Investigation on the thermo-mechanical reliability of bump with different solder shape in ultra-large size FCBGA package

The 5G technologies evolve significantly in telecommunication. One of the important devices is high performace IC with excellent electric characteristics in ultra-large package form factor. FCBGA package was developed to provide a higher density I/O pins accomodation, and a higher transmission speed than conventional wire bond package products. Finite element analysis has played the paramount role in packaging process improvement. In this paper, we demonstrated the assembly, simulation, reliabilty and failure analysis results of ultra-large FCBGA. During the temperature cycling test, bump solder cracking caused by thermal stress was identified. Then finite element analysis was carried out to reveal the influence of different bump solder shapes on the thermal cycling performance. According to the results of experiment and simulation, the bump quility had obviously impacted on the temperature cycle test. Once the package size reaches approximately 100mm*100mm, the non-uniformality of bump shape were easily found in die corner region. Based on our simulation, the lifetime of uneven bump shape would has 20% reduction than normal bump shape.