# Everyday Heat Transfer Problems: Sensitivities to Governing Variables

By
M. Kemal Atesmen
M. Kemal Atesmen
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ISBN:
9780791802830
No. of Pages:
238
Publisher:
ASME Press
Publication date:
2009

Power dissipation in electronic chips is a challenging heat transfer phenomenon, as the chips get smaller and smaller. Most chips or chip sets use copper or aluminum heat sinks to enhance the heat transferred out. These heat sinks are attached in a variety of ways to the chips in order to minimize the thermal resistance between the chip and the heat sink. In this analysis, a chip in the shape of a rectangular box, 10 mm × 10 mm × 0.1 mm, is considered. The chip is attached to its copper heat sink, also in the shape of a rectangular box, 10 mm × 10 mm × 10 mm, by a thermally conductive epoxy of 10 μm thickness.

Transient heat transfer which occurs during the cooling of a chip can generally be solved by using the same energy balance equation as in Chapter 11, without the radiation heat transfer effects. The temperature of a chip can be investigated by using unsteady-state and one-dimensional heat transfer rate equations in rectangular coordinates. Energy balance for a chip can be written as follows:
$Change in internal energy of the chip with respect to time=Power generated by the chip−Energy lost from the chip to its heat sink and to the environment by conduction and by convection heat transfer.$
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