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Pulse Plating of Alloys

IP.com Disclosure Number: IPCOM000037144D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Bindra, P: AUTHOR [+3]

Abstract

This article describes a method to pulse electroplate alloys with simplified bath chemistry minimizing the usage of additives. The bath chemistry consists of a solvent, supporting electrolyte, and soluble metal salts or complexes in solution. The alloy is electroplated by pulsing potentials from E0, potential where no plating takes place, to E2 for metal 1 deposition and then E3 for mainly metal 2 deposition (see Figs. 1 and 2). This method has sufficient adjustable parameters (E2, E3, t2, t3, frequency) to control the deposit composition over a wide range and still yield acceptable grain structure and deposit finish.

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Pulse Plating of Alloys

This article describes a method to pulse electroplate alloys with simplified bath chemistry minimizing the usage of additives. The bath chemistry consists of a solvent, supporting electrolyte, and soluble metal salts or complexes in solution. The alloy is electroplated by pulsing potentials from E0, potential where no plating takes place, to E2 for metal 1 deposition and then E3 for mainly metal 2 deposition (see Figs. 1 and 2). This method has sufficient adjustable parameters (E2, E3, t2, t3, frequency) to control the deposit composition over a wide range and still yield acceptable grain structure and deposit finish.

Sn-Ni alloy can be electroplated by this method from a solution of nickel chloride, tin chloride and hydrochloric acid. Pulse potentials can be used where Sn and Ni are plated independently (Sn reduction potential = -0.136 V vs. NHE, Ni reduction potential = -0.23 V vs. NHE plus high plating overpotential). The frequency and potential magnitude of the pulse electroplating can be adjusted to produce acceptable deposit metallurgy. Pulse electroplating of this alloy eliminates bifluoride ion for complexing Sn, associated hydrofluoric acid in the plating bath, and the list of amine additives utilized to ensure no free Ni is present in solution as insoluble nickel fluoride. Also, alloy compositions different from 50/50 atomic % are possible.

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