DE1270612B - Process for making thin film magnetic data storage devices - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN -007JW PATENT OFFICE

EDITORIAL

Int. Cl .:

Gilb

German class: 21 al -37/30

Number:
File number:
Registration date:
Display day:

1270 612
P 12 70 612.6-53
June 10, 1966
June 20, 1968

The invention relates to a method of manufacturing magnetic thin film data storage devices, such as drums, plates, tapes or strips, for use in electronic computers, and in particular the manufacture of magnetic data storage devices by chemical or non-galvanic deposition.

The chemical or non-galvanic deposition of cobalt and nickel and their alloys is generally known and is essentially a controlled autocatalytic reduction of cobalt and / or nickel ions by hypophosphite ions. The solution used for this purpose generally contains Hypophosphite ions, cobalt and / or nickel ions, organic complexing agents, such as. B. Citrates, and a buffering agent such as ammonium chloride. The pH of the solution can allow for deposition of nickel are in the acidic or alkaline range, but cobalt and cobalt-nickel alloys are used generally deposited from an alkaline solution. Typical catalysts for the process are cobalt, nickel, aluminum and palladium. The chemical deposition of cobalt and cobalt— Nickel on a catalytically active support is z. B. in British patent specification 953,987 and in German patent specification 1160 263.

An important property of magnetic data storage devices is the coercive force of the magnetic Data storage medium. In general, the coercive force should be high for demagnetizing effects to reduce.

Experiments have shown that the coercive force of chemically deposited cobalt is primarily due to the crystal size is determined, at least when the c-axis of the hexagonal structure is parallel runs to the level of the deposit. However, the crystal size depends on the nucleation and growth properties of the reduced cobalt ion.

Heretofore, difficulties have arisen in the manufacture of magnetic data storage devices by that the coercive force of a magnetic coating of such a device with the increase of its Decreasing thickness. However, since it is appropriate from other points of view, the thickness of the magnetic To increase the coating of the device, for example, to increase the magnetic flux and to achieve greater resistance to wear and tear, had to be in relation a compromise has been made on the thickness of the magnetic coating.

The object of the invention is to create a method for producing magnetic data storage methods for producing magnetic ones
Thin film data storage devices

Applicant:

The National Cash Register Company,

Dayton, Ohio (V. St. A.)

Representative:

Dr. A. Stappert, lawyer,

4000 Düsseldorf, Feldstr. 80

Claimed priority:

V. St. v. America June 11, 1965 (463 143)

Devices by which the aforementioned difficulties are eliminated.

The invention is based on the knowledge that in the chemical deposition of several magnetic Layers between which a layer of the same thickness of a catalytically active, but non-magnetic Material, such as non-magnetic nickel, palladium activated copper, or palladium is deposited, a perfect nucleation and a perfect growth with it resulting favorable grain size development takes place, whereby a device is provided at which the coercive force is equal to or greater than that of a single layer of magnetic material, while the total flux is equal to the sum of the magnetic fluxes in each magnetic Layers is.

The method of the present invention for manufacturing a thin film magnetic data storage device is characterized in that a first layer is alternately applied to a non-magnetic carrier made of non-magnetic metal catalytically active for the deposition of nickel and cobalt and on this first layer chemically a second layer of magnetic nickel, cobalt or their compounds deposits.

Another important feature of the invention is based on the finding that when using Palladium as a catalytically active metallic substance in the above process is the resulting coercive force of the device is greater than the coercive force of said second layer.

The invention is described below with reference to the drawings. In these shows

809 560/350

3 4

F i g. 1 is a graph showing the (B) nickel hypophosphite solution (non-magnetic coercive force (measured in Oersted from chemical nickel);

deposited cobalt layers as a function of the ab- η ^ * (0 0315MoI) NiCl · 6HO

storage time on different carriers illustrated- -tJc * ^ i. m'2338 MoD NH Cl ² '

****} **> -. w i. a · ι. * λ ⁵ 19 ^ 84 g / l (0 ^ 0945 mol) H ₃ CeH ₈ O ₇ -H ₂ O,

Fig. 2 erne perspective view of an exit _{? Q2 χ (QQm Mol Nai} | _po . _HQ _

example of execution one by the appointment according to. «< *

Process produced magnetic storage pre- The pH of the solution is adjusted to 8.2 and the

direction, temperature brought to 80 ° C.

