GRAPHITE REINFORCED MAGNESIUM AS AN ALUMINA MATCHING LOW COEFFICIENT OF THERMAL EXPANSION MATERIAL

BECAUSE OF ADVANCES IN INTEGRATED CIRCUIT USE AND MANUFACTURE, NEWER LOGIC AND MEMORY CHIPS ARE MORE POWERFUL AND HENCE GIVE OFF MORE HEAT. DIFFICULTIES HAVE BEEN ENCOUNTERED IN BONDING ALUMINUM CHIP CARRIERS TO ALUMINUM SUPPORT STRUCTURES, BECAUSE THE DIFFERENCE IN THERMAL EXPANSION (CTE) OF THESE MATERIALS CAUSES BOND FAILURE AT THE TEMPERATURES CREATED BY THE LARGER CHIP HEAT DISSIPATION. GRAPHITE/MAGNESIUM (GR/MG) COMPOSITE MATERIAL OFFERS AN ATTRACTIVE ALTERNATIVE TO ALUMINUM FOR SUPPORT STRUCTURES, BOTH BECAUSE OF ITS LOW WEIGHT AND GOOD MECHANICAL PROPERTIES AND BECAUSE ITS CTE CAN BE TAILORED TO MATCH THE CTE OF NEARLY ANY CHIP CARRIER MATERIAL. THE PURPOSE OF THIS PROGRAM IS TO DEMONSTRATE THAT CAST GR/MG CAN BE FABRICATED HAVING A QUASI-ISOTROPIC PLANAR CTE MATCHING THAT OF ALUMINA, AND THAT THERMAL CYCLING DOES NOT CAUSE BOND FAILURE BETWEEN THIS MATERIAL AND AN ALUMINA COATING.