Presently as much as 80% of the heat generated in a microprocessor "hot chip" is conducted to the motherboard through the leads. A better approach would be to remove most of the heat directly from the entire surface of the die via an efficient heat spreader. Diamond has the highest thermal conductivity of all materials, but single crystal diamond is much too expensive for use with microprocessor chips, which are from 5 to 15 mm square. Vapor deposited diamond is also too expensive in any grade having high thermal conductivity. An advanced polycrystalline diamond ceramic material exhibiting thermal conductivity approaching that of single crystal diamond can be made inexpensively in thick pieces to near net shape at ultra-high pressures and high temperatures. This proposal envisions manufacture of a novel polycrystalline diamond heat spreader which will efficiently couple the entire surface of the die to all metal planes in the motherboard and optionally to an external heat spreader on the back plane. Board assembly is facilitated via a straightforward adaptation of present Tape Carrier Package technology. Phase I goal is to demonstrate cool operation of a high performance desktop Pentium processor "hot chip" in a convection-cooled motherboard.
Keywords: Semiconductor Thermal Management, "hot Chip", Microprocessor, Convection Cooling, Heat Spreader, Dia
