Solder Joint Life Prediction Research Articles

Finite element method and experimental study on life prediction of lead-free BGA solder joints using an energy-based approach

Finite element method and experimental study on life prediction of lead-free BGA solder joints using an energy-based approach

Reliability Analysis and Life Prediction of Solder Joints for Avionics Devices With Immersion Cooling

Reliability Analysis and Life Prediction of Solder Joints for Avionics Devices With Immersion Cooling

A Hybrid Method for Predicting Fatigue Life of Lead-Free Solder Joints Under Coupled Electrical–Thermal–Mechanical Fields

A hybrid method was developed in this study for fatigue life prediction (FLP) of lead-free solder (LFS) joints in ball grid array package under the coupled electrical–thermal–mechanical (ETM) fields. A modified constitutive model for lead-free solder joints under coupled ETM fields was proposed to describe the mechanical and fatigue behavior of solder joints under coupled ETM fields. A modified damage model under coupled ETM fields was then developed to obtain the fatigue life of LFS joints under coupled ETM fields. Uniaxial tension tests of an Sn–3.0Ag–0.5Cu (SAC305) solders and coupled multifields fatigue experiments were performed to verify the accuracy, applicability and validity by the modified constitutive model and fatigue damage model under coupled ETM fields. Based on the modified constitutive model and fatigue damage model, a hybrid method, including current, temperature and mechanics parameters, was proposed for the FLP of the LFS joints, which was demonstrated to be able to predict the results well. A hybrid method provides an idea for investigating the fatigue life of lead-free solder joints in coupled fields.

Reliability and thermal fatigue life prediction of solder joints for advanced automotive microelectronics

Reliability and thermal fatigue life prediction of solder joints for advanced automotive microelectronics

Effect of Stress Gradient on Heat Cycle Fatigue Life Prediction of Solder Joints by Repetitive Bending Test

Strength of solder joints is usually evaluated by a shear test and a pull test. The reliability of the solder joint is evaluated by the repetitive pull tests of solder bulk specimens. However, the stress and strain field that caused by thermal load on the solder joint of the product model for estimating the reliability is different from these tests. Therefore, we proposed a repetitive bending test as a reliability test of solder joints producing the stress and strain field caused at the solder joint of product model. We proposed a repetitive multi-point bending test as a method to predict the fatigue life of the solder joint in the thermal cycle test in a short period of time. The influence of strain gradient on the inelastic strain amplitude used for lifetime evaluation is estimated. The controllability of the strain gradient by the three-point bending test parameters is investigated. The effect of residual stress on inelastic strain amplitude during sample preparation for thermal cycle test is also evaluated.

Research on life evaluation method of solder joint based on eddy current pulse thermography.

With the wide usage of electronic packaging technologies such as Ball Grid Array in electronic industry, it is necessary to maintain its quality in order to meet the demand of electronic products for function, integration, and size reduction. However, as the size of solder joints in such technology decreases, the solder joints are more and more prone to defects. To solve the life prediction problem of small-size packages having interconnections in the high-density chip, a method based on the eddy current pulsed thermography (ECPT) is put forward to study the remaining life prediction of solder joints. A 3D induction heating finite element model is established, by which the crack length of defect solder joints can be distinguished using temperature field. At the same time, the remaining life of defect solder joints can be characterized by the length of the crack. Furthermore, the experiments are carried out on solder joints whose diameter is 0.4 mm. Both simulation and experiment results verify that it is reliable and convenient to use 3D induction heating based temperature field from ECPT to evaluate the remaining life of cracks in solder joints.

Comparison of fatigue life prediction methods for solder joints under random vibration loading

The fatigue life prediction of solder joints under random vibration load is one of the most important aspect in design of packaging. A fatigue-life estimation in the frequency domain is proved to have advantages in comparison to the time-domain estimation. This paper presents a comparison of the fatigue life prediction of solder joints under random vibration load by several popular frequency domain methods, including the narrow-band, the Wirsching–Light, the single-moment, the Empirical α0.75, the Tovo–Benasciutti, the Zhao–Baker, and the Dirlik methods. The comparison between these selected frequency domain methods and the traditional Steinberg method was investigated with the help of the relative error. Results indicate that most spectral methods are accurate than the Steinberg method, the Tovo–Benasciutti method is proved to be the best method for the life estimation of solder joints suited not only to the BGA package but also to the PoP package.

