Sorry for posting this here (after already trying the designer council) but
if I don't get a logical scientifical semi-provable response I will be
forced to use the dreaded "10 degree curve" for the rest of my designs....
ouch!


I can't figure out how to select the appropriate temperature curve when
calculating PCB trace widths versus current requirements.
If you use the chart in IPC-D-275 or IPC-2221, you have to select a curve to
get your minimum trace width.
If you use a calculator, it will solve for the temperature rise, but you
still must know if it is acceptable.
So what is acceptable? Anything that won't make the material hit Tg?
I'm trying to avoid the dreaded "Just use the worst case"...
Am I missing something?

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