Effects of Bismuth in Sn-Cu Based Solder Alloys and Interconnects

Kazuhiro Nogita; Mohd A. A. Mohd Salleh; Selena Smith; Yueqin Wu; Stuart D. McDonald; Ahmad Ghazie A. Razak; Shiqian Liu; Tetsuya Akaiwa; Takatoshi Nishimura

doi:10.5104/jiepeng.10.E17-003-1

Technical Papers

Effects of Bismuth in Sn-Cu Based Solder Alloys and Interconnects

Kazuhiro Nogita, Mohd A. A. Mohd Salleh, Selena Smith, Yueqin Wu, Stuart D. McDonald, Ahmad Ghazie A. Razak, Shiqian Liu, Tetsuya Akaiwa, Takatoshi Nishimura

Author information

Kazuhiro Nogita
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Mohd A. A. Mohd Salleh
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Centre of Excellence Geopolymer and Green Technology, School of Materials Engineering, Universiti Malaysia Perlis (UniMAP)
Selena Smith
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Yueqin Wu
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Stuart D. McDonald
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Ahmad Ghazie A. Razak
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Shiqian Liu
Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland
Tetsuya Akaiwa
Nihon Superior Co., Ltd.
Takatoshi Nishimura
Nihon Superior Co., Ltd.

Keywords: Lead-free Solders, Solid Solution Strengthening, Intermetallics, Hardness, Elastic Modulus, Ball Grid Arrays, Nano-indentation

JOURNAL FREE ACCESS

2017 Volume 10 Pages E17-003-1-E17-003-7

DOI https://doi.org/10.5104/jiepeng.10.E17-003-1

Details

Abstract

Additions of 1.5wt%Bi to Sn-0.7wt%Cu-0.05wt%Ni (SN100C) were investigated for their influence on mechanical properties and the intermetallic (IMC) layer formed between the solder and Cu substrates. Solder balls of Sn-0.7wt%Cu (Sn07Cu), SN100C, Sn-0.7wt%Cu-0.05wt%Ni-1.5wt%Bi (SN100CV) and Sn-3wt%Ag-0.5wt%Cu (SAC) were reflowed onto Cu ball grid arrays (BGAs). They were examined in the as reflowed condition and after a heat treatment of annealing at 150°C up to 1,500 hours. The mechanical properties of SN100C, SN100CV and SAC solder balls were investigated by nano-indentation, and cross-sections of the interfacial IMC layer were observed by SEM to determine the morphology and average interfacial IMC layer thickness. It was found that the effect of Bi additions was to increase the lattice parameters and alter the mechanical properties. The near-eutectic microstructure and suppression of Cu₃Sn at the IMC layer that are associated with Ni additions are not altered by the presence of 1.5wt%Bi.

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