摘要:
通过外向法制备纳米Ag颗粒/In-3Ag复合焊料, 研究在多次回流过程中, 添加不同含量的纳米Ag颗粒对In-3Ag焊料焊点基体组织和界面IMC层(intermetallic compound)的影响规律, 采用SEM、HRTEM、能量色散仪(EDS)和电子探针(EPMA)分别对焊点基体及IMC层的微观结构及成分进行观察和分析。研究结果表明: 纳米Ag颗粒能诱发晶粒成核, 多次回流后, 复合焊料基体中颗粒状二次相AgIn2没有明显长大现象; 通过塞积扩散通道和表面吸附效应, 纳米Ag颗粒能显著抑制焊料界面IMC层在多次回流过程的生长; 纳米Ag颗粒的合适添加量为0.5%(质量分数,下同), 当添加1%时, 颗粒团聚, 导致界面处出现球形AgIn2, 降低焊料的力学性能。
Abstract:
Composite solders were prepared through mechanical dispersing and the effects of nano-sized Ag reinforced particulates on In-3Ag solder matrix and interfacial IMC(intermetallic compound) layer after multiple reflows were studied. The microstructures of the solder matrix and IMC layer were investigated using SEM, HRTEM, Energy Dispersive Spectrometer(EDS) and Electron probe Micro-Analysis(EPMA). The results indicate that Ag nanoparticulates nucleate grains and the fine AgIn2 particles in composite solder matrix do not coarsen after multiple reflows. Due to the diffusion path blocking and surface absorption effect, the growth of the interfacial IMC layer is significantly suppressed by Ag nanoparticulates addition. The solder joint with 0.5%(mass fraction) Ag particulates added shows the best mechanical properties. Adding 1% Ag particulates, the particles tend to agglomerate leading to the formation of spherical particles at the interface, which decreases the mechanical properties of solder joint.
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