English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In this study, we evaluated the ultrasonic vibration energy required for Cu-Cu bonding using flip-chip bonding technology in air atmosphere. The transmissibility of the ultrasonic vibration was assumed to be different in bump structures with high or low stiffness values. Therefore, we investigated the bonding strengths of Cu bumps with different aspect ratios (bump heights of 5 μm, 20 μm, and 40 μm). As a result, we found that the 20 μm-high Cu bumps were properly bonded with sufficient bonding strength by comparison with the other bumps. No significant voids that decrease the bonding reliability were present at the Cu-Cu interface of well-bonded Cu bumps. In addition, coplanarity between the bonding head and the stage surface was found to be an important factor for ultrasonic bonding, because it enabled all bumps to start to bond simultaneously.

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