Tan Ai Ting, Tan Ai Wen, Yusof Farazila
Centre of Advanced Manufacturing and Materials Processing (AMMP), Faculty of Engineering, University Malaya, 50603 Kuala Lumpur, Malaysia; Department of Mechanical Engineering, Faculty of Engineering, University Malaya, 50603 Kuala Lumpur, Malaysia.
Ultrason Sonochem. 2017 Jan;34:616-625. doi: 10.1016/j.ultsonch.2016.06.039. Epub 2016 Jun 29.
Techniques to improve solder joint reliability have been the recent research focus in the electronic packaging industry. In this study, Cu/SAC305/Cu solder joints were fabricated using a low-power high-frequency ultrasonic-assisted reflow soldering approach where non-ultrasonic-treated samples were served as control sample. The effect of ultrasonic vibration (USV) time (within 6s) on the solder joint properties was characterized systematically. Results showed that the solder matrix microstructure was refined at 1.5s of USV, but coarsen when the USV time reached 3s and above. The solder matrix hardness increased when the solder matrix was refined, but decreased when the solder matrix coarsened. The interfacial intermetallic compound (IMC) layer thickness was found to decrease with increasing USV time, except for the USV-treated sample with 1.5s. This is attributed to the insufficient USV time during the reflow stage and consequently accelerated the Cu dissolution at the joint interface during the post-ultrasonic reflow stage. All the USV-treated samples possessed higher shear strength than the control sample due to the USV-induced-degassing effect. The shear strength of the USV-treated sample with 6s was the lowest among the USV-treated samples due to the formation of plate-like AgSn that may act as the crack initiation site.
提高焊点可靠性的技术一直是电子封装行业近期的研究重点。在本研究中，采用低功率高频超声辅助回流焊接方法制备了Cu/SAC305/Cu焊点，其中未经过超声处理的样品作为对照样品。系统地研究了超声振动（USV）时间（6秒以内）对焊点性能的影响。结果表明，超声振动1.5秒时，焊料基体微观结构得到细化，但超声振动时间达到3秒及以上时，焊料基体微观结构变粗。焊料基体细化时硬度增加，粗化时硬度降低。除超声振动1.5秒的样品外，界面金属间化合物（IMC）层厚度随超声振动时间的增加而减小。这归因于回流阶段超声振动时间不足，从而加速了超声后回流阶段接头界面处的铜溶解。由于超声诱导脱气效应，所有经过超声处理的样品的剪切强度均高于对照样品。由于形成了可能作为裂纹萌生部位的板状AgSn，超声振动6秒的样品的剪切强度在经过超声处理的样品中最低。
