Heat and current are the two reasons standard FR-4 stops being the right answer. High-Tg laminate keeps the board dimensionally stable; heavy copper carries current without excessive width or temperature rise.
Material and copper options
| Parameter | Capability |
|---|---|
| Tg | Tg 170, 180 and 200 available |
| Td | 260 °C+ decomposition temperature on selected grades |
| Copper weight | 2 oz, 3 oz, 4 oz, 6 oz, 10 oz, 20 oz |
| Layer count | 2-16 layers in heavy copper builds |
| Minimum trace / space | 6 / 6 mil for 2-3 oz; 8 / 8 mil for 4 oz+ |
| Thermal stress | IPC-6012 Class 2 / 3 testing on request |
| Finish | ENIG, HASL-LF, OSP; hard gold for edge contacts |
When to specify high-Tg
- High operating temperatureAutomotive under-hood, power supplies and enclosed industrial controls.
- Multiple reflow cyclesComplex assemblies that go through several soldering passes.
- Thermal cyclingProducts that see repeated heat-up and cool-down in service.
- Lead-free assemblyHigher reflow temperatures favor a higher-Tg laminate.
Heavy copper design notes
Heavy copper changes more than current capacity: minimum trace width, etch tolerance, solder mask resolution and drill aspect ratio all shift. Keep spacing generous, avoid tiny features in the same layer as 4 oz+ copper, and expect a separate process review for 10 oz and above. For current-carrying paths, use the trace width calculator as a starting point and confirm with thermal testing.
Sending a heavy-copper design? Include the copper weight per layer, expected current and any thermal test requirements. We will confirm the etch and mask process before quoting.
Frequently asked questions
What is the maximum copper weight you can build?
Up to 20 oz on selected constructions; 4-6 oz is the most common heavy-copper range.
Does heavy copper change the minimum trace width?
Yes. Minimum trace and spacing increase with copper weight because of etch behavior.
Can you assemble boards with heavy copper?
Yes, with a process review for paste volume and reflow profile on thermally massive boards.