, the silkscreen marks that carry product identity and compliance information, and the PCB stackup that physically realises the four-layer construction described elsewhere in the docs.
Three sub-sections on this page, in narrative order:
- Silkscreen marks and compliance — board identity (S1), CE / UKCA / FCC / RoHS / China EFUP compliance marks (S2 / S7 / S4 / S3), Scadys logo (S5), product-documentation QR code (S6), copyright (S8).
- Fiducial markers — four 0.5 mm bare-copper fiducials (FID1–FID4) supporting pick-and-place machine-vision alignment on both sides of the board.
- PCB stackup detail — the layer-by-layer construction, copper weights, dielectric thicknesses, and surface finish.
The fourth engineer-drawn rectangle on this sheet is an empty placeholder.
The WTI400 board outline, mounting-hole positions, and overall mechanical interface match the shared housing concept that the WTI400 and MDD400 sister product both fit. Mechanical details live in WTI400_V1.2.kicad_pcb and are summarised in the Mounting and board outline section below.
Functional specification and design objectives
The board-level markings and physical construction must:
- carry the regulatory marks required by the target markets — EU RED 2014/53/EU (CE), UK Conformity Assessed (UKCA), FCC Part 15 (USA), RoHS (EU restricted-substances), and China EFUP (Environment Friendly Use Period);
- carry the manufacturer identity (Scadys logo + copyright) and the product identity (board variant + revision), with the variant / revision in copper so it survives silkscreen wear;
- provide a machine-readable pointer (QR code) from the physical board to the live product documentation;
- provide pick-and-place fiducial references with a wide diagonal baseline, mirrored on both copper layers at identical XY coordinates so single-pass setup serves two-sided assembly;
- realise a four-layer stack-up that gives two signal layers and two heavier inner power planes, with the VCC – GNDREF – GNDREF – VCC ordering that forms the digital domain's plane-pair bypass capacitance; and
- present a non-rectangular outline and four-corner M3 mounting pattern compatible with the shared WTI400 / MDD400 panel-mount housing.
Board specification
| Parameter | Value |
|---|---|
| PCB dimensions | 95.2 × 95.2 mm (non-rectangular outline — see Mounting and board outline below) |
| Board thickness | 1.6 mm |
| Layer count | 4 (F.Cu / In1.Cu / In2.Cu / B.Cu) |
| Copper weight | 17.5 µm (0.5 oz) — F.Cu, B.Cu; 35 µm (1 oz) — In1.Cu, In2.Cu |
| Surface finish | ENIG (Electroless Nickel Immersion Gold) |
| Solder mask | Navy blue, both sides; 0.012 mm thickness; pad-to-mask clearance 0.075 mm |
| Min trace / space | Per design rules in the KiCAD project |
| Manufacturing class | IPC-6012 Class 2 |
Silkscreen marks and compliance
All marks listed below are silkscreen unless noted. They sit on the F.Cu (top) and / or B.Cu (bottom) silkscreen layers.
| Ref | Mark | Footprint | Purpose / placement |
|---|---|---|---|
| S1 | WTI400_v1.2 board identity | wti400:Variant | Board identity in copper for version traceability — survives silkscreen wear |
| S2 | CE mark | SILKS:CE_3.5mm | EU Declaration of Conformity (Directive 2014/53/EU Radio Equipment Directive) — applied after the V1.3 compliance pre-screening |
| S3 | RoHS + China EFUP | SILKS:EFUP_RoHS_China_4 | RoHS compliance (EU restricted substances) and China EFUP (Environment Friendly Use Period — "4" = 4-year mark) |
| S4 | FCC mark | SILKS:FCC_3.5mm | FCC Part 15 compliance identifier (US RF emissions). The full FCC ID is carried by the ESP32-S3-WROOM-1 module's own marking (2AC7Z-ESP32S3WROOM1) since the module's pre-certification covers the WTI400's RF emissions |
| S5 | Scadys logo | SILKS:scadys_logo_10x10.f-mask | Manufacturer logo, 10 × 10 mm, F.Mask layer — visible through the soldermask aperture |
| S6 | Product-docs QR code | wti400:qr_docs.scadys.io_products_wti400_10 | Machine-readable link from the physical board to the product docs at docs.scadys.io |
| S7 | UKCA mark | SILKS:UKCA_3.5mm | UK Conformity Assessed mark (post-Brexit UK market replacement for CE on UK-only batches) |
| S8 | Copyright | SILKS:Copyright | © 2025 GM Consolidated Holdings Pty Ltd |
Why FCC ID isn't on the board directly. The ESP32-S3-WROOM-1 module carries its own FCC ID label on the module itself (visible through the module's metal can window). The board-level FCC mark (S4) is the generic Part 15 compliance identifier; the device-specific FCC ID for the WTI400 is the same as the module's because the module's pre-certification covers the device's RF emissions (subject to the antenna keep-out — a physical PCB cutout under the antenna section — documented on the ESP32 Module page).
