JPH1097911A - Composite magnetic element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination of the magnetic powder surface due to a mechanical pulverizing or milling treatment in an org. solvent by wet milling a soft magnetic rough powder material in water to form an oblate powder. SOLUTION: A spherical Fe-Si-Al alloy powder 5000wt. parts is thrown in water 8000wt. parts an milled for 6hr. by an atomizer to obtain an oblate Fe-Si- Al alloy powder. The obtd. powder 900wt. parts is mixed with a polyurethane resin 8wt. parts as an org. binder, isocynate compd. hardening agent 2wt. parts and solvent of cyclohexanone with toluene 40wt. parts to prepare a soft magnetic paste. It is formed into a film by the doctor blade method, hot pressed and cured at 85 deg.C for 24hr. to produce a composite magnetic product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a composite magnetic material obtained by kneading and dispersing a soft magnetic powder in an organic binder.
More specifically, the present invention relates to a composite magnetic body having excellent complex magnetic permeability that is effective for suppressing electromagnetic interference, which is a problem in high-frequency electronic circuits / devices, a method for manufacturing the same, and a method for manufacturing soft magnetic powder used therefor.

[0002] The present invention also relates to a printed wiring board using the composite magnetic material and an electromagnetic interference suppressor that can be used for an electronic device.

[0003]

2. Description of the Related Art Random access memories (RAMs), read-only memories (ROMs), microprocessors (MPUs), central processing units (CPUs), and image processor arithmetic and logic units (IPALUs) have become popular in recent years. ) And logic elements and elements. These logic circuits and logic elements are composed of LSIs and ICs composed of a large number of semiconductor elements as active elements, and are mounted on a printed wiring board. In these logic circuits and logic elements, the operation speed is increased and the signal processing speed is increased, and the frequency is approaching quasi-microwave. In such a logic circuit or the like, a signal that changes at a high speed involves a rapid change in voltage and current, so that the active element generates inductive noise and also causes high-frequency noise. This high frequency noise acts synergistically with crosstalk noise and noise due to impedance mismatch. The high frequency noise is
This is often due to inductive noise generated by the active element.
The inductive noise induces a high-frequency magnetic field on the same surface as the device mounting surface of the wiring board and on the opposite surface.

[0004] Lightening, thinning, and miniaturization of electronic equipment and electronic devices are also rapidly progressing. As a result, the mounting density of electronic components on printed wiring boards has also increased dramatically, and printed wiring such as densely mounted electronic components and signal lines, and wiring between modules, etc., are extremely close to each other. In addition, as described above, the signal processing speed is also increased, so that the above-described induced high-frequency magnetic field not only increases the line-to-line coupling due to electromagnetic coupling on the wiring board, but also causes radiation noise. Interference occurs.

Further, when radiation noise is generated, the radiation noise is radiated to the outside through an external connection terminal, which may adversely affect other devices. Such malfunctions of electronic devices and adverse effects on other devices due to electromagnetic waves are generally called electromagnetic interference.

Conventionally, a filter is connected to a circuit that generates inductive noise in an electronic device, and a problematic circuit (a circuit that generates inductive noise) is removed from a circuit affected by such electromagnetic interference. Measures such as keeping away, performing shielding, and performing grounding are generally adopted.

[0007]

Here, in the case where the above-described electromagnetic interference is to be efficiently treated in a printed wiring board or the like on which electronic components including active elements are mounted at a high density, conventional measures (noise suppression) are required. Method) has the disadvantage that it requires specialized knowledge and experience in noise countermeasures and that it takes time to take countermeasures.

[0008] In particular, in the above-mentioned filter mounting, the filter to be used is expensive, the space for mounting the filter is often limited, the work of mounting the filter is difficult, and the filter is used. There is a disadvantage that the number of steps required for assembling the electronic device increases and the cost increases.

Further, in the conventional method, the effect of suppressing electromagnetic interference between signal lines generated between electronic components in the same circuit and mutual interference due to unnecessary electromagnetic waves is not sufficient.

Furthermore, in order to reduce the size and weight of the electronic device, it is inconvenient to remove or separate the problematic circuit, and it is necessary to eliminate the filter and its mounting space.

In a general printed wiring board used for an electronic device, when a frequency to be handled is low, electromagnetic coupling between signal lines such as electromagnetic induction generated from the inside of the board is relatively small. As the operating frequency becomes higher, the electromagnetic coupling between the signal lines becomes denser, thus causing the above-mentioned problem.

