Investigation of delamination control in plastic package

Abstract

Interfacial delamination control is important for the mechanical reliability of plastic package, especially facing the challenge of lead-free requirement. Efforts of delamination performance improvement including structure, material and process for plastic package were made. It was demonstrated that the improvement of packaging material mechanical properties should depend on the package and purpose and should be the comprehensive consideration of advantage and disadvantage. The fracture mechanics was introduced to explain the mechanism of bumpy interface as the delamination retardant. The moisture absorption experiments of three kinds of molding compound were carried out to confirm that large difference of delamination performance among different molding compounds for the same device in our project was induced by moisture absorption difference, and the relation between the moisture weight absorbed and weight ratio of resin was obtained, given compounds of the same resin. It was substantiated that the moisture absorption of molding compound observes the Fick’s law at (Moisture Sensitivity Level 3) MSL3. Quantitative analyses of the moisture influence at the risk location were conducted to evaluate the risk of delamination with the consideration of vapor pressure during solder reflow, moisture and thermal expansion.