Warpage and Stress Simulation Analysis of Substrate on Substrate Antenna in Package (AiP) for 5G CPE Application

In this paper, a 22 x 22 mm package size AiP which is applied to 5G CPE and has air cavity between substrate and substrate was studied. The air cavity between substrate and substrate is connected by solder balls and control of its stand of height is important to keep antenna performance. But the AiP would have higher solder ball crack risk under reliability test due to larger package size than AiP applied in mobile device. Thus, stress simulation was performed to check high stress location of solder balls under thermal cycle test (TCT) of package level reliability (PLR) and drop test of board level reliability (BLR), and a solution of adding glues was proposed to reduce solder ball crack risk. Warpage simulation was also performed to check warpage performance. Stress simulation showed solder ball stress could be reduced about 30% and 6% for TCT and drop test conditions, respectively. And both reliability results with adding glues showed passed. For package warpage portion, warpage value and contour were close and similar between simulation and moiré measured results. Thus, adding glue was a successful solution to reduce stress and pass reliability tests.