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Re: Potential heating problem

I have been running a little informal test of current carrying capacity. I
am currently (get it) running 2.6 Amperes through a pair of traces (.010 X
.0014) wired in series, embedded in the inner layers, one directly above the
other, of the test board shown. The temperature rise is approximately 60
degrees C over ambient yielding 98 to 107 C as measured on the surface of
the pcb. No discoloration of the board material has been noted.  The traces
are dissipating 1.138 X 2.60 = 2.96 W. No catastrophic failure has been

Now. I predict that if traces are failing at .250 A, those must be small
traces indeed!

Sterling Vaden

Dave Dwelley wrote:

> Do these miniature traces affect our 20 ohm wiring budget?
> What's the typical DC resistance of a patch panel?
> Dave Dwelley
> Jack Andresen wrote:
> >But let me go back to original issue. I have looked at many patch panel
> >PC boards and for various reasons, the traces run from 10 to 18 mils.
> >Possible reasons:
> >1) Making pairs of traces 100 ohm. 2) Trying to get between the RJ45
> >pins. 3) Running a pair between the 110 punch down pins. 4) In general,
> >there is very little space for both compensation and wiring while
> >leaving margins between pairs of traces. 5) People are afraid of too
> >fine traces
> >But it is important to recognize here is no general standard for patch
> >panel traces (as pointed out in one of the responses).