Analysis of Surface Mount Thermal and Thermal Stress Performance

Ongoing analysis of leadless ceramic devices surface mounted to epoxy-glass is described. Finite element (FE) model results for thermal resistance as a function of airspeed, carrier size and spacing, and heatsinking are given. An overview of the thermal stress problem, emphasizing fatigue test design, is presented. The rationales used in choosing thermal cycle amplitudes, methods of heat transfer, definitions of failure, test frequency, and desired cycles to failure are compared to current industry practice and discussed in the context of their impact on test results.