Residual stress in resin-molded IC chips.

Residual stress in IC silicon chips molded using epoxy resin is discussed. Stress-sensing chips were used for the measurement of residual stress which developed during assembly processes for IC plastic packages. It was found that the stress field in a silicon chip was almost equal to the plane stress field. The thermal expansion coefficient of molded resin had a strong effect on the chip stress. Thermal stress fields in the IC plastic packages were analyzed by the finite element analysis method. It was found that the FEM analysis could predict the stress fields in packages with about 10% error. The stress change in IC chips was measured under the reliability test condition for IC packages. It was found that both temperature cycles and moisture in the package had an effect on the stress change of IC chips. But the stress did not change in a room temperature environment.