A comparative study on direct Cu–Cu bonding methodologies for copper pillar bumped flip-chips
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Copper pillar micro bump is one of the platform technologies, which is essentially required for 2.5D/3D chip stacking and high-density electronic components. In this study, Cu–Cu direct thermo-compression bonding (TCB) and anisotropic conductive paste (ACP) bonding methods are proposed for Ø 100 µm Cu-pillar bumped flip-chips. The process parameters including bonding temperature, bonding pressure and time are verified by die shear test and SEM/EDX cross-sectional analysis. The optimal bonding condition for TCB with regards to bonding pressure was defined to be 0.5N/bump at 300 °C or 0.3N/bump at 360 °C. In the case of ACP bonding, the minimum bonding pressure was about 0.3N/bump for gaining a seamless bonding interface.
This project has been supported by the COMET K1 center ASSIC (Austrian Smart Systems Integration Research Center). The COMET (Competence Centers for Excellent Technologies) Program is supported by BMVIT, BMWFW and the federal provinces of Carinthia and Styria.
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