Numerical and experimental analysis of thermosonic bond strength considering interfacial contact phenomena

作者：He, Jun^*; Guo, Yongjin; Lin, Zhongqin

来源：Journal of Physics D: Applied Physics , 2008, 41(16): 165304.

DOI：10.1088/0022-3727/41/16/165304

• Interfacial contact
• Interfacial deformations
• Micro-contact model
• Numerical and experimental analysis
• Real contact area
• Theoretical equation
• Thermo-sonic bonding
• Ultrasonic softening

The theoretical equation of thermosonic bond strength involving interfacial deformation and microcontact phenomena is presented in this study. The constitutive equation of gold considering the ultrasonic softening mechanism was developed based on the thermosonic bonding experiments and coded into the FE software. The numerical model of bonding was established to estimate the surface exposure and the effective normal pressure. The real contact area was calculated by a microcontact model. Accordingly, the nominal bond strength can be obtained and verified by the experimental data. It is found that a better conjunction exists at the edge of the contact area because large surface exposure is produced there, which is also proved by the SEM image of a sheared ball bond. Increasing the bonding force or the ultrasonic power will increase the interfacial plastic deformation, the nominal and real contact areas, but decreases the effective normal pressure. The contact ratio increases to a maximum with the increase in the bonding force, and then decreases while it continues to decrease with the increase in the ultrasonic power. In addition, both the stress analysis and experimental result show that cratering and damage to the pad structure are easily produced below the edge region of the contact area under an excessive bonding force or ultrasonic power.

• 出版日期2008-8-21
• 单位上海交通大学