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Title: Effect of direct current and pulse plating parameters on tin whisker growth from tin electrodeposits on copper and brass substrates
Authors: Ashworth, Mark A.
Wilcox, G.D.
Higginson, Rebecca L.
Heath, R.J.
Liu, Changqing
Keywords: Tin
Electrodeposition
Whisker growth
Pulse plating
Issue Date: 2013
Publisher: © Institute of Materials Finishing. Published by Maney on behalf of the Institute
Citation: ASHWORTH, M.A. ... et al., 2013. Effect of direct current and pulse plating parameters on tin whisker growth from tin electrodeposits on copper and brass substrates. Transactions of the Institute of Metal Finishing, 91 (5), pp. 261 - 268.
Abstract: Electroplated tin finishes are widely utilised in the electronics industry due to their advantageous properties such as excellent solderability, electrical conductivity and corrosion resistance. However, the spontaneous growth of tin whiskers during service can be highly deleterious, resulting in localised electrical shorting or other harmful effects. The formation of tin whiskers, widely accepted as resulting from the formation of compressive stresses within the electrodeposit, has been responsible for a wide range of equipment failures in consumer products, safety critical industrial and aerospace based applications. The numbers of failures associated with tin whiskers is likely to increase in the future following legislation banning the use of lead in electronics, the latter when alloyed with tin, being an acknowledged tin whisker mitigator. Using a bright tin electroplating bath, the effect of process parameters on the characteristic structure of the deposit has been evaluated for deposition onto both brass and copper substrates. The effect on whisker growth rate of process variables, such as current density and deposit thickness, has been evaluated. In addition, the effect of pulse plating on subsequent whisker growth rates has also been investigated, particularly by varying duty cycle and pulse frequency. Whisker growth has been investigated under both ambient conditions and also using elevated temperature and humidity to accelerate the growth of whiskers. Studies have shown that whisker formation is strongly influenced by pulse plating parameters. Furthermore, increasing both current density and thickness of the deposit reduce whisker growth rates. It is also observed that whisker formation is greatly accelerated on brass substrates compared with copper. The basis for this observation is explained.
Description: This article was published in the Transactions of the Institute of Metal Finishing [© Institute of Materials Finishing] and the definitive version is available at: http://dx.doi.org/10.1179/0020296713Z.000000000116
Version: Accepted for publication
DOI: 10.1179/0020296713Z.000000000116
URI: https://dspace.lboro.ac.uk/2134/13613
Publisher Link: http://dx.doi.org/10.1179/0020296713Z.000000000116
ISSN: 0020-2967
Appears in Collections:Published Articles (Materials)

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