Evaluation of Time-Independent and Time-Dependent Strains of Lead-Free Solder by Stepped Ramp Loading Test

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Ken-ichi Ohguchi ◽  
Katsuhiko Sasaki ◽  
Setsuo Aso
Keyword(s):  
Time Dependent ◽  
Lead Free ◽  
Creep Model ◽  
Basic Material ◽  
Loading Test ◽  
Material Constants ◽  
Instantaneous Strain ◽  
Free Solder ◽  
Creep Constitutive Model ◽  
Plastic Creep

This paper proposes a method to estimate basic material constants in an elasto-plastic-creep constitutive model for lead-free solders by conducting only a tensile test. The test employs a stepped ramp wave loading, which repeats instantaneous strain and strain maintenance. Time-independent strains are obtained from the stress-strain relations at the instantaneously strained parts, while the time-dependent strains are obtained from the stress-time relations during the strain maintaining periods. Based on the obtained time-independent and time-dependent strains, the values of the material constants in the elasto-plastic-creep model proposed by the authors are determined. Simulations of the viscoplastic deformations of a Sn–3.0Ag–0.5Cu solder alloy are also conducted to verify the validity of the proposed method.

Evaluation of Time-Independent and Time-Dependent Strains of Lead-Free Solder by Stepped Ramp Loading Test

2007 ◽  
Author(s):  
Ken-Ichi Ohguchi ◽  
Katsuhiko Sasaki ◽  
Setsuo Aso
Keyword(s):  
Time Dependent ◽  
Lead Free ◽  
Loading Test ◽  
Material Constants ◽  
Dependent Strain ◽  
Creep Models ◽  
Free Solder ◽  
Creep Constitutive Model ◽  
Lead Free Solders ◽  
Plastic Creep

This paper proposes a method which can estimate essential material constants of an elasto-plastic-creep constitutive model for lead-free solders by conducting only a tensile test. The test employs a stepped ramp wave loading which repeats instantaneous straining and strain maintaining. The time-independent strains can be evaluated by using the stress-strain relations at the instantaneous straining parts, while the time-dependent strain can be evaluated by using the stress-time relations during the strain maintaining parts. Based on the results of the evaluations, the material constants of the elasto-plastic-creep models are estimated. Simulations of the viscoplastic deformations of Sn-3.0Ag-0.5Cu solder alloy were also conducted to verify the validity of the proposed method.

Time-Independent and Time-Dependent Inelastic Strain Analysis of Lead-Free Solder by Cyclic Loading Test Using Stepped Ramp Waves

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Ken-ichi Ohguchi ◽  
Katsuhiko Sasaki
Keyword(s):  
Cyclic Loading ◽  
Plastic Strain ◽  
Creep Strain ◽  
Thermal Loading ◽  
Time Dependent ◽  
Lead Free ◽  
Creep Model ◽  
Lead Free Solder ◽  
Cyclic Thermal Loading ◽  
Free Solder

We previously proposed an elastic-plastic-creep model to estimate the fatigue strength of lead-free solder joints subjected to cyclic thermal loading. The proposed model requires detailed experimental data regarding the time-independent plastic strain and the time-dependent creep strain during cyclic thermal loading. This paper proposes an experimental method for determining the characteristics of both the plastic and creep strains generated during cyclic loading that employs stepped ramp waves. This method is applied to cyclic tension-compression loadings using a Sn–3.0Ag–0.5Cu lead-free solder for several loading conditions. The method can separate between the time-independent plastic strain and the time-dependent creep strain in cyclic inelastic deformation of solder alloys.

scholarly journals Nonlinear Viscoelastic-Plastic Creep Model of Rock Based on Fractional Calculus

2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Erjian Wei ◽  
Bin Hu ◽  
Jing Li ◽  
Kai Cui ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Fractional Calculus ◽  
Fractional Order ◽  
Engineering Application ◽  
Creep Model ◽  
Nonlinear Viscoelastic ◽  
Rock Creep ◽  
Order Change ◽  
Creep Constitutive Model ◽  
Plastic Creep

A rock creep constitutive model is the core content of rock rheological mechanics theory and is of great significance for studying the long-term stability of engineering. Most of the creep models constructed in previous studies have complex types and many parameters. Based on fractional calculus theory, this paper explores the creep curve characteristics of the creep elements with the fractional order change, constructs a nonlinear viscoelastic-plastic creep model of rock based on fractional calculus, and deduces the creep constitutive equation. By using a user-defined function fitting tool of the Origin software and the Levenberg–Marquardt optimization algorithm, the creep test data are fitted and compared. The fitting curve is in good agreement with the experimental data, which shows the rationality and applicability of the proposed nonlinear viscoelastic-plastic creep model. Through sensitivity analysis of the fractional order β2 and viscoelastic coefficient ξ2, the influence of these creep parameters on rock creep is clarified. The research results show that the nonlinear viscoelastic-plastic creep model of rock based on fractional calculus constructed in this paper can well describe the creep characteristics of rock, and this model has certain theoretical significance and engineering application value for long-term engineering stability research.

The Effects of Temperature Cyclic Loading on Lead-Free Solder Joints of Wafer Level Chip Scale Package by Taguchi Method

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Wen-Ren Jong ◽  
Hsin-Chun Tsai ◽  
Hsiu-Tao Chang ◽  
Shu-Hui Peng
Keyword(s):  
Low Temperature ◽  
Shear Strain ◽  
Solder Joints ◽  
Strain Range ◽  
Lead Free ◽  
Lead Free Solder ◽  
Wafer Level ◽  
Chip Scale Package ◽  
Free Solder ◽  
Plastic Creep

In this study, the effects of the temperature cyclic loading on three lead-free solder joints of 96.5Sn–3.5Ag, 95.5Sn–3.8Ag-0.7Cu, and 95.5Sn–3.9Ag-0.6Cu bumped wafer level chip scale package (WLCSP) on printed circuit board assemblies are investigated by Taguchi method. The orthogonal arrays of L16 is applied to examine the shear strain effects of solder joints under five temperature loading parameters of the temperature ramp rate, the high and low temperature dwells, and the dwell time of both high and low temperatures by means of three simulated analyses of creep, plastic, and plastic-creep behavior on the WLCSP assemblies. It is found that the temperature dwell is the most significant factor on the effects of shear strain range from these analyses. The effect of high temperature dwell on the shear strain range is larger than that of low temperature dwell in creep analysis, while the effect of high temperature dwell on the shear strain range is smaller than that of low temperature dwell in both plastic and plastic-creep analyses.

Sign in / Sign up

Export Citation Format

Share Document