What decides the spacing on a high-voltage board?

The isolation standard and the pollution degree, not the copper weight. Clearance covers the air gap, creepage covers the surface path; slots and cut-outs increase creepage without consuming more board area.

When is thermal relief needed on a power plane?

When a pad connects to a large copper area that would sink too much heat during soldering. Relief spokes keep the joint solderable; the number and width of spokes set the trade-off between assembly and current capacity.

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High-Voltage and High-Current PCB Design

Power boards fail on spacing and heat long before they fail on copper thickness.

Hitech Circuits Engineering Desk

Shenzhen, China · PCB fabrication and assembly

2 min read

Published: 2015-12-14

Last updated: 2026-10-18

Technical review: Process figures checked against our published capability sheet. View capability sheet

High-Voltage and High-Current PCB Design

Spacing before copper

Determine clearance and creepage from the applicable standard and the working voltage, then check that the copper weight still allows the trace width the current needs.

Current and temperature rise

A trace's capacity is limited by the allowed temperature rise, not by a single ampacity number. Wider copper, heavier foil and parallel layers all reduce the rise.

Assembly details

Thermal relief, solder-mask openings and via placement decide whether a power board can be assembled reliably. Review them with the assembly house before tooling.

Technical Specifications

Outer copper: up to 20 oz
Minimum trace / spacing: 0.075 mm / 0.075 mm at 1 oz; wider as weight rises
Board thickness: 0.1–6.0 mm

Frequently Asked Questions

What decides the spacing on a high-voltage board?
The isolation standard and the pollution degree, not the copper weight. Clearance covers the air gap, creepage covers the surface path; slots and cut-outs increase creepage without consuming more board area.
When is thermal relief needed on a power plane?
When a pad connects to a large copper area that would sink too much heat during soldering. Relief spokes keep the joint solderable; the number and width of spokes set the trade-off between assembly and current capacity.

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