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Tin Nickel Reed Switch Plating Process

IP.com Disclosure Number: IPCOM000090405D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Delaney, RA: AUTHOR [+2]

Abstract

Electroplated tin-nickel alloy, having the form Ni(3)Sn(4), relatively large crystal size, and low compressive stresses after annealing, is particularly useful as a reed switch contact material for both high and low level AC circuits. Tin-nickel alloy electroplating baths of the type described by N. Parkenson, Jour.Electrodepositors Tech. Soc., 27, 129, 1950, when prepared and used under the conditions there recommended, do not give such a form after annealing. Altering the bath composition, preparation, plating conditions, and alloy annealing gives such a desired contact surface.

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Tin Nickel Reed Switch Plating Process

Electroplated tin-nickel alloy, having the form Ni(3)Sn(4), relatively large crystal size, and low compressive stresses after annealing, is particularly useful as a reed switch contact material for both high and low level AC circuits. Tin- nickel alloy electroplating baths of the type described by N. Parkenson, Jour.Electrodepositors Tech. Soc., 27, 129, 1950, when prepared and used under the conditions there recommended, do not give such a form after annealing. Altering the bath composition, preparation, plating conditions, and alloy annealing gives such a desired contact surface.

A suitable bath has the following composition: NiCl(2).6H(2)O 250g/1 SnCl(2).2H(2)O 50g/1 NH(4)F-HF 40g/1 NH(4)OH (28-30% NH(3)) 35ml/1. The bath is prepared by the addition to water of the reagents in the sequence listed at 90 degrees C. The use of other addition sequences or temperatures adversely affects the resulting contacts.

Tin-nickel alloy is deposited on coined, annealed, and cleaned reed switch levers from the bath using a current of 37 amps/ft. at 65 degrees C to give a deposit of substantially equal amounts of NiSn and Ni(3)Sn(2), and a trace of Ni(3)Sn(4) with large crystal sizes and low compressive stresses. Altering the plating temperature and current even slightly produces other forms of tin-nickel deposit and alters stresses.

The desired Ni(3)Sn(4) contact is produced by annealing the thus plated levers in flowing forming gas, con...