Evaluation of Interface Delamination in IC Packages Considering the Swelling of Molding Compound due to Moisture Absorption.

Abstract

Adhesion strength evaluation of molding compounds is a critical issue in both structural design and material selection of plastic IC packages. We previously proposed a new adhesion test method that can separate residual stress from adhesion strength, and confirmed that the measured true adhesion strength can be applied to the quantitative prediction of interface delamination in a dry package. This paper describes the influence of moisture absorption of a molding compounds on true adhesion strength. When the average moisture content of an adhesive specimen is the same under the two kinds of moisture conditions (55°C/80%RH, 85°C/85%RH), the drop in true adhesion strength of the specimen that has absorbed moisture at 50°C is about 40 percent of that at 85°C. We also evaluate interface delamination in a moisturizing package by considering both the adhesion strength drop and the swelling of the molding compound caused by moisture absorption. The predicted temperature at which the delamination occurs agrees well with the experimental results for moisture-absorbed packages.