Fretless
Member
Asked Google’s Bard the following prompt:
”You are an expert in electronics, specifically high voltage circuits built using 4 layer PCBs. How would you go about designing the high voltage layer(s) of the circuit and PCB layout? What would be the overall guidelines or rules of thumb you would use?”
Its 3rd draft (selectable from amongst the three answers, or ‘drafts’ as they call it) seemed in many ways to be the most insightful. Maybe because it mentioned using an inner layer for the high voltage plane whereas the others didn’t, and I’d read that before somewhere else.
Anyhow, here’s that 3rd draft for those interested. Hopefully Nathan doesn’t mind me posting in the sushi section given it seems to be where most of the high voltage threads happen. Btw, Bard can analyze circuit schematics, or at least sounds to me like it can haha, I’m not responsible for any hallucinations it might have
:
Designing the high voltage layer(s) of a 4-layer PCB requires careful consideration and adherence to specific guidelines to ensure safety and reliability. Here are some key steps and rules of thumb I would follow:
1. Planning and Safety:
I hope this overview helps! If you have specific questions about your high voltage circuit or PCB layout, feel free to ask.
”You are an expert in electronics, specifically high voltage circuits built using 4 layer PCBs. How would you go about designing the high voltage layer(s) of the circuit and PCB layout? What would be the overall guidelines or rules of thumb you would use?”
Its 3rd draft (selectable from amongst the three answers, or ‘drafts’ as they call it) seemed in many ways to be the most insightful. Maybe because it mentioned using an inner layer for the high voltage plane whereas the others didn’t, and I’d read that before somewhere else.
Anyhow, here’s that 3rd draft for those interested. Hopefully Nathan doesn’t mind me posting in the sushi section given it seems to be where most of the high voltage threads happen. Btw, Bard can analyze circuit schematics, or at least sounds to me like it can haha, I’m not responsible for any hallucinations it might have

Designing the high voltage layer(s) of a 4-layer PCB requires careful consideration and adherence to specific guidelines to ensure safety and reliability. Here are some key steps and rules of thumb I would follow:
1. Planning and Safety:
- Define the application and voltage range: Clearly understand the intended use and maximum voltage the circuit will handle. This helps determine design requirements and risk mitigation strategies.
- Consult safety standards: Follow relevant safety standards like IPC-2221 and IEC 60664 for creepage and clearance distances, material selection, and other safety considerations.
- Prioritize safety features: Implement features like interlocks, high voltage fuses, and grounded enclosures to minimize the risk of accidents and electrical shock.
- Layer Stackup:
- High voltage isolation: Dedicate at least one inner layer solely for high voltage routing. This layer should be separated from other layers by thick dielectric materials with high Comparative Tracking Index (CTI) ratings.
- Ground plane layer: Utilize another inner layer as a dedicated ground plane for reference and return currents. This improves signal integrity and reduces noise coupling.
- Signal layers: Use the outer layers for lower voltage signals and components. This minimizes the risk of accidental contact with high voltage areas.
- Creepage and Clearance:
- Maintain adequate creepage and clearance distances between high voltage traces and other conductors, including ground planes. These distances depend on the voltage level and environmental factors.
- Use design rules in your PCB software to enforce these distances automatically.
- Trace Width and Spacing:
- Use wider traces for high voltage currents to minimize heat dissipation and voltage drops. Consult charts based on voltage, current, and desired temperature rise.
- Maintain sufficient spacing between traces to prevent corona discharge and arcing.
- Component Placement:
- Group high voltage components together in a dedicated area to minimize trace lengths and leakage currents.
- Use high voltage rated components with appropriate creepage and clearance specifications.
- Place components with sensitive low voltage circuits far away from high voltage areas.
- Rounded corners and chamfers: Implement rounded corners and chamfers on traces and board edges to reduce stress concentrations and prevent arcing.
- Solder mask and conformal coating: Apply a thick solder mask over high voltage traces and use conformal coating on the entire board for additional insulation and moisture protection.
- Testing and verification: Thoroughly test the PCB for functionality and safety before deployment. Perform high voltage withstand tests and ensure compliance with relevant standards.
I hope this overview helps! If you have specific questions about your high voltage circuit or PCB layout, feel free to ask.