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摘要:
Reliability of solder joints in electronic packages depends on the mechanical properties of solder materials. Under drop impact loadings, the solder joint undergoes high strain rate deformation. Therefore it is important to investigate the effect of strain rate on the mechanical behavior of the solder materials. In this paper, mechanical properties and stress-strain curves of one lead-containing solder, Sn37Pb, and two lead-free solders, Sn3.5Ag and Sn3.0Ag0.5Cu, were investigated at strain rates ranging from 600s-1 to 2200 s-1 by the split Hopkinson pressure and tensile bar techniques. Based on the experimental data of the quasi-static tensile tests and the split Hopkinson pressure bar tests, elastic-plastic material models independent of the strain rate and Johnson-Cook material models dependent of the strain rate of the three solders were developed and employed to predict mechanical behaviors of solder joints in a board level electronic package under drop impact loadings. The results show that at high strain rates, the two lead-free solders are more sensitive to the strain rate, and their tensile strengths are about 1.5 times greater than that of the lead-containing solder, and their ductility is significantly greater than that of the lead-containing solder. Under the drop impact, the solder joints experience a strain rate of 1000s-1, and the proposed material models in Johnson-Cook form are applicable to predict more realistic stress and strain than the elastic-plastic models independent of strain rate.
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来源 :
Chinese Journal of Theoretical and Applied Mechanics
ISSN: 0459-1879
年份: 2010
期: 3
卷: 42
页码: 439-447
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