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Torsion Fatigue and Multiaxial Ratcheting Fatigue of Lead-free Solder

Author: LiangYongFeng
Tutor: ChenXu
School: Tianjin University
Course: Chemical Process Equipment
Keywords: Lead-free solder Ratchet effect Low cycle fatigue Multiaxial ratcheting Fatigue Life Prediction
CLC: TG425
Type: Master's thesis
Year: 2010
Downloads: 35
Quote: 0
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Abstract

Harm caused to human health and the environment due to the tin-lead solder, lead-free solder to replace tin-lead solder become the inevitable trend of development of electronic packaging. This selection Sn-0.7Cu and Sn-3Ag-0.5Cu two kinds of currently used very widely, as the object of study is also very lead-free solder with good development prospects, the two brazing material under uniaxial and multiaxial loading related The mechanical properties were studied. Sn-3Ag-0.5Cu uniaxially stretched under different strain rates and torsional experiments, analysis showed that Sn-3Ag-0.5Cu has a strong rate of correlation, the tensile strength of the brazing material and the shear strength increases. The significant increase in the strain rate is increased significantly, elastic modulus and shear modulus of the strain rate has little effect. Sn-3Ag-0.5Cu the multiaxial ratcheting effect experiment, with the increasing rate of shear strain and axial stress, ratcheting rate with increasing shear strain rate increased significantly. Failure ratcheting are basically the same, regardless of the magnitude of the shear strain, the number of cycles to failure circle decreases with increasing shear strain amplitude. Both Sn-3Ag-0.5Cu and Sn-0.7Cu solder pure torsional fatigue test, the study found that the elastic shear strain - and the fatigue life is affected by the level of the load being lowered little effect, while the plastic shear strain - fatigue life by the load drops the level of The impact is very obvious. Sn-3Ag-0.5Cu and Sn-0.7Cu the fatigue life is very short, little difference in the magnitude of the shear stress is small, Sn-3Ag-0.5Cu fatigue life is significantly larger in the larger shear strain amplitudes in Sn-0.7Cu. In addition, the Sn-3Ag-0.5Cu ratcheting multiaxial fatigue test, the study shows that the axial stress has no effect on the peak shear stress, axial ratcheting strain rate with the axial stress and shear strain amplitude increases in the double logarithmic plot into a linear relationship between the the the ratchet strain rate and the axial stress and shear strain amplitude. The fatigue life is reduced with the increase in the axial stress and shear strain amplitude. Multiaxial low cycle fatigue life prediction method of Sn-3Ag-0.5Cu multiaxial fatigue life prediction. Did not consider the impact of the axial stress and other effects of political reform, the results are somewhat dangerous. Pro interface method KBM model for more than 1,000 of the fatigue life prediction error is large, the WB model takes into account to the normal strain, but the majority of tests given are somewhat dangerous prediction results. Energy method to predict CHX model, the predicted results are not satisfactory. Consider the method of the fatigue life of the ratchet effect Coffin model prediction error increases with the increase in the axial force becomes larger, the maximum predicted deviation of up to 10 times. Gao-Chen model strain rate to the maximum shear strain and axial ratchet damage control parameter Sn-3.0Ag-0.5Cu multiaxial the ratchet fatigue test to make good predictions.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding materials > Brazing materials
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