Strategies for avoiding delamination in system-in-packaging devices

Approaches such as the modification of substrate design and the use of different types of underfill/epoxy mold compound were proposed to solve the delamination problem in system-in-packaging devices (SiP). Energy dispersive spectroscopy, scanning electronic and acoustic microscopy were employed to evaluate the proposed changes in device structure. The effects of dispensing and curing temperature as well as of viscosity on the underfill penetration ability under the component region were investigated. It was found that besides the excess of flux residue, the root cause of the delamination/expansion problem in SiP devices submitted to high temperatures is the presence of a large size of voids under the component. The use of a substrate design with cavity under the component region containing two entrances and the application of underfill was considered as a solution of the delamination problem. The reliability of this strategy was confirmed by a large sample size of fabricated devices.