Interfacial embrittlement by bismuth segregation in copper/tin–bismuth Pb-free solder interconnect

P. L. Liu, J. K. Shang

Research output: Contribution to journalArticlepeer-review


Microchemistry and mechanical properties of a copper/tin-bismuth Pb-free solder interconnect were examined in the as-reflowed and aged conditions by in situ Auger fracture and interface fracture mechanics techniques. In the as-reflowed condition, the solder-copper interface was highly resistant to fracture, and the fracture mechanism was ductile with the crack path following the interface between the solder alloy and the copper-tin intermetallic phase. Upon thermal aging, bismuth segregation was found to occur on the copper-intermetallic interface. Auger depth profiling indicated that the segregation was confined to about one monolayer from the interface. The segregation was shown to embrittle the interface, resulting in an approximately 5-fold decrease in the interfacial fracture resistance.

Original languageEnglish (US)
Pages (from-to)1651-1659
Number of pages9
JournalJournal of Materials Research
Issue number6
StatePublished - Jun 2001

ASJC Scopus subject areas

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


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