Dependence of wetting temperature on the solder/substrate oxidation in a reductive atmosphere

Lei Zhang, Guangwei Sun, Li Li, J. K. Shang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Fluxless soldering is a desired process for high density solder joint and optical electronic interconnection. There are two species of oxides, one from the copper substrate, and the other from the tin-based solder. To reduce the metallic oxides, hydrogen is always considered. Utilizing hydrogen or forming gas can be a good candidate for the fluxless soldering. So the effectiveness of the reduction processes on the wetting of solder on copper has to be evaluated. The roles of these oxides playing during the process have to be understood that is interesting to scientists and engineers. For these purpose, The wetting behavior of Sn63Pb37 solder on bulk copper in the absence of flux was investigated in a forming gas (5% H2 and 95% Ar) at a series of heating rate. The surface chemistry of the solder and the copper plate was analyzed by X-ray photoelectron spectroscopy (XPS) and the thickness of Cu 2O was estimated. It was found that the wetting temperature increases with the increase of the thickness of Cu2O and heating rate. The wetting temperature versus oxidation time for Cu surface approximately follows a parabolic relation. The measured wetting temperature are found to be close the initial reduction temperature of Cu2O, which implies that once Cu2O is reduced, Sn63Pb37 solder starts to wet copper. An activation energy for wetting was calculated to be 96.4±9 kJ/mol.

Original languageEnglish (US)
Title of host publicationProceedings - 2007 International Symposium on Microelectronics, IMAPS 2007
Pages697-702
Number of pages6
StatePublished - Dec 1 2007
Event40th International Symposium on Microelectronics, IMAPS 2007 - San Jose, CA, United States
Duration: Nov 11 2007Nov 15 2007

Publication series

NameProceedings - 2007 International Symposium on Microelectronics, IMAPS 2007

Other

Other40th International Symposium on Microelectronics, IMAPS 2007
CountryUnited States
CitySan Jose, CA
Period11/11/0711/15/07

Keywords

  • Copper
  • Solder
  • Surface oxidation
  • Wetting

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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