JP2629896B2 - Method of forming ferrite film - Google Patents

Description

The present invention relates to a spinel widely applied to a magnetic recording medium, a magneto-optical recording medium, a magnetic head, a magneto-optical element, a microwave element, a magnetostrictive element, a magneto-acoustic element, and the like. The present invention relates to a method for forming a ferrite film in manufacturing a ferrite film.

2. Description of the Related Art Ferrite plating is, for example, as described in JP-A-59-111929, by contacting an aqueous solution containing at least ferrous ion as a metal ion with a solid surface, and contacting the solid surface with FeOH. ⁺ Or other metal hydroxide ions are adsorbed, and then the adsorbed FeOH ⁺ is oxidized to obtain FeOH 2 ⁺ , which causes a ferrite crystallization reaction with the metal hydroxide ions in the aqueous solution, This means that a ferrite film is formed on the solid surface.

Conventionally, the plating film is homogenized and the reaction rate is improved based on this technology (Japanese Patent Application Laid-Open No. 140713/1985). Ferrite films are formed on various solids by imparting surface activity to the solid surface. Japanese Patent Application Laid-Open No. Sho 61-30674, and Japanese Patent Application Laid-Open No. Sho 61-222924 and Japanese Patent Application Laid-Open No. Sho 61-222924.
There is.

Any ferrite plating may be used as long as the solid to be formed into a film has resistance to the above-mentioned aqueous solution. Further, since the reaction is carried out via an aqueous solution, a spinel ferrite film can be produced at a relatively low temperature (below the boiling point of the aqueous solution). Therefore, the limited range of the solid is smaller than that of other ferrite film manufacturing techniques.

Problems to be Solved by the Invention However, as described above, various improvements have been proposed to the homogeneity of the film or the formation speed of the film. Both were inadequate. That is, sufficient magnetic properties as spinel type ferrite, especially properties as a soft material are not obtained. For this reason, there has been a major problem regarding application to various electronic components and the like.

For the coercive force of the ferrite film, for example, as shown in Metal Surface Technology VOL. 38, No. 9, 1987 P.1, about 100 O
e and the magnetite also contained Mn and Zn (MnZ
The n-type) ferrite has almost the same size.

Means for Solving the Problems In order to solve the above problems, the present invention provides a method for contacting a substrate with a solution containing at least ferrous ions as metal ions and at least two kinds of oxidizing agents for oxidizing ferrous ions. This is a method in which the ferrite film is mixed and supplied to the substrate before the deposition to deposit a ferrite film on the surface of the substrate.

The solution containing at least two types of ferrous ions and at least two kinds of oxidizing agents for oxidizing ferrous ions as metal ions is mixed and supplied to the substrate before contacting the substrate by the method described above, By forming a ferrite film on the substrate surface, a ferrite film having excellent magnetic properties (soft properties), which has not been obtained, can be formed.

Examples Hereinafter, examples of the present invention will be described.

The basic part of the method for forming a ferrite film of the present invention is as follows.
Mostly the same as known methods.

However, in the present invention, a solution containing at least ferrous ions as metal ions and at least two kinds of oxidizing agents for oxidizing ferrous ions is sequentially supplied to the substrate. A ferrite film having a small coercive force (or high magnetic permeability) can be obtained.

There is a known method in which at least ferrous ion and an oxidizing agent for oxidizing ferrous ion are used as metal ions. In the present invention, both of these are present in one solution before they are brought into contact with the substrate. Are supplied to the substrate after being made to react substantially uniformly. For this reason, it was possible to find a phenomenon of improving the soft magnetic properties of the ferrite film (reduced coercive force or high magnetic permeability), which has not been recognized so far. The cause is not clear.

As a result, a reaction (for example, an oxidation reaction) is performed in a plating solution before a plating reaction (deposition on a substrate).
It seems that there is some effect on softening the magnetic properties (low coercive force or high magnetic permeability) of the obtained ferrite film.

Some examples of the method for forming a ferrite film of the present invention will be described with reference to the drawings.

