JP2542593B2 - Manufacturing method of magnetic core - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetic core.

[Background technology]

Amorphous magnetic materials have excellent magnetic properties such as low loss, high magnetic flux density, and high magnetic permeability, and their composition is
There is a combination of non-metal elements such as B, Si, C and P with Fe, Ni and Co as the main components. For example, in atomic%, Fe ₈₀ P
₂₀ , Fe ₆₂ Cr ₁₂ Mo ₈ B ₈ , Fe ₄₀ Ni ₄₀ P ₁₄ B ₆ etc.

When an amorphous magnetic material is used as a magnetic core for a transformer or a choke, generally, a ribbon-shaped magnetic ribbon having a thickness of 100 μm or less is wound to produce a wound magnetic core, and annealing is performed for strain relief and improvement of magnetic characteristics.

However, the wound magnetic core after annealing is brittle and cracks or chips due to external force.

The magnetic characteristics of the magnetic core after annealing are highly sensitive to external force and are closely related to the magnetostriction of the amorphous magnetic material. Although the magnetostriction changes variously depending on the composition, for example, in the case of amorphous Fe ₇₉ B ₁₆ Si ₅ mainly composed of Fe, 27 × 10 ^-6 , Fe ₈₁
B _13.5 Si _3.5 C ₂ has a positive magnetostriction such as 30 × 10 ^-6 and shows magnetic deterioration with compressive stress. Therefore, it is necessary to minimize the influence of stress and maintain and fix the wound magnetic core.

Therefore, in order to wind the magnetic core and use it for a transformer or a choke, there are a method of enclosing the magnetic core in a case and a method of molding with a resin.

The method of putting it in the case is effective in this respect, but the space factor is less than 50% due to the thickness of the case and the like, which is disadvantageous in terms of downsizing and cost.

The method of molding a magnetic core using a resin is to fix the magnetic core as a solid by immersing the magnetic core in a liquid such as an epoxy resin or a silicone resin and hardening the magnetic core, and it is possible to form a thin thickness. Since compressive stress is applied to the magnetic core, the magnetic properties are significantly deteriorated. In this case, since the magnetic flux density is lowered and the coercive force is increased, when such a magnetic core is used as a transformer, heat is generated due to an increase in iron loss and it cannot be put to practical use. Therefore, at present, most of the commercially available magnetic cores are enclosed in a case.

[Object of the Invention]

An object of the present invention is to form a resin coating on the surface of a magnetic core of an amorphous magnetic material having magnetostriction,
It is an object of the present invention to provide a method of manufacturing a magnetic core with less deterioration of magnetic characteristics.

[Disclosure of Invention]

The method of manufacturing a magnetic core of the present invention is a method of manufacturing a magnetic core of the present invention, a magnetic core forming step of forming a magnetic core with an amorphous magnetic material having magnetostriction, and a gas at a high temperature while rotating a rotary chamber accommodating the magnetic core at room temperature. And a step of forming a film of the resin by polymerizing the resin on the surface of the magnetic core to solidify the resin by supplying the resin which has been decomposed and decomposed to the magnetic core.

According to the constitution of the present invention, since the resin coating is formed by substituting the gaseous resin into a solid on the surface of the magnetic core and polymerizing it, compressive stress is not applied to the magnetic core at the time of forming the coating, so that deterioration of magnetic characteristics is prevented. You can Moreover, since the gasified resin is supplied to the magnetic core while rotating the magnetic core in the rotating chamber, the entire surface of the magnetic core can be uniformly exposed to the resin, so that the resin coating can be made uniform.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2. That is, this magnetic core manufacturing method comprises a magnetic core forming step of forming a magnetic core from an amorphous magnetic material having magnetostriction, and a resin vaporized and decomposed at a high temperature is polymerized and solidified on the surface of the magnetic core 1 at a room temperature to form a film of the resin. And a film forming step for forming.

In the step of forming the magnetic core, an amorphous magnetic material having a positive magnetostriction, for example, Fe ₇₈ B ₁₃ Si ₉ having a thickness of 25 μm ± 2 μ is used.
m, width 5 mm, mainly made of iron, an amorphous magnetic material was used to make a core of a wound core with an outer diameter of 15 mm, an inner diameter of 5 mm, and a height of 5 mm, and
Annealing is performed at 400 ° C for about 2 hours.

Before the film forming step, silane treatment is performed to maintain the adhesion between the resin and the magnetic core. In the silane treatment process, the resin is dipped in a solvent and then subjected to silane coupling treatment, followed by drying,
Go through the steps of solvent cleaning and drying. The treatment time for solvent cleaning is from several seconds to several tens of seconds, but other times are 20 to 30 minutes. In the silane coupling treatment, A-174 (γ-methacryloxypropyltrimethoxysilane) is hydrolyzed to form a silane coupling represented by the following formula on the surface of the magnetic core.
After bathing with a mixed solution of 5 ml of -174, 500 ml of pure water, and 500 ml of solvent, 1
Aging at night. The usable period is about one day.