F i g. 3 to 7 graphical representations of the io The carrier to be coated is in this example coercive force depending on the Ablagüngs- a brass plate, which is first cleaned by immersion in acetone, which is illustrative of time (measured in minutes), then rinsed and converted into 20% curves . Hydrochloric acid is immersed and rinsed off again. Then from Fig. 1 shows that the coercive force is catalyzed by immersion in a solution of palladium on various types of carriers chemically ab- 15 dium chloride (0.5 g PdCl ₂ per liter and 5 ecm of congested cobalt coating with increasing thickness of centered HCl per liter). The catalyzed level of the same, ie with the increase in the deposit carrier, is then reduced to 15 to 300 seconds in the nickel time. The cobalt was immersed in the following solution (B), the time of immersion solution deposited: not critical, but preferably 60 seconds

20 to a layer of non-magnetic

7.5 g / l (0.0315MoI) CoCl ₂ · 6H ₂ O, nickel to deposit on the support. The carrier will

3.51 g / l (0.0332 mol) of NaH ₂ PO _{2 .H 2} O, then taken out of the nickel solution and placed in

12.5 g / l (0.2338 mol) NH ₄ Cl, depending on the desired coercive force

19.84 g / L (0.0945 mol) H ₃ C ₆ H ₈ O? · H ₂ O. immersed in the cobalt solution (A) for 2.5 to 30 minutes,

25 so that a magnetic cobalt

The pH was 8.2, and the temperature of the layer being deposited. After removal of the solvent 8O ⁰ C. As was seen, the carrier of the cobalt solution (A), is it for a coercive force in on a polyethylene terephthalate support previously for the formation of the first nickel layer produced thin films with a first selected time period in the solution (B) immersed, then layer of non-magnetic nickel (curve ä) removed from this at 30 and amounting to 600 Oersted for an already for the Hereiner deposition time of 5 minutes (corresponding to the position of the first cobalt layer selected time period of a thickness of about 1200 Å) incorporated into the solution (A). However, these steps decrease with a deposition time of 40 minutes and are repeated until the desired total (corresponding to a thickness of about 10,000 Å) to the thickness of the cobalt has been achieved. 340 Oersted exits. Curve b represents a brass substrate with a first layer of non-magnetic brass substrate during the nickel manufacturing process, while curve c shows one with palladium that the coercive force of the layers of the activated brass substrate affects the total thickness of the deposited cobalt, as shown by FIG. FIG. 2 shows a perspective view according to curves a, b and c in FIG. 3, it is practically dependent on the magnet produced by the method according to the invention.

Table data storage device with a carrier 21 The graphic representation of this figure shows the

made of non-magnetic material, e.g. B. a non * · coercive force of cobalt in Oersted (ordinate) as

metallic material, such as polyethylene terephthalate, function of the total deposition time in minutes

or a metallic stiffener such as phosphor bronze. (Abscissa). Curves 0, b and c each represent one

The coating on the carrier consists of alternating cobalt and non-magnetic

the deposits of catalytic but non-magnetic nickel layers, the

table layers 22 made of catalytic nickel, aluminum * the last-mentioned material the first on the carrier

miniüm or palladium or other catalyzed stored layer forms. The curve α corresponds to one

Metals or alloys and magical layers of multi-layer coating

23 made of cobalt, nickel or alloys thereof. 50 which the individual cobalt layers each through a

The following are examples of the invention according to the 2.5 minute immersion in the cobalt

Fahrens for the production of magnetic data storage HypöphosphitlÖsuög is obtained. The curves b

Devices. In these examples it is understood and c correspond to the coatings for which the

that the coating consisting of several layers deposition time of the individual cobalt layers 5 or

each formed on one side of the carrier is> 55 10 minutes. The curve * d corresponds to a

while its other side is suitably covered by a single layer of cobalt coating

is covered. and illustrates the decrease in coercive

For example force with increasing thickness, as is the case with homogeneous ones

The following aqueous solutions are prepared: magnetic films is the case.

