The effect of polyimide surface morphology and chemistry on package cracking induced by interfacial delamination

The increasingly severe demands of concurrently increasing die size while reducing package size have made the mechanical stability of novel surface mount technologies a primary concern. The dominant issue is device failure due to package cracking caused by interfacial delamination between the polyimide-coated chip surface and the epoxy molding resin. To investigate the effect of polyimide surface morphology and chemistry on molding resin adhesion, devices were fabricated with different types of epoxy molding resins, polyimides, reactive ion etch (RIE) treatments, cure temperatures, cure atmospheres, and cleaning chemicals. The samples were characterized with scanning acoustic tomography (SAT), X-ray photo emission spectroscopy (XPS), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and various package-level reliability tests. The results of the characterizations and an explanation of the primary factors affecting interfacial adhesion are presented in this paper.<>