Reliability study of high-end Pb-free CBGA solder joint under various thermal cycling test conditions

This paper described a ceramic ball grid array (CBGA) and its second level reliability. The CBGA uses a substrate with high coefficient of thermal expansion (CTE) and leadfree soldering. The reworkability of the BGA package and board was also studied. The results have shown that this package is reworkable without a significant reliability reduction in the board level reliability. The reliability of solder joints in different chains is monitored and reported separately during the thermal cycling test to understand the impact of the distance to the neutral point. A finite element model of the test setup was created and modeling results were compared with the thermal cycling reliability test data. Acceleration factor has calculated for irregular temperature profiles as compared to the standard ATC profile. The impact of the highest temperature during the temperature cycle as well as the temperature range was shown to follow traditional Norris-Landzberg's equation. A recommendation is made to use the acceleration factor for translating the test data between different temperature cycling scenarios.