Development of Mechanical Locking Micro-Anchor Structures for aQFN Package Application

Due to a weak adhesion, the delamination occurred frequently in the interface between the epoxy compounds and lead that results in a performance failure normally. Several treatments, such as plasma and chemical modifications, have been developed and applied to enhance the bonding force in the interface of both materials. In this study, an anchor shape of the lead, as a mechanical locking microstructure, was developed and fabricated on the lead to improve the bonding of packaged epoxy molding compound. The fabrication technique was composed of three mainly steps which are the photolithography, chemical wet etching and electroplating process. The parameters of each step were studied and obtained for the fabrication of copper micro-anchor structure. Furthermore, force-displacement curves corresponding to the separation were obtained from the finite element simulations using a linear elastic model. The simulation result showed that the pull-off force was raised by 69 percent.