Jeong Gyuwon, Yu Dong-Yurl, Baek Seongju, Bang Junghwan, Lee Tae-Ik, Jung Seung-Boo, Kim JungSoo, Ko Yong-Ho
Advanced Functional Technology R&D Department, Institute of Industrial Technology (KITECH), 156 Gaetbeol-ro, Yeonsu-gu, Incheon 21999, Korea.
School of Advanced Materials Science & Engineering, Sungkyunkwan University, 2066 Seobu-Ro, Jangan-gu, Suwon, Gyeonggo-do 16419, Korea.
Materials (Basel). 2021 Jan 11;14(2):335. doi: 10.3390/ma14020335.
The effects of Ag nanoparticle (Ag NP) addition on interfacial reaction and mechanical properties of Sn-58Bi solder joints using ultra-fast laser soldering were investigated. Laser-assisted low-temperature bonding was used to solder Sn-58Bi based pastes, with different Ag NP contents, onto organic surface preservative-finished Cu pads of printed circuit boards. The solder joints after laser bonding were examined to determine the effects of Ag NPs on interfacial reactions and intermetallic compounds (IMCs) and high-temperature storage tests performed to investigate its effects on the long-term reliabilities of solder joints. Their mechanical properties were also assessed using shear tests. Although the bonding time of the laser process was shorter than that of a conventional reflow process, Cu-Sn IMCs, such as CuSn and CuSn, were well formed at the interface of the solder joint. The addition of Ag NPs also improved the mechanical properties of the solder joints by reducing brittle fracture and suppressing IMC growth. However, excessive addition of Ag NPs degraded the mechanical properties due to coarsened AgSn IMCs. Thus, this research predicts that the laser bonding process can be applied to low-temperature bonding to reduce thermal damage and improve the mechanical properties of Sn-58Bi solders, whose microstructure and related mechanical properties can be improved by adding optimal amounts of Ag NPs.
研究了添加银纳米颗粒（Ag NP）对使用超快激光焊接的Sn-58Bi焊点界面反应和力学性能的影响。采用激光辅助低温键合工艺，将不同Ag NP含量的Sn-58Bi基焊膏焊接到印刷电路板的有机表面防腐剂处理过的铜焊盘上。对激光键合后的焊点进行检查，以确定Ag NPs对界面反应和金属间化合物（IMC）的影响，并进行高温存储测试，以研究其对焊点长期可靠性的影响。还通过剪切试验评估了它们的力学性能。尽管激光工艺的键合时间比传统回流工艺短，但在焊点界面处仍形成了良好的Cu-Sn IMC，如CuSn和CuSn。添加Ag NPs还通过减少脆性断裂和抑制IMC生长提高了焊点的力学性能。然而，过量添加Ag NPs会由于AgSn IMC粗化而降低力学性能。因此，本研究预测，激光键合工艺可应用于低温键合，以减少热损伤并改善Sn-58Bi焊料的力学性能，通过添加适量的Ag NPs可改善其微观结构和相关力学性能。
