Phosphorus Distribution in Electroless NiP Deposits

Abstract

In general, the solderability and bondability of electroless nickel (EN) deposits are greatly affected by the phosphorus contents in the deposited nickel films. This paper describes the phosphorus distribution and content in the EN films at both the initial stages and following steady state of deposition conditions. lt was found that phosphorus contents in the deposits at the initial stages indicate higher values than the following steady state deposition. The highest phosphorus content in the films was obtained from the citric acid bath among the tested complexing agent s. Phosphorus rich layer was formed at the top of the surface of EN deposits. And the P rich layer around 20 to 40nm is produced at the initial stages of deposition and this layer is always staid at the top of the deposited surface along with the progress of deposition reaction. © 2002, The Japan Institute of Electronics Packaging. All rights reserved.