Application of Non-UV BG Tape on Assembly of Flip-Chip Package with Copper Pillar Bump

Abstract

UV tape is widely used in the assembly process of flip-chip package. The adhesiveness of this kind tape will decrease after exposing under UV light. By using this character, the UV tape could be easily peeled off from the bump side of flip-chip wafer after wafer back grinding(BG) process. But in the case of flip-chip die integrated with eflash unit Non-UV BG tape need to be used in stead of UV BG tape since eflash is sensitive to UV light and the data stored in it could be damaged after exposing under UV light. The adhesiveness of Non-UV BG Tape is stronger than UV BG Tape after UV exposure. Therefore, when removing it after BG process, bump crack or die crack could be happened. In this paper, key parameters in Non-UV BG taping process have been studied through assembly design of experiment(DOE). As a result, SB370-SV(Mitsui) tape is successfully applied on a flip-chip wafer with copper pillar bump with 4hrs window time to remove which is acceptable and feasible in actual assembly production.