Effects of phosphorus on microstructure and fluidity of Sn-0.7Cu-0.05Ni lead-free solder

K. Nogita, C. M. Gourlay, J. Read, T. Nishimura, S. Suenaga, A. K. Dahle

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


Phosphorus is often added to wave-solder baths as an anti-oxidation agent. Despite this practice, there is little information on how phosphorus influences the solidification and flow properties of new lead-free solders such as Sn-0.7Cu-0.05Ni. This paper investigates the effects of phosphorus content on microstructure and maximum fluidity length in Sn-0.7Cu-0.05Ni-xP alloys containing 0-0.08 mass% phosphorous. Ppm levels of phosphorous are found to cause Sn-JrP, Ni-xP-(Sn) and Cu-xP-(Sn) intermetallic compounds to form in the liquid solder. The IMCs are less dense than liquid Sn and float towards the surface of the melt driven by buoyancy. It is shown that P-free Sn-0.7Cu-0.05Ni solidifies with a near-eutectic microstructure whereas, when P is added to this alloy, a significant volume fraction of primary Sn dendrites form once the P content exceeds ∼0.01 mass% P. It is further shown that P additions decrease the ability of Sn-0.7Cu-0.05Ni to flow as it solidifies.

Original languageEnglish
Pages (from-to)443-448
Number of pages6
JournalMaterials Transactions
Issue number3
Publication statusPublished - Mar 2008

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


Dive into the research topics of 'Effects of phosphorus on microstructure and fluidity of Sn-0.7Cu-0.05Ni lead-free solder'. Together they form a unique fingerprint.

Cite this