Development of two different molding methods in 2.5D package with 20 μm or less fine bump pitch CoW structure

The requirement of high I/O counts is increasing in 2.xD package for high speed communication between chips, and fine bump pitch is one of the method which is studied extensively and implemented in the production. we demonstrate the underfilling and molding process with two different methods. One is the traditional capillary underfill (CUF) injection with solid epoxy molding compound (EMC) molding process, and the other one is liquid compression mold underfill (LCMUF) molding process. By setting the filler average particle size of CUF and LCMUF to 1 μm or less, we were able to fill the bumps with a minimum pitch of 15 μm. Furthermore, in wafer evaluation, both methods were able to fill all the dies on the wafer with controlled wafer warpage. Solid EMC molded wafer proceed through the process successfully, and the warpage was measured at each step. This result showed a good correlation with the simulation, demonstrating the effectiveness of the simulation in predicting warpage.