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The Purple of Cassius A Recurrent Gold Finger, Tabplating Problem

The Purple of Cassius A Recurrent Gold Finger, Tabplating Problem Over the past 20 years there has been a recurrent problem of a purplebluish stain appearing on the laminate materials of finished printed circuit boards between the goldplated fingers. The origin of this staining has been traced back to the PWB fabrication plant and it is generally accepted to be related to either the gold plating bath andor the solder stripper chemistry. In this paper the authors report their investigation of this phenomenon and show that, far from being a benign, cosmetic defect, this purple stain poses a potentially serious metallic contamination to the laminate surface of the PWB. The purple colour arises from generation of a colloidal gold chromophore known as the Purple of Cassius, which has been known since ancient times and has been in commercial use in the glass and ceramics industry for at least 300 years. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Circuit World Emerald Publishing

The Purple of Cassius A Recurrent Gold Finger, Tabplating Problem

Circuit World , Volume 19 (1): 9 – Apr 1, 1992

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0305-6120
DOI
10.1108/eb046189
Publisher site
See Article on Publisher Site

Abstract

Over the past 20 years there has been a recurrent problem of a purplebluish stain appearing on the laminate materials of finished printed circuit boards between the goldplated fingers. The origin of this staining has been traced back to the PWB fabrication plant and it is generally accepted to be related to either the gold plating bath andor the solder stripper chemistry. In this paper the authors report their investigation of this phenomenon and show that, far from being a benign, cosmetic defect, this purple stain poses a potentially serious metallic contamination to the laminate surface of the PWB. The purple colour arises from generation of a colloidal gold chromophore known as the Purple of Cassius, which has been known since ancient times and has been in commercial use in the glass and ceramics industry for at least 300 years.

Journal

Circuit WorldEmerald Publishing

Published: Apr 1, 1992

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