LEAD FRAME MOISTURE BARRIER FOR MOLDED PLASTIC ELECTRONIC PACKAGES

摘要

Electronic packages that consist of dies sealed within hollow plastic enclosures with electrically conductive leads penetrating the enclosure walls to access the die circuitry are manufactured by applying a heat-curable adhesive to the leads at only those locations where the surfaces of the leads will interface with the enclosure material, molding the package around the leads, and curing the adhesive during the molding process or during a post-cure. The adhesive is formulated to form a gas-tight seal around the leads and to maintain the seal during the thermal cycling that the components are exposed to during the typical procedures involved in manufacturing the packages and in making the electrical connections to other circuitry, as well as the typical environmental changes that the finished and installed product is exposed to during use. In particular, the adhesive is selected to accommodate differences in the coefficients of thermal expansion between the leads and the enclosure material while still maintaining a vapor-tight seal.