1994 Volume 43 Issue 495 Pages 1615-1621
Cyclic thermal stress tests were carried out by using aluminum chip embedded resin specimens as the model of an insulating epoxy material for semiconductor packaging or electrode molding in large scale apparatus, and the morphology of fracture pattern and the reliability were discussed.
The tests showed four types of fracture patterns, and the life distribution of each fracture pattern obeyed Weibull distribution. Thus, in the case where the specimen fractured with several patterns, the statistical study has to be carried out for each pattern by determining the life distribution for each one in detail.
The experiments made in different heating baths at various temperature conditions showed that the effects of these variables on lives depended on fracture patterns. The test results of the experiments with constant temperature difference showed that the mean life decreased with decreasing temperature range above the glass transition temperature (Tg). On the other hand, the test results with constant cooling temperature indicated that the temperature difference above Tg had an influence on the mean life, though the effect was less than that in the glassy state range.