Thermal Fatigue Life Study for Film-BGA
This study aims to investigate the effect of a 96 I/O Film-BGA package of surface mounted components on the thermal induced nonlinear viscoplastic deformation of solder balls during temperature cyclic loading between -40¢J to 125¢J. Specifically, it aims to study the trend effect of the joint fatigue life with respect to four control factors of the PI (Polyimide) thickness, die size, die thickness, and the upper copper trace thickness. Then, two different package types of Fan-in and Fan-out design in terms of the joint fatigue life are discussed. Due to the structure/loading symmetry, a three-dimension octant finite element structure was modeled to capture the entire package structural behaviors and a formulation of Modified Coffin-Manson was used to predict the joint fatigue life.
Under temperature cyclic loading, the study results show that the die size, die thickness, and PI thickness had significant impact on the solder joint fatigue life, especially the effect of applying die size to the joint, but the upper copper trace thickness had little effect on the joint fatigue life. The study results also show that the package type of Fan-out design had higher joint fatigue life than that the package type of Fan-in design did for this Film-BGA package. In addition, by using the Taguchi method, the research could find the intensity of affected fatigue life due to the selected four control factors, and determine the optimized design by means of the optimized dimensions of the control factors. Then, the use of the ANOVA (analysis of variance) method helped the researcher predict the optimized joint fatigue life in comparison with the study results by using ANSYS finite element software analysis.
Advisor:none; none; none
School:National Sun Yat-Sen University
School Location:China - Taiwan
Source Type:Master's Thesis
Keywords:film substrate ball grid array viscoplasticity fatigue life
Date of Publication:06/20/2002