Flow test for electronic foam encapsulants

There are many problems related to repeatability and the standardization of test results in evaluating rigid foam. Techniques were sought to determine the most suitable foams for encapsulating electronic modules containing discrete electrical components. The amount of foam flowing into intricate cavities varies with the foam and the specific configuration. This study sought to evaluate methods of determining the ability of resin to flow through restricted and intricate flow paths. Current foam evaluation problems include those of whether molds should be open or closed, and how molds should be loaded, since foams can be made to give strength variations of 3 to 1, depending on the preparation techniques. Density variations of almost 2 to 1 may result, depending on the openness of the mold.