For example, a schematic diagram of an example device is shown in FIG. Reference numeral 3 denotes a base on which a ferrite film is to be formed. 4 is the substrate 3
It is a turntable that can be attached and turned. The plating solution is one solution at the time of supply to the substrate 3, but in order to suppress unnecessary reactions before the plating reaction as much as possible and to reduce the variation in the characteristics of the obtained ferrite film, or to facilitate the control, It is better to prepare the solution necessary for plating in several parts. This figure shows a case where the image is divided into two parts. These liquids are mixed in the mixing section 1 and mixed.
The reacted plating solution is supplied to the substrate 3 via the nozzle 2. As a mixing method of the mixing section 1, an appropriate method such as a method in which a liquid is dropped from two nozzles, mixed with a funnel, and discharged from one port, or a method in which two tubes are combined into one and the liquid is discharged from the nozzle. What is necessary is just to select a method. By appropriately selecting the shape and structure of the nozzle, the liquid can be supplied to the base 3 in the form of a drop or a spray. Numerals 5 and 6 are tanks for storing the respective plating solutions. Also,
As shown in the figure, a portion for performing a ferrite plating reaction, such as the base 3 and the turntable 4, is partitioned by a case, and in some cases, a non-oxidizing (eg, nitrogen) gas is sent into the case to form a non-oxidizing atmosphere. You can also. The tank 6 contains, for example, sodium sulfite NaNO as an oxidizing agent.
With _2, put the aqueous solution containing the ammonium acetate CH ₃ COONH ₄ (oxidation solution) as a further buffer or complexing agent,
An aqueous solution (reaction liquid) containing at least ferrous ion is put in the tank 5 and the liquid is supplied to the mixing section 1 by a pump or the like. The ferrite film obtained when the reaction solution further contains Ni ions and Zn ions is a NiZn-based ferrite film,
The ferrite film obtained when ions and Zn ions are contained is a MnZn-based ferrite film. In addition, each ion can be included. For example, it is an element having a spinel structure, such as Mg, Co, Cu, or Li, or various additive elements. Each liquid is supplied to the base 3 while being rotated by the turntable 4. The turntable 4 is heated to 50-100
Heat to ° C. In this way, a ferrite crystallization reaction is performed on the base 3 to form a ferrite film on the base 3.

Further, FIG. 2 shows a schematic view of an apparatus according to an example of another method. The mixing section 1, tanks 5 and 6 are the same as those in FIG. The plating reactor 7 and the water bath 8 are different parts of the method. That is, in the present method, unlike the method shown in FIG. 1, the plating can be performed without using a rotating table and in a state where the plating reaction portion and the like are isolated from gas. The base 3 on which a ferrite film is to be formed is incorporated in the plating reaction section 7. In the plating reaction section 7,
The plating solution is physically made to uniformly flow over the surface of the substrate 3. The mixture 1 and the plating reaction section 7 are set in a water bath 8 to be heated to 50 to 100 ° C. Thus, a ferrite film is deposited on the surface of the substrate 3 set in the plating reaction section 7.

Further, FIG. 3 shows a schematic diagram of an apparatus as an example of another method. This is almost the same as the method shown in FIG. 2, but a method in which a ferrite film is formed only on a certain portion of one surface of the substrate 3. Each of the plating solutions is supplied from the tanks 5 and 6 to the mixing section 1 via a pump, and the plating solutions are mixed and reacted at that portion and sent to the plating reaction section 7. A part of the base 3 on which a ferrite film is to be formed is incorporated in the plating reaction section 7. In the plating reaction section 7,
As in the method shown in FIG. 2, the plating solution is made to flow thinly and uniformly on the surface of the substrate 3 physically. The mixing unit 1, the plating reaction unit 7, and the substrate 3 are set in a water bath 8 to heat them to 50 to 100 ° C. Thus, a ferrite film is deposited on a part of the surface of the substrate 3 set in the plating reaction section 7.

As described above, in any of the three types of methods described above, it was possible to produce a ferrite film having less variation in the base 3 and desirable magnetic properties by mixing two solutions after heating the two plating solutions. Heating temperatures range from about 50 ° C to below the boiling point of the solution.

The material of the base 3 is not particularly limited. Some examples are polyimide films, various plastics such as polyethylene terephthalate (PET), metals such as copper, nickel, silver, gold, tungsten, molybdenum, platinum, palladium, iron, iron alloys, and various organic laminates. Board,
That is, there are various kinds of glasses, ceramics, etc., such as a laminate of paper base epoxy, glass cloth base epoxy, glass base polyester, glass cloth base Teflon, and the like.

