Effect of substrate flexibility on solder joint reliability. Part II: finite element modeling

2005 ◽  
Vol 45 (1) ◽  
pp. 143-154 ◽  
Author(s):  
Y.C. Lin ◽  
X. Chen ◽  
Xingsheng Liu ◽  
Guo-Quan Lu
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Finite Element Modeling ◽  
Solder Joint Reliability ◽  
Element Modeling ◽  
Joint Reliability

Estimating the Vibration Fatigue Life of Quad Leaded Surface Mount Components

1993 ◽  
Vol 115 (2) ◽  
pp. 195-200 ◽  
Author(s):  
D. B. Barker ◽  
Y. S. Chen ◽  
A. Dasgupta
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Finite Element Modeling ◽  
Stress Analysis ◽  
Empirical Equation ◽  
Solder Joint Reliability ◽  
Surface Mount ◽  
Joint Reliability ◽  
Vibration Fatigue

This paper discusses the assumptions and details of the fatigue life calculations required to predict the fatigue life of quad leaded surface mount components operating in a vibration environment. A simple approximate stress analysis is presented that does not require complex finite element modeling, nor does it reduce the problem to a simple empirical equation or rule of thumb. The goal of the new method is to make PWB vibration solder joint reliability information available to the designer as early as possible and in an easily understood and implemented manner.

The Effect of Intermetallic Compound in Solder Joint Fatigue Life Prediction Using Finite Element Modeling

2003 ◽  
Author(s):  
Mohammad Masum Hossain ◽  
Dereje Agonafer ◽  
Puligandla Viswanadham ◽  
Tommi Reinikainen
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Intermetallic Compound ◽  
Solder Joint ◽  
Finite Element Modeling ◽  
Life Prediction ◽  
Temperature Cycling ◽  
Fatigue Life Prediction ◽  
Element Modeling ◽  
Solder Joint Fatigue

The life-prediction modeling of an electronic package requires a sequence of critical assumptions concerning the finite element models. The solder structures accommodate the bulk of the plastic strain that is generated during accelerated temperature cycling due to the thermal expansion mismatch between the various materials that constitute the package. Finite element analysis is extensively used for simulating the effect of accelerated temperature cycling on electronic packages. There are a number of issues that need to be addressed to improve the current FEM models. One of the limitations inherent to the presently available models is the accuracy in property values of eutectic 63Sn/37Pb solder or other solder materials (i.e. 62Sn/36Pb/2Ag). Life prediction methodologies for high temperature solders (90Pb/10Sn, 95Pb/5Sn, etc.) or lead-free based inter-connects materials, are almost non-existent due to their low volume use or relative infancy. [1] Another major limitation for the models presently available is excluding the effect of intermetallic compound (Cu6Sn5, Cu3Sn) formation and growth between solder joint and Cu pad due to the reflow processes, rework and during the thermal aging. The mechanical reliability of these intermetallic compounds clearly influences the mechanical integrity of the interconnection. The brittle failures of solder balls have been identified with the growth of a number of intermetallic compounds both at the interfaces between metallic layers and in the bulk solder balls. In this paper, the effect of intermetallic compound in fatigue life prediction using finite element modeling is described. A Chip Scale Package 3D Quarter model is chosen to do the FE analysis. Accelerated temperature cycling is performed to obtain the plastic work due to thermal expansion mismatch between the various materials. Solder joint fatigue life prediction methodologies were incorporated so that finite element simulation results were translated into estimated cycles to failure. The results are compared with conventional models that do not include intermetallic effects. Conventionally available material properties are assumed for the eutectic 63Sn/37Pb solder and the intermetallic material properties. The importance of including intermetallic effect in finite element modeling will be discussed.

Inverse Derivation of Constants for the Constitutive Equation and Fatigue Model of Pb-Free Solder Joints Based on Experiment Results, Finite Element Simulation and Virtual Optimization Methodology

2012 ◽  
Author(s):  
Weidong Xie ◽  
Mudasir Ahmad
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Constitutive Equation ◽  
Solder Joint ◽  
Test Results ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Fatigue Model ◽  
End Use ◽  
Free Solder

Solder joint reliability of Pb-free ball grid array (BGA) components, one of the most commonly used microelectronic devices, is one of the major concerns in product development and qualification. Accelerated Thermal Cycling (ATC) testing, though very time consuming and costly, remains the most prevalent means to evaluate solder joint reliability under certain end-use conditions. Wherever the test results are not readily available, a fine-tuned and well-benchmarked modeling methodology is of significance in producing quick-turn judgments and risk assessments to expedite product development. The two most critical elements in simulating solder joint reliability are 1) the solder constitutive equations, which describe the solder creep behavior under different working conditions, and 2) the fatigue model which ties the damage index from finite element modeling together with the experimental results. In this study, a novel approach has been explored in which the constants of the constitutive equation and fatigue model for Sn-based Pb-free solder joints were derived inversely based on ATC results of a ceramic BGA test vehicle. In order to cover the typical end-use conditions of the targeted products, the test vehicle was assembled onto PCBs with two different thicknesses and then thermal cycled under three different temperature profiles. The basic idea was that all of the constants, both for the constitutive equation and the fatigue life prediction model, were initially given as a range. Then by utilizing modeFrontier®, a multi-objective optimization software, the finite-element model was coupled with the virtual optimization algorithm to derive simultaneously all the constants that yielded the best fatigue life predictions compared to the test results. To simplify the problem without compromising the generality, a hyperbolic sine creep constitutive equation and Coffin-Manson fatigue model were selected in the analysis. There were a total of 6 constants to be determined; the initial ranges of the constants were defined by fitting the creep experimental data for a variety of Sn-based solder materials. Available in other publications, the selected solder materials cover a wide range of both Ag and Cu content which therefore represent the typical behavior of the most commonly adopted solder materials by the industry. To reduce the computational cost and enable fast convergence of multiple-generation iterations required by the multiple objective optimization algorithms, a very-well benchmarked submodel has been employed. Furthermore, by utilizing ANSYS® high performance computing (HPC) capability and cloud computing, the computational time was reduced significantly. An overall good correlation was achieved between the fatigue life prediction using the constants derived by this approach and the test characteristic life.

