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Regulating Coercivity Of Magnetic Thin Films

IP.com Disclosure Number: IPCOM000096909D
Original Publication Date: 1962-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Tsu, I: AUTHOR [+2]

Abstract

Various degrees of coercivity are required for various computer applications. A particular coercivity is readily obtained by electroless plating, if a thin film less than 1,000 A degrees in thickness is desired. Thus, if a bath is utilized at a pH of 7.5 to 8.5 and a temperature of 95 degrees C., containing: Cobalt Chloride (or Cobalt Sulfate) CoCl(2) * 6H(2)0 30 g/l Sodium Citrate (or Ammonium Citrate) Na(3)C(6)H(5)O(7) * 2H(2)0 50 g/l Sodium Hypophosphite NaH(2)PO(2) * H(2)O 15 g/l Ammonium Hydroxide NH(4)OH (28%) 40 ml/l the following coercivities are obtained: -40 oersteds at 150 A degrees, 120 oersteds at 450 A degrees, 480 oersteds at 550 A degrees, and 700 oersteds at 1000 A degrees and above.

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Regulating Coercivity Of Magnetic Thin Films

Various degrees of coercivity are required for various computer applications. A particular coercivity is readily obtained by electroless plating, if a thin film less than 1,000 A degrees in thickness is desired. Thus, if a bath is utilized at a pH of 7.5 to 8.5 and a temperature of 95 degrees
C., containing:

Cobalt Chloride (or Cobalt Sulfate) CoCl(2) * 6H(2)0 30 g/l

Sodium Citrate (or Ammonium Citrate) Na(3)C(6)H(5)O(7) *

2H(2)0 50 g/l

Sodium Hypophosphite NaH(2)PO(2) * H(2)O 15 g/l

Ammonium Hydroxide NH(4)OH (28%) 40 ml/l the following coercivities are obtained: -40 oersteds at 150 A degrees, 120 oersteds at 450 A degrees, 480 oersteds at 550 A degrees, and 700 oersteds at 1000 A degrees and above.

Generally, however, thin films of more than 1000 A degrees are needed and other ways of varying coercivities are necessary. In such a case, coercivities ranging from 5 to 1400 oersteds are obtained by varying the deposition rate from a plating bath. Low coercivity thin films are obtained by plating slowly and high coercivity thin films by plating rapidly. Plating rates are varied by changing the bath temperature, pH, additive mixtures, etc. The coercivity of a 1000 A degrees thin film is varied from 150 oersteds at a plating rate of 10 A degrees per second to 800 oersteds at 20 A degrees per second. This is by varying the complexing agent (sodium citrate, ammonium citrate, or a combination of sodium citrate and ammonium ch...