Further, the surface roughness of the substrate 3 is determined by the center line average roughness (R
If a) is 0.01 μm or more, the deposition rate of the ferrite film can be improved. This is because the fine particles produced in the aqueous solution have a positive effect on the adsorption, oxidation reaction or ferrite crystallization reaction of FeOH ⁺ , particularly on the adsorption, etc.
, That is, the surface that is undergoing a ferrite crystallization reaction, or gathers, and further promotes and contributes to film growth. In addition, it is considered that the presence of the surface roughness of a certain degree or more increases the substantial surface area of the substrate 3 and also increases the area involved in reactions such as adsorption.

Experimentally, those which are particularly compatible with the formation of a ferrite film are those containing any one or more of oxygen, nitrogen, and sulfur, or especially oxides.

Examples of this oxide include alumina (Al ₂ O ₃ ), mullite (3Al ₂ O ₃ · 2SiO ₂ ), beryllia (BeO), steatite (MgO · SiO ₂ ), forsterite (2MgO · SiO ₂ ), and magnesia ( Various ceramics such as MgO), titania (TiO ₂ ), titania + zirconia (ZrO ₂ ), titania + magnesia, Al ₂ O ₃ —SiO ₂ .B ₂ O ₃ , Al ₂ O ₃ —PbO.SiO ₂ .B
₂ O ₃ , Al ₂ O ₃ −MgO ・ SiO ₂・ B ₂ O ₃ , Al ₂ O ₃ −CaO ・ MgO ・ SiO ₂
· B glass ceramic, such as ₂ O _3, CuO, or the like metal oxide or oxides containing iron such as ferrite, such as NiO.

 Next, more specific examples of the present invention will be described.

(Example 1) Chloride was added to ion-exchanged water (hereinafter simply referred to as water) 2.
An aqueous solution (reaction liquid) in which 4 g of iron, 6 g of manganese chloride, and 50 mg of zinc chloride were respectively dissolved was prepared. As another solution, 1 g of sodium nitrite and ammonium acetate were added to water 2.
After dissolving 10 g, an aqueous solution (oxidizing solution) adjusted to pH = 9 with aqueous ammonia was prepared.

Using these solutions, ferrite plating was performed with an apparatus as shown in FIG. Nitrogen gas at 1.5 min / min
To obtain a non-oxidizing atmosphere, and the turntable 4 was kept at 90 ° C. by a heater. The turntable 4 was rotated at a speed of 300 revolutions per minute. The solution was supplied dropwise at a flow rate of 80 ml per minute. The substrate 3 used for plating is an alumina substrate.

For comparison, except for the mixing section 1 of the apparatus shown in FIG. 1, two types of plating solutions were supplied to the substrate 3 in the form of sprays using separate nozzles, and were supplied under the same conditions as those described above. And ferrite plating.

When the magnetic properties of the ferrite film obtained by the method of the present invention and the ferrite film prepared for comparison were measured, Hc of the ferrite film obtained by the method of the present invention was 1% of Hc of the film prepared for comparison. / 10, indicating that the ferrite film obtained by the method of the present invention exhibited excellent soft magnetic properties.

(Example 2) A reaction solution was prepared by dissolving 4 g of ferrous chloride, 4 g of nickel chloride and 100 mg of zinc chloride in water 2. Further, a liquid in which 0.5 g of sodium nitrite and 1 g of ammonium acetate were dissolved in water 2 was prepared as an oxidizing liquid.

Using these solutions, ferrite plating was performed in the same manner as in Example 1 using an apparatus as shown in FIG.

The substrate 3 used for plating was an alumina substrate, and various surface roughnesses thereof as shown in Table 1 in terms of center line average roughness (Ra, μm unit) were used.

Table 1 shows the thickness of the plating film on each substrate 3 and the deposition rate of the ferrite film. The values in Table 1 are the average film thickness of a portion of 14 × 21 mm in the base 3. Ra = 0.01μm or more substrate (substrate
No.B and later), a ferrite film with a uniform film thickness could be obtained at an unprecedentedly high deposition rate.