In the above formula, M is the surface of the magnetic core and N is the resin.

In the film forming process, the resin is para-xylene (parylene BPX-C manufactured by Union Carbide) as a casting resin.
As shown in FIGS. 1 and 2, paraxylene raw material A is evaporated and vaporized in the evaporation furnace 1 at about 160 ° C., and then heated in the decomposition furnace 2 to about 700 ° C. to decompose, The monomer gas is sucked into the vapor deposition furnace 3 by the vacuum pump 4. In the vapor deposition furnace 3, the annealed magnetic core 7 is housed in the rotary chamber 5 and the rotary chamber 5 is rotated to uniformly expose the surface of the magnetic core 7 to the gas so that the surface of the magnetic core 7 at room temperature (about 25 ° C.) is polymerized. A film of polyparaxylene is formed on the surface of the magnetic core 7. The gas leaving the vapor deposition furnace 3 is cooled to about −70 ° C. in the cooling unit 6 and solidified.

The coating thickness of the magnetic core 7 thus formed was measured and found to be about 20 μm. Further, the magnetic core was naturally dropped from a height of 3 m onto the concrete floor, but it was found that the magnetic core 7 was not cracked or chipped, and had sufficient strength and was firmly fixed and maintained.

The test results of the magnetic properties are shown in the table below in comparison with the conventional treatments of epoxy resin and silicone resin.

In this table, magnetic flux density and residual magnetic flux density are Gauss, coercive force is Oersted, iron loss W (20 / 3K) is volume (c
The unit is mW per c). Epoxy (epoxy resin XN1184 manufactured by Ciba-Geigy) and silicon (silicon resin TSE350 manufactured by Toshiba Silicon Co., Ltd.) are obtained by dipping and hardening the magnetic core after annealing. However, these conventional resins show remarkable deterioration in magnetic properties. It was revealed that the resin of the example was within 5% and was extremely excellent.

According to this embodiment, since the resin coating is formed by substituting the gaseous resin into a solid on the surface of the magnetic core and polymerizing it, compressive stress is not applied to the magnetic core during the formation of the coating, so that the deterioration of the magnetic characteristics can be prevented. it can.

Further, in this embodiment, the thickness of the resin coating on the surface of the magnetic core is 20
The magnetic core can be extremely thin and less than μm, and the magnetic core can be firmly fixed and maintained. Therefore, the magnetic core can be protected against external forces such as falling and vibration and can be made strong, and the space factor can be remarkably improved as compared with the case and other conventional resins, and the characteristics of the transformer and the choke can be improved. it can.

Furthermore, the resin coating is necessary from the viewpoint of protecting the magnetic core and windings and preventing wear of the magnetic core, but a particularly thin film can be coated, and pinholes are extremely small.
Moreover, barrel processing of the magnetic core is possible, and it protects the winding wire from disconnection. When compared with the fluorine resin coating, the winding protection and wear resistance were almost the same, but it was advantageous in terms of film thickness control and cost.

〔The invention's effect〕

According to the method of manufacturing a magnetic core of the present invention, since a resin coating is formed by substituting a gaseous resin into a solid on the surface of the magnetic core and polymerizing the resin, a compressive stress is not applied to the magnetic core at the time of forming the coating, so that deterioration of magnetic characteristics is prevented. Can be prevented. Moreover, since the gasified resin is supplied to the magnetic core while rotating the magnetic core in the rotating chamber, the entire surface of the magnetic core can be uniformly exposed to the resin, so that the resin coating can be made uniform.

[Brief description of drawings]

FIG. 1 is an explanatory view of a film forming step of one embodiment of the present invention,
FIG. 2 is a partial detailed view thereof.

Claims (3)

(57) [Claims] 1. A magnetic core forming step of forming a magnetic core from an amorphous magnetic material having magnetostriction, and a resin which is vaporized and decomposed at a high temperature is supplied to the magnetic core while rotating a rotary chamber accommodating the magnetic core at room temperature. A method of manufacturing a magnetic core, which comprises a step of polymerizing the resin on the surface of the magnetic core to solidify the resin to form a film of the resin. 2. The magnetic core according to claim 1, further comprising a silane coupling treatment step of forming a silane coupling on the surface of the magnetic core between the magnetic core forming step and the coating forming step. Production method. 3. The method for producing a magnetic core according to claim 1, wherein the resin is a paraxylene resin.