JPS63136307A - Manufacture of laminated magnetic core - Google Patents

Abstract

PURPOSE:To prevent dispersion of insulation performance by forming an insulation oxide coating film to the surface of a magnetic thin plate made of a magnetic material including Nb by means of the chemical processing. CONSTITUTION:A magnetic material including Nb is used as the material forming laminated magnetic cores 1ch-4ch and the insulation oxidation coating film is formed on the surface of the magnetic thin plate by the chemical processing. As the oxidation processing method, for example, an aq. soln. of nitric acid including nitric acid ions is used as an electrolyte, a 'Permalloy(R)' strip is used as the anode and anodic oxidation is applied by the electrolysis. The surface of the 'Permalloy(R)' strip is oxidized by the processing above and a strong insulating oxide film having much Nb content, light heat resistance and not susceptible to reduction is formed. Thus, the laminated magnetic core with excellent insulation and without dispersion is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a 'jii layer magnetic core, which is made of a laminate of magnetic thin plates having a predetermined shape and is used in magnetic heads, transformers, solenoids, motors, etc. be.

[Prior Art] The above-mentioned laminated magnetic core is widely used for magnetic cores such as magnetic cores in order to reduce eddy current loss. In recent years, magnetic materials that form the magnetic thin plates of a laminated magnetic core include niobium (Nb) in its composition in order to increase the hardness of the laminated magnetic core and improve its wear resistance, and to improve its magnetic properties. For example, Permalloy (registered trademark: Hard Palm) containing Nb is used.

Conventional methods for manufacturing such a 21-layer magnetic core include the following methods.

a. Continuously form magnetic core-shaped magnetic thin plates from a hoop material of magnetic material by pressing, stack these magnetic thin plates with gaps between them, and weld the magnetic thin plates together using, for example, a laser to form an integral laminate. After joining, the laminate is magnetically annealed in hydrogen at an annealing temperature of 1000°C to 1100°C.

b. Apply an insulating adhesive to the surface of the magnetic thin plate that has been magnetically annealed first, laminate the magnetic thin plates through this adhesive layer, and solidify the adhesive by applying heat and pressure to integrate the whole. .

After laminating the C0 magnetic thin plates with gaps in between, an insulating adhesive with good fluidity is infiltrated into the gaps between the thin plates, and is solidified to integrate the whole.

d. An insulating film such as silicon oxide is formed on the surface of the magnetic thin plate by sputtering, and then the magnetic thin plates are laminated and integrated.

[Problems to be Solved by the Invention] Among these methods, method a has the advantage that the number of steps is small, and since magnetic annealing is performed after lamination, magnetic annealing can be performed efficiently all at once, and the cost is low.

However, in this method, the laminated magnetic thin plates may be welded together due to the high heat during magnetic annealing.

In this case, the insulation between the magnetic thin plates deteriorates, eddy current loss increases, and its dispersion increases. When a laminated magnetic core is used in a magnetic head, the characteristics of the head deteriorate, especially in a high frequency region, and there is an adverse effect that the recording efficiency deteriorates due to a decrease and variation in impedance, and the variation in head characteristics increases.

In order to prevent welding, it is sufficient to lower the annealing temperature, but even if annealing is performed below the appropriate temperature, the magnetic thin plate will not have the originally good magnetic properties.

In addition, in method b, the efficiency of the adhesive application operation is low, and it is difficult to control the adhesive film thickness (coating thickness). Also,
The adhesive between the magnetic thin plates may flow out due to the pressure applied during adhesion, causing the thin plates to come into contact with each other, and the function of the adhesive as an insulating layer may be impaired.

Furthermore, in method C, the quality of the insulation depends on the degree of penetration of the adhesive, and the variation in insulation is relatively large, resulting in a lack of reliability.

Furthermore, method d has the problem that sputtering is very costly.

[Means for Solving the Problems] In the present invention, in order to solve the above-mentioned problems, in the method for manufacturing a laminated magnetic core, niobium (Nb) is added in the composition.
A method for producing a laminated magnetic core comprising a laminated body of magnetic thin plates of a predetermined shape that are made of a magnetic material containing magnetically annealed and have a predetermined shape, the method comprising a step of forming an insulating oxide film on the surface of the magnetic thin plates by chemical treatment. Adopted.

[Function] According to such a configuration, the formation of the insulating oxide film is performed by chemical oxidation treatment that can be performed in large quantities at one time,
Compared to forming an insulating film using an insulating adhesive or sputtering, this method is extremely efficient and inexpensive, and the film thickness can be easily controlled and variations in film thickness can be suppressed. Then, a laminated magnetic core with good insulation between the magnetic thin plates via the insulating oxide film and uniformity and arrogance can be manufactured.

