FCLGA Study with Polymide (PI) Removal from Chip Surface

With the increasing demand for high-performance computing and the rapid development of advanced packaging, semiconductor product design has become even more crucial to meet high performance and reliability requirements. In pursuit of these goals, packaging assembly manufacturing requires substantial optimization in both process and material, especially in the presence of new IC design direction to adopt wafer surface without polyimide passivation as a form of simplification in wafer fabrication. A significant challenge is in optimizing the packaging assembly processes to improve adhesion between the epoxy mold compound material and the die interface, which decreases after the removal of die surface polyimide. Additionally, the removal of die surface polyimide can lead to interaction effects between the epoxy mold compound material and the die surface during molding process, potentially increasing the risk of ESD failure.This study focused on optimization of packaging assembly processes to overcome the adhesion challenges in IC chips without surface polyimide (PI). Flip Chip LGA was used a the test vehicle. The risk assessment analysis and corresponding process evaluation results were discussed in detail. Factors such as pre-mold plasma power, gas flow, time and mold transfer pressure were examined thoroughly to enhance the adhesion between the die top surface and the EMC (Epoxy Molding Compound) interface. The results revealed that, by optimizing the packaging assembly processes, the product could meet application and reliability requirements even with the die surface polyimide removal.In summary, optimization of manufacturing processes was proven to be effective in addressing the delamination risk caused by the removal of die surface polyimide, hence achieving the required product performance. This achievement enables simplification of wafer fabrication process which also supports sustainability effort.