Corrosion of RoHS-Compliant Surface Finishes in Corrosive Mixed Flowing Gas Environments

Recently, the corrosion resistance of printed wiring board (PWB) finishes has generated considerable interest due to field failures observed in various parts of the world. This study investigates the corrosion issues associated with the different lead-free PWB surface finishes. Corrosion products on...

Full description

Saved in:

Bibliographic Details
Published in:	Journal of electronic materials 2012-03, Vol.41 (3), p.611-623
Main Authors:	Hannigan, K., Reid, M., Collins, M.N., Dalton, E., Xu, C., Wright, B., Demirkan, K., Opila, R.L., Reents, W.D., Franey, J.P., Fleming, D.A., Punch, J.
Format:	Article
Language:	eng
Subjects:	Applied sciences Characterization and Evaluation of Materials Chemistry and Materials Science Circuit boards Copper Corrosion Corrosion mechanisms Corrosion products Corrosion resistance Electronics Electronics and Microelectronics Exact sciences and technology Gases Gold Instrumentation Materials Materials Science Metals. Metallurgy Optical and Electronic Materials Printed circuits Scanning electron microscopy Silver Solid State Physics
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Recently, the corrosion resistance of printed wiring board (PWB) finishes has generated considerable interest due to field failures observed in various parts of the world. This study investigates the corrosion issues associated with the different lead-free PWB surface finishes. Corrosion products on various PWB surface finishes generated in mixed flowing gas (MFG) environments were studied, and analysis techniques such as scanning electron microscopy, energy-dispersive x-ray, x-ray diffraction, focused ion beam, and scanning Auger microscopy were used to quantify the corrosion layer thickness and determine the composition of corrosion products. The corrosion on organic solderability preservative samples shows similar corrosion products to bare copper and is mainly due to direct attack of copper traces by corrosive gases. The corrosion on electroless nickel immersion gold occurs primarily through the porosity in the film and is accelerated by the galvanic potential between gold and copper; similar results were observed on immersion silver. Immersion tin shows excellent corrosion resistance due to its inherent corrosion resistance in the MFG environment as well as the opposite galvanic potential between tin and copper compared with gold or silver and copper.
ISSN:	0361-5235 1543-186X