[Embodiments] Hereinafter, details of embodiments of the present invention will be described with reference to the attached drawings.

FIG. 1A shows the flow of manufacturing steps for a laminated magnetic core according to a first embodiment of the present invention.

According to this embodiment, first, in step S1 of FIG. 1(A), chemical treatment is applied to the surface of a permalloy strip containing niobium (Nb) in its composition, as the material for the magnetic thin plate of the laminated magnetic core. The treatment forms an oxide film.

This process is performed as follows using the procedure shown in the flowchart of FIG. 1(B).

First, as a surface cleaning step shown in step Sll in FIG. 1(B), the surface of the permalloy strip material is cleaned with an organic solvent such as Freon or alcohol, water, or the like to degrease and remove dirt.

Next, as a surface oxidation treatment step in step S12, for example, a permalloy band material is immersed in an aqueous solution of nitric acid (HNO:l) while being continuously fed out and wound once. At this time?
j! I acid concentration varies depending on usage conditions, but is 0.01-1
It is desirable to set it within the range of 0.4 mol/no, for example, 0.1 to 1. Set to On+ol/41.

In addition, as an oxidation treatment method other than this, nitrate ions (N
There is a method of anodic oxidation by electrolysis using a nitric acid aqueous solution containing Oi ions as an electrolyte and a permalloy strip material as an anode. There is also a method of spraying a nitric acid aqueous solution.

Although the set temperature and treatment time of the nitric acid aqueous solution during the oxidation treatment vary depending on the ion concentration or acid concentration of the nitric acid aqueous solution, the treatment can be performed at a temperature of 10 to 60° C. and an immersion time of about 10 seconds to 15 minutes.

Through such treatment, the surface of the permalloy strip material is oxidized, and an insulating oxide film is formed on the surface by the oxide. At this time, the Fe and Ni in the permalloy are eluted first, leaving Nb, which is difficult to dissolve in nitric acid, to form a strong oxide film with a high Nb content, high heat resistance, and resistance to reduction.

After the oxidation treatment is completed, in step S13 of FIG. 1(B),
Wash away the nitric acid aqueous solution from the permalloy strip material by washing with water.
After that, the permalloy strip is dried in step S14.

After forming the insulating oxide film in this manner, in step S2 of FIG. 1(A), a magnetic thin plate having a predetermined shape corresponding to the shape of the laminated magnetic core is punched out from the permalloy strip material by press working.

Next, in step S3, a predetermined number of magnetic thin plates are aligned according to the thickness of the magnetic core (@ne), and in step S4, several points around the thin plates are welded by a heating means such as a laser to make the magnetic thin plates. The thin plates are joined together and integrated into a laminate.

In this case, as shown in steps 33' to 55', the magnetic thin plates are successively aligned in excess of the predetermined number, welded in a continuous state, and then the continuous laminate is adjusted to the thickness of the magnetic core. You may also choose to separate each task separately.

Next, in step S5, the laminated body is magnetically annealed in hydrogen at an annealing temperature of 1000° C. to 1100° C. to complete a laminated magnetic core.

By the way, the order of the steps described above is not limited to this. Second to fifth embodiments of the present invention in which the order of the steps is changed will be described below with reference to FIGS. 2 to 5.

``No. L Actual'' Example E FIG. 2 shows the flow of the manufacturing process according to the second embodiment of the present invention.

In this embodiment, in the first step 521, Nb
A core-shaped magnetic thin plate is punched out from the permalloy strip material containing the permalloy material by press working, and then in step S22, the magnetic thin plate is deburred.

Thereafter, in step S23, an insulating oxide film is formed on the surface of the magnetic thin plate by a process corresponding to that described with reference to FIG. 1(B). In other words, treatments such as immersion in a nitric acid aqueous solution are carried out in the state of a core-shaped magnetic thin plate.

After that, steps S24-32B or 524'-S26'
, S26, the magnetic thin plates are aligned, welded, and magnetically annealed in the same manner as steps 53 to S5 to 53' to 35' and S5 of the first embodiment, and a laminated magnetic core is completed.

FIG. 3 shows a manufacturing process according to a third embodiment of the present invention.

In this embodiment, as shown in steps 331 to S33 to 531 to 534' in FIG. The laminated body is separated, and then, in step S34, an oxide film is formed by a process corresponding to FIG. 1(B).

