Abstract
In general, the integrated circuit (IC) is molded by epoxy resin. The molding in the package of IC includes both heating and cooling processes. Basically, substances expand when raised their temperature and contract when cooled. Thermal stresses occur when any portion of the thermal expansion or contraction in the plastic molded IC is constrained. In particular, these are induced during the cooling process (thermal contraction). It has been reported that, the thermal stresses have a variety of bad influence for the molded IC.
We have been analyzed in a part of the molding material by the photoelastic method. In the photoelastic method, mold resin must be transparent, but real mold resin is opaque to contain filler and so on. Therefore it is impossible to measure thermal stresses. Consequently, in this study, the finite element method was used as one of computer simulation methods, and the thermal stress disrtibution was analyzed in a molded IC section by this method. As the result, a part of maximum stress distribution values nearly agree with any portion of IC failures, and thermal stress values of opaque resin have approximately twice as much as those of transparent resin.
