Research on the Board Level Reliability of High Density CBGA and CCGA under Thermal Cycling

Area Array package becomes more popular in ceramic packages, for its ability in increasing the number of interconnects. As for high density ceramic packages, typically CBGA (ceramic ball grid array) and CCGA (ceramic column grid array) with the maximum I/O counts over 1000, the board level reliability has become a big concern.This paper focuses on the evaluation of board level reliability of CBGA and CCGA through thermal cycling tests, and the fatigue life prediction of board level interconnections by finite element method (FEM). Except for traditional solder balls and solder columns, a new type solder column with copper ribbon wrapped on the surface is also studied. Firstly, PCBs with daisy chains are designed and thermal cycling test are conducted for both CBGA and CCGAs. The loop resistance of the daisy chain is used to detect the failure of the test samples. Failure modes of CBGA and CCGAs are analyzed, and the fatigue life data of the interconnections are obtained and compared. Then, based on the test samples, the FEM method is used for the fatigue life prediction of the interconnections. Different damage parameters and fatigue life prediction equations are compared. Equations based on non-elastic strain energy density and non-elastic strain range are chosen for the fatigue life prediction of CBGA and CCGAs separately. The simulation results well agreed with the test results.