In other words, immersion in a nitric acid aqueous solution is carried out in the form of a laminate. When immersed, the nitric acid aqueous solution naturally penetrates between the laminates due to capillary action, but in order to promote penetration, ultrasonic vibration or vacuum treatment may be applied. Methods such as reducing the pressure or, conversely, increasing the pressure are used.

After that, annealing is performed in step S35 to complete the laminated magnetic core. Note that annealing may be performed in a continuous laminate that is not separated, and the laminate may be separated after annealing.

1 soil 111 Next, FIG. 4 shows the flow of the manufacturing process according to the fourth embodiment of the present invention.

In this embodiment, first, in step S41.42, a magnetic thin plate is punched and deburred, and then in step S43.
Magnetic annealing is performed in step S44, and then, in step S44, an oxide film is formed by the process described above. However, since the magnetic thin plate is degreased and dirt is removed during magnetic annealing, surface cleaning is not necessary.

After that, in step S45, the magnetic thin plates are aligned, and in step S4
As shown at 6 to 346', the magnetic thin plates are bonded or welded together to integrate the whole to complete a laminated magnetic core.

Table n Next, FIG. 5 shows a manufacturing process according to a fifth embodiment of the present invention.

In this embodiment, first, a magnetic thin plate is punched out in step S51, and then in step S52. Aligning and welding the magnetic thin plates in S53, or steps 552' to S5
4', weld in continuous alignment and then separate the thickness of the laminate.

Next, in step S54, magnetic annealing is performed on the laminated body, and finally, in step S55, an oxide film is formed by the same process as described above.

According to the t51 to fifth embodiments of the present invention as described above,
Formation of an insulating oxide film is performed by chemical oxidation treatment that can process a large amount at once, and is extremely efficient and inexpensive compared to forming an insulating film using an insulating adhesive or sputtering. It is easy to manage, and variations in film thickness can be suppressed. Moreover, an excellent laminated magnetic core with good insulation between the magnetic thin plates through the insulating oxide film and no variation can be manufactured.

Regarding individual examples, in the first to third examples,
Since magnetic annealing is finally performed on the laminate, magnetic annealing can be performed all at once efficiently and at low cost.

In this case, before magnetic annealing, the surface of the magnetic thin plate contains a large amount of Pb, has excellent heat resistance, and forms a strong insulating oxide film with a high melting point. Even if the metal parts of the metal parts try to melt together, the coating prevents this, and it is possible to prevent the magnetic thin plates from welding together as in the case of conventional method a. Note that the insulating oxide film according to this example is strong and difficult to be reduced, and remains without being completely reduced during magnetic annealing.

Further, in the case of the fourth and fifth embodiments, since the oxide film is formed after magnetic annealing, there is no fear of reduction of the film, and the insulation provided by the film is more perfect. In addition, Figure 1 (B
), surface cleaning of the magnetic thin plate in step Sll becomes unnecessary.

As described above, according to the embodiments of the present invention, an excellent laminated magnetic core with good insulation properties and no variation can be manufactured at low cost. When a magnetic core (laminated core) of 1, for example, 7 magnets is manufactured as a laminated magnetic core by the method of the embodiment, the impedance of the magnetic head is high due to good insulation and no variation, and the impedance is small. This makes it possible to improve the recording efficiency of the head and suppress variations in characteristics.

The table below and FIG. 7 show data supporting such effects, and were obtained by the conventional manufacturing method a under the same conditions as the manufacturing method of the second embodiment of the present invention.

The first of the four-channel auto-reverse type magnetic head lO for a cassette tape recorder as shown in FIG.
-4th channel magnetic core (laminated core) lch~4c
h was created, the impedance of 80 KHz was measured for each head, and the average impedance and variation ±3σ'1t-L were compared. In the diagram of FIG. 7, the center of the triangle indicates the average value of impedance, and the extent of both sides of the triangle indicates dispersion. In addition, samples A and B are according to the second embodiment of the present invention, and A has an annealing temperature of 1050"C, and B has an annealing temperature of 100"C.
The temperature was 0° C., and sample C was produced by conventional manufacturing method a. The basic structure of the magnetic head 1O shown in FIG. 6 is a known one, in which the magnetic cores lch to 4ch are fitted into a case 5 together with a coil (not shown), and the magnetic cores lch to 4ch are provided with a magnetic gap G. The magnetic cores 1ch to 4ch are fixed by a fixing member 6 with the tip end face facing the opening 5b of the magnetic tape sliding surface 5a of the case.

As is clear from this table and FIG. 7, the average impedance of Samples A and H according to the second embodiment is significantly higher than that of Sample C of the conventional example, and the variation is significantly smaller, and the effect of the embodiment is You can check it.

