Effect of Cooling Rate on Intermetallic Compounds Formation in Sn-Ag-Cu-In Solder

Abstract:

The effect of the cooling rate in bonding on IMCs formation and their morphology in the solder joint with Sn-3.0Ag-0.7Cu-5.0In (mass%) lead-free solder was investigated. As the substrate, the Cu plate and the Cu plate with electroplated Ni were prepared. Bonding was conducted in the vacuum atmosphere, and bonding temperature and time were 300°C and 10 minutes, respectively. The cooling rates in the bonding were changed from 0.02°C/s to 0.2°C/s. In both Cu/Cu and Cu/Ni joints, scallop-shaped IMCs form at the joint interfaces regardless of the cooling rate. In the Cu/Cu joint, Cu₆(Sn,In)₅ and Cu₃(Sn,In) layers form at the joint interface. In the Cu/Ni joint, (Cu,Ni)₆(Sn,In)₅ and (Cu,Ni)₃(Sn,In) layers form at the joint interface with Cu and the (Cu,Ni)₆(Sn,In)₅ layer forms at the joint interface with Ni. Die shear force of the Cu/Ni joints are a little larger than those of the Cu/Cu joints. Fracture occurs in the boundary between the scallop-shaped layer or the granular IMC layer and the layered IMC in both joints. The cooling rate from the peak temperature to solidification is an important factor to decide the shape of formed IMC. When the cooling rate is high and supercooling becomes large, formation of pillar-shaped IMCs occurs easily.

• Periodical: Materials Science Forum (Volume 941)
• Pages: 2075-2080
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.2075
• Online since: December 2018
• Authors: Kenji Miki*, Tatsuya Kobayashi, Ikuo Shohji, Yusuke Nakata
• Keywords: Cooling Rate, Fatigue Properties, Intermetallic Compound, Pillar-Shape, Scallop-Shape, Sn-Ag-Cu-In Solder

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