Thermomechanical Analysis of Solder Joints Under Thermal and Vibrational Loading

2001 ◽  
Vol 124 (1) ◽  
pp. 60-66 ◽  
Author(s):  
Cemal Basaran ◽  
Rumpa Chandaroy

Due to the coefficient of thermal expansion (CTE) mismatch between the bonded layers, the solder joint experiences cycling shear strain, which leads to short cycle fatigue. When semiconductor devices are used in a vibrating environment, additional strains shorten the fatigue life of a solder joint. Reliability of these joints in new packages is determined by laboratory tests. In order to use the FEM to replace these expensive reliability tests a unified constitutive model for Pb40/Sn60 solder joints has been developed and implemented in a thermo-viscoplastic-dynamic finite element procedure. The model incorporates thermal-elastic-viscoplastic and damage capabilities in a unified manner. The constitutive model has been verified extensively against laboratory test data. The finite element procedure was used for coupled thermo-viscoplastic-dynamic analyses for fatigue life predictions. The results indicate that using Miner’s rule to calculate accumulative damage by means of two separate analyses, namely dynamic and thermo-mechanical, significantly underestimates the accumulative total damage. It is also shown that a simultaneous application of thermal and dynamic loads significantly shortens the fatigue life of the solder joint. In the microelectronic packaging industry it is common practice to ignore the contribution of vibrations to short cycle fatigue life predictions. The results of this study indicate that damage induced in the solder joints by vibrations have to be included in fatigue life predictions to accurately estimate their reliability.

1990 ◽  
Vol 112 (2) ◽  
pp. 135-146 ◽  
Author(s):  
H. K. Charles ◽  
G. V. Clatterbaugh

An extensive finite element modeling and experimental testing program has been carried out to determine the most optimum design parameters for solder joints in surface mount applications. Although the analysis and testing (power cycling and thermal cycling) has been carried out for a variety of package styles, particular attention will be paid to the result for leadless ceramic chip carriers. This package is particularly useful in certain high performance military and commercial applications. Analysis and experimentation indicate that increased fatigue life under power cycling can be attained by fabricating solder joints with large fillets and low standoff heights. The large fillet geometry significantly reduces harmful stress concentrations while increasing the net cross-sectional area within the joint. Both factors tend to improve the fracture toughness of the joint. The temperature and frequency dependencies of solder joint fatigue life under power cycling testing is discussed. The observed frequency dependence can be minimized by eliminating harmful tensile strain components thus reducing harmful stress relaxation and tensile induced oxygen embrittlement of grain boundaries. Temperature cycling studies indicate joints with slightly higher standoffs and low fillet angles are more resistant to cyclic fatigue than pillar type joints which tend to focus shear strains at the interfaces. Solder joints can be tapered to improve overall reliability but, in most cases, tapering will provide only a small increase in fracture toughness of the joint through the elimination of stress concentrations. Additional fatigue life increases can be obtained only through an enlargement of the joint cross-sectional area. Aspects of the above results will be presented in detail along with design guidelines for creating high reliability solder joints for various application scenarios.


2011 ◽  
Vol 264-265 ◽  
pp. 1660-1665
Author(s):  
Yong Cheng Lin ◽  
Yu Chi Xia

More and more solder joints in circuit boards and electronic products are changing to lead free solder, placing an emphasis on lead free solder joint reliability. Solder joint fatigue failure is a serious reliability concern in area array technologies. In this study, the effects of substrate materials on the solder joint thermal fatigue life were investigated by finite element model. Accelerated temperature cycling loading was imposed to evaluate the reliability of solder joints. The thermal strain/stress in solder joints of flip chip assemblies with different substrates was compared, and the fatigue life of solder joints were evaluated by Darveaux’s crack initiation and growth model. The results show the mechanisms of substrate flexibility on improving solder joint thermal fatigue.


Author(s):  
Chang-Chun Lee ◽  
Kuo-Ning Chiang

For the purpose of enhancing the solder joint reliability of a wafer level chip scaling package (WLCSP), the WLCSP adopted the familiar design structure where both the stress compliant layer with low elastic modulus and the dummy solder joints are considered as structural supports. However, the predicted fatigue life of the solder joints at the internal part of the packaging structure using the conventional procedures of finite element simulation are higher than under actual conditions as a result of the perfect bonding assumption in the modeling. In this research, in order to improve the thermo-mechanical reliability of the solder joints, a node tie-release crack prediction technique, based on non-linear finite element analysis (FEA), is developed and compared with the estimation of the solder joint reliability using conventional methodology. The predicted results of reliability, using the novel prediction technique, show a lower fatigue life of the solder joint than that when using conventional one when the fracture regions in the dummy solder joints are simulated under quasi-steady state. At the same time, the result of the thermal cycling test also shows good agreement with the simulated result when using the proposed node tie-release crack prediction analysis.


1994 ◽  
Vol 116 (4) ◽  
pp. 265-273 ◽  
Author(s):  
N. Paydar ◽  
Y. Tong ◽  
H. U. Akay

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.


1999 ◽  
Vol 121 (2) ◽  
pp. 61-68 ◽  
Author(s):  
R. Chandaroy ◽  
C. Basaran

In the electronic industry, the dominant failure mode for solder joints is assumed to be thermal cycling. When semiconductor devices are used in vibrating environment, such as automotive and military applications, dynamic stresses contribute to the failure mechanism of the solder joint, and can become the dominant failure mode. In this paper, a damage mechanics based unified constitutive model for Pb40/Sn60 solder joints has been developed to accurately predict the thermomechanical behavior of solder joints under concurrent thermal and dynamic loading. It is shown that simultaneous application of thermal and dynamic loads significantly shorten the fatigue life. Hence, damage induced in the solder joint by the vibrations have to be included, in fatigue life predictions to correctly predict the reliability of solder joints. The common practice of relating only thermal cycling induced inelastic strain to fatigue life can be inadequate to predict solder joint reliability. A series of parametric studies were conducted to show that contrary to popular opinion all dynamic loading induced strains are not elastic. Hence, vibrations can significantly affect the fatigue life and reliability of solder joints in spite of their small mass.


2001 ◽  
Vol 42 (5) ◽  
pp. 809-813 ◽  
Author(s):  
Young-Eui Shin ◽  
Kyung-Woo Lee ◽  
Kyong-Ho Chang ◽  
Seung-Boo Jung ◽  
Jae Pil Jung

Author(s):  
Fei Song ◽  
Ke Li

Abstract In this paper, a hybrid computational framework that combines the state-of-the art machine learning algorithm (i.e., deep neural network) and nonlinear finite element analysis for efficient and accurate fatigue life prediction of rotary shouldered threaded connections is presented. Specifically, a large set of simulation data from nonlinear FEA, along with a small set of experimental data from full-scale fatigue tests, constitutes the dataset required for training and testing of a fast-loop predictive model that could cover most commonly used rotary shouldered connections. Feature engineering was first performed to explore the compressed feature space to be used to represent the data. An ensemble deep learning algorithm was then developed to learn the underlying pattern, and hyperparameter tuning techniques were employed to select the learning model that provides the best mapping, between the features and the fatigue strength of the connections. The resulting fatigue life predictions were found to agree favorably well with the experimental results from full-scale bending fatigue tests and field operational data. This newly developed hybrid modeling framework paves a new way to realtime predicting the remaining useful life of rotary shouldered threaded connections for prognostic health management of the drilling equipment.


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