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Electroless nickel bumping of aluminium bondpads. Part 1 - surface pre-treatment and activation

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posted on 2008-10-22, 13:26 authored by David HuttDavid Hutt, Changqing Liu, Paul ConwayPaul Conway, David Whalley, Samjid H. Mannan
Electroless nickel bumping of aluminum (Al) bondpads followed by solder paste printing is seen as one of the lowest cost routes for the bumping of wafers prior to flip-chip assembly. However, the electroless nickel bumping of Al bondpads is not straightforward and a number of activation steps are necessary to enable the nickel deposit to form a strong, electrically conductive bond with the Al. For the electroless nickel coating of mechanical components made of aluminum, a zincate activation process has been used for many years, however extension of these techniques to semiconductor wafers requires careful control over these pretreatments to avoid damage to the very thin bondpads. This paper reports a number of experiments designed to characterize the activation of Al bondpads to electroless nickel plating, focusing on the effects of solution exposure time and bondpad composition. In addition, the results are discussed in the context of other studies presented in the literature to provide an understanding of the mechanism of the zincate activation process applied to Al bondpads.



  • Mechanical, Electrical and Manufacturing Engineering


HUTT, D. A. ...et al, 2002. Electroless nickel bumping of aluminium bondpads. Part 1 - surface pre-treatment and activation. IEEE transactions on components and packaging technology, 25 (1), pp. 87-97


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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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