Hi ! Everyone. Last week I ordered a 4OZ copper thickness of PCB in PCBwing.com , as a high-power drive. They told me that this requires a larger space. I think this all will help, you can pay attention to your own design.

 

 

Just because it's 4 oz copper doesn't mean it's going to carry a ton of current, you still need to do the proper calculations that we all have to regarding copper thickness.

Simple circular mils on a PC board don't add up the way they do with common wire.

 

Marshallf3,
Although I'm sure you're aware of how to calculate required trace widths, have you seen PCBtrace?

Roman Black has it hosted on his site: http://www.romanblack.com/pcbtemp.htm

Pretty handy freeware tool.

 

Trace spacing should be determined by the operating voltage of a product (creepage/clearance requirements). That dimension they list is simply because of the fabrication process to avoid reduced spacing issues while etching heavy copper.

 

Marshallf3,
Although I'm sure you're aware of how to calculate required trace widths, have you seen PCBtrace?

Roman Black has it hosted on his site: http://www.romanblack.com/pcbtemp.htm

Pretty handy freeware tool.

Thanks, I've seen and used a couple of different ones that are out on the web. There are still times however that I'll etch the circuit on common 1 oz and add an additional piece of bare wire acrss a trace that has to carry a lot of current such as the output legs of a power FET driver. No reason to make the whole board out of thick stuff, it's far too cost prohibitive and as mentioned during the etching process you get concave areas between the resist and the board itself. If you specify too thin of a line width half of the center area of the trace can be etched away.

 

And, I may be restating the obvious, but on multi-layer boards, use multiple layers for high current traces. Through-board components will make a high-current connection with all layers, but surface mount needs multiple adjacent, large(ish) vias.