JPS63308722A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a magnetic metallic layer directly on a glass substrate having a porous surface by impregnating a soln. of palladium or silver compd. into said substrate and immersing the substrate in a nonmagnetic nonelectrolytic liquid. CONSTITUTION:An Na2O-B2O3 glass phase elutes and the porous glass which consists of SiO2 having fine pores is obtd. if, for example, Na2O-B2O3-SiO2 borosilicate glass is heated and phase-separated to an SiO2 component and Na2O-B2O3 and this glass is immersed in an acid soln. or hot water. This porous glass is immersed into the soln. of the compd. of palladium or silver to impregnate the liquid contg. the palladium ions or silver ions into the fine pores. The reducing agent in the plating liquid reduces the palladium ions or silver ions and the metal palladium or metal silver deposits if this glass is immersed in the electroless plating liquid. The electroless plating is thus started. The glass disk formed with the deflectless magnetic film by the plating is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plated magnetic storage medium for a magnetic storage device used as a storage device for computers and the like.

[Conventional technology]

BACKGROUND ART Conventionally, aluminum alloy substrates and glass substrates have been used as magnetic disk substrates on which magnetic films are formed using thin film forming techniques such as buffing and electroless plating.

However, aluminum alloy 1) Soft and poor workability.

2) Since it is soft, the crush resistance and wear resistance of the magnetic disk and head are poor.

Therefore, a nonmagnetic underlayer is formed on the aluminum alloy, and the underlayer is polished to obtain a smooth surface before use. As the underlayer, an electroless nickel phosphorus plating film is usually used because it is nonmagnetic and hard.

On the other hand, glass substrates 1) Hard and easy to work with 2) It is non-magnetic.

3) Compared to electroless nickel phosphorus plating film, it is harder and has better lash resistance and wear resistance between the magnetic disk and head.

Moreover, unlike aluminum plates, there is no need to form an electroless nickel plating film, which simplifies the process of manufacturing magnetic disks, and is thought to make it possible to improve yields and reduce costs.

Thin-film magnetic disks are positioned as future disks for high recording densities, and efforts are being made to make the magnetic film thinner and have higher coercive force. However, the recording density is determined not only by the characteristics of the magnetic disk but also by the combination with the magnetic head. When using the same magnetic head, to achieve high recording density, the magnetic head's 7 light height should be lowered (
There is a need to. However, it is known that if the flyhide of the magnetic head is reduced, the crush resistance and wear resistance with the disk will deteriorate.

As a result of the above, glass substrates that are low in cost and have good crush resistance and abrasion resistance have come to be used as disk substrates compatible with high recording densities.

When manufacturing magnetic disks by electroless plating using glass substrates suitable for high recording density disks, the sufficiently cleaned glass substrate is usually immersed in a stannous chloride solution as a pretreatment for electroless plating. After passing through the activating process, which involves immersing in a catalyst solution such as palladium chloride and silver nitrate, it is immersed in a non-magnetic electroless plating solution to form a non-magnetic film, and then immersed in an electroless magnetic plating solution. , a magnetic plating film is formed.

The sensitizing process is a process in which divalent tin ions are adsorbed onto the glass substrate.Since the adsorption power of divalent tin ions is large, divalent ions are absorbed onto everything immersed in the stannous chloride solution. is absorbed.

The activating step is a step in which divalent tin ions adsorbed on the glass substrate in a catalyst solution react with palladium ions or silver ions to form catalyst nuclei of palladium and silver.

301 + + p dM + -> 3 n 4 +
10P d@(catalytic nucleus) Sn ″ ″ +2Ag″−*Sn′ ″ +2
Ag" (Catalytic Nucleus) After activation, it is optional whether to form a magnetic plating film through a non-magnetic film or directly without a non-magnetic film.

It is well known that the magnetic properties of a magnetic film are structurally sensitive, and that the magnetic properties change depending on the underlying structure even when immersed in the same plating solution.

Therefore, whether or not to use a nonmagnetic film is determined depending on the desired magnetic properties. An electroless nickel film is usually used as the nonmagnetic film.

[Problem to be Solved by the Invention 3] As can be seen from the above steps, when a glass substrate used as a high recording density substrate is subjected to an electroless plating pretreatment process, an electroless plating film is formed only on the glass substrate. (An electroless plating film is also formed around the jig that supports the glass substrate.)

