Breakthroughs in the Analysis of Leakage Failures in PBGA Packages

In the event of leakage failures in plastic ball grid array packages (PBGA), standard failure analysis procedure includes acid etching (called decapsulation) of the mold compound to expose the die. Those that are recovering after decapsulation were just closed as a random event caused by a foreign material (FM) in the mold compound. The need to determine the actual defect, which was suspected to have been removed during decapsulation, prompted other ways of characterizing and understanding the failure other than the standard failure analysis flow. Failure analysis (FA) tools and methods that are normally not utilized for analysis of leakage failures will be showcased here like mechanical grinding of mold compound, energy dispersive X-ray (EDX) and conductive atomic force microscopy (C-AFM) analyses. In this paper, we would like to present how we used these tools to find the defect, to fully characterize it and to use the data for rootcausing efforts