金凸点热超声倒装焊工艺研究  

Gold Bump Thermosonic Flip Chip Bonding Process

作　　者：李金龙[1] 张文烽 赵光辉[1] 李双江[1] LI Jinlong;ZHANG Wenfeng;ZHAO Guanghui;LI Shuangjiang(The 24th Research Institute of China Electronics Technology Group Corporation,Chongqing 400060,P.R.China)

机构地区：[1]中国电子科技集团公司第二十四研究所,重庆400060

出　　处：《微电子学》2024年第4期671-675,共5页Microelectronics

基　　金：集成电路与微系统全国重点实验室基金资助项目(614280204030217)。

摘　　要：系统地研究了金凸点热超声倒装焊工艺参数,结果表明:焊接压力越大,芯片剪切强度越大,其随着焊接压力的提高而升高。压力不足会导致凸点形变量不足,与基板接触程度不足,压力过大会造成凸点严重变形,凸点已完全平坦化,沿四周过度扩展,焊接压力约为35~45 g/球比较合理;超声功率在40%及以上,剪切力趋于平缓,根据试验结果,使用的超声功率应该从“剪切力/超声功率”曲线的“上坡段”选取,约40%比较合理;随着焊接时间的延长,剪切力先增大,后逐渐减小,对焊接时间而言,过长的超声时间是无效的,反而会使本来已实现焊接的界面反复摩擦和塑性形变而损伤,结合强度降低,合理的焊接时间为1 s左右。经试验考察,当前的焊接工艺参数,在经历长寿命,以及比较严苛的温度应力之后,具有较好的可靠性。Herein,the ultrasonic flip chip bonding process parameters of golden bumps,including welding force,ultrasonic power,and welding time,are systematically studied.Results reveal that the greater the welding force,the greater the die shear force;insufficient welding force can lead to an insufficient bump shape change and poor contact with the substrate;and excessive welding force causes severe deformation of the bump,resulting in it being completely flattened and spreading along the perimeter to eventually squeeze the chip pad.A reasonable welding force was determined to be in the range of 3545 g/ball.Furthermore,the greater the ultrasonic power,the greater the die shear force.When the ultrasonic power is 40%or above,the die shear force tends to be flat,whereas when the ultrasonic power exceeds 60%,the frame of the chip pad will crack.Thus,a reasonable ultrasonic power value should be 40%.Finally,the die shear force of the chip first increases and then decreases as the welding time increases.However,if the ultrasonic time is excessively long,it can damage the welded interface by repeated friction and plastic deformation.When bonding strength is low,an optimal welding time of 1 s is recommended.

关 键 词：微电子封装 倒装焊 金凸点 热超声倒装焊 

分 类 号：TN305.94[电子电信—物理电子学]