Advanced system in package with fan-out chip on substrate

In conclusion, FOCoS is successfully developed for advanced SiP. FOCoS is aimed to a large package size and high I/O density (> 1000 I/Os) for high-end application. The existing fan-out and flip-chip techniques provide FOCoS with a short time to market. Moreover, FOCoS has a low cost and thin package potential as compared with 2.5D advanced package by ignoring the interposer. The multi-layers RDL are adopted to interconnect between chip and substrate. The connection on fan-out chip is spreading to a wider pitch through stack via and fine pitch. The challenges of multi-layer RDL and large size fan-out product have been systematic investigated and overcome in new product development stage. Enhanced Ti etching recipe and the PR exposure for optimization are adopted to solve the delamination between PI layers and PR residue issue, respectively. Consequently, FOCoS has passed the product reliability test of TCT700, HAST96 and HTST1000.