Fatigue Properties and Microstructure of SnAgCu Bi-Based Solder Joint

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Minghong Jian ◽  
Sinan Su ◽  
Sa'd Hamasha ◽  
Mohammad M. Hamasha ◽  
Atif Alkhazali
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Solder Joint ◽  
Solder Joints ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Fatigue Performance ◽  
Fatigue Properties ◽  
Solder Alloys ◽  
Plastic Strain Range

Abstract The reliability of solder joints plays a critical role in electronic assemblies. SnAgCu solder alloys with doped elements such as Bi and Sb is one of the candidates for high reliability applications. However, the mechanical and fatigue properties of the actual solder joint structure have not been studied for these new alloys. In this paper, a cyclic fatigue test was conducted on individual real solder joints of different alloys, including SnAgCu, SnCu–Bi, SnAgCu–Bi, and SnAgCu–BiSb. The fatigue property of those solder joints was analyzed based on the characteristic fatigue life and stress–strain, hysteresis, loops. The results show that solder joints with both Ag and Bi content have a better fatigue resistance than the solder joints with Ag or Bi content only. The results of SnAgCu and SnCu–Bi solder alloys show similar fatigue performance. Also, the fatigue performance of SnAgCu–Bi is close to SnAgCu–BiSb in the accelerated test. But the SnAgCu–Bi alloy is estimated to have a longer characteristic life under low-stress amplitude cycling. The microstructure analysis shows a bismuth-rich phase formed around the Ag3Sn precipitates. Adding bismuth in the solder alloy can significantly improve the fatigue properties through solid solution hardenings. On another hand, the plastic strain range and work dissipation were measured from the hysteresis loops for all tests. The Morrow Energy and the Coffin–Manson models were developed from the fitted data to predict the fatigue life as a function of work dissipation and plastic strain range.

scholarly journals Isothermal Fatigue Behavior of Sn-Pb Solder Joints

1990 ◽  
Vol 112 (2) ◽  
pp. 94-99 ◽  
Author(s):  
T. S. E. Summers ◽  
J. W. Morris
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Strain Rate ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Load Drop ◽  
Plastic Strain Range ◽  
Double Shear ◽  
Isothermal Fatigue ◽  
Fatigue Data

Isothermal fatigue data were collected for the compositions 5Sn-95Pb, 20Sn-80Pb, 40Sn-60Pb, 50Sn-50Pb and 63Sn-37Pb within the binary Sn-Pb system. All of these compositions are commercially available and include those most commonly used. Because Sn-rich solders are rarely used, they were not investigated here. The fatigue life was defined by a 30 percent load drop. The solders were tested in a double shear configuration joined to copper at 75° C. The displacement rate chosen was 0.01 mm/min, which corresponds to a strain rate of 1.5 × 10−4s−1 for our specimen configuration, over a 10 percent plastic strain range. Additionally, the microstructural changes during fatigue are presented. The various solder compositions studied exhibit strikingly different as-solidified microstructures. These differences are discussed in terms of their effect on the isothermal joint failure mechanism and joint isothermal fatigue life.

Quantitative Mechanism of Significant Benefits of Underfill in Flip-Chip Assemblies

2003 ◽  
Vol 125 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Xia Cai ◽  
Liu Chen ◽  
Qun Zhang ◽  
Bulu Xu ◽  
Weidong Huang ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Cross Sections ◽  
Flip Chip ◽  
Solder Joints ◽  
Axial Strain ◽  
Strain Range ◽  
Interface Stress ◽  
Acoustic Microscopy ◽  
Plastic Strain Range ◽  
Element Simulation

The thermal fatigue failure of SnPb solder joints of flip chip on board with and without underfill for two types of flip-chip packages was investigated by conducting thermal cycling test, scanning acoustic microscopy observation, and cross section inspection. The corresponding 3-D finite element simulation was performed to analyze the effects of underfill on thermomechanical behavior. The viscoelasticity of underfill and the viscoplasticity of solder were considered in the 3-D simulations. The Coffin-Manson equation with material constants C=5.54,β=−1.38 was fitted from the combination of the lifetime measured and the shear plastic strain range simulated by 3-D model. In the case with underfill, the plastic strain of every solder joint becomes very similar and little dependent on the position of solder joints. The modeled axial strain distribution coincided well with the distribution of microstructure coarsening visible in cross sections. The mismatch of thermal expansion resulted in an overall warpage of the assembly for the case with underfill, which decreased the shear deformation of the solder joints and increased the interface stress on the chip. The interface stress distribution from the 3-D simulation agreed very well with the experimental observations.