In the above shielding, the conductor shield is a measure against electromagnetic interference utilizing reflection of electromagnetic waves caused by impedance mismatch with the space. Electromagnetic coupling due to reflection is promoted, and as a result, secondary electromagnetic interference is often caused.

As a measure against the secondary electromagnetic interference, it is effective to suppress unnecessary radiation by utilizing the magnetic loss of the magnetic material. That is, unnecessary radiation can be suppressed by arranging a magnetic material having a large magnetic loss between the shield body and the unnecessary radiation source. Here, the thickness d of the magnetic material required for suppression is μ ″>
Since it is inversely proportional to μ ″ in a frequency band that satisfies the relationship μ ′, a thin electromagnetic interference suppressor, that is, a composite composed of a shield and a magnetic material, that meets the above-mentioned requirements for downsizing and weight reduction of electronic devices, In order to obtain this, a magnetic material having a large imaginary part magnetic permeability μ ″ is required. In addition, the unnecessary radiation described above is
In many cases, the components span a wide frequency range,
In many cases, it is difficult to specify a frequency component related to electromagnetic interference. Therefore, there is a demand for an electromagnetic interference suppressor capable of coping with unnecessary radiation of a wider frequency.

[0014] In particular, as the size and thickness of the portable telephone device are reduced, it is also required to have excellent mechanical properties.

Therefore, a technical problem of the present invention is to prevent contamination of the magnetic powder surface generated by mechanical pulverization or grinding treatment in an organic solvent, and to provide a high affinity for a strongly polar binder. Another object of the present invention is to provide a soft magnetic powder having excellent dispersibility and a method for producing the same, and to provide a composite magnetic material having excellent magnetic properties and mechanical properties using the same and a method for producing the same. is there.

Another technical object of the present invention is to provide an electromagnetic interference suppressor using the composite magnetic material.

[0017]

Means for Solving the Problems The inventors of the present invention have found that when the powder is ground in an organic solvent such as toluene, the surface of the powder is contaminated by mechanochemical reaction or oil contamination and becomes lipophilic. The present inventors have found that a hydrophilic surface can be realized by a measure such as using water as a solvent at the time of crushing, and have accomplished the present invention.

Normally, when a fine metal powder is put into water or further ground in water, the oxidation of the metal powder proceeds to the inside of the powder, and as a result, magnetic properties are greatly deteriorated. Although there is a problem, the present inventors have found that the oxidation does not proceed to the inside of the powder by giving a specific element as a constituent element of the alloy, and have enabled the realization of the present invention. Here, in order to prevent the oxidation of the metal fine powder from proceeding to the inside thereof, it is sufficient that the oxide film formed on the surface of the powder is a stable and strong film, and it is generated quickly.
Elements satisfying this condition include Si and Al.
Fe-Si as a soft magnetic material having a composition having both of them
-Al alloy (Sendust) is known.

According to the present invention, there is provided a composite magnetic material comprising substantially flat soft magnetic powder and an organic binder, wherein the flat soft magnetic powder is obtained by wet-milling raw material coarse powder in water. A composite magnetic material characterized by being processed into a flat shape by the treatment is obtained.

According to the present invention, there is also provided a composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, wherein the flat soft magnetic powder is processed into a flat shape. After that, a composite magnetic material characterized by being washed with water is obtained.

Further, according to the present invention, there is provided a composite magnetic material characterized in that the soft magnetic powder is processed into a flat shape by wet grinding.

Further, according to the present invention, there is obtained a composite magnetic material characterized in that the soft magnetic powder has at least Al and / or Si as an alloy composition.

According to the present invention, there is provided a composite magnetic material characterized in that the soft magnetic powder is an Fe-Si-Al alloy (Sendust) powder.

According to the present invention, there is provided a composite magnetic material characterized in that the organic binder has a solubility parameter Sp value of 8 or more.

According to the present invention, there is provided an electromagnetic interference suppressor substantially consisting of the composite magnetic material described in any of the above and a conductive material.

Further, according to the present invention, in the method for producing a composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, the flat soft magnetic powder is obtained by mixing a raw material powder in water. A method for producing a composite magnetic material characterized by being processed into a flat shape by wet grinding.

According to the present invention, in the method for producing a composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, the flat soft magnetic powder is processed into a flat shape. After that, a manufacturing method of the composite magnetic material characterized by being washed with water is obtained.