Effects of Strain Rate and Amplitude Variations on Solder Joint Fatigue Life in Isothermal Cycling

The behavior of lead-free solder alloys under realistic service conditions is still not well understood. Life prediction of solder joints relies on conducting accelerated tests and extrapolating results to service conditions. This can be very misleading without proper constitutive relations and without understanding the effects of cycling parameter variations common under realistic service conditions. It has been shown that the fatigue life depends on the inelastic work accumulation, independently of cycling-induced material property variations, which explains the breakdown of damage accumulation rules and allows the development of a modified Miner's rule. This paper discusses the interacting effects of strain rate and amplitude variations on solder joint fatigue life. Individual SnAgCu solder joints with two different Ag contents (SAC305 and SAC105) were tested in low cycling shear fatigue under single and varying amplitudes with different strain rates. Such a shear fatigue experiment allows the measurement of work accumulation and the evolution of solder deformation properties during cycling. The results showed that cycling with a lower strain rate at fixed amplitude causes more damage per cycle. Alternating between mild amplitude at a high strain rate and harsh amplitude at a low strain rate leads to ongoing increases in the rate of damage at the mild amplitude and thus relatively rapid failure. In comparing SAC305 with SAC105, the effect of strain rate on both alloys is almost the same, and SAC305 is still more fatigue resistant than SAC105 in varying amplitude cycling with any strain rate.

Remaining-Life Prediction of Solder Joints Using RF Impedance Analysis and Gaussian Process Regression

Solder joints are among the most common failure sites in electronic assemblies. This paper presents a prognostic approach that allows for the remaining useful life prediction of solder joints using an RF impedance analysis and the Gaussian process (GP) regression. While the solder joints were exposed to a mechanical stress condition to generate fatigue failures, the RF impedance of the solder joint was continuously monitored. The RF impedance provided an early indication of the impending solder-joint failure in the form of a gradual increase prior to the end of life. A GP model was applied to the RF impedance obtained from the fatigue tests in order to estimate the remaining life of the solder joint in real time. It was demonstrated that the GP model successfully predicted the time to failure of the solder joint with high accuracy prior to failure. The prediction performance was also evaluated using prognostic metrics.

An evaluation of dwell time and mean cyclic temperature parameters in the Engelmaier model

The Engelmaier model is a strain-range-based fatigue model for evaluating the life expectancy of solder joints under power and temperature cycling. The model relates cycles to failure to a strain range metric using a power law relationship. In Engelmaier’s original formulation in 1983, the exponent term in the power law relationship was defined to be a function of mean cyclic temperature and cyclic frequency. Engelmaier replaced the cyclic frequency with dwell time in 1988 without explanation.This paper provides a rationale and the implications for changing the formulation of the exponent term of the Engelmaier model. Using non-linear regression, model constants are derived for Engelmaier model formulations with cyclic frequency and dwell time parameters. A t-statistic measure is estimated to quantify the influence of cyclic frequency and dwell time parameters on the cycles to failure. In tin-based lead-free solders, the absolute values of the t-statistic for cyclic frequency are approximately 3–10% higher than that for dwell time. The higher absolute value of a t-statistic identifies a stronger dependence of cycles to failure on cyclic frequency than on dwell time. Then, the feasibility of replacing the mean cyclic temperature parameter in the exponent term with time-averaged cyclic temperature using t-statistic measures is explored. Based on the evaluation of t-statistic measures, the authors recommend the Engelmaier model with cyclic frequency and mean cyclic temperature parameters to be used for solder joint life prediction.

Thermal cycling life prediction of Sn-3.0Ag-0.5Cu solder joint using type-I censored data.

