ICA slim sector model for the analysis of solder joint reliability

The finite element method has been used extensively for the assessment of solder joint reliability. A number of different modeling techniques exists. Due to the huge increase in the number of chip-to-board interconnections, it is getting impractical to perform conventional 3D analysis of packages considering the standard quarter or one-eight models. The strip model has been popularly used to reduce the number of nodes required for the analysis. However, this model has been found to have serious errors and some new techniques need to be developed. This work presents a novel technique called the slim sector model in which only a slim sector adjacent to the diagonal of the package is analysed. The strain history and the resulting fatigue life prediction of three slim sector models as well as the strip model were compared to those for the standard one-eighth model. Study on the accuracy and stability of different models were carried out. It was found that the 1 1/2 -pitch slim sector model gave the most accurate and consistent results with relatively high time efficiency. While the strip model was easier to implement, its accuracy was poor.