Evaluation of Ultrasonic Vibration Energy on Cu-Cu Direct Bonding for Flip-Chip Interconnection

Arai, Yoshiyuki; Nimura, Masatsugu; Tomokage, Hajime

doi:10.5104/jiepeng.7.8

Cited by 4 publications

(1 citation statement)

References 10 publications

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“…1,2) Although ultrasonic bonding can be performed in air and at room temperature, it requires high bonding pressures and involves a significant deformation of the copper in the bond. 3,4) Friction stir welding can also be performed in air, but the temperature of the joint will be high, resulting in significant deformation. 5,6) In addition, any aforementioned joining method requires a tool to be pressed against the joint to apply pressure and is not suitable for joining narrow gaps where the tool cannot access.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Bonding of Copper by Copper Electrodeposition

et al. 2022

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Bonding copper in the solid state requires either a high temperature, large deformation, or high vacuum. In the present study, copper was butt-bonded using a K-shaped groove at 298 K under no bonding pressure through copper electrodeposition. The initial gap between the faying surfaces of the copper rods were gradually filled with the electrodeposition of copper from the center to the periphery. No significant defects were observed in the bond layer, and a high joint strength of approximately 240 MPa was obtained. There were three regions in the bond layer: fine columnar grain region, ultrafine grain region, and recrystallized grain region. The size of the ultrafine grains was several tens of nanometers, and the microhardness was larger than that of the base metal. As electrodeposition progressed, there were insufficient additives for electrodeposition near the center of the bond layer, and recrystallization occurred owing to self-annealing.

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