Measurements and FEM analyses of strain distribution in small Sn specimens with few crystal grains

Takumi Sasaki, Atsushi Yanase, Dai Okumura, Yoshiharu Kariya, Masaaki Koganemaru, Toru Ikeda

Research output: Contribution to journalArticle

Abstract

Soldering is used to bond a semiconductor chip to a print circuit board (PCB). It is known that Sn, which is the base metal of Pb-free solder, shows remarkable crystal anisotropy. Clarifying the effect of Sn anisotropy on strain distribution is important for lifetime evaluation. The strain distribution in a micro specimen was measured under a tensile test by a digital image correlation method (DICM) with a microscope. Strain distributions were also analyzed by the finite element method with Hill's anisotropic yield criterion and the crystal plasticity finite element analysis (CPFEA) with considering the critical resolves shear stress (CRSS) of each slip system. The deformation of the crystal structure of ¢-Sn depends on the size, number, and orientation of crystal grains. The CRSS was noticeably different for each slip system, and the yield stress varied with the orientation of crystal grains. Although the CPFEA without considering strain hardening was effective for predicting deformation within crystal grains, it is necessary to consider the strain hardening of crystals to predict the stress-strain curve of a micro specimen.

Original languageEnglish
Pages (from-to)868-875
Number of pages8
JournalMaterials Transactions
Volume60
Issue number6
DOIs
Publication statusPublished - 2019 Jan 1

    Fingerprint

Keywords

  • Anisotropic
  • Crystal plasticity
  • DICM
  • Finite element method
  • Hill's yield criterion
  • ¢-Sn

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this