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Control Of Coercivity Of Thin Ferromagnetic Films Deposited On High Resistance Substrates

IP.com Disclosure Number: IPCOM000095447D
Original Publication Date: 1964-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Koretzky, H: AUTHOR

Abstract

Ferromagnetic films having high coercivities can be deposited onto high resistance substrates by electro-deposition techniques. A bath-soluble alcohol metal sulfate, together with an alkali metal hypophosphite or hypophosphorous acid, are added to standard acidic electroplating baths to give the required control of coercivity to the deposited ferromagnetic films on a high resistance substrate.

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Control Of Coercivity Of Thin Ferromagnetic Films Deposited On High Resistance Substrates

Ferromagnetic films having high coercivities can be deposited onto high resistance substrates by electro-deposition techniques. A bath-soluble alcohol metal sulfate, together with an alkali metal hypophosphite or hypophosphorous acid, are added to standard acidic electroplating baths to give the required control of coercivity to the deposited ferromagnetic films on a high resistance substrate.

The degree of coercivity control is illustrated by the following example. Electroplating is accomplished using the basic bath composition and conditions found in Table I. Table I

Ammonium Chloride (NH(4)Cl) - 70 gm/l

Cobalt Sulfate (CoSO(4) * 7H(2)O) - 60 gm/l

Nickel Sulfate (NiSO(4) * 6H(2)O) - 40 gm/l

pH 3.0

Temperature 50 degrees C

Current 0.75 amperes/inch of cathode

width in each of four stations

Time 10 seconds in each of four

stations (as described below)

The coercivity controlling ingredients, sodium hypophosphite and sodium-2-ethylhexyl sulfate, are added to the basic electroplating bath in the varying amounts given in Table II. Table II

Coercivity (oersteds)

High

Sodium hypophosphite Sodium-2-ethylhexyl Massive Resistance (gm/l) sulfate (gm/l) Cathode Cathode

0 0 160 160

0 0.095 160 160

0.75 0.095 385 670

0.75 0 385 385

1.00 0 530 530

Each electroplating bath composition is used to electrodeposit a nickel-cobalt layer onto a massive brass cathode panel and a cathode. The latter is composed of polyethylene terephthalate polyester having a 6.5 ohms per square electroless nickel coating on it. The respective cathodes are, in each case, immersed into the electroplating bath and current activated for 3 seco...