Hi everyone,

I’ve designed a PCB in KiCAD for the first time for a 220V AC application, and I’d love to get your feedback on its safety, reliability, and general design practices. Below are the details of the board and its key design elements:

PCB Design Details

1. Board Dimensions:
   • Board size: 82mm x 128mm.
   • Material: FR4, 1.6mm thick.
2. Layer Stack:
   • Two copper layers: 35µm thickness each.
   • Solder masks: Top and bottom.
3. Solder Pads:
   • Pads for Live (L), Neutral (N), and Ground (GND) are through-hole padswith:
     • Drill size: 3mm.
     • Pad size: 5mm.
   • Test points are included for easier maintenance and testing.
4. Trace Design:
   • Copper trace widths:
     • 5mm for high-current traces (designed for 10A).
     • Smaller traces for signal or low-power connections.
5. Clearance and Creepage:
   • Clearance between high-voltage traces exceeds 3mm.
   • Pads and traces are separated to avoid arcing or short circuits.
6. Fuse Integration:
   • Dedicated fuse pads for overcurrent protection.
   • Standard cartridge fuse footprints are used (5x20mm).
7. Edge Cuts:
   • Defined board outline for A4-sized design.
8. Markings:
   • Labels and silkscreen text to identify connections, such as:
     • 220V AC
     • Switch Pads
     • Fuse Pads
     • Dist Pads for distribution.

Concerns and Questions

1. Trace Widths:
   • Are the 5mm traces sufficient for carrying 10A at 220V AC with 1 oz copper? Should they be widened further?
2. Clearance:
   • The high-voltage clearance is designed for a 3mm minimum. Is this safe enough for 220V AC, or should it be increased for better insulation?
3. Through-Hole Pads:
   • The 3mm drill holes are intended for soldering wires directly. Are these robust enough, or should additional strain relief be considered?
4. Safety Recommendations:
   • Are there any additional safety measures I should include, such as:
     • Conformal coating to protect against moisture.
     • Additional insulation slots between high-voltage components.
5. General Feedback:
   • Does the layout follow best practices for high-voltage circuits? Are there any oversights or areas for improvement?

 

See https://www.mclpcb.com/blog/pcb-trace-width-vs-current-table/
Also what is the system used for?
Have you considered using appropriate earth ground techniques for any possible metallic enclosure etc?

 

If G1 is ground then there is possibly a violation of the creepage and clearance distances between G1 and L1 on the 3-pin connector. Bring the track from L1 parallel to the track from N1 then put a right angled bend in it to get to L4.

 

If G1 is ground then there is possibly a violation of the creepage and clearance distances between G1 and L1 on the 3-pin connector. Bring the track from L1 parallel to the track from N1 then put a right angled bend in it to get to L4.

That's one of things I was worried about, I wanted to keep as space in the middle to cut a shape in the middle.

 

Where are your mounting holes, dont forget them. Both top corners, especially the top right where the switch is, seems impossible to add a mounting hole.. you might end up with some weird situations for assembly. Also one of the mounting holes can (or should) distribute Ground to the rest of the assembly.

 

Also one of the mounting holes can (or should) distribute Ground to the rest of the assembly.

Most standards require a safety earth connection that is separate from any fixings, although a functional earth may be through the board fixings.
(It doesn‘t matter if you are mounting it on plastic pillars)

 

Certainly the switch portion needs consideration: Is the switch directly attached to the PCB? or are those points for wire connections to the switch? Likewise the power connection.

 

Watch the spacing G1 to L1. Keep it as wide as you can.

 

Indicate a "hazardous voltage" or "dangerous voltage" area on the silkscreen so that anyone working this area is reminded of shock hazard.