JPH0758645B2 - Ferrite coating liquid - Google Patents

Description

The present invention is used as a magnetic thin film such as a thin film inductor, a thin film magnetic head, a magnetic sensor, a magnetic shield, etc. The present invention relates to a ferrite coating solution for forming a thin film.

[Problems to be Solved by Prior Art and Invention]

Conventionally, there have been the following methods for obtaining a magnetic thin film by applying a solution.

That is, a solution of an inorganic metal salt corresponding to the component of ferrite is applied to the target product, and pyrolyzed by baking this.
This is a method of obtaining a ferrite thin film by oxidation.

However, this method has the following problems. That is, a), when the inorganic metal salt is thermally decomposed, a corrosive gas such as a strong acid is generated, which adversely affects the manufacturing equipment, the working environment, and other parts of the object.

B) Since the decomposition reaction of the inorganic metal salt is rapid and difficult to control, it is difficult to form a uniform and dense film.

As a method for solving the above problems
There is a method using a metal alkoxide as a seed.

That is, it is a method in which a solution obtained by hydrolyzing a metal alkoxide corresponding to a component of ferrite is applied to a target object in a nitrogen substitution atmosphere and then baked to obtain a ferrite thin film.

However, a sol solution obtained by simply hydrolyzing a metal alkoxide has poor film-forming properties, lacks compositional uniformity, and has poor storage stability, and is therefore not practical as a ferrite coating liquid.

In particular, for the purpose of forming a Fe-Ni-based ferrite film containing two kinds of transition metals, no successful case has been found yet. The reason is given below. Incidentally, such a liquid is used for the purpose of producing fine powder of iron oxide or ferrite.

A) Since it is easily decomposed and agglomerated by moisture or oxygen in the air, the coating operation must be performed in a state where the humidity is completely removed, preferably in an atmosphere in which nitrogen is replaced.

B), the transition metal alkoxides necessary for ferrite such as iron and nickel have a poor film-forming property because the oxide obtained by hydrolyzing them is likely to be powder.

C), because the reaction rate differs for each alkoxide component,
The components are likely to segregate and the composition tends to be non-uniform. Therefore, it is difficult to form a homogeneous composite oxide film.

D), the storage stability of the liquid is poor because the dispersion of the sol containing the transition metal element is unstable and precipitation occurs. Therefore, the production of sol solution and the coating operation must be performed continuously.

The present invention has been made in view of the above points, it is possible to apply in the air without the need for using special equipment, it is possible to form a uniform and highly pure ferrite thin film with good characteristics, and It is to provide a ferrite coating liquid having good storage stability.

[Means and Actions for Solving the Problems]

According to the present invention for solving the above-mentioned problems, a ferrite coating liquid is used as an organic solvent containing iron n-butoxide, nickel ethoxyethoxide (or nickel acetylacetonate), zinc ethoxyethoxide, and 2-ethoxyethanol. It was prepared by diluting a composition consisting of the above with an organic solvent containing 2-ethoxyethanol and adding water mixed with acetic acid to cause hydrolysis. This solution is a sol solution.

As a result of selecting iron n-butoxide, nickel ethoxyethoxide (or nickel acetylacetonate) and zinc ethoxide as the organic metal, the rate of the hydrolysis reaction was adjusted and a uniform and stable sol solution was obtained. . Further, the homogeneity of the film was improved, and a ferrite coating solution capable of forming a dense ferrite thin film having high magnetic permeability was obtained.

The amount of acetic acid is preferably 0.5% or more and 2% or less with respect to the entire ferrite coating liquid. As a result, the pH was adjusted to dissociate the precipitate and increase the dispersibility of the sol. Where the amount of acetic acid is 0.5
If the content is less than 10%, this effect is not exhibited, and if it exceeds 2%, cracks occur in the film fired using this ferrite coating solution.

Further, when this acetic acid was mixed with water for hydrolysis, it was possible to suppress the occurrence of precipitation itself, further improve dispersion stability, and increase the concentration of organic metal.

