基板间距对超声协振复合钎焊SnBi-xAl_2O_3微焊点组织及性能的影响

Effect of substrate distance on microstructure and properties of SnBi-xAl_2O_3 micro joint soldered by ultrasonicassisted soldering

采用超声协振复合钎焊的新方法,选取Al_2O_3含量为1.5%(质量分数)的SnBi复合钎料,并选用0.5mm,0.8mm和1mm三种铜基板间距制成微型对接接头,借助于显微硬度计和自制的微力学测试系统对其力学性能进行表征,采用扫描电子显微镜对试样的显微组织和断口形貌进行观察,并利用能谱仪检测金属间化合物的成分。研究结果表明:超声协振复合钎焊的方法可以促进液态钎料在基板上的扩展,提高润湿性,充满焊缝。随着基板间距的增大,钎料合金的组织细化,界面处的IMC条带区逐步变薄,提高了焊点的可靠性。靠近复合钎料处为Cu_6Sn_5IMC,靠铜基板处为Cu_3SnIMC。适当提高基板间距,有助于显微硬度、抗拉强度和断后伸长率的提高。

New ultrasonic-assisted soldering technology was adopted to weld mini butt joint by SnB i composite solder with 1. 5 wt% Al_2O_3 in content and 0. 5 mm,0. 8 mm and 1 mm in copper substrate distance,respectively. The mechanical properties of the mini butt joint were tested by means of the micro hardness tester and home-made micro mechanical test system. The microstructure of the samples were analyzed by scanning electron microscope,and the compositions of intermetallic compounds was detected by the energy disperse spectroscopy. The results showed that the ultrasonic-assisted soldering method can promote the spreadability of liquid solder on the substrate,and improve the wettability. With the increase of the substrate distance,the microstructures in soldered seam are finer,the IMC zone at the interface becomes gradually thinner,and the reliability of the soldered joint is improved. IMC Cu_6Sn_5 and IMC Cu_3Sn appear near the composite solder and the copper substrate. The micro hardness,tensile strength and elongation of the joint can be increased by increasing the substrate distance.