JPS6160887A - Formation of nonconductive film - Google Patents

Abstract

PURPOSE:To form a nonconductive film of a uniform thickness having superior insulation by subjecting the surface of an iron-base member to oxidation treatment with an acidic permanganate soln. CONSTITUTION:The surface of an iron or iron alloy substrate such as a thin plate having the shape of a magnetic core is treated with the acidic permanganate soln. such as a soln. of KMnO4 in sulfuric acid. The preferred concn. of permanganate ions in the treating soln. is about 0.01-1 mole/l. The treatment is carried out by immersion, spraying or electrolysis. The treated substrate is washed and dried. By this method a nonconductive film of uniform thickness having superior insulation can be formed simply and efficiently.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a method of forming a nonconductor coating, and more specifically, the present invention relates to a method for forming a nonconductor coating, and more particularly, the present invention relates to a method for forming a nonconductor coating, and more specifically, a nonconductor coating 11 is formed on the surface of a member made of iron or an iron alloy, such as a magnetic core of a magnetic head. The present invention relates to a method for forming a nonconductor film.

[Prior Art] As the structure of the magnetic core of a magnetic head that records information Q'+Ij in sliding contact with a magnetic recording medium, a magnetic core-shaped magnetic material is used to reduce eddy current loss caused by a signal magnetic field during recording and reproduction. A structure in which a plurality of Fl temporary plates (hereinafter referred to as core thin plates) are laminated with a nonconductor film (insulating film) interposed therebetween is known.

The method for forming and laminating the nonconducting film of this laminated core is to apply an insulating adhesive to the surface of the thin core plate, and then
One method is to laminate the core thin plates and solidify the adhesive to fix the whole thing, or after laminating the core thin plates, insulating adhesive with good fluidity is infiltrated into the dense and thin interface between the thin plates, and this is then solidified to fix the whole thing. Conventionally, a method of fixing the

However, with the former method, the number of people applying the adhesive is low and it is difficult to control the adhesive film thickness (application thickness), and with the latter method, the quality of the insulation depends on the degree of penetration of the adhesive. However, it has the disadvantage of relatively poor insulation properties.

On the other hand, in addition to the above-mentioned method, a method is also known in which a nonconductor film such as silicon oxide is formed on the core thin plate by sputtering, but this method has the drawback of being very expensive.

The conventional method for forming a nonconducting film as described above is applied not only to magnetic cores but also to other members made of iron or iron alloys, and the above-mentioned drawbacks are common in both cases.

[Purpose] The present invention was made in view of the above circumstances, and it is possible to form a nonconducting film with excellent insulation properties on the surface of a member made of iron or an iron alloy with a uniform thickness, and to do so efficiently. It is an object of the present invention to provide a method for forming a nonconductor coating pattern that can be formed at low cost.

[Example] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Here, it is assumed that a nonconducting wave +1A is formed on the surface of the base material forming the core thin plate of the magnetic core described above.

The process of forming a nonconductor film according to this example is shown in Figure A1.

As shown in the figure, in the first step S1, the surface of the above-mentioned base material is washed with water or the like.

In the next step S2, the surface of the substrate is treated with a permanganate-intoxicating solution (hereinafter referred to as a treatment solution). This treatment solution includes, for example, sodium permanganate, potassium permanganate, etc., in an acid solution such as sulfuric acid. Use a solution dissolved in The permanganate ion concentration of the treatment solution was 0.01-1 mo.
It is preferable to set it to l/l, more preferably 0.1
-0.2 mol/l. Also, the acid concentration is 0.0
It is preferably set to 5 to 1 mol/l, more preferably 0.2 to 0.4 mol/l.

If the permanganate ion concentration and acid concentration are lower than the above lower limit, the formation of the nonconductor film will be delayed, while if it is higher than the above upper limit, the redissolution of the formed nonconductor film will be large and the substrate will be etched. There is also fear.

Specific treatment methods include immersing the substrate in the treatment solution, spraying the treatment solution onto the substrate, or electrolyzing the substrate using the treatment solution as an electrolyte and the substrate as an anode. There are methods such as electrolytic oxidation.

In addition, the liquid temperature and treatment time during treatment vary depending on the ion concentration and acid concentration mentioned above, but the liquid temperature is approximately 10 to 50°C.
The processing time is approximately 10 seconds to 10 minutes.

Through the above treatment, the surface of the base material is oxidized uniformly,
As shown in FIG. 2, nonconducting waves [2] of uniform thickness are formed seamlessly on the surface of the base material 1.

Thereafter, in step S3 of FIG. 1, the base material 1 is washed with water and then dried to complete the entire process.

Next, two specific examples in which a nonconductor film was actually formed using the above-described method will be described.

In the first example, 0.1 potassium permanganate was used as the treatment liquid.
Using an aqueous solution of 0.2 mol/l of sulfuric acid at a temperature of 45°C, a thin core plate made of 7.8 permalloy and whose surface had been previously cleaned was immersed in this treatment solution for 5 minutes, then taken out and washed with water. , dried.

When the resulting sample was inspected, it was found that a nonconductive film with a uniform thickness of about 0.5 lm was formed, and the insulation of the sample surface by this film was good.

In the second example, 0.2 potassium permanganate was used as the treatment liquid.
mol/l, using an aqueous solution of sulfuric acid 0.4 mol/I,
The solution temperature was set to 45°C, the same as above, and the same core thin plate as above was immersed in this treatment solution for 10 minutes, then taken out and washed with water.
Dry.

When the resulting sample was inspected, it was found that a nonconducting film with a uniform nλ thickness and a thickness of about 1 m was formed, and the insulation of the sample surface by this film was good.

As can be confirmed from the above specific examples, according to the method of this embodiment, a nonconductor film having a uniform thickness and excellent insulation properties can be formed.

In addition, according to the method of this embodiment, a treatment liquid with a relatively simple composition, called permanganate acidic liquid, is used, and immersion, spraying,
Alternatively, the nonconductor film can be formed by a simple and efficient processing method such as electrolytic oxidation that can process a large amount at once.

The method for forming a nonconductor film of the present invention as described above is applicable not only to the above-mentioned core thin plate but also to all members made of iron or iron alloys.

[Effect] As is clear from the above explanation, according to the method for forming a nonconductor film of the present invention, the surface of a member made of iron or an iron alloy is oxidized with a permanganate acidic solution, thereby forming a nonconductor film. Since a film is formed, a nonconductor film having a uniform II decay thickness and excellent insulation properties can be formed extremely efficiently and at low cost. It is particularly suitable for use in forming a nonconducting film on a core thin plate of a magnetic core having a laminated structure, and by using the method of the present invention, the characteristics of the magnetic core can be improved.

[Brief explanation of the drawing]

Figure i1 is a flowchart explaining the process of forming a nonconductor film according to an embodiment of the present invention, and Figure 82 is a core with a nonconductor film formed on the surface by the above process. FIG. 1...Base material 2...Nonconductor plate 11 first
Figure 2

Claims (1)

[Claims] A method for forming a nonconductor film, which comprises forming a nonconductor film by oxidizing the surface of a member made of iron or an iron alloy with a permanganate acid solution.