A Novel Method to Study Strain-induced Delamination in Plastic IC Packages using an Digital Image Correlation Tool

Scanning acoustics microscopy (SAM), Moire interferometry and Finite Element Analysis (FEA) based predictions has been largely used in package reliability study to deliver results critical to the thermo-mechanical risk assessments. Complementary to these tools, a novel method of package stress analysis, which involved directly measuring the deformation of an actual package, have been developed, and known as the digital image correlation (DIC) technology in recent years. In this study, this novel DIC technique is used to analyze the thermal-mechanical deformation and strain characteristics of 2 devices before internal physical defect formed. In the first case, the ability of DIC to identify a potential failing unit before delamination occur and detectable with a standard ultrasonic screening was demonstrated in a blind test. In the second case, DIC verified the existence of a quiescent strain within a package before the unit is due to fail for DA delamination /crack related electrical failure after temperature cycling test.