Effect of carbon nanotubes and their dispersion on electroless Ni–P under bump metallization for lead-free solder interconnection
Chan, Yan Cheong
Date of Issue2014
School of Materials Science and Engineering
Electroless Ni–P under bump metallization (UBM) has advantages of even surface, low cost and simplicity to deposit, but their mechanical strength, corrosion resistance and stability still face challenges under high soldering temperature. Incorporating carbon nanotubes (CNTs) into electroless Ni–P UBM might be expected to provide Ni–P–CNT composites with high mechanical strength and stability. Ni–P–CNT composite coatings as well as Ni–P coatings were fabricated by electroless plating process. In order to homogeneously disperse CNTs in composite coatings, acid pre-treatment and surfactant dispersant were introduced. During composite electroless plating, the ultrasonic agitation was also employed. In this study, scanning electronic microscopy (SEM) was used to observe the morphology and the CNTs were proved to be uniformly distributed in Ni–P–CNT coatings by SEM and atomic force microscopy. It was verified that the surface of the composite was quite smooth and continuous; CNTs are equably embedded in the matrix, which is advantageous for conductivity, mechanical strength and corrosion resistance. Shear tests were conducted to evaluate the effect of CNT reinforcement on the mechanical properties of joints, and the joints with CNT additions exhibited higher shear strength at different reflow cycles. Moreover, deposition mechanism of CNTs with Ni was analyzed and confirmed by transmission electron microscopy. Factors that affecting plating process was also discussed, and the optimum plating condition was suggested in this study.
DRNTU::Engineering::Materials::Microelectronics and semiconductor materials
Journal of materials science : materials in electronics
© 2014 Springer Science+Business Media New York. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of materials science : materials in electronics, Springer Science+Business Media New York. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1007/s10854-014-1929-8].