Surface properties and solderability behaviour of nickel-phosphorus and nickel-boron deposited by electroless plating

Citation
Ym. Chow et al., Surface properties and solderability behaviour of nickel-phosphorus and nickel-boron deposited by electroless plating, SURF INT AN, 31(4), 2001, pp. 321-327
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
SURFACE AND INTERFACE ANALYSIS
ISSN journal
0142-2421 → ACNP
Volume
31
Issue
4
Year of publication
2001
Pages
321 - 327
Database
ISI
SICI code
0142-2421(200104)31:4<321:SPASBO>2.0.ZU;2-A
Abstract
X-ray photoelectron spectroscopy (XPS), scanning Auger microscopy (SAM), at omic force microscopy (AFM) and wetting force measurements have been applie d to various nickel deposits prepared by standard electroless plating for p robing the origins of solderability behaviour of 'electroless nickel'. By c ontrolling the plating chemicals and plating conditions, three kinds of ele ctroless nickel deposits have been prepared, namely electroless nickel-high phosphorus (EN-HP), electroless nickel-low phosphorus (EN-LP) and electrol ess nickel-boron (EN-B). Wetting balance measurements confirmed the soldera bility strength decreased in the order of EN - B > EN - LP > EN - HP. Unexp ectedly, among the three EN deposits, EN-B was found by XPS to have the thi ckest surface oxide, which opposes the traditional correlation of good sold erability with thin surface oxide. On the other hand, SAM and AFM studies s howed that the average nodule size increased in the order of EN - B < EN - LP < EN - HP. Accordingly, there appeared to be a correlation of small nodu le size with good solderability. Solderability of 'electroless nickel' thus depended more on surface morphology than on surface oxidation. Nevertheles s, further studies of the wetting kinetics of the EN deposits revealed that among the three EN deposits EN-HP had the oxide structure that was most di fficult to penetrate and thus the slowest to 'wet'. The structure of the su rface oxide therefore was found to affect the wetting kinetics of 'electrol ess nickel'. Copyright (C) 2001 John Wiley & Sons, Ltd.