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Browse Prior Art Database

Plating a Copper Commutation Surface onto Aluminum Winding Conductors

IP.com Disclosure Number: IPCOM000077619D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Parker, JE: AUTHOR [+2]

Abstract

The low inertia armature of a high torque - low inertia motor, such as the direct-current capstan motor of a magnetic tape unit, includes winding conductors which directly engage the motor's brushes. These conductors are formed of aluminum to lower the armature's mass. A commutation track is formed of the aluminum conductors by plating a layer of copper onto selected portions of the aluminum conductors.

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Plating a Copper Commutation Surface onto Aluminum Winding Conductors

The low inertia armature of a high torque - low inertia motor, such as the direct-current capstan motor of a magnetic tape unit, includes winding conductors which directly engage the motor's brushes. These conductors are formed of aluminum to lower the armature's mass. A commutation track is formed of the aluminum conductors by plating a layer of copper onto selected portions of the aluminum conductors.

The armature is first formed in tube, disk or cone shape from a thin insulating substrate which supports the aluminum conductors. All areas of the aluminum conductors, with the exception of the commutation track, are then masked with passive masking, such as rubber tape, wax or an inflatable rubber bladder. The purpose of this passive masking is to isolate the underlying aluminum conductors from the copper plating solution during a subsequent electroplating procedure, which deposits a copper commutation layer onto the unmasked aluminum conductors.

When the masking is not complete, plating solution leaks under the masking and forms a galvanic reaction with the underlying aluminum conductors, causing pitting of these conductors. This unwanted effect is eliminated by placing a sacrificial anode, such as magnesium, under the masking, in electrical contact with the aluminum conductors. Any plating solution which now leaks under the masking enters into galvanic action with the magnesium and does not a...