Micro-welding using laser-generated ultrasound
Micro-welding using laser-generated ultrasound
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DOI：
10.1109/estc.2016.7764718
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发表时间：
2016-09
期刊：
影响因子：
--
通讯作者：
G. Dou;M. Gower;A. Holmes
中科院分区：
文献类型：
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作者：
G. Dou;M. Gower;A. Holmes
我们展示了一种新的微焊接过程中，激光产生的应力波产生的键合位点附近的直接金属-金属键的形成协助。该工艺已被用于将铜凸点硅倒装芯片附着到银金属化基板上。脱粘试验被用来定性研究所产生的芯片基板债券。结果发现，一般情况下，铜银焊接强度超过凸点与芯片之间的粘附强度。在脱粘后进行了单独的碰撞剪切试验，结果显示剪切强度约为116 MPa。采用扫描电子显微镜（SEM）和聚焦离子束扫描电子显微镜（FIB-SEM）对试样进行了分析，结果表明焊接为直接铜-银固态扩散焊。这种新工艺允许在低温下直接进行金属-金属键合，并对键合参数进行局部控制。应用设想在先进的电子封装，其中低工艺温度或高操作可靠性是必需的。
We demonstrate a novel micro-welding process in which laser-generated stress waves produced close to the bonding site assist in the formation of direct metal-metal bonds. The process has been used to attach copper-bumped silicon flip-chips to silver-metallized substrates. De-bonding tests were used to study qualitatively the resulting chip-substrate bonds. It was found that generally the copper-silver welding strength exceeded the adhesion strength between bump and chip. Individual bump shear tests were carried out after de-bonding and showed shear strengths of ~116 MPa. In addition, scanning-electron-microscope (SEM) and focused-ion-beam-scanning-electron-microscope (FIB-SEM) imaging were used to analyse the test samples, revealing that the welding was direct copper-silver solid-state diffusion welding. This new process allows direct metal-metal bonding at low temperature and with localized control over the bonding parameters. Applications are envisaged in advanced electronics packaging where low process temperature or high operational reliability are required.