A Procedure for Automated Shape and Life Prediction in Flip-Chip and BGA Solder Joints

1996 ◽  
Vol 118 (3) ◽  
pp. 127-133 ◽  
Author(s):  
G. Subbarayan
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Life Prediction ◽  
Flip Chip ◽  
Solder Joints ◽  
Three Dimensional ◽  
Reliability Estimation ◽  
Element Mesh ◽  
Shape Prediction ◽  
Dimensional Finite Element

In this paper, a three-dimensional shape prediction model and a finite element solution procedure for flip-chip and BGA solder joints are developed. The developed system is capable of calculating the solder joint geometry and the fatigue life automatically without any intervention from the user. The automation achieved will enable fast reliability estimation and improved accuracy, since the two-dimensional finite element mesh used for solder shape prediction is used to generate the three-dimensional finite element mesh for stress analysis. The implementation of the procedure is verified using the solution for a flip-chip joint from literature, and the capability of the code is demonstrated on a hypothetical three-dimensional solder joint with square pads that are rotated with respect to each other, and offset from each other. The system developed in the study represents the first instance of an integrated, automated finite element procedure for both shape and fatigue life prediction in general three-dimensional solder joints. The automation achieved in the system enables fast reliability estimation in a design environment, and the optimal design of flip-chip and BGA solder joint configurations for maximum life.

Effect of hourglass shape solder joints on underfill encapsulation process: numerical and experimental studies

2020 ◽  
Vol 32 (3) ◽  
pp. 147-156
Author(s):  
Muhammad Naqib Nashrudin ◽  
Zhong Li Gan ◽  
Aizat Abas ◽  
M.H.H. Ishak ◽  
M. Yusuf Tura Ali
Keyword(s):  
Solder Joint ◽  
Numerical Method ◽  
Flip Chip ◽  
Solder Joints ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Cross Sectional ◽  
Content Type ◽  
Filling Time ◽  
Encapsulation Process

Purpose In line with the recent development of flip-chip reliability and underfill process, this paper aims to comprehensively investigate the effect of different hourglass shape solder joint on underfill encapsulation process by mean of experimental and numerical method. Design/methodology/approach Lattice Boltzmann method (LBM) numerical was used for the three-dimensional simulation of underfill process. The effects of ball grid arrays (BGA) encapsulation process in terms of filling time of the fluid were investigated. Experiments were then carried out to validate the simulation results. Findings Hourglass shape solder joint has shown the shortest filling time for underfill process compared to truncated sphere. The underfill flow obtained from both simulation and experimental results are found to be in good agreement for the BGA model studied. The findings have also shown that the filling time of Hourglass 2 with parabolic shape gives faster filling time compared to the Hourglass 1 with hemisphere angle due to bigger cross-sectional area of void between the solder joints. Practical implications This paper provides reliable insights to the effect of hourglass shape BGA on the encapsulation process that will benefit future development of BGA packages. Originality/value LBM numerical method was implemented in this research to study the flow behaviour of an encapsulation process in term of filling time of hourglass shape BGA. To date, no research has been found to simulate the hourglass shape BGA using LBM.

Thermomechanical Durability Analysis of Flip Chip Solder Interconnects: Part 2—With Underfill

1999 ◽  
Vol 121 (4) ◽  
pp. 237-241 ◽  
Author(s):  
K. Darbha ◽  
J. H. Okura ◽  
S. Shetty ◽  
A. Dasgupta ◽  
T. Reinikainen ◽  
...  
Keyword(s):  
Finite Element ◽  
Flip Chip ◽  
Three Dimensional ◽  
Element Model ◽  
Empirical Models ◽  
Two Dimensional ◽  
Solder Interconnects ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Underfill Material

The effect of underfill material on reliability of flip chip on board (FCOB) assemblies is investigated in this study by using two-dimensional and three-dimensional finite element simulations under thermal cycling stresses from −55°C to 80°C. Accelerated testing of FCOB conducted by the authors reveals that the presence of underfill can increase the fatigue durability of solder interconnects by two orders of magnitude. Similar data has been extensively reported in the literature. It is the intent of this paper to develop a generic and fundamental predictive model that explains this trend. While empirical models have been reported by other investigators based on experimental data, the main drawback is that many of these empirical models are not truly predictive, and can not be applied to different flip chip architectures using different underfills. In the proposed model, the energy-partitioning (EP) damage model is enhanced in order to capture the underlying mechanisms so that a predictive capability can be developed. A two-dimensional finite element model is developed for stress analysis. This model accounts for underfill over regions of solder in an approximate manner by using overlay elements, and is calibrated using a three-dimensional finite element model. The model constant for the enhanced EP model is derived by fitting model predictions (combination of two-dimensional and three-dimensional model results) to experimental results for a given temperature history. The accuracy of the enhanced EP model is then verified for a different loading profile. The modeling not only reveals the influence of underfill material on solder joint durability, but also provides the acceleration factor to assess durability under life cycle environment, from accelerated test results. Experimental results are used to validate the trends predicted by the analytical model. The final goal is to define the optimum design and process parameters of the underfill material in FCOB assemblies in order to extend the fatigue endurance of the solder joints under cyclic thermal loading environments.

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