scholarly journals The Attempt of the Low-Cycle Fatigue Life Description of Chosen Creep-Resistant Steels Under Mechanical and Thermal Interactions

2017 ◽  
Vol 62 (4) ◽  
pp. 2349-2353
Author(s):  
J. Okrajni ◽  
A. Marek
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Plastic Strain Range ◽  
Mechanical Fatigue ◽  
Versus Parameter ◽  
Creep Resistant Steels

AbstractThe study focuses on the problem of determination of low-cycle fatigue properties for the chosen group of creep-resistant steels used in the power and chemical industries. It tries to find the parameter which would describe well the fatigue life and take into account mechanical loads and temperature. The results of LCF tests have been presented in the paper. New parameter P has been introduced. This parameter joins a plastic strain range, a stress range and temperature. The fatigue life has been predicted versus parameter P. The comparison of the predicted and observed values of fatigue life shows the agreement between these values. The method of fatigue life prediction formulated in this way is expected to describe the behavior of materials under thermo-mechanical fatigue.

scholarly journals Microstructure-sensitive critical plastic strain energy density criterion for fatigue life prediction across various loading regimes

2020 ◽  
Vol 476 (2236) ◽  
pp. 20190766 ◽  
Author(s):  
Ritwik Bandyopadhyay ◽  
Veerappan Prithivirajan ◽  
Alonso D. Peralta ◽  
Michael D. Sangid
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Strain Ratio ◽  
Material Point ◽  
Plastic Strain Energy

In the present work, we postulate that a critical value of the stored plastic strain energy density (SPSED) is associated with fatigue failure in metals and is independent of the applied load. Unlike the classical approach of estimating the (homogenized) SPSED as the cumulative area enclosed within the macroscopic stress–strain hysteresis loops, we use crystal plasticity finite element simulations to compute the (local) SPSED at each material point within polycrystalline aggregates of a nickel-based superalloy. A Bayesian inference method is used to calibrate the critical SPSED, which is subsequently used to predict fatigue lives at nine different strain ranges, including strain ratios of 0.05 and −1, using nine statistically equivalent microstructures. For each strain range, the predicted lives from all simulated microstructures follow a lognormal distribution. Moreover, for a given strain ratio, the predicted scatter is seen to be increasing with decreasing strain amplitude; this is indicative of the scatter observed in the fatigue experiments. Finally, the lognormal mean lives at each strain range are in good agreement with the experimental evidence. Since the critical SPSED captures the experimental data with reasonable accuracy across various loading regimes, it is hypothesized to be a material property and sufficient to predict the fatigue life.

A Finite Element Study of Factors Affecting Fatigue Life of Solder Joints

1994 ◽  
Vol 116 (4) ◽  
pp. 265-273 ◽  
Author(s):  
N. Paydar ◽  
Y. Tong ◽  
H. U. Akay
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Hold Time ◽  
Strain Range ◽  
Cycle Life ◽  
Finite Element Program ◽  
Factors Affecting

The elastic-plastic-creep characteristics of solder joints are implemented in a nonlinear finite element program ABAQUS by developing user defined material subroutines. An eutectic Pb-Sn solder joint of a resistor carrier under thermal cycling between 125°C and −55°C is modeled, and the effect of various parameters on the solder joint cycle life is evaluated. The strain range of the solder joint under thermal cycling loads is calculated, which is then converted into solder joint cycle life through a fatigue-life relationship proposed by Engelmaier (1983). The parameters studied include: ramp time, hold time, grain size, initial temperature, constitutive equations, material properties for solder alloys, and mesh refinement. The effects of these variations on the fatigue life of solder joints are illustrated. The described method can serve as a tool in the design and manufacturing of surface-mount (SMT) assemblies.

