[SI-LIST] Thermal Profile WITHIN a trace
- From: <dbrooks9@xxxxxxxxxxxxxxx>
- To: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Tue, 31 Jul 2012 14:59:07 -0700
Assume a typical trace carrying moderate current. It has still ai= r on one
side and board material on the other side. It will reach an equili= brium
temperature above the ambient based on the i^2*R heating and the conv=
ectioncooling. I am wondering about the thermal profile WITHIN the trace. =
We would normally assume that copper is such a good thermal conductor that =
the thermal profile would be uniform. But we would assume that the conducti=
vity is so good that the current density would be uniform, too, and we know=
that there are exceptions to that (e.g. skin effect.) Since the boundary c=
onditions would be different at the still air and at the board material, I =
believe there must be a thermal profile within the trace.
How much variation might there be in point temperatures within the = trace?
Carrying this argument one step further, as= sume we measure the temperature
of the trace using two methods:1= . Measuring the resistance (therefore
measuring the average temperature of = all points within the trace)2. Using
an IR microscope (therefore= measuring the temperature at one point on the
surface of the trace.)= Assuming the measurements are correctly made, how
much difference migh= t there be in the measurements based on internal
thermal profiles?
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