Because solder joint interconnections are the weaknesses of microelectronic packaging, their reliability has great influence on the reliability of the entire packaging structure. Based on an accelerated life test the reliability assessment and life prediction of lead-free solder joints using Weibull distribution are investigated. The type-I interval censored lifetime data were collected from a thermal cycling test, which was implemented on microelectronic packaging with lead-free ball grid array (BGA) and fine-pitch ball grid array (FBGA) interconnection structures. The number of cycles to failure of lead-free solder joints is predicted by using a modified Engelmaier fatigue life model and a type-I censored data processing method. Then, the Pan model is employed to calculate the acceleration factor of this test. A comparison of life predictions between the proposed method and the ones calculated directly by Matlab and Minitab is conducted to demonstrate the practicability and effectiveness of the proposed method. At last, failure analysis and microstructure evolution of lead-free solders are carried out to provide useful guidance for the regular maintenance, replacement of substructure, and subsequent processing of electronic products.

Fatigue life prediction of solder joints with consideration of frequency, temperature and cracking energy density

Solder joints between semiconductors and a printed circuit board may fail due to temperature change or vibration. To assess the durability of solder joints a mechanical fatigue test was conducted instead of a thermal cycling test, and a resistance change was monitored to detect a failure at real time. Fatigue tests were conducted for five different semiconductors at three different frequencies, temperatures and displacements, and a fatigue life prediction equation with consideration of frequency, temperature and cracking energy density was proposed. It was shown that all the fatigue test data could be represented appropriately by the prediction equation.

A computational method for evaluating the damage in a solder joint of an electronic package subjected to thermal loads

Purpose– The purpose of this paper is to introduce a novel computational method to evaluate damage accumulation in a solder joint of an electronic package, when exposed to operating temperature environment. A procedure to implement the method is suggested, and a discussion of the method and its possible applications is provided in the paper.Design/methodology/approach– Methodologically, interpolated response surfaces based on specially designed finite element (FE) simulation runs, are employed to compute a damage metric at regular time intervals of an operating temperature profile. The developed method has been evaluated on a finite-element model of a lead-free PBGA256 package, and accumulated creep strain energy density has been chosen as damage metric.Findings– The method has proven to be two orders of magnitude more computationally efficient compared to FE simulation. A general agreement within 3 percent has been found between the results predicted with the new method, and FE simulations when tested on a number of temperature profiles from an avionic application. The solder joint temperature ranges between +25 and +75°C.Practical implications– The method can be implemented as part of reliability assessment of electronic packages in the design phase.Originality/value– The method enables increased accuracy in thermal fatigue life prediction of solder joints. Combined with other failure mechanisms, it may contribute to the accuracy of reliability assessment of electronic packages.

A numerical approach on life-prediction of solder joints under combined loading for chip packaging system

The aim of this paper is to provide a numerical approach to predict the lifetime of solder joints by considering combined loading based on the damage superposition. The deformations of solder joints are calculated under vibration and thermal cycling loading respectively. The calculated results are defined as boundary conditions of the multi-axial loading. The strain/stress is investigated by finite element method based on the Chaboche model. The fatigue damage and creep damage are calculated by using the Manson-Coffin equation. It reveals that there is a strong non-linear impact on the lifetime due to the interaction of the combined loading. The trend of the simulation results basically agrees with that of the tests results. The approach can be used to predict the solder joint lifetime under combined loading.

Reliability estimation for large-area solder joints using explicit modeling of damage

The issues of available cyclic fatigue models in life prediction of large-area solder joints using finite-element analysis (FEA) are discussed. In this paper, a new FEA approach called successive initiation (SI) is modified and introduced in conjunction with energy partitioning (E-P) damage model to resolve some of the issues with available damage models such as geometry and scale dependency and provide a solution to large-area solder joints. This new technique models damage explicitly, meaning that it separates initiation from propagation by monitoring the plastic and creep damage at the tip of the crack successively. The SI technique could be easily used with continuous loadings of different types and frequencies. The modeling approach is then implemented on a power device with large-area solder. Sensitivity study is conducted with the help of the experiment to determine the right initiation threshold for smooth crack initiation and propagation. The results of modeling are then compared with available experimental data for the same power device. The comparison shows that using the damage model constants generated for small solder joints such as ball-grid array or chip-scale package could significantly overpredict the life of larger area solders. New E-P damage model constants for large-area solder joints are obtained and presented by calibrating the modeling to the experiment.