Thermal Cycling Reliability Predictions for PBGA Assemblies That Include Aging Effects

2013 ◽  
Author(s):  
Mohammad Motalab ◽  
Muhannad Mustafa ◽  
Jeffrey C. Suhling ◽  
Jiawei Zhang ◽  
John Evans ◽  
...  
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Failure Criteria ◽  
Lead Free ◽  
Aging Effects ◽  
Solder Joint Reliability ◽  
Reliability Models ◽  
Joint Reliability ◽  
Free Solder

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. Traditional finite element based predictions for solder joint reliability during thermal cycling accelerated life testing are based on solder constitutive equations (e.g. Anand viscoplastic model) and failure models (e.g. energy dissipation per cycle model) that do not evolve with material aging. Thus, there will be significant errors in the calculations with lead free SAC alloys that illustrate dramatic aging phenomena. In this research, we have developed a new reliability prediction procedure that utilizes constitutive relations and failure criteria that incorporate aging effects, and then validated the new approach through correlation with thermal cycling accelerated life testing experimental data. As a part of this work, a revised set off Anand viscoplastic stress-strain relations for solder have been developed that included material parameters that evolve with the thermal history of the solder material. The effects of aging on the nine Anand model parameters have been determined as a function of aging temperature and aging time, and the revised Anand constitutive equations with evolving material parameters have been implemented in commercial finite element codes. In addition, new aging aware failure criteria have been developed based on fatigue data for lead free solder uniaxial specimens that were aged at elevated temperature for various durations prior to mechanical cycling. Using the measured fatigue data, mathematical expressions have been developed for the evolution of the solder fatigue failure criterion constants with aging, both for Coffin-Manson (strain-based) and Morrow-Darveaux (dissipated energy based) type fatigue criteria. Similar to the findings for mechanical/constitutive behavior, our results show that the failure data and associated fatigue models for solder joints are affected significantly by isothermal aging prior to cycling. After development of the tools needed to include aging effects in solder joint reliability models, we have then applied these approaches to predict reliability of PBGA components attached to FR-4 printed circuit boards that were subjected to thermal cycling. Finite element modeling was performed to predict the stress-strain histories during thermal cycling of both non-aged and aged PBGA assemblies, where the aging at constant temperature occurred before the assemblies were subjected to thermal cycling. The results from the finite element calculations were then combined with the aging aware fatigue models to estimate the reliability (cycles to failure) for the aged and non-aged assemblies. As expected, the predictions show significant degradations in the solder joint life for assemblies that had been pre-aged before thermal cycling. To validate our new reliability models, an extensive test matrix of thermal cycling reliability testing has been performed using a test vehicle incorporating several sizes of fine pitch PBGA daisy chain components. Before thermal cycling began, the assembled test boards were divided up into test groups that were subjected to several sets of aging conditions (preconditioning) including different aging temperatures (T = 25, 55, 85 and 125 C) and different aging times (no aging, and 6 and 12 months). After aging, the assemblies were subjected to thermal cycling (−40 to +125 C) until failure occurred. As with the finite element predictions, the Weibull data failure plots have demonstrated that the thermal cycling reliabilities of pre-aged assemblies were significantly less than those of non-aged assemblies. Good correlation was obtained between our new reliability modeling procedure that includes aging and the measured solder joint reliability data.

Parameterized Modeling of Thermomechanical Reliability for CSP Assemblies

2003 ◽  
Vol 125 (4) ◽  
pp. 498-505 ◽  
Author(s):  
Bart Vandevelde ◽  
Eric Beyne ◽  
Kouchi (G.Q.) Zhang ◽  
Jo Caers ◽  
Dirk Vandepitte ◽  
...  
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Empirical Model ◽  
Prediction Models ◽  
Solder Joints ◽  
Coefficient Of Thermal Expansion ◽  
Solder Joint Reliability ◽  
Joint Geometry ◽  
Joint Reliability ◽  
Area Array

Finite element modeling is widely used for estimating the solder joint reliability of electronic packages. In this study, the electronic package is a CSP mounted on a printed circuit board (PCB) using an area array of solder joints varying from 5×4 up to 7×7. An empirical model for estimating the reliability of CSP solder joints is derived by correlating the simulated strains to thermal cycling results for 20 different sample configurations. This empirical model translates the inelastic strains calculated by nonlinear three-dimensional (3D) finite element simulations into a reliability estimation (N50% or N100 ppm). By comparing with the results of reliability tests, it can be concluded that this model is accurate and consistent for analyzing the effect of solder joint geometry. Afterwards, parameter sensitivity analysis was conducted by integrating a design of experiment (DOE) analysis with the reliable solder fatigue prediction models, following the method of simulation-based optimization. Several parameters are analyzed: the PCB parameters (elastic modulus, coefficient of thermal expansion, thickness), the chip dimensions (area array configuration), and the parameters defining the solder joint geometry (substrate and chip pad diameter, solder volume). The first study analyzes how the solder joint geometry influences the CSP reliability. A second study is a tolerance analysis for six parameters. These parameters can have a tolerance (=accuracy) of their nominal value, and it is shown that these small tolerances can have a significant influence on the solder joint reliability.

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