This is because: 1) An electroless plating film is formed on the extra surface of the jig, which accelerates the deterioration of the plating bath.

2) The electroless plating film formed on the jig must be etched for each step, which increases the number of extra steps.

3) If the electroless plating film formed on the jig comes off and falls into the plating bath, there is a risk that the electroless plating bath will decompose.

There is a problem.

Furthermore, stannous chloride as a sensitizer reacts with oxygen in the air to form stannic acid, which becomes solid and floats in the stannous chloride solution. If floating stannic acid adheres to the glass substrate,
This portion is not activated and becomes a pinhole in the electroless plating film, resulting in an area where no signal can be recorded, a so-called defect.

When forming a magnetic film on a glass substrate by electroless plating,
The usual pretreatment steps of sensitizing and activating lead to premature deterioration or, in extreme cases, decomposition of the electroless plating solution. Moreover, it is necessary to etch the electroless plating film on the jig every time, which increases the cost of the magnetic disk. Furthermore, magnetic disks have many defects, which is a fatal drawback in that they are not suitable for high-density disks.

An object of the present invention is to provide a glass disk in which a magnetic film is formed by plating, which does not have the above-mentioned drawbacks.

[Means for solving problems]

In order to solve this problem, the present invention impregnates a glass substrate whose surface is porous with a solution of palladium or a silver compound, and immerses it in a non-magnetic electroless plating solution. , a non-magnetic electroless plated film is formed, and a magnetic metal layer is formed by electroless plating through the non-magnetic plated film, or a magnetic metal layer is directly formed by electroless plating without using the non-magnetic plated film. It is characterized by the fact that it has been formed.

There are many glass substrates having a porous layer on the surface, such as Corning's Vycor type porous glass. Examples include: 1) Vycor type porous glass 2) PPG porous glass 3) CeO* 5Nbt Os type porous glass 4)
S ios ” Pa Os-based porous glass 5) Sto
w “Ge0t-based porous glass 6) Shirasu porous glass 7) Porous glass obtained from alkali-free glass 8) Polymerization waste oxide-containing porous glass 9) Mullite-based porous crystal glass 10) Porous high silicon There is acid bubble glass.

Porous glass utilizes the phase separation phenomenon of glass.

Taking Nat O-B* Os -3i Ox-based borosilicate glass as an example, heating the glass can cause Stow
The components and Nano-Btus are phase separated.

When this phase-separated glass is immersed in an acid solution or hot water, the Nag O-B*Os glass phase is eluted and a porous glass of SiOx component with pores is obtained.

The pore size of glass varies depending on the glass components and heat treatment temperature. Furthermore, after making porous glass, it is possible to dissolve the sio* component and increase the pore diameter by immersing it in an alkaline solution. The pore diameter is variable from several tens to several thousand angstroms, and the pore diameter of the glass substrate of the present invention may be any size within this range.

By immersing this porous glass in a solution containing a palladium or silver compound, the pores are impregnated with a solution containing palladium ions or silver ions. Therefore, the pore diameter of the glass substrate may be large enough to be impregnated with a liquid containing palladium ions or silver ions.

Next, when this porous glass is immersed in an electroless plating solution, the reducing agent in the electroless plating solution reduces palladium ions or silver ions, so that metallic palladium or gold Wj4m is precipitated and acts as a catalyst. Then electroless plating starts.

Palladium ions or silver ions have extremely weak adsorption power, and do not absorb into the jig that supports the porous glass substrate.
Therefore, no electroless plating film is deposited on the jig.

Furthermore, since no stannous chloride solution is used as a sensitizer, an electroless plating film with fewer defects can be obtained.

Furthermore, since the stannous chloride tank and its cleaning tank can be omitted from the plating process, costs can be reduced.

This will be explained in detail below using examples.

[Example 1] Circular, smooth, mirror-finished borosilicate glass substrate with a diameter of 95 mm (Rmaxo, 05 μm, Ra 0.003 μm)
By baking at 550°C for 1 hour, phase separation was effected into a SiO* component and a B*Os-NagO component.

The ingredients of borosilicate glass are S　i　O＊　60　w　t% B x Os 30 wt% N a * 0 10 w t% It is.

