中国物理B ›› 2022, Vol. 31 ›› Issue (1): 16101-016101.doi: 10.1088/1674-1056/ac0e24

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Mechanism of microweld formation and breakage during Cu-Cu wire bonding investigated by molecular dynamics simulation

Beikang Gu(顾倍康)1, Shengnan Shen(申胜男)1,2,†, and Hui Li(李辉)1,2,‡   

  1. 1 School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China;
    2 The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
  • 收稿日期:2021-03-10 修回日期:2021-06-21 接受日期:2021-06-24 出版日期:2021-12-03 发布日期:2021-12-28
  • 通讯作者: Shengnan Shen, Hui Li E-mail:shen_shengnan@whu.edu.cn;li_hui@whu.edu.cn
  • 基金资助:
    Project supported by the National Key R&D Program of China (Grant No. 2019YFB1704600) and the Hubei Provincial Natural Science Foundation of China (Grant No. 2020CFA032).

Mechanism of microweld formation and breakage during Cu-Cu wire bonding investigated by molecular dynamics simulation

Beikang Gu(顾倍康)1, Shengnan Shen(申胜男)1,2,†, and Hui Li(李辉)1,2,‡   

  1. 1 School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China;
    2 The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
  • Received:2021-03-10 Revised:2021-06-21 Accepted:2021-06-24 Online:2021-12-03 Published:2021-12-28
  • Contact: Shengnan Shen, Hui Li E-mail:shen_shengnan@whu.edu.cn;li_hui@whu.edu.cn
  • Supported by:
    Project supported by the National Key R&D Program of China (Grant No. 2019YFB1704600) and the Hubei Provincial Natural Science Foundation of China (Grant No. 2020CFA032).

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摘要： Currently, wire bonding is the most popular first-level interconnection technology used between the die and package terminals, but even with its long-term and excessive usage, the mechanism of wire bonding has not been completely evaluated. Therefore, fundamental research is still needed. In this study, the mechanism of microweld formation and breakage during Cu-Cu wire bonding was investigated by using molecular dynamics simulation. The contact model for the nanoindentation process between the wire and substrate was developed to simulate the contact process of the Cu wire and Cu substrate. Elastic contact and plastic instability were investigated through the loading and unloading processes. Moreover, the evolution of the indentation morphology and distributions of the atomic stress were also investigated. It was shown that the loading and unloading curves do not coincide, and the unloading curve exhibited hysteresis. For the substrate, in the loading process, the main force changed from attractive to repulsive. The maximum von Mises stress increased and shifted from the center toward the edge of the contact area. During the unloading process, the main force changed from repulsive to attractive. The Mises stress reduced first and then increased. Stress concentration occurs around dislocations in the middle area of the Cu wire.

关键词: Cu-Cu wire bonding, bonding mechanism, atomic stress, molecular dynamics simulation

Abstract: Currently, wire bonding is the most popular first-level interconnection technology used between the die and package terminals, but even with its long-term and excessive usage, the mechanism of wire bonding has not been completely evaluated. Therefore, fundamental research is still needed. In this study, the mechanism of microweld formation and breakage during Cu-Cu wire bonding was investigated by using molecular dynamics simulation. The contact model for the nanoindentation process between the wire and substrate was developed to simulate the contact process of the Cu wire and Cu substrate. Elastic contact and plastic instability were investigated through the loading and unloading processes. Moreover, the evolution of the indentation morphology and distributions of the atomic stress were also investigated. It was shown that the loading and unloading curves do not coincide, and the unloading curve exhibited hysteresis. For the substrate, in the loading process, the main force changed from attractive to repulsive. The maximum von Mises stress increased and shifted from the center toward the edge of the contact area. During the unloading process, the main force changed from repulsive to attractive. The Mises stress reduced first and then increased. Stress concentration occurs around dislocations in the middle area of the Cu wire.

Key words: Cu-Cu wire bonding, bonding mechanism, atomic stress, molecular dynamics simulation

中图分类号:  (Structure of nanoscale materials)

  • 61.46.-w
02.70.Ns (Molecular dynamics and particle methods) 02.70.-c (Computational techniques; simulations) 61.82.Bg (Metals and alloys)