Analysis of PC Chip Heat Sink Design

Royce TattonME 340

Dr. SolovjovFall 2006

The Problem

• Problem 3.137 in Incropera and DeWitt

• Comparison of two fin arrays to be used as PC chip heat sink

• Which provides more heat transfer (better cooling)?

The Chip

• Material – Ceramic Porcelain• Dimensions – 53 X 57 X 10 mm• Temperature – 75° C Maximum

Design A

• Dimensions – 3 X 3 X 30 mm• Number – 6 X 9 array (54 total)• Material – 6061 Aluminum• Convection Coefficient – 125 W/m2K

Design B

• Dimensions – 1 X 1 X 7 mm• Number – 14 X 17 array (238 total)• Material – 6061 Aluminum• Convection Coefficient – 375 W/m2K

Methods

• Use COSMOSWorks 2006 to determine maximum flux and temperature distribution in Design A and Design B

• Compare to analytical results

Setup of Problem

• Simplify by reducing to ¼ of the total geometry along symmetry planes

• Apply temperature constraints to chip surfaces

• Apply convection loads to top chip surface and fins

Results – Design A

• Maximum chip temperature of 75°C (348.15 K)

• Resultant heat flux of 7.807E+5 W/m2

Temperature Plot Heat Flux Plot

Results – Design B

• Maximum chip temperature of 75°C (348.15 K)• Resultant heat flux of 1.002E+6 W/m2

• Design B provides greater cooling of chip

Temperature Plot Heat Flux Plot

Conclusions

• Design B provides better cooling to the chip

• Results agree with the results of the problem in the textbook

• Conduction coefficient very significant factor

• “Bigger” is not always better

Recommendation

• Always perform heat transfer analysis before making decision on intuition

• Further analysis with radiation and other materials to find a better fin design