(A) Cobalt-hypophosphite solution: Example 2

7.5 g / l (0.0315 mol) CoCl ₂ 6H ₂ O, ^In ff ^en i ^B f ^ls P ^M ? **** the same solutions (A)

12.5 Il (0.2338 mol) KH ₄ Cl, ^ ^) ™ ^em Ba ^ l beaateL The with emem

1984g / l (00945MoI) HCHO -HO coating, however, the carrier is a poly-

3 [51 g / lK0332 mol) NaH ₂ PbJ-H ₂ O. ' 6 ₅ Ethyleneterephthalätbänd. This is initially in

^'J ζ aa acetone cleaned, then 4urch immersion in a

The pH of the solution is adjusted to 8.2 and the tin chloride solution (5 g of SnGl ₈ per liter and 10 ecm

Temperature brought to 8O ⁰ C. fconcentrated HCl per liter) catalyzed and then

rinsed and immersed in a palladium chloride solution (0.5 g PdCl ₂ per liter and 5 ecm concentrated HCl per liter). The rest of the procedure with alternating immersion in solutions (B) and (A) is carried out as in Example 1.

The results obtained in Example 2 are shown in FIG. 4 shown. Curves α and c correspond to cobalt layers with deposition times of 2.5 and 10 minutes, respectively, while curve d corresponds to a homogeneous cobalt coating.

Example 3

The following aqueous solutions are prepared: (A) cobalt-hypophosphite solution (see Example 1);

(C) Palladium chloride solution: PdCl ₂ = 0.5 g / l,
concentrated HCl = 5 cc / 1.

The carrier is cleaned in a conventional manner, the cleaning being dependent on the type of Material depends, d. H. of whether it is a non-conductor or a conductor. If a non-conductor is used, then it must be dipped in a tin chloride solution, rinsed and dipped in the palladium chloride solution (C) will. When using a metal support, it is generally only necessary to insert it into the Dip the palladium chloride solution (C). The carrier is after the catalyzing depending on the desired coercive force 2 to 20 minutes immersed in the cobalt solution (A), so that a magnetic Cobalt layer forms. It is then removed from this solution and placed in solution (C) for 1 minute dipped to create a layer of palladium on top of the cobalt layer. After that, the carrier will be back for a period corresponding to the initially selected period Time brought back into solution (A), removed from it and immersed in solution (C) for 1 minute, then removed from this and returned to solution (A). The proceedings will continue until until the desired coercive force and thickness is achieved.

The results obtained in Example 3 using a brass support activated with the palladium are shown in FIG. 5 shown. As in FIG. 3, curves a, b and c correspond to cobalt layers with deposition times of 2.5, 5 and 10 minutes, respectively, while curve d corresponds to a homogeneous cobalt coating.

Example 4

The following aqueous solutions are prepared: (A) cobalt-hypophosphite solution (see Example 1);

(C) Palladium chloride solution (see Example 2);

(D) Alkaline formaldehyde-copper complex solution;

(E) catalyst: an aqueous solution of 1.7 g / l PdCl ₂ , 500 cc / l HCl (concentrated), 83 g / l SnCl ₂ ;

(F) Accelerator: 10% perchloric acid solution (HClO ₄ ).

The brass support is cleaned, immersed in the catalyst (E) for 5 minutes, then rinsed off and immersed in the accelerator (F) for 5 minutes. It is then rinsed off again and for 10 minutes into the copper solution kept at a temperature of 25 ° C (D) immersed, so that a copper layer is formed on the carrier. Then the wearer will be 30 seconds Immersed in the palladium chloride solution for up to 1 minute and then in the cobalt solution (A) and left there for 2 to 20 minutes so that a magnetic layer is formed on the palladium-catalyzed copper layer. The carrier will then

ίο taken out and immersed in the copper solution for about 10 minutes (D), after which it was again immersed in the palladium chloride solution (B) for 30 seconds to 1 minute will. Then it is again immersed in the non-galvanic cobalt solution (A) for a period of time equal to that of the initial immersion in this solution. This procedure is repeated until the desired coercive force or total thickness of the cobalt is reached is. The results are shown in FIG. 6 shown for a multilayer cobalt coating, copper catalyzed with palladium is used as the intermediate layer and brass is used as the carrier material became. A deposition time of 5 minutes was planned for each cobalt layer. the

s5 coercive force is of the total thickness of the magnetic Material independent.