Next, the sol solution having a uniform dispersion could be obtained by following the procedure of compounding the organometallic compound as follows (a to c).

When a, nickel ethoxide, zinc ethoxide, and iron n-butoxide are used, it is desirable to finally mix the iron n-butoxide. This is because iron n-butoxide has a dark color and it is difficult to monitor abnormalities such as precipitation if it is mixed first.

b. When nickel acetylacetonate, zinc ethoxide, and iron n-butoxide are used, zinc ethoxyethoxide is mixed after mixing nickel acetylacetonate and iron n-butoxide. If this procedure is not followed, precipitation will occur and a uniform solution will not be obtained.

c, the above organometallic compounds are the required amount of 2 prepared in advance.
Mixing in ethoxyethanol is preferred. This operation prevents the occurrence of precipitation and contributes to maintaining the dispersion of the sol solution.

Further, by selecting the total amount of the organometallic compound as shown below (a or b), a sol solution having good dispersion stability can be obtained. If it exceeds this range, the sol becomes unstable and precipitates.

When a, nickel ethoxide, zinc ethoxide, and iron n-butoxide are used, the amount is 0.6 mol or less per 1 ferrite coating liquid.

b, 0.3 mol or less per 1 ferrite coating liquid when nickel acetylacetonate, zinc ethoxide, and iron n-butoxide are used.

When nickel acetylacetonate, zinc ethoxyethoxide and iron n-butoxide are used, the number of moles of nickel acetylacetonate is set to 3 times or less the number of moles of iron n-butoxide so that the sol having good dispersion stability can be obtained. A solution was obtained. If the amount of nickel acetylacetonate exceeds this, zinc ethoxyethoxide reacts and precipitates, so that stable dispersibility cannot be obtained.

As a result of mixing 2-ethoxyethanol as an organic solvent by 40% or more by volume with respect to the entire ferrite coating liquid, the evaporation rate of the solvent in the atmosphere is adjusted, coating workability is significantly improved, and a uniform film is formed. Could be formed.

〔Example〕

Next, the first and second embodiments of the present invention will be described in detail.

<First Embodiment> FIG. 1 is a diagram showing an outline of an apparatus for producing a ferrite coating liquid according to the present embodiment.

As shown in the figure, this device is composed of an N ₂ gas supply device 1, a dehumidifier 2, a heating and stirring device 3, and a reflux device 4.

Further, FIG. 2 is a diagram showing a manufacturing process for manufacturing the ferrite coating liquid according to the present embodiment using this apparatus.

The method for producing the ferrite coating liquid will be described below with reference to FIGS. 1 and 2.

First heating stirrer with N ₂ gas N ₂ gas supply unit 1 3
The atmosphere inside the is passed through the dehumidifier 2 and replaced with dried nitrogen.

Next, about 100 ml of 2-ethoxyethanol as an organic solvent is put into the endoscope of the heating and stirring device 3.

Next, while stirring this liquid, zinc ethoxide, nickel ethoxide,
Each toluene solution of iron n-butoxide is charged in this order.

The concentration of each toluene solution is as shown in FIG. However, the amounts of the respective toluene solutions charged do not have to be the same.

Then, this mixed solution is heated and boiled at 108 ° C. with stirring, and this state is maintained for 2 hours (this operation is referred to as “reflux”).

Then, the mixture is allowed to cool to about 30 ° C while stirring.

Next, the solution obtained by mixing water, 2-ethoxyethanol and acetic acid is gradually added into the heating and stirring device 3 to perform hydrolysis.

Here, the amount of water is the number of moles equal to the amount given by the following equation. That is, [blending amount of water (mol)] = [iron n-butoxide (mol)] × 3 <+ [zinc ethoxide (mol)] × 2 + [nickel ethoxide (mol)] × 2 The amount of is 2% by volume with respect to the total amount of the ferrite coating liquid to be obtained.

The mixing ratio of 2-ethoxyethanol and water is by volume.
It was 100: 2.

