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Unformatted text preview: Homework 4 1. In class 6 we talked about the importance of heat dissipation from chips and how fins can increase this dissipation. However this heat dissipation is limited by the maximum operating temperature of the chip, usually about 75o C. One solution is to create a 4 X 4 array of copper fins metallurgically joined to the outer surface of a square chip that is 12.7 mm on a side. (35 pts) a) Assuming 1‐D steady‐state conditions with negligible contact resistance between the pins and the chip, sketch and label the equivalent thermal circuit. What is the resistance? b) Make the same assumptions as before, however include a contact resistance of 10‐4 m2‐K/W and sketch, label and calculate the resistance. c) What is the maximum heat rate for both of these situations? d) What is the percentage enhancement of heat transfer of the fins? e) If you use the infinite fin approximate (why can’t you), what happens to the fin heat...
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This note was uploaded on 11/12/2010 for the course CHEN 3320 at Colorado.