Auger electron spectroscopy element profiles and interface with substrates of electroless deposited ternary alloys

Electroless NiMeP alloys (Me = Cu, Sn, Sb) with high phosphorus content (similar to 11 weight percent) and a low weight percent of the third component (Me) have been plated in acidic baths onto aluminum, iron, and nickel. Scanning Auger electron spectroscopy is applied to study the element profiles and interface with the substrates. Generally the third component follows the profiles of Ni and P, which proves the alloy formation. A surface enrichment in the third element (Me) is observed in all cases. It is very strong when tin is the third component and very weak in the case of antimony, which is more or less uniformly distributed through the thickness. Decrease of surface concentration of phosphorus is noticed when NiSbP is plated. In Cu profiles three different zones exist: a surface enrichment zone, a groove (a zone of reduced concentration), and a plateau (a zone of almost constant concentration). There is no enrichment in the third element at the interface with the substrate for all three alloys and three substrates. At the interface with aluminum prepared for electroless plating with double zincate pretreatment complete dissolution of the zincate layer has been established.