Thermal management in PowerPC microprocessor multichip modules applications

Thermal management considerations of PowerPC microprocessor multichip modules are discussed in this paper. Flow bypass effects on both PowerPC 603 and PowerPC 604 MCM heat sink and module thermal performance were quantified by computational fluid dynamics and conjugate conduction analysis. In PowerPC 603 MCM application, the heat sink thermal resistance can vary as large as 80% due to such effects, while in PowerPC 604 MCM application, the variation in thermal resistance can be as large as 100%. The conjugate heat transfer features in both PowerPC 603 and PowerPC 604 MCM were examined. Results show that the percentage of module power entering into the heat sink seems quite independent of the module component thermal properties. In general, about 70% of the module heat enters into the heat sink for PowerPC 603 MCM and about 85% of the module heat enters into the heat sink for PowerPC 504 MCM. Both module thermal resistances and the percentage of chip and module power distributions are affected by those material properties. Their effects were studied to understand the MCM thermal characteristics and to define the critical design parameters for thermal performance optimization