Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Variation of Thermal Cycling Life Prediction of PBGA Microprocessor Components with Substrate Properties
by Mohammad Motalab, Ahmad Shahedi Shakil, Toufiq Rahman, Jeffrey C. Suhling

Abstract:
The modern trend is to decrease the size of microprocessor components, at the same time, the number of I/O of the silicon chip microprocessors have been greatly increased over the last few years, which means high BUS speed, high amount of heat generation and much more elevated temperature operation. Plastic ball grid array (PBGA) is one of the most widely used microprocessor components in electronic packaging industries. Due to the complex nature of the configuration of the package, when subjected to temperature fluctuation, thermal stresses are developed inside the package. Severe stresses may develop when the packages are exposed to harsh environments e.g. spaceship, automobile etc. where extreme fluctuation of temperature may occur. So the PBGA packages are often subjected to thermal cycling which ultimately causes fatigue failure in solder balls of the package. The thermal cycling life of a PBGA package may depend on the properties of its constituent materials. Particularly this study aims at investigating the effects of substrate mechanical properties on the prediction of thermal cycling life of the critical solder joint in a PBGA package. In experiments, it has been found that from package to package there is significant variation in elastic modulus of the Bismaleimide-Triazine (BT) substrate material. Finite element analysis results show that there is large degradation in thermal cycling life of the solder ball for a package with low elastic modulus BT material when it is compared with the results that obtained for higher value of elastic modulus.

Keywords: plastic ball grid array (PBGA), solder, thermal cycling life, mechanical properties, finite element method

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