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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