In addition, as a magnetic material forming the magnetic thin plate of the laminated magnetic core,
The important point is to use a material containing Nb, as mentioned earlier, this will form a strong oxide film on the surface of the magnetic thin plate that has a high content of Nb, has excellent heat resistance, has a high melting point, and is difficult to reduce. Ru. Further, by using a magnetic material containing Nb, the magnetic properties of the llt layer magnetic core are improved and the hardness is increased. In particular, in the case of the magnetic core (A-layer core) of a magnetic head, increasing the hardness increases the
I Abrasion resistance can be improved.

[Effects of the Invention] As is clear from the above description, in the method for manufacturing a laminated magnetic core according to the present invention, magnetic thin plates of a predetermined shape made of a magnetic material containing niobium (Nb) and magnetically annealed are laminated. Consisting of the body'! ! In the method for manufacturing an i-layer magnetic core, a configuration including a step of forming an insulating oxide film on the surface of the magnetic thin plate by chemical treatment is adopted, so that magnetic (Il: insulation between the thin plates) is formed. The material was selected because of its excellent effect of being able to produce a superior planted-layered magnetic core with good properties and no variation at a low cost.

[Brief explanation of the drawing]

FIG. 1(A) is a flow chart showing the flow of the manufacturing process according to the first embodiment of the present invention, FIG. 1(B) is a flow chart showing the processing flow of the oxide film forming step in FIG. 1(A), 2 to 5 are flowcharts showing the manufacturing process flow according to the second to fifth embodiments of the present invention, respectively, and FIG. 6 is a plan view of a 4-channel auto-reverse magnetic head for a cassette tape recorder. 7 are graphs showing the average and dispersion of impedance at 80 KHz for a head using a magnetic core manufactured by the method of the embodiment and a head manufactured by the conventional method with the structure shown in FIG. 6, respectively. lch~4ch...Magnetic core 5...Case 6...Fixing material lO...Magnetic head

Claims (1)

[Scope of Claims] 1) A method for manufacturing a laminated magnetic core comprising a laminate of magnetically annealed magnetic thin plates having a predetermined shape made of a magnetic material containing niobium (Nb) in the composition, wherein the surface of the magnetic thin plate is chemically coated. 1. A method for manufacturing a laminated magnetic core, the method comprising the step of forming an insulating oxide film by a chemical treatment. 2) The method for manufacturing a laminated magnetic core according to claim 1, wherein the formation of the oxide film by the chemical treatment is performed in a step before the magnetic annealing. 3) The laminated magnetic core according to claim 2, wherein the joining for integrating the magnetic thin plates as a laminate is performed by welding, and the welding is performed in a step before the magnetic annealing. Production method. 4) The method for manufacturing a laminated magnetic core according to claim 1, wherein the formation of the oxide film by the chemical treatment is performed in a step subsequent to the magnetic annealing. 5) The joining for integrating the magnetic thin plates as a laminate is performed by adhesion, and the adhesion is performed in a step after the formation of the oxide film by the chemical treatment. The method for manufacturing a laminated magnetic core described in . 6) The joining for integrating the magnetic thin plates as a laminate is performed by welding, and the welding is performed in a step after the formation of the oxide film by the chemical treatment. The method for manufacturing a laminated magnetic core described in . 7) The laminated magnetic core according to claim 4, wherein the magnetic thin plates are joined together as a laminate by welding, and the welding is performed in a step before the magnetic annealing. Production method. 8) Niobium (N) is included in the composition as the magnetic material of the magnetic thin plate.
The method for manufacturing a laminated magnetic core according to any one of claims 1 to 7, characterized in that permalloy containing b) is used. 9) Claims 1 to 8 are characterized in that the surface treatment of the magnetic thin plate is performed with an aqueous solution containing nitrate ions (NO_3^-) as the chemical treatment for forming the oxide film. The method for manufacturing a laminated magnetic core according to any one of the above. 10) The method for manufacturing a laminated magnetic core according to claim 9, wherein the surface treatment is performed by immersing the magnetic thin plate in an aqueous solution containing nitrate ions (NO_3^-). 11) The method for manufacturing a laminated magnetic core according to claim 9, wherein the surface treatment is performed by electrolytically oxidizing the surface of the magnetic thin plate in an aqueous solution containing nitrate ions (NO_3^-). 12) The method for manufacturing a laminated magnetic core according to claim 3, 6, or 7, wherein the welding of the magnetic thin plates is performed using a laser.