A liquid encapsulate material has been developed which has the super low modulating characteristics. It can relax the thermal stresses caused by differences in the coefficient of thermal expansion between ceramics and the encapsulating materials. These stresses become especially intense during the reflow process, temperature cycling tests, and other heat-dependent processes. The conventional encapsulating material for BGA, CSP and SMD on ceramic substrates shows poor reliability during reflow process, temperature cycling test etc., because of the large difference in the coefficients of thermal expansion between the two materials. For this reason, the conventional encapsrate material had a limited scope of application, so the usual encapsulating method was hermetic encapsulation, which made it difficult to miniaturize components. We have given a solution to these problems and also have improved the moisture resistance characteristics and adhesion ability to the substrate, realizing good reflow resistance and resistance to temperature cycling test under on-board conditions. The developed material is expected to enable large packages such as MCM (Multi-Chip Module) to be encapsulated with resin.
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