XPS STUDY OF THE OXIDATION BEHAVIOR OF THE CU3SN INTERMETALLIC COMPOUND AT LOW-TEMPERATURES

The oxidation of Cu-Sn intermetallic compounds is of significant techn ological interest in relation to the wetting behavior of Sn-base solde rs to Cu and Cu alloys. However,there are very few studies on this sub ject in the literature. In this present study, oxide films formed on t he intermetallic compound Cu3Sn in pure O-2 at temperatures <350 degre es C have been analyzed using XPS. Single-phase samples of different C u-Sn intermetallic compounds, made by hot isostatic pressing of rapidl y solidified powders, were provided by NIST. The sample surfaces were mechanically cleaned, and oxidized in situ in the XPS chamber. Results obtained so far indicate that the oxidation behavior of epsilon-Cu3Sn , in terms of both microchemistry and growth kinetics, is strongly tem perature dependent. A tin oxide film was observed at 150-200 degrees C , while a mixed copper and tin oxide film was noted at 350 degrees C. Results for oxidation of epsilon-Cu3Sn are interpreted in terms of ava ilable phase equilibria and growth kinetics data.