Effect of Cu stud microstructure and electroplating process on intermetallic compounds growth and reliability of flip-chip solder bump

Guo Wei Xiao, Philip Ching Ho Chan, Annette Teng, Jian Cai, Matthew M.F. Yuen

Research output: Journal article publicationJournal articleAcademic researchpeer-review

25 Citations (Scopus)


In electroplating-based flip-chip technology, the Cu stud and solder deposition processes are two of the most important factors affecting the reliability of solder joints. The growth of Cu-Sn intermetallic compounds (IMC) also plays a critical role. In this paper, the effect of Cu stud surface roughness and microstructures on the reliability of solder joint was studied. The surface roughness of the Cu stud was increased as the Cu electroplating current density increased. The micro-structural morphology of the Cu-Sn IMC layer was affected by Cu stud surface structure. We found the growth rate of IMC layer increased with the increasing of Cu stud grain size and surface roughness during aging test. The growth kinetics of Cu-Sn intermetallic compound formation for 63Sn/37Pb solder followed the Arrhenius equation with activation energy varied from 0.78 ev to 1.14 ev. The ratios of Cu3Sn layer thickness to the total Cu-Sn IMC layer thickness was in the range of 0.5 to 0.15 for various Cu microstructures at 150 °C during thermal aging test. The shear strength of solder bump was measured after thermal aging and temperature/humidity tests. The relationship between electroplating process and reliability of solder joints was established. The failure mode of solder joints was also analyzed.
Original languageEnglish
Pages (from-to)682-690
Number of pages9
JournalIEEE Transactions on Components and Packaging Technologies
Issue number4
Publication statusPublished - 1 Dec 2001
Externally publishedYes


  • Copper
  • Electroplating
  • Flip-chip
  • Growth kinetics
  • Intermetallic compound
  • Reliability
  • Solder bump

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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