A Nonlinear and Time Dependent Finite Element Analysis of Solder Joints in Surface Mounted Components Under Thermal Cycling

Pao, Yi-Hsin; Chen, Kuan-Luen; Kuo, An-Yu

doi:10.1557/proc-226-23

Cited by 21 publications

(8 citation statements)

References 9 publications

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“…For example, Hall [9][10] measured deformations and hysteresis experimentally for the case of a leadless ceramic chip carrier soldered to an FR4 printed wiring board and subjected to thermal cycling. Pao [11][12][13] used a 2-beam geometry to successfully measure the thermo-mechanical hysteresis of a variety of Sn-based alloys. Haacke, et al [14] described a test assembly and reported both hysteresis and thermomechanical fatigue data for Sn-Pb solder, while Raeder and co-workers [15] reported thermomechanical deformation behavior of Sn-Bi eutectic solder under fatigue loading in terms of plastic strain energy density.…”

Section: Introductionmentioning

confidence: 99%

The effects of aging on the cyclic stress-strain behavior and hysteresis loop evolution of lead free solders

Mustafa

Cai

Suhling

et al. 2011

2011 IEEE 61st Electronic Components and Technology Conference (ECTC)

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Solder joints in electronic assemblies are typically subjected to thermal cycling, either in actual application or in accelerated life testing used for qualification. Mismatches in the thermal expansion coefficients of the assembly materials leads to the solder joints being subjected to cyclic (positive/negative) mechanical strains and stresses. This cyclic loading leads to thermomechanical fatigue damage that involves damage accumulation, crack initiation, crack propagation, and failure. While the effects of aging on solder constitutive behavior (stress-strain and creep) have been examined in some detail, there have been no prior studies on the effects of aging on solder failure and fatigue behavior.In this investigation, we have examined the effects of several parameters (aging, temperature, strain/stress limits, and solder alloy composition) on the cyclic stress-strain behavior of lead free solders. Uniaxial SAC lead free solder specimens were subjected to cyclic (tension/compression) mechanical loading. Samples were cyclically loaded under both strain control (constant positive and negative strain limits) and stress control (constant positive and negative stress limits). The hysteresis loop size (area) was calculated from the measured cyclic stress-strain curves for a given solder alloy and temperature. This area represents the strain energy density dissipated per cycle, which can be typically correlated to the damage accumulation in the joint.Most tests in this investigation were performed with SAC105 solder alloy.However, the effect of solder composition was examined in a limited way by testing four SAC alloys (SAC105, SAC205, SAC305, SAC405) with varying silver content (1-4%) under strain controlled cycling. In addition, the effect of the testing temperature has also been studied by performing cyclic testing of SAC405 samples at four different temperatures (25, 50, 75, and 100 o C).Prior to cyclic loading, the specimens in this study were aged (preconditioned) at 125 o C for various aging times (0-6 months). From the recorded cyclic stress-strain curves, we have been able to characterize and empirically model the evolution of the solder hysteresis loops with aging. Similar to solder stress-strain and creep behaviors, there is a strong effect of aging on the hysteresis loop size (and thus the rate of damage accumulation) in the solder specimens. The observed degradations in the fatigue/cyclic behavior of the lead free solders are highly accelerated for lower silver content alloys (e.g., SAC105), and for aging and testing at higher temperatures. In our current work, we are also subjecting aged solder samples to cyclic loading until failure occurs.Our ultimate goal is to understand the effects of aging on the thermomechanical fatigue life.

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Section: Introductionmentioning

confidence: 99%

The effects of aging on the cyclic stress-strain behavior and hysteresis loop evolution of lead free solders

Mustafa

Cai

Suhling

et al. 2011

2011 IEEE 61st Electronic Components and Technology Conference (ECTC)

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show abstract

“…For example, Hall [72][73] measured deformations and hysteresis experimentally for the case of a leadless ceramic chip carrier soldered to an FR4 printed wiring board and subjected to thermal cycling. Pao [74][75][76] used a 2-beam geometry to successfully measure the thermo-mechanical hysteresis of a variety of Sn-based alloys. Haacke, et al [77] described a test assembly and reported both hysteresis and thermomechanical fatigue data for Sn based solder, while Raeder and co-workers [78] reported thermomechanical deformation behavior of Sn-Bi eutectic solder under fatigue loading in terms of plastic strain energy density.…”

Section: Cyclic Stress-strain Behavior Of Solder Materialsmentioning

confidence: 99%

“…However, the effect of solder composition was examined in a limited way by testing four SAC alloys (SAC105, SAC205, SAC305, SAC405) with varying silver content (1-4%) under strain controlled cycling. In addition, the effect of the testing temperature has also been studied by performing cyclic testing of SAC405 samples at four different temperatures (25,50,75, and 100 C).…”

Section: Introductionmentioning

confidence: 99%

The Effects of Aging of the Cyclic Stress-Strain and Fatigue Behaviors of Lead Free Solders

