Prediction for Thermal Residual Stress between Electric Wires during Reliability Assessment by Heat Cycle Test with Finite Element Analysis

摘要

In recent years, the study of Chip on Board (COB) structures with LSI chips mounted on the substrate has attracted much attention. One of the main technical problems is that the internal electrical wires may disconnect during the heat cycle process due to the differences in the thermal expansion coefficients between component materials. In order to prevent thermal expansion deformation the wires are encased in resin. Until now, the relationship between the physical properties of the resin and the thermal residual stress in the wires has been seldom reported.In this work, the influence of resin physical properties on the thermal residual stress generated during the heat cycle process was theoretically analyzed via finite element analysis. The results show that the thermal residual stress generated in the wire during the heating process is larger than that during the cooling process. During heating the thermal residual stress was influenced by the storage modulus of the rubbery state (ER).