Further, according to the present invention, there is provided a method for producing a composite magnetic material, characterized in that the soft magnetic powder is processed into a flat shape by wet grinding.

Further, according to the present invention, there is provided a method for producing a composite magnetic material, wherein the organic binder has a solubility parameter Sp value of 8 or more.

The organic binder which can be used in the present invention includes NBR rubber, polystyrene, polymethacrylate, polyvinyl acetate, polyvinyl chloride,
Examples include polycarbonate, epoxy resin, polyurethane, vinyl acetate-vinyl chloride copolymer, polyester, nylon, and the like, but are not limited thereto.

In the present invention, a rust preventive may be added in addition to the soft magnetic powder and the binder.

Further, according to the present invention, a substantially flat soft magnetic powder to be used together with an organic binder in a composite magnetic material, wherein the flat soft magnetic powder is obtained by converting a raw material coarse powder into a flat powder in water. Thus, a soft magnetic powder characterized in that it has been processed into a powder is obtained.

Further, according to the present invention, a substantially flat soft magnetic powder to be used together with an organic binder in the composite magnetic material, wherein the flat soft magnetic powder is processed into a flat shape, A soft magnetic powder characterized by being washed with water is obtained.

Further, according to the present invention, there is obtained a soft magnetic powder characterized in that the soft magnetic powder is processed into a flat shape by wet grinding.

According to the present invention, there is further provided a method for producing a substantially flat soft magnetic powder to be used together with an organic binder for a composite magnetic material, wherein the raw material powder is processed into a flat shape in water. Thus, a method for producing a soft magnetic powder, characterized by obtaining a soft magnetic powder in a shape, is obtained.

Further, according to the present invention, in the method for producing a substantially flat soft magnetic powder to be used together with an organic binder in a composite magnetic material, the raw material powder is processed into a flat shape and then washed with water. As a result, a method for producing a soft magnetic powder characterized by obtaining the flat soft magnetic powder is obtained.

Further, according to the present invention, there is provided a method for producing a soft magnetic powder, wherein the raw material powder is processed into a flat shape by wet milling.

[0038]

Embodiments of the present invention will be described below.

(Verification Example 1) First, spherical Fe—Si—A particles having an average particle diameter of 17 μm and manufactured by a water atomizing method.
(1) 5000 parts by weight of an alloy (Sendust) powder were prepared, put into 8000 parts by weight of water, ground for 6 hours using an attritor, and flattened into Fe-Si-A.
1 alloy powder A was obtained. Next, the obtained flat powder A9
0 parts by weight, 8 parts by weight of a polyurethane resin as an organic binder, 2 parts by weight of an isocyanate compound as a curing agent, and 40 parts by weight of a mixture of cyclohexanone and toluene as a solvent were mixed to prepare a soft magnetic paste. A film was formed by a blade method, subjected to hot pressing, and then cured at 85 ° C. for 24 hours to obtain a magnetic sheet sample 1 for verification.

(Verification Example 2) First, spherical Fe—Si—A particles having an average particle diameter of 17 μm produced by a water atomizing method.
5,000 parts by weight of an alloy (Sendust) powder were prepared, put into 8000 parts by weight of n-hexane, and milled using an attritor for 6 hours to obtain a flat Fe-processed powder.
-Si-Al alloy powder was obtained. 4,000 parts by weight of the obtained flat alloy powder and 10 parts by weight of Merck's Extran as a detergent were put into 8000 parts by weight of water and stirred for 2 hours using a high-speed stirrer generally called a dissolver. Water was removed by suction filtration. Further, this was dried under reduced pressure to obtain a Fe-Si-Al alloy powder B for verification. Next, 90 parts by weight of the obtained flat powder B were mixed with 8 parts by weight of a polyurethane resin as an organic binder, 2 parts by weight of an isocyanate compound as a curing agent, and 40 parts by weight of a mixture of cyclohexanone and toluene as a solvent, and mixed. A magnetic paste was prepared, formed into a film by a doctor blade method, subjected to hot pressing, and then cured at 85 ° C. for 24 hours to obtain a magnetic sheet sample 2 for verification.

Comparative Example 3 A comparative sample was prepared in the same manner as the magnetic sheet sample for verification 2 except that washing with a high-speed stirrer was not performed in the preparation of the magnetic sheet sample 2 for verification. Magnetic sheet sample 3 was produced.

