An optical characterization technique for hygroscopic expansion of polymers and plastic packages

In this paper, we have described a new simultaneous 3-D optical system for characterizing electronic packages. This optical system is able to capture high resolution, online whole field data set. We are able to use this optical system to determine the coefficient of hygroscopic expansion (CHE) in moulding compound by correlating the weight gain and hygro-strain information obtained. In this study, we have used this optical system to evaluate the hygroscopic expansion of a fully cured moulding compound, XJA-9. We have also studied the effect of moisture diffusion on the deformation of plastic IC package. It was found that moisture diffusion could reverse the warpage of the plastic package. The study showed that moisture may cause severe changes to the internal stress field of plastic packages that would usually occur unnoticed or underestimated.