Mustafa

Roberts

Suhling

et al. 2013

Volume 1: Advanced Packaging; Emerging Technologies; Modeling and Simulation; Multi-Physics Based Reliability; MEMS and NEMS; M

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Solder joints in electronic assemblies are typically subjected to thermal cycling, either in actual application or in accelerated life testing used for qualification. Mismatches in the thermal expansion coefficients of the assembly materials cause the solder joints to be subjected to cyclic (positive and negative) mechanical strains and stresses. This cyclic loading leads to thermomechanical fatigue damage that involves damage accumulation, crack initiation, crack propagation, and failure. In addition, 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. While the effects of aging on solder constitutive behavior (stress-strain and creep) have been examined in some detail, there have been no prior studies on the effects of aging on solder failure and fatigue behavior. Aging leads to both grain and phase coarsening, and can cause recrystallization at Sn grain boundaries. Such changes are closely tied to the damage that occurs during cyclic mechanical loading. In this investigation, we have examined the effects of aging on the cyclic stress-strain behavior and fatigue life of lead free solders. Uniaxial solder test specimens (SAC105 and SAC305) have been prepared and subjected to cyclic stress/strain loading at different aging conditions. A four-parameter hyperbolic tangent empirical model has been used to fit the entire cyclic stress-strain curve and the hysteresis loop size (area) was calculated using definite integration for a given strain limit. This area represents the energy dissipated per cycle, which is correlated to the damage accumulation in the joint. Using the recorded cyclic stress-strain curves, the evolution of the solder hysteresis loops with aging have been characterized and empirically modeled. Similar to solder stress-strain and creep behavior, there is a strong effect of aging on the hysteresis loop size (and thus the rate of damage accumulation) in the solder specimens. Fatigue experiments were also performed, where the uniaxial specimens were subjected to cyclic loading over a particular strain range until failure. Fatigue failure in the experiments was defined to occur when there was a 50% peak load drop during mechanical cycling. Prior to testing, the specimens were aged (preconditioned) at 125 °C for various aging times, and then the samples were subjected to cyclic loading at room temperature (25 °C). It was found that aging decreased the mechanical fatigue life, and the effects of aging on the peak load drop have been studied. It has also been observed that degradations in the fatigue/failure behavior of the lead free solders with aging are highly accelerated for lower silver content alloys (e.g., SAC105). Various empirical failure criteria such as the Coffin-Manson model and the Morrow model have been used to fit the measured data, and the parameters in the models have been determined as a function of the aging conditions.

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“…The elastic strain rate tensor is defined in a compact form as where E is the elastic modulus, U the Poisson's ratio, oij the Cauchy stress tensor, t the time and S;j the Kronecker delta. The temperature dependence of the elastic modulus of the lead-rich Pb-Sn alloy is assumed to be similar to that of the pure lead in [13] with some modification as where a is the coefficient of thermal expansion. In this study, the temperature dependence of n for the lead-rich Pb-Sn alloy was assumed to be the same as that of the eutectic Pb-Sn alloy in [17].…”

Section: Constitutive Theorymentioning

confidence: 99%

Nonlinear finite element simulation of thermoviscoplastic deformation of C4 solder joints in high density packaging under thermal cycling

Hong

Burrell

1995

IEEE Trans. Comp., Packag., Manufact. Technol. A

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A nonlinear finite element model has been used to simulate the thermally induced viscoplastic deformation of the controlled collapse chip connections (C4) solder joints in a high density single chip module (SCM). The dependence of solder joint deformation on the tin content was demonstrated for various lead-rich lead-tin alloys with the tin content varying from 2 wt.% to 10 wt.%. A thermoviscoplasticity theory was introduced for modeling the inelastic stress-strain response of the Pb-Sn alloys. In the theory, the creep and plasticity were separately considered and formulated. The Garofalo hyperbolic sine law was used to model the creep behavior, while the Prandtl-Reuss equation was used for the rate independent plastic deformation. The modeled SCM consists of a 5-mm silicon chip attached to a 50-nun alumina substrate by an array of C4 with diameter of 0.1 m m on a 0.2-mm YO pitch. A cyclic temperature load of 0-100" C at a frequency of 3 cycles per hour was applied to the SCM. It is concluded that the decrease of the tin content induces a decrease of the equivalent creep strain and Mises stress, but an increase of the equivalent plastic strain for the edge C4 in the SCM.

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A Nonlinear and Time Dependent Finite Element Analysis of Solder Joints in Surface Mounted Components Under Thermal Cycling

Cited by 21 publications

References 9 publications

The effects of aging on the cyclic stress-strain behavior and hysteresis loop evolution of lead free solders

The effects of aging on the cyclic stress-strain behavior and hysteresis loop evolution of lead free solders

The Effects of Aging of the Cyclic Stress-Strain and Fatigue Behaviors of Lead Free Solders

Nonlinear finite element simulation of thermoviscoplastic deformation of C4 solder joints in high density packaging under thermal cycling

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