Process development of five- and six-side molded WLCSP

This paper reports the progress of 5- and 6-side (5s/6s) molded WLCSP development. A 6.3 mm × 6.7 mm image sensor test vehicle was used to develop the 5s molding process and a 0.63 mm × 0.33 mm test vehicle was used to develop the 6s molding process. Various molding compound materials and processes, including die attach, compression molding, de-flash, laser dicing, were investigated in depth. Experiments targeting at warpage reduction, chip crack prevention, and residue cleaning on solder balls were carried out. Reliability tests based on JEDEC standards were performed to characterize the package reliability and no failures have been found in the test samples using 5s and 6s molded package structures.