For comparison, each of the two liquids was sprayed using the above-described various alumina substrates, except for the mixing section 1.
Plating was performed in the same manner. Although the thickness of the obtained ferrite film was almost the same, the Hc of the film was different, and the softness of the plated film obtained by the method of the present invention was 5 to 10 times (comparison of Hc).
Met.

(Example 3) 2 g of ferrous chloride, 3 g of nickel chloride and 80 mg of zinc chloride were respectively dissolved in water 2 to prepare a reaction solution. further,
An oxidizing solution was prepared by dissolving 2 g of sodium nitrite and 5 g of ammonium acetate in water 2.

Ferrite plating was performed in the same manner as in Example 1 using these solutions. The substrate 3 used was mainly MgO.SiO ₂ , M
gO, BeO, Al ₂ O ₃ -SiO ₂ / B ₂ O ₃ glass ceramic substrate,
There are nine types of quartz glass plate, oriimide film, stainless steel plate, copper plate, and copper-clad glass cloth base epoxy. The thickness of each plating film obtained is about the same, about 2.4 μm
(At a deposition rate of 0.048 μm / min), a film having a uniform thickness and sufficient adhesion strength.

For comparison, two plating solutions were sprayed except for the mixing section 1 of the apparatus shown in FIG. 1, and plating was performed in the same manner. Plating is performed on each of the nine types of bases 3,
The magnetic properties of the obtained ferrite film were measured.

The magnetic properties of the ferrite film obtained by the method of the present invention and the ferrite film prepared for comparison were compared.
The Hc ratio was 1: 8 to 10, and the ferrite film obtained by the method of the present invention exhibited better soft magnetic properties.

(Example 4) The same reaction liquid and oxidizing liquid as those in Example 1 were prepared respectively.

Using these solutions, ferrite plating was performed using the apparatus shown in FIG. The plating time was one hour. The substrate 3 used is an alumina substrate.

The obtained ferrite film showed the same magnetic characteristics as the ferrite film obtained in Example 1.

(Example 5) As in Example 2, two reaction solutions and two oxidizing solutions were prepared.

Using these solutions, using the device shown in FIG. 3,
Ferrite plating was performed on the alumina substrate. The plating time was one hour.

The obtained ferrite film showed the same magnetic properties as the film obtained in Example 2.

Effect of the Invention According to the present invention, as described above, after mixing a plating solution, sequentially supplying the mixed solution to a substrate, and forming a ferrite film, a soft ferrite that has not been achieved by the conventional method of forming a ferrite film. A ferrite film exhibiting the above magnetic characteristics can be produced. Thereby, a ferrite film having magnetic properties sufficient for application to various electronic components and the like can be obtained.

[Brief description of the drawings]

FIGS. 1, 2 and 3 are schematic views of an apparatus used in an embodiment of the method for forming a ferrite film of the present invention. 1 ... mixing section, 2 ... nozzle, 3 ... substrate, 4 ... rotary table, 5,6 ... tank, 7 ... plating reaction section, 8 ... water bath.

Claims (7)

(57) [Claims] 1. A method comprising mixing at least ferrous ions as a metal ion and a solution containing at least an oxidizing agent for oxidizing ferrous ions before contacting the substrate with the substrate and supplying the mixed solution to the substrate to form a ferrite on the surface of the substrate. A method for forming a ferrite film, comprising depositing a film. 2. The method for forming a ferrite film according to claim 1, wherein the surface roughness of the substrate surface is not less than 0.01 μm and not more than 0.8 μm in center line average roughness (Ra). 3. The method for forming a ferrite film according to claim 1, wherein the substrate or the surface of the substrate is mainly composed of a substance containing at least one element of oxygen, nitrogen or sulfur. 4. The method for forming a ferrite film according to claim 1, wherein the substrate or the substrate surface is mainly composed of an oxide. 5. The method according to claim 1, wherein the substrate or the surface of the substrate is a curved surface. 6. The method for forming a ferrite film according to claim 4, wherein the oxide is mainly Al ₃ O ₃ . 7. The method for forming a ferrite film according to claim 4, wherein the substrate or the substrate surface is an oxide ceramic.