Low-Cycle Fatigue Life of Continuously Cyclic-Hardening Material

2020 ◽  
Author(s):  
Zhong Zhang ◽  
Xijia Wu
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Root Mean Square ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Square ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Hardening Material ◽  
Plastic Strain Range

Abstract A general fatigue life equation is derived by modifying the Tanaka-Mura-Wu dislocation pile-up model for variable strain-amplitude fatigue processes, where the fatigue crack nucleation life is expressed in terms of the root mean square of plastic strain range. Low-cycle fatigue tests were conducted on an austenitic stainless steel. at 400°C and 600°C, the material exhibits continuously cyclic-hardening behaviour. The root mean square of plastic strain ranges is evaluated from the experimental data for each test condition at strain rates ranging from 0.0002/s to 0.02/s. The variable-amplitude Tanaka-Mura-Wu model is found to be in good agreement with the LCF data, which effectively proves Miner’s rule on the stored plastic strain energy basis.

scholarly journals Prediction of mechanical properties and fatigue life of nano silver paste in chip interconnection

2020 ◽  
Author(s):  
Hui YANG ◽  
Jihui Wu
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Stress And Strain ◽  
Nano Silver ◽  
Finite Element Software ◽  
Flip Chips ◽  
Empirical Correction ◽  
Prediction Of Mechanical Properties

Abstract The simulation of nano-silver solder joints in flip-chips is performed by the finite element software ANSYS, and the stress-strain distribution results of the solder joints are displayed. In this simulation, the solder joints use Anand viscoplastic constitutive model, which can reasonably simulate the stress and strain of solder joints under thermal cycling load. At the same time this model has been embedded in ANSYS software, so it is more convenient to use. The final simulation results show that the areas where the maximum stresses and strains occur at the solder joints are mostly distributed in the contact areas between the solder joints and the copper pillars and at the solder joints. During the entire thermal cycling load process, the area where the maximum change in stress and strain occurs is always at the solder joint, and when the temperature changes, the temperature at the solder joint changes significantly. Based on comprehensive analysis, the relevant empirical correction calculation equation is used to calculate and predict the thermal fatigue life of nano-silver solder joints. The analysis results provide a reference for the application of nano-silver solder in the electronic packaging industry.

A Direct Method on the Evaluation of Cyclic Steady State of Structures With Creep Effect

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Haofeng Chen ◽  
Weihang Chen ◽  
James Ure
Keyword(s):  
Fatigue Damage ◽  
Mechanical Load ◽  
Direct Method ◽  
Load Condition ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Cyclic Behavior ◽  
Direct Evaluation ◽  
Plastic Strain Range ◽  
Creep Fatigue

This paper describes a new extension of the linear matching method (LMM) for the direct evaluation of cyclic behavior with creep effects of structures subjected to a general load condition in the steady cyclic state, with the new implementation of the cyclic hardening model and time hardening creep constitutive model. A benchmark example of a Bree cylinder and a more complicated three-dimensional (3D) plate with a center hole subjected to cyclic thermal load and constant mechanical load are analyzed to verify the applicability of the new LMM to deal with the creep fatigue damage. For both examples, the stabilized cyclic responses for different loading conditions and dwell time periods are obtained and validated. The effects of creep behavior on the cyclic responses are investigated. The new LMM procedure provides a general purpose technique, which is able to generate both the closed and nonclosed hysteresis loops depending upon the applied load condition, providing details of creep strain and plastic strain range for creep and fatigue damage assessments with creep fatigue interaction.

Low-Cycle Fatigue Life of Continuously Cyclic-Hardening Material

2021 ◽  
Author(s):  
Zhong Zhang ◽  
Xijia Wu
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Root Mean Square ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Square ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Hardening Material ◽  
Plastic Strain Range

Abstract A general fatigue life equation is derived by modifying the Tanaka-Mura-Wu dislocation pile-up model for variable strain-amplitude fatigue processes, where the fatigue crack nucleation life is expressed in terms of the root mean square of plastic strain range. Low-cycle fatigue tests were conducted on an austenitic stainless steel. At 400 ? and 600 ?, the material exhibits continuously cyclic-hardening behaviour. The root mean square of plastic strain ranges is evaluated from the experimental data for each test condition at strain rates ranging from 0.0002/s to 0.02/s. The variable-amplitude Tanaka-Mura-Wu model is found to be in good agreement with the LCF data, which effectively proves Miner's rule on the stored plastic strain energy basis.

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