CBGA to FR4 printed circuit board with no underfill thermal mismatch study

With the turn of the century, BGA-type packages are now widely used in the microelectronic industry. From a passive component manufacture that uses ceramic (alumina) as its main substrate carrier, the reliability of ceramic BGA (CBGA) packages mounted to FR4 printed circuit board is still a noteworthy concern. The reliability concern is for the different thermal expansion rates of the two substrate materials and how that CTE mismatch creates added stress on the BGA solder joint when thermal cycled. The point of thermal fatigue in a solder joint is an important factor of CBGA packages and knowing how many thermal cycles can be run before failure in the solder BGA joint is a must for designing a reliable CBGA package. In this paper, we describe a reliable, quick, FEA method to accurately predict the number of thermal fatigue cycles to produce a crack failure in the CBGA solder joint