Alternating layers of chemically deposited cobalt and chemically reduced, non-magnetic Nickel or copper activated with palladium result

Coatings whose coercive force is independent of the total thickness of the magnetic material. Alternating However, layers of chemically deposited cobalt and palladium result in coatings whose coercive force increases with the total thickness of the magnetic material.

Example 5
The following aqueous solutions are prepared:

(B) Non-magnetic nickel hypophosphite solution
(see example 1);

(G) Nickel hypophosphite solution (magnetic):

45.7.5 g / l (0.0315MoI) NiCl ₂ -OH ₂ O,

12.5 g / l (0.2338 mol) NH ₄ Cl,
19.84 g / l (0.0945MoI) H ₃ C ₆ H ₈ O ₇ -H ₂ O,
1.75 g / L (0.0166 mol) NaH ₂ PO ₂ - H ₂ O.

The pH of the solution is brought to 8.2 and the temperature to 80 ° C.

A polyethylene terephthalate carrier is cleaned and catalyzed by immersion in a tin chloride solution (5 g SnCl ₂ per liter and 10 ecm concentrated HCl per liter), then rinsed and in a palladium chloride solution (0.5 g PdCl ₂ per liter and 5 ecm concentrated HCl per liter) submerged. A first layer of non-magnetic nickel is deposited from solution (B), the deposition time being about 1 minute. The support is then immersed in the solution (G) for 5 minutes so that a magnetic nickel layer is formed on the non-magnetic layer, after which it is taken out and immersed in the solution (B) for 1 minute. After immersion in solution (B), the carrier is alternately immersed in the two solutions for the times already specified until the desired total thickness of the magnetic material is achieved. The results are

in Fig. 7, the curve b corresponding to the magnetic nickel layers, the deposition time of which is 5 minutes in each case. The intermediate layers are the non-magnetic nickel layers. The coercive force of the coating, which consists of several layers of nickel, is independent of the total thickness of the magnetic material. Curve d corresponds to a homogeneous magnetic nickel coating and shows that the coercive force of such a coating is strongly dependent on its thickness. Although the level of coercive force of single layer nickel coatings is not high enough for high density data storage devices, this example shows that the multilayer deposition technique is applicable to magnetic materials other than cobalt.

It is obvious to a person skilled in the art that several layers consisting of several layers Co-Ni, Co-Ni-Fe or Ni-Fe alloys instead of those described in the previous examples pure cobalt or nickel layers can be used in the same way.

Claims (7)

Patent claims: 1. A method of manufacturing a thin film magnetic storage device characterized in that that one alternates a first layer on a non-magnetic support Made of non-magnetic metal that catalyzes the deposition of nickel and cobalt and a second layer of magnetic nickel, cobalt, chemically on top of this first layer or their compounds are deposited. 2. The method according to claim 1, characterized in that the fabric of the first layer consists of a Palladium chloride solution and the substance of the second layer deposited from a cobalt hypophosphite solution will. 3. The method according to claim 1, characterized in that that the fabric of the first layer consists of a non-magnetic nickel hypophosphite solution and the fabric of the second layer is deposited from a cobalt hypophosphite solution. 4. The method according to claim 1, characterized in that the catalytically active metallic Material is non-magnetic nickel. 5. The method according to claim 4, characterized in that the fabric of the first layer of a non-magnetic nickel-hypophosphite solution and that of the second layer of a cobalt-hypophosphite solution is deposited, 6. The method according to claim 1, characterized in that that the catalytically active metallic substance is copper activated with palladium, 7. The method according to any one of claims 2 to 6, characterized in that the magnetic Substance made of cobalt and / or nickel or alloys thereof. Considered publications:
German Patent No. 1160 263;
British Patent No. 953,987. For this purpose 2 sheets of drawings 809 560/350 6.68 © Bundesdruckerei Berlin