Characterization of interfacial adhesion damage induced by accelerated life testing

The purpose of this effort was to characterize statistically and experimentally the interfacial adhesion damage of generic dual in-line packages (DIP´s) exposed to accelerated stress conditions. DIP´s, consisting of three parallel gold conductors in a meander pattern on a 24 pin Al₂O₃ ceramic substrate spin-coated with Pyralin PI-2555 polyimide with and without an adhesion promoter (APS), were chosen as the test vehicles. Leakage current measurements and optical microscopy were employed to monitor the degradation process at the interface between the polyimide and the substrate. In order to characterize the damage adequately, the entire surface of each DIP was analyzed. A two-parameter Frechet cumulative distribution function (cdf) was found to be excellent for characterizing the statistical scatter in the geometrical features, such as, the cross-sectional area of the damage located over the interface. It was observed that the adhesion damage tends to be larger and clustered for more severe testing conditions. It was demonstrated that APS statistically improves long-term reliability. Furthermore, interfacial adhesion damage was not initiated solely by contamination at the interface