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用扫描电镜和能量色散仪分别对In3Ag焊料焊点基体及其与铜基板界面IMC(Intermetallic compound)层的组织结构进行观察和分析,用力学试验机测试焊点的剪切强度,研究了电子封装中回流次数对In3Ag焊料微观组织和剪切性能的影响。结果表明:随着回流次数的增加,基体中二次相AgIn2显著长大,由颗粒状变为长条状,界面IMC层(成分为(Ag,Cu)In_2)的厚度线性增加,其生长由界面反应速率和组元扩散速率混合控制,焊点剪切强度呈下降趋势,由1次回流的5.03 MPa降到5次回流的2.58 MPa;回流1、2、3次后焊点剪切断裂方式均为焊料内部韧性断裂,回流5次后断裂机制转变为韧脆混合断裂。
Scanning electron microscopy and energy disperser were used to observe and analyze the microstructure of In3Ag solder joint matrix and intermetallic compound (IMC) interface with copper substrate respectively. The shear strength of solder joint was tested by mechanical testing machine. Effect of Reflow Times on Microstructure and Shear Properties of In3Ag Solder. The results show that with the increase of reflow number, the secondary phase AgIn2 in the matrix grows significantly from granular to elongated, and the thickness of the interface IMC layer (composed of (Ag, Cu) In_2) increases linearly. The growth of The interfacial reaction rate and the component diffusion rate are mixedly controlled, and the shear strength of the solder joints shows a downward trend, decreasing from 5.03 MPa of primary return to 2.58 MPa of five return; Both of the internal toughness of the solder fracture, back five times the fracture mechanism into a ductile-brittle fracture.