As a result, the ferrite coating liquid according to this example is obtained.

Next, in order to evaluate this ferrite coating solution, its relative magnetic permeability μ ′ was measured by the following method.

That is, first, this ferrite coating solution is applied on a conwafer using a spin coater, and baked at 500 ° C. for 10 minutes.

Repeat this operation 10 times.

Next, main firing is performed in the atmosphere under the temperature conditions shown in FIG.

The ferrite thin film sample thus obtained was subjected to a magnetization curve with a vibrating magnetic susceptibility meter, and the relative permeability μ ′ was calculated from this.

Here, FIG. 5 is a diagram showing the relationship between the blending ratio of the organic metal in the ferrite coating liquid and the relative magnetic permeability μ ′ when the ferrite coating liquid is fired to a film thickness of 7000 to 8000Å by the above method.

As shown in the figure, with the ferrite coating liquid according to this example, a high relative magnetic permeability μ ′ was obtained.

<Second Embodiment> The manufacturing apparatus shown in FIG. 1 was used also in the second embodiment.

Further, FIG. 6 is a view showing a manufacturing process for manufacturing the phyllite coating liquid according to this example using this apparatus.

The method for producing the ferrite coating liquid will be described below with reference to FIGS. 1 and 6.

First, in a heating and stirring device 3, nickel acetylacetonate powder and 2-etheoxyethanol (about
100 ml).

Then, using the N ₂ gas supply device 1, the atmosphere inside the heating and stirring device 3 is replaced with dry nitrogen.

Next, this solution is heated to 100 ° C., and while stirring, the nickel acetylacetonate is dissolved, and then toluene solutions of iron n-butoxide and zinc ethoxyethoxide are added in this order.

The concentration of each toluene solution is as shown in FIG.

Next, this liquid was kept at 108 ° C and refluxed for 2 hours.
At 0 ° C to 100 ° C, a mixed solution of water, 2-ethoxyethanol and acetic acid is added and hydrolyzed.

The method of preparing this mixed solution is the same as in the case of the first embodiment.

However, the blending amount of water is [blending amount of water (mol)] = [iron n-butoxide (mol)] x 3 + [nickel acetylacetonate (mol)] x 2 + [zinc ethoxyethoxide (mol)] It is × 2.

Then, by cooling the sol solution obtained as described above to room temperature, the ferrite coating liquid according to the present embodiment can be obtained.

The evaluation of this ferrite coating liquid was also carried out by measuring its relative magnetic permeability μ'in the same manner as in the first embodiment.

FIG. 8 shows the mixing ratio of the organic metal in the ferrite coating liquid and the ferrite coating liquid in the first
It is a figure which shows the relationship of relative magnetic permeability μ'when baked to a film thickness of 3000 to 8000Å by the same method as in the example.

As shown in the figure, a high relative magnetic permeability μ ′ was also obtained by the ferrite coating liquid according to this example.

〔The invention's effect〕

As described in detail above, the ferrite coating liquid according to the present invention has the following excellent effects.

(1) Since an organic metal containing a metal alkoxide was selected as in the present invention, the rate of the hydrolysis reaction was adjusted, a uniform and stable sol solution as a ferrite coating solution with good characteristics was obtained, and the homogeneity of the film was obtained. , A ferrite coating solution capable of forming a dense ferrite film having a high magnetic permeability was obtained. Moreover, the storability of the liquid and the film-forming property were good, and it was possible to apply in the atmosphere.

(2) Further, since acetic acid was mixed with water for hydrolysis, the occurrence of precipitation was suppressed, the dispersion stability was further enhanced, and the concentration of the organic metal could be increased. Further, since the amount of the acetic acid is limited to a predetermined amount, PH can be adjusted to dissociate the precipitate and increase the dispersibility of the sol, and cracks do not occur in the film obtained by firing the ferrite coating solution.