Why both CE and UKCA marks are present. Post-Brexit, the UK market requires UKCA rather than CE marking on goods placed on the UK market specifically. The WTI400 carries both so a single fabrication run can serve both EU and UK markets — the compliance test reports themselves are technically equivalent (both based on the same harmonised standards under different statutory instruments).
Mark permanence.
| Mark | Visible on | Permanence |
|---|---|---|
| S1 board identity | Copper (not silkscreen) | Permanent — copper etch survives field handling and solder wash |
| S2 CE, S4 FCC, S7 UKCA | F.Cu silkscreen | Standard silkscreen — durable in field use, may wear under prolonged direct contact |
| S3 RoHS / EFUP | F.Cu silkscreen | Same |
| S5 Scadys logo | F.Mask aperture | Visible through soldermask opening; very durable |
| S6 QR code | F.Cu silkscreen | Critical that the QR remains legible — survives operator wear under normal helm conditions |
| S8 Copyright | F.Cu silkscreen | Standard silkscreen |
Field heritage. The WTI400 V1.2 silkscreen has been in service on the test vessel for approximately 1,000 sea miles. Subjective inspection confirms the marks remain legible after that field exposure (open-deck installation, salt environment, UV exposure). The prior MLI400 V1.0 hardware revision (the WTI400's predecessor — installed on the same test vessel during the circumnavigation) used the same silkscreen process and survived an order of magnitude more sea miles without mark degradation.
Fiducial markers
Four 0.5 mm bare-copper fiducial markers (with 1.5 mm soldermask openings) form two mirrored pairs:
| Ref | Layer | Pair |
|---|---|---|
| FID1 | F.Cu | Front, top-left pair (mirrors with FID3) |
| FID2 | F.Cu | Front, bottom-right pair (mirrors with FID4) |
| FID3 | B.Cu | Back, co-located with FID1 |
| FID4 | B.Cu | Back, co-located with FID2 |
The pattern mirrors the MDD400 sister product's fiducial layout because the two share the same physical board outline (housing-compatible). A wide diagonal baseline between FID1 and FID2 gives the pick-and-place's angular-correction calculation low sensitivity to fiducial-detection noise — a 50 µm placement uncertainty at each fiducial translates to a fraction of a degree of angular correction error, well below the 0.5° typical pick-and-place placement tolerance.
The mirrored front / back placement at identical XY coordinates means the same vision-system fixturing can index both sides without re-teaching coordinates — saves setup time on two-sided assembly runs.
