Re: [CAD_CAM_EDM_DRO] Re: Max Trace Current CNC interface PCB

Here's a graph for quick reference

www.uslink.net/~cybercir/cir7.htm

The graph assumes a max derated current for a temp rise of 20 degrees or
less. The book that Alan references has much more detail and is a great
reference.

James

>
> A .010" trace will handle that current nicely .. at zero degrees
> Kelvin.
>
> The actual figure for current as a function of trace width is related
> to the AMBIENT TEMPERATURE.
>
> I'd try to hunt down Printed Circuit Design by Ginsberg.
> ISBN 0-07-023309-8 Fabulous reference.
>
> Also, you may want to read ANSI/IPC document D-949.
>
> For power applications, I've always used a 20 degree C rise as a VERY
> conservative figure. From the charts in the book above, to keep a trace
> carrying 20 amps from rising only 20 degrees C, a trace of 700 cross-
> sectional mils is required. With two ounce copper plating, this is a
> trace .250" wide.
>
> If a person is willing to tolerate a 60 degree C rise, only half that is
> required.
>
> These figures are for INTERNAL traces. Strangley, external traces, as
> would be found on a simple two sided PCB, require about 2.5 times the

copper.

>
> Note that 2 ounce copper is unusual, and normally must be specially
> requested. Also, the above rules only apply to COPPER plating.
>
> Alan