High modulus DAF Introduction to decrease thin die WB crack issue

The trend for flash storage package size miniaturization and capacity increasing has created increasing demand for thin die application. Up to now, 30um even 25um die was applied. These thin dies suffered serious WB crack risk especially in overhang layers. In this paper, we report recent advances in using high modulus DAF to solve thin die WB crack issue. We carried out finite element analysis (FEA) to simulate DAF modulus influence to overhung layer die stress and WB die deflection. Also, DAF with different modulus was adopted to check its performance during WB. FEA showed that die deflection reduced by 15% and the back side die stress decreased by 11% with high modulus DAF. Real sample build DOE proved that high modulus DAF can help to decrease thin die WB die crack ratio and decrease die deflection. Moreover, higher DAF modulus will achieve lower max die deflection. Overall, this paper demonstrate that high modulus DAF application can help to solve thin die crack issue so as to improve product yield and quality.