Flux-free direct chip attachment of solder-bump flip chip by Ar + H2 plasma treatment

Soon Min Hong, Choon Sik Kang, Jae Pil Jung

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


The flux-free flip-chip bonding process using plasma treatment was investigated. The effect of plasma-process parameters on Sn oxide-etching characteristics was evaluated by Auger depth-profile analysis. The die-shear test was performed to evaluate the adhesion strength of an Sn-37mass%Pb and Sn-3.5mass%Ag solder-bump flip chip that was bonded after plasma treatment. The Ar + H2 plasma treatment reduced the thickness of the oxide layer on the Sn surface. The addition of H2 to the Ar plasma improved the oxide-etching characteristics. A low chamber pressure was more effective in oxide etching. The die-shear strength of the plasma-treated Sn-Pb and Sn-Ag solder flip chip was higher than that of the nontreated chip but lower than that of the fluxed chip. The difference in the die-shear strength between the plasma-treated specimen and the nontreated specimen increased with increasing bonding temperature. The plasma-treated flip chip fractured at the solder/top-surface metallurgy (TSM) interface at low bonding temperature, but at the solder/ under-bump metallurgy (UBM) interface at high bonding temperature.

Original languageEnglish
Article number49
Pages (from-to)1104-1111
Number of pages8
JournalJournal of Electronic Materials
StatePublished - 2002


  • Bump
  • Die-shear strength
  • Flip chip
  • Flux-free
  • Fracture surface
  • Oxide layer
  • Pb-free solder
  • Plasma


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