| Parameter | Value | Notes |
|---|---|---|
| Fiducial copper diameter | 0.5 mm | Per IPC-7351 Class 2 recommendation |
| Soldermask opening | 1.5 mm | 3× copper diameter — sufficient for vision-system contrast |
| F/B co-location accuracy | 0 µm (by design) | FID1 / FID3 and FID2 / FID4 share the same XY in the .kicad_pcb |
| Vision-system suitability | Confirmed by V1.2 production assembly | Same fiducial pattern used on MDD400 sister product |
PCB stackup detail
The physical stack-up, from top to bottom:
| Layer | # | Type | Thickness | Dielectric below | Notes |
|---|---|---|---|---|---|
| F.Cu | 1 | Signal + plane | 17.5 µm (0.5 oz) | F.Cu prepreg | Component side; carries VCC pour in the digital region, GNDREF moat fills under SMPS / CAN-power / wind-LDO islands |
| In1.Cu | 2 | Power plane | 35 µm (1 oz) | Core | Unbroken GNDREF in the digital region (one half of the VCC plane pair); GNDREF moat inside the SMPS island |
| In2.Cu | 3 | Power plane | 35 µm (1 oz) | B.Cu prepreg | Unbroken GNDREF in the digital region (other half of the plane pair); domain-dependent fills elsewhere |
| B.Cu | 4 | Signal + plane | 17.5 µm (0.5 oz) | — | Back-of-board; carries VCC pour in the digital region (mirrors F.Cu), GNDREF fills under SMPS / CAN-power / wind-LDO islands |
The VCC – GNDREF – GNDREF – VCC layer ordering across the digital region creates two distributed VCC↔GNDREF plane-pair capacitors (F.Cu↔In1.Cu and In2.Cu↔B.Cu, each separated by 0.1855 mm prepreg). The plane-pair capacitance is what gives the digital domain GHz-frequency bypass with no parasitic ESL or ESR — see the Power Supply page for the full rationale and the ESP32 Module page for the force-commutated discrete-cap topology that hands off to the plane pair above the discrete caps' self-resonance.
In the SMPS, CAN-bus power, and wind-LDO islands, all four layers carry GNDREF inside a copper-keepout moat that contains switching return currents.
Across isolation boundaries (CAN domain to digital domain; legacy-serial domain to digital domain), all four layers carry copper-free 1.4 mm creepage gaps. The wind-transducer connector also has a copper-free isolation gap up to the FL2 common-mode filter's GND_WIND ↔ GNDREF star point — see the Wind Interface page.
The stackup specification has been validated by the V1.2 production assembly and the ~1,000 sea miles of in-service operation on the test vessel. Quantitative impedance / capacitance measurements have not been re-taken explicitly — the in-service performance (Wi-Fi link stability, no observed EMC issues from co-located equipment, no field-failure modes attributable to the stackup) is the empirical confirmation.
PCB Layout
No per-circuit pcb_review layout file exists for the board-level markings; the layout notes below are consolidated from this page's own mounting, outline, and stackup remarks (the per-region copper-fill and isolation-gap detail is in the PCB stackup detail section above).
Mounting and board outline
The WTI400 V1.2 board has a non-rectangular outline shared with the MDD400 V2.9 sister product (both fit the same housing concept). Board extent:
| Parameter | Value |
|---|---|
| Board outline | Non-rectangular with rounded corners (~2.4 mm radius) and a step on the right-hand edge for the enclosure interface |
| Board extent (KiCAD coordinates) | x: 66.4–161.6 mm, y: 42.4–137.6 mm |
| Mounting hole pattern | Four-corner pattern matching the housing's panel-mount inserts |
Each mounting hole is sized for M3 hardware plus standoffs. The four mounting holes engage the housing's panel-mount inserts; no additional mechanical retention is needed. The same mounting-hole pattern is used on the MDD400 sister product so the two products are interchangeable from a housing-attachment perspective.
The right-side edge step accommodates the wind-transducer connector tab cluster (J4–J9) that protrudes through a dedicated housing aperture — this is the one outline difference of practical consequence between the WTI400 and the MDD400 (which has no transducer-side tabs).
