Epoxy Molding Compound Bleeding Reduction on Surface Mount Semiconductor Device

Abstract

Epoxy Molding Compound (EMC) bleed consists of a transparent layer of resin which mainly could occur during molding injection at material packing stage. Resin bleeds on exposed pad of a Surface Mount Device (SMD) can significantly impact the solderability performances of the package, causing failure of the product. De-flashing process after molding is generally performed to eliminate the resin bleed. However, deflashing can be performed on post-plated leadframes without critical drawback, while it is not recommended on pre-plated leadframes due to the high risk of damaging the finishing surface. In this study, an alternative approach aimed to reduce or eliminate molding compound bleed by optimizing the inorganic part of the molding compound formulation is presented. Besides the quality improvement, the presented approach provides an economical advantage since, by tuning the properties of the filler inside the EMC, it is possible to eliminate the de-flashing process from the assembly flow of a package and consequently reduce the manufacturing cost.