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Published on: September 28, 2020
Correlation between the Microstructures of Bonding Interfaces and the Shear Strength of Cu-to-Cu Joints Using
Jing-Ye Juang1, Chia-Ling Lu2, Yu-Jin Li3
1Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan. david.mse03g@g2.nctu.edu.tw.
Abstract:
Highly (111)-oriented Cu pillar-bumps were bonded to highly (111)-oriented Cu films at temperatures ranging from 200 °C/100 °C to 350 °C/100 °C in N₂ ambient conditions. The microstructures of the bonded interfaces affected the shear strength performance of the bonded Cu joints. The bonded interfaces at 300 °C/100 °C and 350 °C/100 °C had far fewer voids than interfaces bonded at 200 °C/100 °C and 250 °C/100 °C. In addition, grain growth took place across the bonding interfaces at temperatures above 300 °C/100 °C. The corresponding orientation map (OIM) showed the preferred orientation of large grown grains to be <100>. Shear tests revealed that the fracture mode was brittle for joints bonded at 200 °C/100 °C, but became ductile after bonded above 300 °C/100 °C. Based on the results, we found that voids and grain growth behavior play import roles in the shear strength performance of bonded Cu joints.
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