Damage Path Simulation of Solder Bumps Under Mechanical Fatigue Tests

Fatigue life prediction of solder joints is one of the most important areas of research in the development of reliable electronic packages. In the present study, the new method of estimating the crack propagation, called 'damage path simulation', was applied for solder bumps under the mechanical fatigue tests. The new method is based on finite element analysis without geometrical crack model, and on the characteristic damage model assumed for solder. Damage paths from the entire circumference in the vicinity of the interface were simulated, and they were finally combined at the center of bumps. The extension of the damage path showed good agreement with the behavior of crack propagation observed in the mechanical fatigue tests. In the case of solder bumps, the effects of the assessment of the previous damage on the extension rate of the damage path might be critical issue. However, the effects of the assessment of the previous damage were relatively small, in consideration of the large scattering in the results of mechanical fatigue tests. It was confirmed that the number of cycles to the fatal failure of solder bumps can be accurately estimated by the damage path simulation. It was concluded that the estimation of the crack propagation based on the proposed method is satisfactory for engineering purposes.

726 損傷パスシミュレーションによるSn-37Pbはんだのき裂進展評価(GS.A 先端材料の破壊と強度)

Fatigue life prediction of solder joints is one of the most important areas of research in the development of reliable electronic packages. In the present days, a new method of estimating the crack propagation, which was based on finite element analysis without geometric crack model, was examined. On the basis of damage model for solder, the new method called 'damage path simulation' was verified for CT specimens of Sn-37Pb solder. The extensions of damage path in the cases of different mesh sizes and element types were compared. The extensions of damage path showed comparatively good agreement with the behavior of the crack propagation observed in the fatigue tests using CT specimens, in the case that the mesh size was comparable to the grain size of solder.

Damage Path Simulation of Solder Joints

Fatigue life prediction of solder joints is one of the most important areas of research in the development of reliable electronic packages. In the present study, a new method of estimating the crack propagation, which is based on finite element analysis without geometrical crack model, was examined. On the basis of a damage model assumed for solder, the new method called 'damage path simulation' was verified for solder joints in QFP (Quad Flat Package). It was clear that the extension of the damage path showed good agreement with the behavior of crack propagation observed in the actual thermal cycle tests. Damage path extension from a pointed end of outer lead was also simulated simultaneously with that from the upper surface of the solder fillet, and both damage paths were finally combined. The advantage of the proposed method was especially evident when the fatigue cracks were initiated from two or more regions. The effects of the frequency of thermal cycle were also discussed. It was shown that the frequency of thermal cycle has a noticeable effect on the crack propagation rate. It was concluded that the estimation of the crack propagation in solder joints based on the proposed method is satisfactory for engineering purposes.

Strain Energy Density Criterion for Reliability Life Prediction of Solder Joints in Electronic Packaging

This study concerns the prediction of crack growth rate for solder joints in electronic packages under thermal cycling. The crack growth rate, which is dependent on the intrinsic solder property and the current stress state, is calculated based on the strain energy density criterion. The critical value of the strain energy density represents the intrinsic property of the solder. The comparison of the crack growth predictions with the experimental measurements demonstrates the applicability of the strain energy density criterion for the reliability life prediction of solder joints.

A cohesive zone model for low cycle fatigue life prediction of solder joints

A cohesive zone model is proposed in this paper in an effort to predict the low cycle fatigue life of solder joints plastically deformed under cyclic loading. Damage mechanics is incorporated into the cohesive law to account for the gradual loss of stiffness and strength of solder materials under cyclic loading. The damage evolution law is assumed to be a function of accumulated plastic strain. It has been demonstrated that, once the parameters of the cohesive zone model are determined via one particular cyclic test, it is then able to predict the fatigue life of solder joints made of the same materials system under different loading conditions.