Analysis of PC Chip Heat Sink Design Royce Tatton ME 340 Dr. Solovjov Fall 2006

The Problem Problem 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/m 2 K

Design B Dimensions – 1 X 1 X 7 mm Number – 14 X 17 array (238 total) Material – 6061 Aluminum Convection Coefficient – 375 W/m 2 K

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 ( K) Resultant heat flux of 7.807E+5 W/m 2 Temperature PlotHeat Flux Plot

Results – Design B Maximum chip temperature of 75°C ( K) Resultant heat flux of 1.002E+6 W/m 2 Design B provides greater cooling of chip Temperature PlotHeat 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