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A Conversion-Electron Mssbauer Study of Tin-Based Compounds Formed During Pads Treatment (Plasma-Assisted Dry Soldering) of a Solder Foil

Published online by Cambridge University Press:  10 February 2011

Robert C. Reno  and
Brett Piekarski
Robert C. Reno
Affiliation:
Physics Department, University of Maryland Baltimore County, Baltimore MD 21250, reno@umbc.edu
Brett Piekarski
Affiliation:
Physics Department, University of Maryland Baltimore County, Baltimore MD 21250, reno@umbc.edu
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Abstract

We have used conversionelectron Mössbauer spectroscopy (CEMS) to examine the surfaces of solder foils treated in a plasma assisted dry soldering (PADS) system which has been developed1 to convert surface oxides to more desirable fluorides in order to protect the solder surface prior to assembly and to eliminate the need for flux during the soldering process. CEMS samples only the outer 1 μm of a solder foil and this, coupled with the fortuitous fact2 that Mössbauer spectroscopy is 10–20 times more sensitive to oxides and fluorides than to the metallic form of solder, means that surface layers of oxides and fluorides as thin as 10 nm can be detected and chemically identified. We have followed the evolution of surface layers produced in PADS treatments ranging from 7 minutes to several hours. Our results show that fully treated foils contain surface layers of SnF2 and Sn2F6. Partially treated foils also contain some SnO2 and perhaps a small amount of SnO. No Sn2OF2 or SnF4 was produced during any portion of the PADS treatment cycle.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 445: Electronic Packaging Materials Science IX , 1996 , 223
Copyright
Copyright © Materials Research Society 1997

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References

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