Reliability design for exposed pad and low-profile leadframe package

This paper focused on the delamination study of low profile leadframe package with exposed pad (eLQFP). In this type of package, a specification of silver plating area is required for bond pad. With the shrinkage of the non-plating pad area, and because of low adhesion strength between silver and mold compound, the interface of mold compound and die-pad in the silver plating area may potentially delaminate especially after moisture sensitivity level 3 test (MSL3) and IR reflow. The study is to define a design guideline and mold compound selection rule for minimum delamination after MSL3 & IR reflow. Firstly, a safety factor K is defined as delamination guideline. Then the structure parameters were prioritized for their impact to the factor K. Thirdly, a DOE was carried out to study the mold compound property effect on the delamination. Guided by the simulation in structure and mold compound study, a group of test vehicles were designed to validate the reliability. The result shows the well-defined safety factor K was workable for eLQFP failure evaluation.