Journal of Electronic Materials

, Volume 35, Issue 1, pp 89–93 | Cite as

Microstructure, solderability, and growth of intermetallic compounds of Sn-Ag-Cu-RE lead-free solder alloys

  • C. M. T. Law
  • C. M. L. Wu
  • D. Q. Yu
  • L. Wang
  • J. K. L. Lai
Article

Abstract

The near-eutectic Sn-3.5 wt.% Ag-0.7 wt.% Cu (Sn-3.5Ag-0.7Cu) alloy was doped with rare earth (RE) elements of primarily Ce and La of 0.05–0.25 wt.% to form Sn-3.5Ag-0.7Cu-xRE solder alloys. The aim of this research was to investigate the effect of the addition of RE elements on the microstructure and solderability of this alloy. Sn-3.5Ag-0.7Cu-xRE solders were soldered on copper coupons. The thickness of the intermetallic layer (IML) formed between the solder and Cu substrate just after soldering, as well as after thermal aging at 170°C up to 1000 h, was investigated. It was found that, due to the addition of the RE elements, the size of the Sn grains was reduced. In particular, the addition of 0.1wt.%RE to the Sn-3.5Ag-0.7Cu solder improved the wetting behavior. Besides, the IML growth during thermal aging was inhibited.

Key words

Lead-free solder rare earth (RE) elements solderability test intermetallic layer 

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Copyright information

© TMS-The Minerals, Metals and Materials Society 2006

Authors and Affiliations

  • C. M. T. Law
    • 1
  • C. M. L. Wu
    • 1
  • D. Q. Yu
    • 1
    • 2
  • L. Wang
    • 2
  • J. K. L. Lai
    • 1
  1. 1.Department of Physics and Materials ScienceCity University of Hong KongHong Kong, SARPeople’s Republic of China
  2. 2.Department of Materials EngineeringDalian University of TechnologyDalianPeople’s Republic of China

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