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采用自制的蠕变装置研究Sn-0.7Cu-2Bi无铅钎料在温度60～120℃、压力30～50MPa下的压入蠕变性能,利用光学显微镜、SEM和XRD对钎料组织在蠕变前后的变化进行了分析。结果表明:随着温度和应力的增加,钎料的蠕变速率增大;Sn-0.7Cu-2Bi主要由Sn、Bi、Cu6Sn5三相组成,Bi固溶在Sn中造成晶格的畸变阻碍晶体滑移面的位错运动,导致其变形抗力大为增加,且晶界处偏聚的Bi颗粒对位错有钉扎作用,能提高钎料的抗蠕变性能;Sn-0.7Cu-2Bi钎料蠕变后出现回复再结晶,最终导致晶粒长大。
The creep behavior of Sn-0.7Cu-2Bi lead-free solder at 60 ~ 120 ℃ and 30 ~ 50MPa pressure was studied by self-made creep device. The microstructure of Sn-0.7Cu-2Bi solder was studied by means of optical microscope, SEM and XRD. Before and after the changes were analyzed. The results show that the creep rate of solder increases with the increase of temperature and stress. Sn-0.7Cu-2Bi mainly consists of three phases of Sn, Bi and Cu6Sn5. The solid solution of Bi in Sn causes the lattice distortion The dislocation movement of the slip surface resulted in a significant increase of deformation resistance, and Bi particles segregated at the grain boundary pinned the dislocations and improved the creep resistance of the solder. Sn-0.7Cu-2Bi solder After the material appears to resume creep recrystallization, eventually leading to grain growth.