JPH05299873A - Wave absorbing method for article, wave absorbing structure for article printed board ferrite sheet used for wave absorption and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the leakage and radiation of electromagnetic wave from electronic equipment to the outside by enclosing an electric wave source and an article with a ferrite sheet the main component of which is ferrite, and molding a printed board out of the ferrite sheet thereby to absorb the electric wave by ferrite. CONSTITUTION:An electric wave source 1 and an article 2 incorporating the electric wave source 1 are enclosed and covered with a ferrite sheet 3 obtained by molding and hardening a material mainly composed of fine ferrite particles into a thin sheet, or a printed board is molded out of the ferrite sheet and the electric wave is absorbed by the material properties of ferrite. As the method of enclosing a covering, the ferrite sheet 3 is used, and an inner case 4 is provided for directly enclosing the printed board, microcomputer chip and the like of the electric wave source 1, and the inner case 4 itself is formed from the ferrite sheet 3 or the ferrite sheet 3 is applied on and bonded to the inner surface of the inner case 4. Alternatively, the printed board as the electric wave source 1 is formed from the ferrite sheet 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for absorbing electromagnetic waves of various articles, in which radio waves and electromagnetic waves generated from various electric and electronic machines and articles are prevented from radiating to the outside of these various articles, and radio wave absorption of various articles. The present invention relates to a structure, a printed circuit board, a ferrite sheet used for electromagnetic wave absorption, and a method for manufacturing the ferrite sheet.

[0002]

2. Description of the Related Art Conventionally, there are problems called EMC (electromagnetic compatibility) and EMI (electromagnetic interference) regarding radio waves and electromagnetic waves, and useful and useless radiation emitted from a myriad of electric and electronic devices with the development of science and technology. Electromagnetic waves are becoming full, and electronic devices such as computers and controllers, which are heavily used in ICs and LSIs, must endure the disturbances due to these external electromagnetic waves and noise regardless of whether they are for industrial use or consumer use.
This EMI becomes more and more important as the development of electronics and the progress of computerization and automation progresses, and some measures (such as automobile computers) are taken. For example, iron plates, copper foil, etc. are used as a reflection type for shielding from the outside world. I used an aluminum plate.

However, regarding electromagnetic wave leakage and radiation of electric and electronic equipment called EMC, TEMPEST
There is a special standard called `` Electrical electromagnetic wave '', which is designed to suppress unnecessary electromagnetic waves emitted by itself, but there is no efficient one. It was done incompletely by changing it to, or attaching a punching metal with a hole that is very small compared to the wavelength of the microwave to the window of the microwave oven.

[0004]

DISCLOSURE OF THE INVENTION The present invention is designed to prevent leakage and emission of radio waves and electromagnetic waves from electric and electronic devices so as to meet the EMC (electromagnetic environment compatibility) standard. An object of the present invention is to provide an electromagnetic wave absorbing method for articles, an electromagnetic wave absorbing structure for various articles, a printed circuit board, a ferrite sheet used for electromagnetic wave absorption, and a manufacturing method of the ferrite sheet.

[0005]

SUMMARY OF THE INVENTION The present invention is based on the above-mentioned prior art, and is based on the electromagnetic wave leakage from electric / electronic equipment and the like.
In view of the problem that MC problem occurs, the radio wave source and various items are surrounded by a ferrite sheet containing ferrite as a main component,
Cover, or mold the printed circuit board with a ferrite sheet,
By absorbing radio waves with ferrite, electromagnetic waves are prevented from leaking and radiating from electronic devices to the outside, and the above problems are solved.

[0006]

According to the present invention, a ferrite sheet is formed into a thin plate containing ferrite as a main component, or a thin sheet ferrite sheet material is semi-dried to obtain a radio wave source, various articles,
Molded into a shape corresponding to the printed circuit board, dried and baked to form the inner case and outer case that surround and cover the radio wave source and various items with the above ferrite sheet, or the inner case and the outer case have ferrite sheets. Sticking,
By adhering or forming the printed circuit board with a ferrite sheet, the electric wave generated from the electric wave generation source, various articles and the printed circuit board are absorbed by the material characteristics of the ferrite.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Various electric / electronic devices and articles such as IC and L
A radio wave source 1 such as an SI, a printed circuit board (IC board), a microcomputer chip, a computer, a controller, a telephone (a mobile phone or a desk) and various articles 2 incorporating the radio wave source 1 are thin plate-shaped with ferrite fine particles as a main component. Enclosed and covered with a ferrite sheet 3 that has been molded and hardened, etc., or molded a printed circuit board with a ferrite sheet, and then radio waves (electromagnetic waves, microwaves such as millimeter waves, centimeter waves, ultra-high-frequency waves, ultra-short waves, short-waves, medium-waves, long-waves, etc. (Hereinafter referred to as radio wave) is absorbed by the material characteristics of ferrite.

Next, the radio wave absorption structure of various articles according to the present invention will be described. As a method of enclosing and covering, a ferrite sheet 3 having two types of shapes described later is used, and a printed circuit board (IC) of the radio wave generation source 1 is used. An inner case 4 that directly surrounds the board), the microcomputer chip, etc. is provided, and the inner case 4 itself is formed of the ferrite sheet 3, or the ferrite sheet 3 is attached or adhered to the inner surface of the inner case 4. The outer case 5 itself of various articles 2 such as electronic devices is formed of the ferrite sheet 3, or the ferrite sheet 3 is attached or adhered to the inner surface of the outer case 5, or the printed circuit board which is the radio wave generation source 1 is a ferrite sheet. It is formed by 3.

