A study of a new flip chip packaging process for diversified bump and land combination

Flip chip packages using plastic substrates are becoming popular in the IC packaging market. However, it still has not been standardized as a real mass production system. We have newly developed a flip chip packaging technology using a nonconductive underfill resin sheet. The process flow of the new flip chip packaging is as follows. First, the underfill sheet is laminated onto substrate. Next, the bumped die is aligned and attached onto substrate which is covered by the underfill sheet under proper heat and pressure. The bumps under the die penetrate the resin and to reach the metal land of the substrate. Finally curing the underfill sheet and metal connection are carried out. We have studied the possibility of applying this packaging technology to a diversified bump and land combination by changing the underfill component and process parameters. The electrical stability and package warpage under several stress test conditions, such as JEDEC Level-3 and TST, have been evaluated in this study. After this evaluation, we found that the packages which have been built with proper resin components and process parameters show good performance for all of these reliability tests almost regardless of bump and land materials.