This phase-separated borosilicate glass substrate was immersed for 30 minutes in a 3N sulfuric acid solution heated to 90°C to elute the BxOs-NagO phase. As a result, this glass substrate became a porous glass substrate with an average pore diameter of about 100 pores.

This substrate was immersed in Fudoshuma bath preparation solution manufactured by Nippon Kanizen Co., Ltd. for 5 minutes, and thoroughly rinsed with water.

Thereafter, the substrate was immersed in an electroless nickel phosphorus plating solution 5K-100 manufactured by Nippon Kanigen ■ to form an electroless plating film on the substrate. The plating conditions were 85° C. and 3 minutes of immersion time, and the plating film thickness was 2,500 mm.

A magnetic film was formed by immersing this plated film-coated substrate in a magnetic plating solution having the following composition.

Cobalt sulfate 0.07 mol/1 Nickel sulfate 0.03 mol/1 Sodium tartrate 0.2 mol/1 Sodium malate
0.4mol/1・sodium succinate O, 1m
ol/1・boric acid 0.2mol/
1. Ammonium sulfate O, 1 mol/1 liter Sodium hypophosphite 0.15 mo+/1. PH=9.0
(Adjusted with sodium hydroxide)・Temperature
The immersion time in the plating solution at 75°C was 1 minute, and the thickness of the magnetic film was 8.
00 people, and the holding power was 8500e.

At this time, no plating film was formed on the jig supporting the glass substrate.

A holding film, a lubricating film, a 100-layer film of Citechrome, and a 400-layer film of carbon were formed on a glass substrate with a magnetic film by sputtering.

After this, in order to test the number of pinholes in the magnetic film, a mini monolithic head with a gear tooth width of 18 μm was used to test the number of pinholes in the magnetic film.
A recording/reproduction test was conducted using an Adelphi Certifier, but no defects were detected.

[Example 2] Five pieces of circular borosilicate glass having the same shape and composition as Example 1 were prepared.
By baking at 50°C for 24 hours, the components of 5iO1 and B
Phase separation of the components of mOs-NagO was performed.

This phase-separated borosilicate glass substrate was immersed for 2 hours in a 5N sulfuric acid solution heated to 90°C, and then
It was immersed in the prescribed sodium hydroxide solution for 1 hour. As a result, this glass substrate became a porous glass substrate with an average pore diameter of about 250 pores.

This substrate was immersed in Nippon Kanigen Co., Ltd.'s Leftsumer bath preparation solution for 5 minutes, and after thorough washing with water, Example 1
A magnetic film was formed by immersing it in the same magnetic plating solution under the same conditions.

The thickness of the magnetic film is 1000 mm, and the holding force is 7000 mm.
It was e.

As in Example 1, no plating film was deposited on the jig supporting this glass substrate.

Further, after forming a protective film of 100 chromium and 400 carbon, a recording/reproduction test was conducted in the same manner as in Example 1, but similarly no defects were detected.

[Example 3] Nag O-Bm Os CeOs ' 3Nbt
A glass substrate having the same shape as in Example 1 was produced using 06 series glass. Phase separation and crystallization were performed by heat treatment at 600°C for 12 hours, and the NazO-BtO phase was eluted by immersion in 5-regular sulfuric acid at 90°C for 1 hour. As a result, a glass substrate having an average pore diameter of 800 was obtained.

Using this substrate, a magnetic film was formed and a chromium carbon protective film was formed in the same steps as in Example 1, and then a recording/reproduction test was conducted. As in Example 1, no defects were detected.

〔Effect of the invention〕

As can be seen from the above embodiments, in the magnetic recording medium of the present invention, no excess plating is deposited on the jig during the manufacturing process, and the magnetic plating bath is prevented from deteriorating early. In addition, by not using a stannous chloride solution as a sensitizer, the process can be simplified, and since stannic acid does not adhere to the glass substrate, pinholes do not occur in the magnetic film ( It had a positive effect.

that's all ゛＼〜′

Claims (1)

[Claims] A glass substrate whose surface is a porous layer is impregnated with a solution of palladium or a silver compound,
A nonmagnetic electroless plating film is formed by immersion in a nonmagnetic electroless plating solution, and a magnetic metal layer is formed by electroless plating via the nonmagnetic plating film, or,
A magnetic recording medium characterized in that a magnetic metal layer is directly formed by electroless plating without using the non-magnetic plated film.