Using these samples, a frequency of 40 MHz
Was measured for magnetic permeability and breaking strength. The results obtained are shown in Table 1 below.

[0043]

[Table 1]

From the results, the following is clear.
That is, in the verification samples 1 and 2 using the soft magnetic powder washed with water, polyurethane, which is a resin having a higher polarity, is used as compared with the comparative sample using the soft magnetic powder that has been ground in an organic solvent. Due to the excellent affinity with the resin, good magnetic permeability characteristics and mechanical characteristics (rupture strength) are obtained.

Here, the wet milling treatment refers to a case where a ball mill, a sand mill, an attritor or the like, which is a medium stirring type mixing / milling machine, is used as the milling equipment, and the material to be kneaded contains a solvent. On the other hand, dry milling refers to a case where a mill is performed in the air (or in a specific atmosphere) using a stamp mill, a jaw crusher mill, or the like.

[0046]

As described above, in the present invention, it is possible to prevent contamination of the magnetic powder surface generated by mechanical pulverization or grinding in an organic solvent, and to make the powder surface hydrophilic. So that the solubility parameter Sp value is 8
It is possible to provide a magnetic powder having a high affinity even when the above-mentioned organic binder having a large polarity is used and capable of realizing excellent dispersibility, and a method for producing the same. A composite magnetic material having excellent physical properties and a method for producing the same can be provided.

Further, according to the present invention, it is possible to provide an electromagnetic interference suppressor using a composite magnetic material having the above advantages.

Claims (17)

[Claims] 1. A composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, wherein the flat soft magnetic powder is obtained by wet-milling a raw material coarse powder in water. A composite magnetic body processed into a flat shape. 2. A composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, wherein the flat soft magnetic powder is processed into a flat shape and then washed with water. A composite magnetic material characterized in that: 3. The composite magnetic body according to claim 2, wherein
The composite magnetic material, wherein the soft magnetic powder is processed into a flat shape by wet grinding. 4. The composite magnetic material according to claim 1, wherein the soft magnetic powder comprises at least A
A composite magnetic material comprising l or / and Si as an alloy composition. 5. The composite magnetic body according to claim 4, wherein the soft magnetic powder (in the composite magnetic body) is an Fe—Si—Al alloy (Sendust) powder. 6. The composite magnetic material according to claim 1, wherein the organic binder has a solubility parameter Sp value of 8 or more. 7. An electromagnetic interference suppressor substantially comprising the composite magnetic body according to claim 1 and a conductive material. 8. A method for producing a composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, wherein the flat soft magnetic powder is obtained by wet-milling a raw material coarse powder in water. A method for producing a composite magnetic material, characterized in that the composite magnetic material is processed into a flat shape. 9. A method for producing a composite magnetic material comprising a substantially flat soft magnetic powder and an organic binder, wherein the flat soft magnetic powder is processed into a flat shape and then washed with water. A method for producing a composite magnetic material, comprising: 10. The method of manufacturing a composite magnetic material according to claim 9, wherein the soft magnetic powder is processed into a flat shape by wet grinding. . 11. The method for producing a composite magnetic material according to claim 9, wherein the organic binder has a solubility parameter Sp value of 8 or more. Method. 12. A substantially flat soft magnetic powder used together with an organic binder in a composite magnetic material, wherein the flat soft magnetic powder is obtained by processing a raw material coarse powder into a flat shape in water. A soft magnetic powder characterized by the above-mentioned. 13. A substantially flat soft magnetic powder to be used together with an organic binder in a composite magnetic material, wherein the flat soft magnetic powder is processed into a flat shape and then washed with water. A soft magnetic powder characterized by the following. 14. The soft magnetic powder according to claim 13, wherein the soft magnetic powder is processed into a flat shape by wet grinding. 15. A method for producing a substantially flat soft magnetic powder to be used together with an organic binder in a composite magnetic material, wherein the raw soft powder is processed into a flat shape in water to form the flat soft magnetic powder. A method for producing a soft magnetic powder, comprising: 16. A method for producing a substantially flat soft magnetic powder to be used together with an organic binder in a composite magnetic material, wherein the raw material powder is processed into a flat shape and then washed with water to obtain the flat soft magnetic powder. A method for producing a soft magnetic powder, comprising obtaining a magnetic powder. 17. The method for producing a soft magnetic powder according to claim 16, wherein the raw material powder is processed into a flat shape by wet grinding.