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Date: | Wed, 16 Dec 1998 09:44:25 -0600 |
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Subject: temperature rise on a trace
Date: Wed, 16 Dec 1998 09:11:02 -0600
From: [log in to unmask]
To: [log in to unmask]
This comes from any undergrad heat transfer book.
Assuming worst case, no heat lost to air or conducted away through the epoxy of
the board, then
Temp rise = (Power x time)/(mass of copper trace x specific heat of copper)
Power = current^2 x resistance of trace
density of copper is 8954 kg/m^3
specific heat of copper is 383 J/kg C
You can figure it out from here.
Tony Kordyban
Tellabs Operations
(For more info on things like this, check out my book "Hot Air Rises and Heat
Sinks: Everything You Know About Cooling Electronics Is Wrong", available from
ASME Press, or amazon.com)
Hiteshew, Michael wrote:
>
> Hi,
> I have a little physics problem maybe someone can help me with. I'm
> looking
> for an equation to solve for the temperature rise in a trace with a given
> amperage over
> a given period of time. Here's the problem:
> A copper (inner layer) trace will have 6 amps on it (under short
> circuit conditions)
> for a maximum of 128 microseconds. For a given trace width and length, I can
> calculate
> the DC resistance. What I can't calculate is the temperature rise on that
> trace over that
> time. Obviously, I need to know this to ensure I don't approach the fusing
> temperature
> of the copper.
> I'll turn this into a science project if I have to, but I'm
> wondering if anyone has
> this equation at their fingertips. Thanks in advance if you do.
>
> Michael Hiteshew
> Lockheed Martin Launching Systems
> [log in to unmask]
> (410) 682-1259
>
>
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