(西北工业大学 材料学院 凝固技术国家重点实验室，西安710072)
摘 要: Hg3In2Te6(MIT)晶体是一种新型的短波红外光电探测材料，采用热压超声球焊的方法实现MIT红外探测器与外电路的引线连接，探讨MIT复合电极厚度及结构对键合率的影响规律，研究超声功率和键合压力对第一焊点的外观形貌和键合强度的影响机理。结果表明：在化学抛光后的MIT晶片表面蒸镀0.2 μm In、1.0 μm Au制备In/Au复合电极时，键合率显著提高，达到100%；MIT与In/Au复合电极间存在一定的互扩散，促进了键合过程的形成；超声功率与键合压力对焊点形貌和键合强度影响最大，当超声功率为0.45~0.55 W、键合压力为0.5~0.6 N时，焊球与引线的直径比约为3.5，焊点变形适中，有效键合面积较大，90%以上的断裂发生在引线位置，表明此种工艺参数下形成的键合强度高、可靠性好。
关键字: Hg3In2Te6芯片；热压超声键合；Au 电极；In中间层
（Northwestern Polytechnical University, School of Materials Science and Engineering,
State Key Laboratory of Solidification Processing, Xi’an 710072, China）
Abstract:In order to realize the connection of Hg3In2Te6 (short for MIT), a new type of near-infrared photoelectric material, with outer circuits, the thermo-sonic bonding technology between MIT electrode and down-lead wire was used, and the influence of the electrode thickness and structure on the bonding ratio was studied. Furthermore, the effects of ultrasonic power and bonding pressure on the first joint morphology and bonding strength were also analyzed. The results show that the bonding rate increases (reaching 100%) when 0.2 μm In interlayer was inserted between MIT wafer after chemical polish and the Au electrode with thickness of 1 μm. XPS analysis results show that inter-diffusion between MIT and In/Au composite electrode promotes the bonding process. The welding ball morphology and bonding quality are mainly affected by the ultrasonic power and bonding pressure. When the ultrasonic power and the bonding pressure are about 0.45-0.55 W and 0.5-0.6 N, respectively, the diameter ratio between the ball and wire is about 3.5, and more than 90 % failure position occurs at wire by tensile test, indicating the perfect shape of welding ball and good bonding strength and reliability can be reached.
Key words: Hg3In2Te6 chip; thermo-sonic bonding; Au electrode; In interlayer
