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    烧结银层多孔结构对烧结银接头剪切性能的影响

    Effect of Sintered Silver Layer Porous Structure on Shear Properties of Sintered Silver Joint

    • 摘要: 将镀银铜片、微米银焊膏和镀银铜片堆叠成“三明治”结构,然后在不同烧结压力(0,0.5,1,3,6 MPa)下热压烧结制备烧结银接头,研究了烧结压力对接头中间烧结银层孔隙率、孔径及层厚的影响;采用试验与有限元模拟相结合的方法对烧结银接头进行剪切性能测试,分析烧结银层多孔结构特征对烧结银接头剪切性能的影响。结果表明:随着烧结压力的增大,烧结银层的孔隙率由19.3%降至7.5%,平均孔径由1 560 nm降至1 390 nm,层厚由67 μm降至36 μm,烧结银接头的断裂模式由混合断裂模式向层间断裂模式转变,烧结银层的塑性变形程度增大;模拟得到不同烧结压力下烧结银层的层间断裂微观形貌以及接头的载荷-位移曲线和抗剪强度均与试验结果基本吻合,其中在有压烧结条件下抗剪强度的最大相对误差为13%,验证了有限元模拟方法的准确性;随着烧结银层孔隙率由7.5%增至15.1%,剪切载荷达到峰值时烧结银层的变形程度变小,接头的抗剪强度降低40%;随着烧结银层平均孔径由1 390 nm增至1 510 nm,剪切载荷达到峰值时烧结银层的变形程度变化不大,接头的抗剪强度降低6%;随着烧结银层层厚由36 μm增至53 μm,剪切载荷达到峰值时烧结银层的变形程度变大,接头的抗剪强度增加24%。

       

      Abstract: The silver-plated copper sheet, micron silver solder paste and silver-plated copper sheet were stacked into a“sandwich”structure, and then the sintered silver joints were prepared by hot pressing and sintering under different sintering pressures (0, 0.5, 1, 3, 6 MPa). The effects of sintering pressure on the porosity, pore size and layer thickness of the sintered silver layer in the middle of the joint were studied. The shear property of sintered silver joints was tested by combining test and finite element simulation, and the influence of porous structure characteristics of the sintered silver layer on the shear properties of sintered silver joints was analyzed. The results show that with the increase of sintering pressure, the porosity of the sintered silver layer decreased from 19.3% to 7.5%, the average pore size decreased from 1 560 nm to 1 390 nm, and the layer thickness decreased from 67 μm to 36 μm; the fracture mode of the sintered silver joint changed from the mixed fracture mode to the interlaminar fracture mode, and the plastic deformation degree of the sintered silver layer increased. The simulation of interlaminar fracture micromorphology of the sintered silver layer and the load-displacement curve and shear strength of the sintered silver joint under different sintering pressures were basically consistent with the test results, and the maximum relative error of the shear strength under pressure sintering conditions was 13%, which verified the accuracy of the finite element simulation. As the porosity of the sintered silver layer increased from 7.5% to 15.1%, the deformation degree of the sintered silver layer decreased when the shear load reached the peak and the shear strength of the joint decreased by 40%. As the average pore size of the joint increased from 1 390 nm to 1 510 nm, the deformation degree of the sintered silver layer did not change much when the shear load reached the peak, and the shear strength of the joint decreased by 6%. As the layer thickness of the sintered silver layer increased from 36 μm to 53 μm, the deformation degree of the sintered silver layer increased when the shear load reached the peak and the shear strength of the joint increases by 24%.

       

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