Thermomechanical fatigue performance of lead-free chip scale package assemblies with fast cure and reworkable capillary flow underfills

Hongbin Shi, Cuihua Tian, Toshitsugu Ueda

    Research output: Contribution to journalArticle

    3 Citations (Scopus)

    Abstract

    In this paper, we present the results of temperature cycling test for full and partial capillary flow underfilled lead-free chip scale packages (CSPs), the tests were carried out on the basis of JEDEC standard. Two kinds of representative fast cure and reworkable underfill materials are used in this study, and CSPs without underfills were also tested for comparison. The test results show that the two underfill materials reduce the thermomechanical fatigue performance of CSP assemblies. The underfill with high Tg and storage modulus yielded better performance; indeed, the coefficient of thermal expansion (CTE) is also very critical to the thermomechanical fatigue performance, but its effects is not so obvious in this study owing to the similar CTEs of the underfills used. In addition, the negative effect of a partial underfill pattern is smaller than that of a full underfill pattern. Failure analysis shows that the dominant failure mode observed is solder cracking near the package and/or printed circuit board pads.

    Original languageEnglish
    Article number05EE04
    JournalJapanese Journal of Applied Physics
    Volume51
    Issue number5 PART 2
    DOIs
    Publication statusPublished - 2012 May

    ASJC Scopus subject areas

    • Engineering(all)
    • Physics and Astronomy(all)

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