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Materials and processes issues in fine pitch eutectic solder flip chip interconnection

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journal contribution
posted on 22.10.2008 by Changqing Liu, M.W. Hendriksen, David Hutt, Paul Conway, David Whalley
New product designs within the electronics packaging industry continue to demand interconnects at shrinking geometry, both at the integrated circuit and supporting circuit board substrate level, thereby creating numerous manufacturing challenges. Flip chip on board (FCOB) applications are currently being driven by the need for reduced manufacturing costs and higher volume robust production capability. One of today’s low cost FCOB solutions has emerged as an extension of the existing infrastructure for surface mount technology and combines an under bump metallization (UBM) with a stencil printing solder bumping process, to generate mechanically robust joint structures with low electrical resistance between chip and board. Although electroless Ni plating of the UBM, and stencil printing for solder paste deposition have been widely used in commercial industrial applications, there still exists a number of technical issues related to these materials and processes as the joint geometry is further reduced. This paper reports on trials with electroless Ni plating and stencil paste printing and the correlation between process variables in the formation of bumps and the shear strength of said bumps at different geometries. The effect of precise control of tolerances in squeegees, stencils and wafer fixtures was examined to enable the optimization of the materials, processes, and tooling for reduction of bumping defects.



  • Mechanical, Electrical and Manufacturing Engineering


LIU, C. ...et al, 2006. Materials and processes issues in fine pitch eutectic solder flip chip interconnection. IEEE Transactions on Components and Packaging Technologies, 29 (4), pp. 869-876


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This is a journal article. It was published in the journal IEEE transactions on components, packaging and manufacturing technologies [© IEEE], and is available from: http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6144. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.






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