TY - JOUR

T1 - Detection of joining mechanisms at different locations of the wire/substrate interface during ultrasonic wire bonding via a PZT-based sensor array

AU - Long, Yangyang

AU - Arndt, Matthias

AU - Sun, Chen

AU - Dencker, Folke

AU - Wurz, Marc

AU - Twiefel, Jens

N1 - Funding Information: The support from the German Research Foundation (Project number: 329797820 ) is gratefully acknowledged.

PY - 2023/3

Y1 - 2023/3

N2 - Ultrasonic (US) wire bonding is a very complex process during which different mechanisms occur at different locations of the bonding interface. The change of these local mechanisms stays unclear. In this study, a 3 × 4 piezoceramic-based sensor array was created to in-situ measure the local tangential forces at different locations of the interface; by analyzing these forces, corresponding mechanisms were derived. The results showed the largest tangential forces on the two central columns, the smallest tangential forces on the columns at the four corners, and the largest expansion of the contact area on the remaining six columns (peripheral columns). In the beginning of the bonding process, a “1st fast increase – plateau – 2nd fast increase” of tangential force stage was detected on nearly all columns. In the following process, the tangential forces on the central columns decreased due to the decrease of the local normal forces; later, the decrease could be compensated by microweld formation. As the local normal forces increased, a gradual increase of tangential force occurred on the peripheral columns. This increasing stage could also occur on the corner columns while the increase was much smaller. The specific curves at different moments exhibited complex features consisting of static and sliding friction, microweld formation and breakage. Compared to central columns, sliding friction played a more dominating role on peripheral and corner columns. These findings deepen the understanding of mechanisms occurring at different locations of the bonding interface and provide potential to enhance the bonding process via changing the substrate structure.

AB - Ultrasonic (US) wire bonding is a very complex process during which different mechanisms occur at different locations of the bonding interface. The change of these local mechanisms stays unclear. In this study, a 3 × 4 piezoceramic-based sensor array was created to in-situ measure the local tangential forces at different locations of the interface; by analyzing these forces, corresponding mechanisms were derived. The results showed the largest tangential forces on the two central columns, the smallest tangential forces on the columns at the four corners, and the largest expansion of the contact area on the remaining six columns (peripheral columns). In the beginning of the bonding process, a “1st fast increase – plateau – 2nd fast increase” of tangential force stage was detected on nearly all columns. In the following process, the tangential forces on the central columns decreased due to the decrease of the local normal forces; later, the decrease could be compensated by microweld formation. As the local normal forces increased, a gradual increase of tangential force occurred on the peripheral columns. This increasing stage could also occur on the corner columns while the increase was much smaller. The specific curves at different moments exhibited complex features consisting of static and sliding friction, microweld formation and breakage. Compared to central columns, sliding friction played a more dominating role on peripheral and corner columns. These findings deepen the understanding of mechanisms occurring at different locations of the bonding interface and provide potential to enhance the bonding process via changing the substrate structure.

KW - Local mechanisms

KW - Sensor array

KW - Stick-slip behavior

KW - Tangential force distribution

KW - Ultrasonic wire bonding

UR - http://www.scopus.com/inward/record.url?scp=85143523358&partnerID=8YFLogxK

U2 - 10.1016/j.jmatprotec.2022.117826

DO - 10.1016/j.jmatprotec.2022.117826

M3 - Article

AN - SCOPUS:85143523358

VL - 312

JO - Journal of Materials Processing Technology

JF - Journal of Materials Processing Technology

SN - 0924-0136

M1 - 117826

ER -