Next, a method for producing a ferrite sheet according to the present invention will be described. A slurry 6 containing ferrite fine particles and powder as a main component and an organic solvent such as a binder and a plasticizer mixed therein is adhered on a film 7 in a thin plate shape. Then, the film 7 and the organic solvent are removed by drying and firing to form a thin plate-like (0.05 mm to 2 mm) ferrite sheet 3 containing ferrite as a main component.

Further, as the film 7, a resin film such as polypropylene is used. As a method of attaching, a film is formed by forming a hole under the sludge container 8 and pulling the film 7 as shown in FIG. It is performed by adhering it onto the surface or spraying it on the film 7.

In the second manufacturing method, a highly viscous plastic (clay-like) containing ferrite as a main component is extruded into a thin plate, for example, and dried and fired to form a thin ferrite sheet 3. .

Also, as a method of enclosing and covering the radio wave source 1 and various articles 2, when the inner case 4 and the outer case 5 themselves are formed of the ferrite sheet 3, or the inner case 4 and the outer case 5 having a complicated shape are supported. To do so, the thin sheet-shaped primary-molded ferrite sheet raw material before drying in the above-described manufacturing method is semi-dried (primary drying), and the radio wave source 1 and the inner case 4 and the outer case 5 corresponding to various articles 2 are manufactured.
Etc. are molded (secondary molding), dried (secondary drying) and fired to surround the radio wave source 1 directly or the various articles 2.

[0013]

In summary, according to the present invention, the radio wave source 1 and various articles 2 are ferrite sheets 3 containing ferrite as a main component.
Since the printed circuit board is surrounded or covered with or the printed circuit board is made of ferrite as a main component and the electric wave is absorbed by the ferrite, various kinds of articles 2 can be obtained by absorbing the electric wave generated from the microcomputer chip by the material characteristic of the ferrite. It is possible to easily prevent the radio wave leakage radiation from the.

Further, since ferrite is used as a main component and formed into a thin plate, radio wave leakage radiation from various articles 2 can be achieved simply by attaching it to the interior case 4 and exterior case 5 of the radio wave source 1 such as a microcomputer chip having a simple shape. It can be easily prevented.

Further, since it is molded into a shape corresponding to the radio wave source 1, various articles 2 and a printed circuit board, the inner case 4 and the outer case 5 of the radio wave source 1 or the ferrite sheet 3 for sticking can be manufactured. It can be settled, the appearance can be improved, and radio wave leakage radiation from various articles 2 can be easily prevented.

Further, the slurry 6 containing ferrite as a main component is adhered on the film 7 in a thin plate shape and dried or fired, or a plastic material containing ferrite as a main component is molded into a thin plate shape and dried and fired. The thin sheet ferrite sheet 3 can be easily manufactured without requiring a special manufacturing apparatus, or the ferrite sheet 3 containing ferrite as a main component can be manufactured by firing.

Further, since the thin ferrite sheet material is semi-dried and formed into a shape corresponding to the radio wave source 1, various articles 2 and a printed circuit board, and dried and fired, the radio wave source 1
The inner case 4, the outer case 5 and the like corresponding to the above, or the ferrite sheet 3 to be attached can be easily formed, which is a great practical effect.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view of a mobile phone according to the present invention in a radio wave shielded state.

FIG. 2 is a perspective view, partly in section, of a personal computer in a radio wave shielded state according to another embodiment.

FIG. 3 is a perspective view of a printed circuit board in a state in which a radio wave is shielded according to another embodiment.

FIG. 4 is a partial cross-sectional perspective view of a telephone that is a radio wave shield according to another embodiment.

5 is a partial enlarged cross-sectional view illustrating a partial cross-sectional portion of FIGS. 1, 2, and 4. FIG.

FIG. 6 is a partially enlarged sectional view of another embodiment of FIG.

FIG. 7 is a side view of another embodiment with a radio wave shielded by an interior case.

8 is a side view of another embodiment of FIG. 7. FIG.

FIG. 9 is a schematic view showing an example of a method for manufacturing a ferrite sheet.

[Explanation of symbols]

 1 Radio Wave Source 2 Various Items 3 Ferrite Sheet 4 Interior Case 5 Exterior Case 6 Sludge 7 Film

Claims (8)

[Claims] 1. A radio wave absorbing method for various articles, characterized in that a radio wave source and various articles are surrounded and covered by a ferrite sheet containing ferrite as a main component, and radio waves are absorbed by the ferrite. 2. A radio wave source and various articles are surrounded and covered by an inner case and an outer case, and the inner case and the outer case are formed of a ferrite sheet containing ferrite as a main component, or the inner case and the outer case are provided with a ferrite sheet. Sticking,
Electromagnetic wave absorption structure for various articles characterized by being bonded. 3. A printed circuit board formed by using ferrite as a main component. 4. A ferrite sheet used for electromagnetic wave absorption, characterized by being formed into a thin plate containing ferrite as a main component. 5. The ferrite sheet used for electromagnetic wave absorption according to claim 4, which is molded into a shape corresponding to a radio wave source, various articles and a printed circuit board. 6. A method for producing a ferrite sheet, which comprises depositing a slurry containing ferrite as a main component on a film in a thin plate shape, drying and firing. 7. A method for producing a ferrite sheet, which is characterized in that a plastic material containing ferrite as a main component is formed into a thin plate shape, dried and fired. 8. The thin plate-shaped ferrite sheet raw material is semi-dried, molded into a shape corresponding to a radio wave generation source, various articles, and a printed circuit board, and dried and fired.
Alternatively, the method for producing a ferrite sheet according to Item 7.