Thermal Cycle Reliability of Microwave Components in CBGA Package with Different Dispensing Methods for Spaceborne Radar

With the development of active plased array antannas towards miniaturization, high integration and lightweight, there is an inevitable shift from modularization to system level package (SIP) for microwave components. Ceramic ball grid array (CBGA) is one of the most common device packaging methods, and it has become the preferred packaging method for microwave components such as T/R modules. Due to their extensive use in commercial applications, the thermal cycling characteristics of CBGA and other SIPs have been extensively reported in the literature. However, very limited data is available for thermal cycling behavior of microwave components with CBGA package commonly used for spaceborne applications. This paper analyzes and investigates the solder joint reliability of CBGA packaging devices with different dispensing methods under thermal cycles (-50°C~100°C). Optical microscopy (OM) and scanning electron microscopy (SEM) were used to study the crack growth and failure analysis of CBGA packages with and without adhesive. The results demonstrated that a large CTE adhesive (adhesive A) can actually cause earlier failure than packages without adhesive reinforcement. CBGA packages with edge-bond adhesive C and corner staking adhesive B can improve thermal cycle reliability. A CTE almost matching the CTE for printed circuit board (PCB) and ceramic substrates proved to be the most effective in improving board-level reliability of microwave components. Edge-bond adhesive C provides 3~4 times improvement of temperature cycle life compared to be the no-edge bonding condition. Moreover, long L-type adhesive can improve the board-level reliability of CBGA more effectively than the short L-type adhesive.