Flip chip solder joint fatigue life model investigation

Author(s):  
A. Yeo ◽  
C. Lee ◽  
J.H.L. Pang
2020 ◽  
Author(s):  
Hui Yang ◽  
Jihui Wu

Abstract In order to improve the interconnect properties of nano-silver solders, we have developed a new tin-doped nano-silver paste (referred to as silver tin paste). The hard brittle phase Ag3Sn formed by the soldering of the silver tin paste acts as a second phase strengthening effect, which significantly improves the shear strength of the solder joint and has the potential to be widely used in the power electronics packaging industry. In this paper, the viscoplastic and elastic composite model is used to simulate the inelastic deformation behavior of flip chip nano silver tin solder joint under uniaxial shear load. The simulated stress-strain response curve agrees well with the experimentally measured data. The finite element method is used to simulate the interconnection state of flip chip solder joints under thermal cycling conditions. It can be seen that the inelastic strain of the silver tin solder joint has increased, and it can be inferred that as this strain increases further, the chip connection will be broken. The fatigue life of silver tin paste is predicted by the creep fatigue life model. Compared with the pure nano silver paste, the equivalent plastic strain of the silver tin paste is reduced and the fatigue life is significantly improved. It is indicated that the solder joint reliability of nano silver paste can be improved by tin doping. The analysis results provide reference data for the development of new nano solder.


Author(s):  
Mei-Ling Wu

This paper focuses on global model uncertainty analysis, that is, how the input data uncertainty (global model data) affects the output data (solder joint fatigue life cycle). From the output data issue, how do we estimate uncertainty for each result (solder joint fatigue life cycle)? Assume the model structure is corrected, how do we estimate a physics of failure (PoF) and predict time to failure or cycle to failure? Identifying an approach for quantifying the combination of input and uncertainty would enable the determination of more realistic confidence limits on Physics of Failure (PoF) predictions. The goal of this present work is how some uncertainty might affect the prediction outcome. The effect of prediction model used and the calculation approach is also studied in this work.


2016 ◽  
Vol 2016 (1) ◽  
pp. 000106-000110
Author(s):  
Jia-Shen Lan ◽  
Stuwart Fan ◽  
Louie Huang ◽  
Mei-Ling Wu

Abstract In this paper, the solder joint failure and the solder joint fatigue life in the Thin-profile Fine-pitch Ball Grid Array (TFBGA) Package was investigated by performing the drop test, and implementing a simulation model. Owing to the need to meet the increasing demands for functionality, microelectronic package reliability can be compromised and has become the key issue when executing drop tests. During impact in drop test, the deformation of PCB due to bending and mechanical shocks can cause solder joint crack. While this is a well-known issue, observing the solder joint responses during the test execution can be a challenge. Therefore, in this work, a simulation model approach has been developed to investigate the stress and strain of the solder joint during the drop test. In this research, the JEDEC Condition B drop test was simulated, characterized by 1500G peak acceleration and 0.5 ms duration. The drop test simulation model was successful in predicting the solder joint fatigue life with different solder joint materials, such as SAC105 and SAC1205N, while also facilitating result comparison to identify the most optimal structure.


1997 ◽  
Vol 119 (3) ◽  
pp. 171-176 ◽  
Author(s):  
T. E. Wong ◽  
L. A. Kachatorian ◽  
B. D. Tierney

A Taguchi design of experiment approach was applied to thermostructural analyses of a gull-wing solder joint assembly. This approach uses a minimum number of finite element analyses to evaluate the impact of solder joint assembly parameters on fatigue life of the assembly. To avoid costly complex modeling efforts for each parametric case study, a commercially available program, MSC/PATRAN’s PATRAN Command Language, was used to automatically create finite element models of a two-dimensional gull-wing solder joint assembly based on nine parameters. Modeling time was dramatically reduced from days to a few minutes for each detailed lead/solder model. Two sets of parametric studies were conducted to evaluate the impact of variation of the six parameters. The analysis results indicate that lead ankle radius is the most critical parameter affecting solder joint total fatigue life, and lead and minimum solder thicknesses are the next most critical ones. Therefore, to effectively improve the solder joint fatigue life margin, it is recommended to: (1) increase the minimum solder thickness; (2) use thinner lead; and (3) use a larger lead ankle radius, even though this may require reducing lead shin length. By implementing only the last recommendation to modify the current solder joint assembly, the fatigue life margin in this design could, in general, be improved by 27 percent or more.


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