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Control of Magnetic Properties of Deposits from an Electroless Cobalt Solution

IP.com Disclosure Number: IPCOM000095589D
Original Publication Date: 1964-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Dunlap, WN: AUTHOR

Abstract

The coercivity of magnetic deposits from electroless cobalt baths containing hypophosphite ion can be controlled over a broad range of values. The control is accomplished by the addition of small amounts of ferrous ion to the plating bath.

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Control of Magnetic Properties of Deposits from an Electroless Cobalt Solution

The coercivity of magnetic deposits from electroless cobalt baths containing hypophosphite ion can be controlled over a broad range of values. The control is accomplished by the addition of small amounts of ferrous ion to the plating bath.

The graph illustrates the effect upon the coercivity of the resulting magnetic deposit from the addition of small amounts of ferrous ion to an electroless cobalt bath. The following bath composition and operating conditions are used: Cobalt Sulfate CoSO(4). 7H(2)O 34.5 gm/l. Sodium Hypophosphite NaH(2)PO(2).H(2)O
20.0 gm/l. Sodium Citrate Na(3)C(6)H(5)O(7)- 2H(2)O: 35.0 gm/l. Ammonium Sulfate (NH(4))(2)SO(4) 66.0 gm/l. Ammonium Hydroxide NH(4)OH Sufficient to raise initial pH to 9.0/+0.2/(-0.0) Ferrous Citrate Fe(2)C(6)H(5)O(7)-2H(2)O 1.0 to
3.0 gm/l. Operating pH range 8.8-9.0 measured at 50 degrees C Temperature 75-85 degrees C Time of Plating 20-60 seconds

The coercivity of the magnetic deposit can be controlled in the range of approximately 150 oersteds to 900 oersteds, depending upon the amount of ferrous ion added to the bath. The addition of the ferrous ion also serves to increase the deposit's residual induction. The controlling effects of the ferrous ion on the deposit are due to the codeposition with cobalt of minor amounts of metallic iron.

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