COEFFICIENTS OF THERMAL-EXPANSION OF METAL-MATRIX COMPOSITES FOR ELECTRONIC PACKAGING

Finite element analyses of the effective coefficient of thermal expans ion (CTE) of metal-matrix composites are presented, with a focus on co mposites with potential for use in electronic packaging applications. The analyses are based on two-dimensional plane strain and axisymmetri c unit-cell models. The brittle phase is characterized as an isotropic elastic solid with isotropic thermal expansion. The possibility of pl astic deformation, described by an isotropic-hardening flow rule, is a llowed for in the ductile phase. A wide range of reinforcement volume fractions is considered. The effects of phase geometry, phase contigui ty, ductile phase material properties, processing-induced residual str esses, and brittle particle fracture are considered. The CTE is found to be much less sensitive to phase distribution effects than is the te nsile stiffness. The results show that there is a significant dependen ce of the overall CTE on the phase contiguity (i.e., on whether the br ittle or the ductile phase is continuous).