Effects of poss-silanol addition on whisker formation in Sn-based Pb-free electronic solders

Sihan Liu, Limin Ma, Yutian Shu, K. N. Subramanian, Andre Lee, Fu Guo

    Research output: Research - peer-reviewArticle

    • 3 Citations

    Abstract

    Previous studies have indicated that silanol in the form of polyhedral oligomeric silsesquioxane (POSS) trisilanol could form strong bonds with solder matrix without agglomeration, and inhibit diffusion of metal atoms when subjected to high ambient temperature and/or high current density. Addition of POSS-trisilanol has also been shown to improve the comprehensive performance of Sn-based Pb-free solders, such as shear strength, resistance to electromigration, as well as thermal fatigue. The current study investigated the whisker formation/growth behaviors of Sn-based Pb-free solders (eutectic Sn-Bi) modified with 3 wt.% POSS-trisilanol. Solder films on Cu substrates were aged at ambient temperature of 125 C to accelerate whisker growth. The microstructural evolution of the solder films' central and edge areas was examined periodically using scanning electron microscopy. Bi whiskers were observed to extrude from the surface due to stress/strain relief during growth of Sn-Cu intermetallic compounds (IMCs). Addition of POSS-trisilanol was shown to retard the growth of Bi whiskers. The IMCs formed between POSS-modified solders and the Cu substrate showed smoother surface morphology and slower thickness growth rate during reflow and aging. It was indicated that POSS particles located at the phase boundaries inhibited diffusion of Sn atoms at elevated temperatures, and thus limited the formation and growth of IMCs, which resulted in the observed inhibition of Bi whisker growth in POSS-modified solders.

    LanguageEnglish (US)
    Pages26-32
    Number of pages7
    JournalJournal of Electronic Materials
    Volume43
    Issue number1
    DOIs
    StatePublished - Jan 2014

    Profile

    Soldering alloys
    silanol
    solders
    electronics
    Intermetallics
    Temperature
    intermetallics
    Atoms
    Substrates
    Lead-free solders
    ambient temperature
    atoms
    Thermal fatigue
    Electromigration
    Microstructural evolution
    Phase boundaries
    Shear strength
    Eutectics
    Surface morphology
    Current density

    Keywords

    • isothermal aging
    • Sn-based solder
    • Whisker

    ASJC Scopus subject areas

    • Electrical and Electronic Engineering
    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Materials Chemistry

    Cite this

    Effects of poss-silanol addition on whisker formation in Sn-based Pb-free electronic solders. / Liu, Sihan; Ma, Limin; Shu, Yutian; Subramanian, K. N.; Lee, Andre; Guo, Fu.

    In: Journal of Electronic Materials, Vol. 43, No. 1, 01.2014, p. 26-32.

    Research output: Research - peer-reviewArticle

    Liu, Sihan ; Ma, Limin ; Shu, Yutian ; Subramanian, K. N. ; Lee, Andre ; Guo, Fu. / Effects of poss-silanol addition on whisker formation in Sn-based Pb-free electronic solders. In: Journal of Electronic Materials. 2014 ; Vol. 43, No. 1. pp. 26-32
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