PCB Fabrication

How to order Domoriks PCBs from a fab, source components, and assemble boards.

Ordering PCBs

The Gerber files for both modules are in their respective GitHub repositories. Any standard PCB fab will accept them.

Fab Notes
JLCPCB Low cost, fast. Minimum 5 boards. Also does PCBA (assembly).
PCBWay Good quality, slightly higher price. Good for prototypes.
Aisler European fab (Germany). Faster delivery to EU.
OSH Park US fab, purple boards, per-board pricing, excellent quality.

PCB settings (both modules)

Parameter Value
Layers 2
Thickness 1.6 mm
Surface finish HASL or ENIG
Copper weight 1 oz
Colour Any (black recommended for DIN-rail aesthetics)
Min hole size 0.3 mm

Gerber export from KiCad

If you modify the design, re-export Gerbers from KiCad:

  1. Open the .kicad_pcb file
  2. File → Fabrication Outputs → Gerbers
  3. Set output folder to gerbers/
  4. Enable all layers: F.Cu, B.Cu, F.Silkscreen, B.Silkscreen, F.Mask, B.Mask, Edge.Cuts
  5. Export Drill Files as well (Excellon format)
  6. Zip the gerbers/ folder and upload to the fab

PCBA (assembly) at JLCPCB

JLCPCB can assemble most components for you if you also order the BOM:

  1. Export BOM from KiCad: File → Fabrication Outputs → BOM
  2. Export CPL (Component Placement List): File → Fabrication Outputs → Component Placement
  3. On JLCPCB’s order page, enable PCB Assembly and upload BOM + CPL
  4. Review the LCSC part matches (most standard parts are stocked)
  5. Note: through-hole parts (screw terminals, DIP sockets) must be hand-soldered

The bom.csv in each repository already contains LCSC part numbers for JLCPCB PCBA.

💡 Pcba tip

Order PCBA for SMD components only. The screw terminals, relay sockets, and DIP switch are easy to hand-solder and are often not stocked by JLCPCB.

Key components

Relay Module BOM highlights

Reference Part Notes
U1 STM32G030F6P6 MCU, TSSOP-20
U2 SN65HVD3082E RS-485 transceiver, SOIC-8
RY1–RY8 Songle SRD-05VDC-SL-C or Omron G5LE-1 5V SPDT relay
Q1–Q8 2N7002 or BSS138 N-MOSFET relay driver
D1–D8 1N4148 Flyback diodes
PSU1 RAC02-24SK/277 or similar 24V→5V DC/DC (or use separate 5V supply)
J1 Phoenix Contact 1844370 or equiv. 4-pos 5.08mm screw terminal
J2–J9 Phoenix Contact 1844354 or equiv. 3-pos 5.08mm screw terminal

Switch Module BOM highlights

Reference Part Notes
U1 STM32G030F6P6 MCU
U2 SN65HVD3082E RS-485 transceiver
U3 PC817 ×8 Optocoupler for input isolation
R1–R8 10kΩ Input pull-ups
J1 4-pos screw terminal Power + bus
J2–J9 2-pos screw terminal Switch inputs

Hand assembly tips

  1. Solder SMD components first — MCU, transceiver, MOSFETs, diodes, passives
  2. Test 3.3V and 5V rails before soldering relays
  3. Relays last — they are the heaviest components and stress the board if handled roughly before solder is cured
  4. Flux is your friend — use flux paste on pads before placing TSSOP packages
  5. Check with a magnifier — TSSOP-20 pins are 0.65mm pitch; bridges are common

Flashing firmware before installation

Flash the STM32 via SWD before mounting the board in the cabinet. You’ll need an ST-Link V2 (cheap clones work) or a JLink. See the Firmware docs.

⚠ Test before cabinet installation

Always bench-test a new board — verify power rails, Modbus communication, and all relay channels — before mounting it in your cabinet.

← Wiring Guide Building & Flashing Firmware →