Hygroscopic behavior and in-line thermo-mechanical treatment of polymeric material effects on PBGA warpage

The interaction of hygroscopic behavior and thermo-mechanical treatment of polymeric material is highly interesting, not only from the warpage and coplanarity point of view but also from the in-plane deformation characteristics. Since the moisture absorption of substrates has been classified as one of the indicators to qualify package materials, in this study, package warpage relating the substrate quality and package process flow was addressed. The package size effect on package warpage and coplanarity was examined The hygroscopic behavior of plastic packages on warpage was investigated by two different storage patterns such as dry packing and on-floor exposure. Moreover, the in-line thermo-mechanical treatment (clamping) effect on warpage vs. hygroscopic behavior was discussed. Finally, from Moire interferometry, the fringe patterns of specimens with and without clamping and before and after soaking were compared. It is shown that clamping is able to control the warpage successfully.