Developments in selective high thermal conductivity orientation in CTE-compatible substrate and package component materials

Abstract

Market requirements for through-plane thermal conductivity improvements capable of adequately dissipating heat loads from high heat flux semiconductor devices also require that such materials provide coefficient of thermal expansion compatibility to certain package material sets. Higher through-plane conductivity combined with CTE compatibility must be obtained in materials that are cost-effective and capable of displacing existing copper alloys, copper laminates, Kovar, and similar package materials. Applications by market include commercial, military, and industrial electronics and semiconductor modules. Such materials must also meet requirements for stiffness and strength, to prevent distortion under typical clamping forces applied, and have low density relative to copper. Novel uses of carbon fibers and the latest experimental data are introduced, illustrating the use of such carbon fibers inserted into a proven, rigid structural metal matrix composite material that has known practical attributes: CTE compatibility, isotropic thermal conductivity, low density, and high stiffness and strength. The baseline material is manufactured in a cost-effective, net shape process. Comparative data including cost projections for several materials offering both CTE compatibility and various levels of thermal conductivity, isotropic and anisotropic, are given.