(3) When nickel acetonate, zinc ethoxyethoxide, and iron n-butoxide are used, zinc ethoxide is mixed after mixing nickel acetylacetonate and iron n-butoxide. A sol solution was obtained.

(4) Since the total amount of the organometallic compound is selected to be a predetermined amount, a sol solution having good dispersion stability and causing no precipitation is obtained.

(5) Since 2-ethoxyethanol as an organic solvent is mixed in a volume of 40% or more with respect to the entire ferrite coating liquid, the evaporation rate of the solvent in the atmosphere is adjusted, the coating workability is remarkably improved, and the uniformity is improved. A film could be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an apparatus for producing a ferrite coating liquid according to the present invention, FIG. 2 is a diagram showing a production process for producing a ferrite coating liquid according to a first embodiment using this apparatus, and FIG. The figure shows the concentration of each organometallic toluene solution, Fig. 4 shows the temperature conditions when this ferrite coating solution is main-baked in the atmosphere, and Fig. 5 shows the blending of organometallic compounds in the ferrite coating solution. FIG. 6 is a diagram showing the relationship between the ratio and the relative magnetic permeability μ ′ when the ferrite coating liquid is fired to a film thickness of 7000 to 8000Å, and FIG. 6 is a diagram showing the manufacturing process for producing the ferrite coating liquid according to the second embodiment. FIG. 7 is a diagram showing the concentration of each organometallic toluene solution, and FIG. 8 is a blending ratio of the organometallic compound in the ferrite coating liquid and Thickness of the door coating solution 3000
It is a figure which shows the relationship of relative magnetic permeability μ'when baked to 8000Å.

Continuation of the front page (56) Reference JP-A-61-136683 (JP, A) JP-A-59-213603 (JP, A) JP-A-59-213665 (JP, A) JP-B-38-15463 (JP , B1) International publication 89/03110 (WO, A)

Claims (2)

[Claims] 1. An iron n-butoxide {Fe (O.C ₄ H ₉ ) ₃ },
Nickel ethoxide (Ni (O ・ C ₂ H ₄・ O ・ C
₂ H ₅ ) ₂ } and zinc ethoxide (Zn (O · C ₂ H ₄ ·
O · C ₂ H ₅ ) ₂ } and an organic solvent containing 2-ethoxyethanol, and then hydrolyzed by adding water diluted with an organic solvent containing 2-ethoxyethanol and blended with acetic acid. A ferrite coating liquid comprising a sol solution produced by the above, and further having the following requirements (A), (B) and (C). (A) The total content of the iron n-butoxide, nickel ethoxide, and zinc ethoxide should be 0.6 mol or less per liter of the ferrite coating liquid. (B) The amount of acetic acid is 0.5% or more and 2% or less by volume with respect to the entire ferrite coating liquid. (C) The amount of 2-ethoxyethanol is 40% or more by volume based on the whole ferrite coating liquid. 2. Iron n-butoxide {Fe (O.C ₄ H ₉ ) ₃ } and nickel acetylacetonate. And zinc ethoxide (Zn (O ・ C ₂ H ₄・ O ・ C
₂ H ₅ ) ₂ } and an organic medium containing 2-ethoxyethanol, and diluted with an organic solvent containing 2-ethoxyethanol and added with water containing acetic acid to produce a composition by hydrolysis. A ferrite coating liquid comprising a sol solution as described above, and further having the following requirements (A), (B), (C), (D), and (E). (A) After mixing the nickel acetylacetonate and iron n-butoxide, mixing the zinc ethoxyethoxide. (B) The total content of the above-mentioned iron n-butoxide, nickel acetylacetonate and zinc ethoxyethoxide should be 0.3 mol or less per liter of the ferrite coating liquid. (C) The amount of the nickel acetylacenate compounded is not more than 3 times the molecular number of iron n-butoxide. (D) The amount of acetic acid is 0.5% or more and 2% or less by volume with respect to the entire ferrite coating liquid. (E) The amount of 2-ethoxyethanol is 40% or more by volume based on the whole ferrite coating liquid.