Bonding mechanism of ultrasonic wedge bonding of copper wire on Au/Ni/Cu substrate

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• 作者：Yan-hong TIAN ; Chun-qing WANG ; Y. Norman ZHOU
• 关键词：copper wire ; ultrasonic wedge bonding ; bonding mechanism ; wear action
• 刊名：Transactions of Nonferrous Metals Society of China
• 出版年：2008
• 出版时间：February 2008
• 年：2008
• 卷：18
• 期：1
• 页码：132-137
• 全文大小：853 K

文摘

The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature. Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX, pull test, shear test and microhardness test. The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing. The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible, and the wedge bonding is achieved by wear action induced by ultrasonic vibration. The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.