Components
| Ref | Type | Layer | Function | Source |
|---|---|---|---|---|
| S1 | Copper board ID WTI400_v1.2 | F.Cu copper | Permanent product / variant identifier | wti400:Variant footprint |
| S2 | CE silkscreen mark | F.Cu silkscreen | EU RED 2014/53/EU compliance | SILKS:CE_3.5mm |
| S3 | RoHS / China EFUP silkscreen | F.Cu silkscreen | EU RoHS + China EFUP (4-year mark) | SILKS:EFUP_RoHS_China_4 |
| S4 | FCC silkscreen mark | F.Cu silkscreen | FCC Part 15 compliance | SILKS:FCC_3.5mm |
| S5 | Scadys logo | F.Mask aperture | Manufacturer identity, 10 × 10 mm | SILKS:scadys_logo_10x10.f-mask |
| S6 | Product-docs QR code | F.Cu silkscreen | Machine-readable link to live docs | wti400:qr_docs.scadys.io_products_wti400_10 |
| S7 | UKCA silkscreen mark | F.Cu silkscreen | UK Conformity Assessed | SILKS:UKCA_3.5mm |
| S8 | Copyright silkscreen | F.Cu silkscreen | © 2025 GM Consolidated Holdings Pty Ltd | SILKS:Copyright |
| FID1 | Fiducial marker | F.Cu | Pick-and-place vision alignment, top-left pair | 0.5 mm copper, 1.5 mm mask opening |
| FID2 | Fiducial marker | F.Cu | Pick-and-place vision alignment, bottom-right pair | 0.5 mm copper, 1.5 mm mask opening |
| FID3 | Fiducial marker | B.Cu | Mirror of FID1 on the back | 0.5 mm copper, 1.5 mm mask opening |
| FID4 | Fiducial marker | B.Cu | Mirror of FID2 on the back | 0.5 mm copper, 1.5 mm mask opening |
Testing & Verification
V1.2 is in service. The marks and fiducials have been validated by the V1.2 production assembly and by the in-service deployment on the test vessel. A few items remain open for the V1.3 production fabrication run.
Hardware bring-up (rig at the bench):
QR-code URL resolution— Validated on the V1.2 boards in service. Scan S6 with a phone QR reader; pass if the URL matches the live product-docs URL exactly.Compliance-mark legibility— Validated; marks survive open-deck installation. Photograph each mark under typical installation lighting; pass if all are readable at arm's length.Pick-and-place fiducial recognition— Validated through V1.2 production assembly; pick-and-place detected FID1–FID4 on both F.Cu and B.Cu setups without operator override.
Gaps & next version
Before next production run
- Copyright year update — Refresh S8 to the production year if it differs from 2025. The current silkscreen footprint reads "© 2025".
- Re-scan QR code URL — Confirm the deployed URL still matches the silkscreen QR (
qr_docs.scadys.io_products_wti400_10) on the PCB before fabrication; a typo or path change ships a broken QR.
Next version (V1.3)
- Compliance test reports — The CE, UKCA, and FCC marks on the silkscreen indicate the device is designed for compliance with the corresponding standards. The actual test reports that authorise affixing those marks are part of the V1.3 compliance pre-screening campaign (CISPR 32 conducted emissions, FCC Part 15 radiated, RED 2014/53/EU harmonised standards, NMEA 2000 conformance). The marks should not be affixed on production boards until the test reports are signed off.
References
- IPC-A-600: Acceptability of Printed Boards.
- IPC-6012: Qualification and Performance Specification for Rigid Printed Boards.
- IPC-7351: Generic Requirements for Surface Mount Design and Land Pattern Standard (fiducial-marker dimensions).
- EU, Radio Equipment Directive (RED) 2014/53/EU.
- FCC, Part 15 — Radio Frequency Devices.
- UK Government, UKCA Marking.
- EU, RoHS Directive 2011/65/EU.
- China SJ/T 11364-2014, Marking for the Restricted Use of Hazardous Substances in Electronic and Electrical Products (EFUP / China RoHS).
- NMEA 2000 Network Specification — IEC 61162-1 / SAE J1939 family.
Related pages
- Power Supplies — the VCC-digital plane-pair bypass that the four-layer stack-up physically realises
- ESP32-S3 Module — the antenna keep-out cutout and the force-commutated discrete-cap topology that hands off to the plane pair
- Wind Interface — the right-side edge-step connector cluster and the GND_WIND ↔ GNDREF isolation gap
- External Connectors — the connector roster behind the board-outline tab cluster
- Sister-product reference: MDD400 V2.9 PCB Markings & Compliance — same board outline and stack-up; minor differences in board-identity and QR-code URL