JPS6057700A - Electromagnetic shielding material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an electromagnetic shield suitable for use in electronic (several electronics) housings, etc.

(Technical Background) Metals have conventionally been used as electromagnetic shielding materials to shield radiation noise in electronic devices such as computer equipment.

However, with the shift to plastic equipment housing, etc., a conductive film is formed on the surface of the synthetic resin that makes up the housing by zinc spraying or conductive coating. There are problems such as the strength of the coating (= one-piece strength).Subsequently, attempts were made to form an electromagnetic shield suitable for uses such as housings by combining it with a conductive abrasive resin.

Conventional electromagnetic shielding shrines such as those described above attenuate the amount of transmission by reflecting most of the incident radio waves and shield the radiation shield, but with this, the reflected waves are almost the same as the incident waves: If you use such traditional electromagnetic shielding in a computer case, for example, without attenuation,
The internal radiated noise energy accumulates, causing interference to the unit itself, or the accumulated and amplified radiated noise is transmitted from the connectors and parts of the cable hoko that are not sufficiently shielded.

I'm not sure what to do!) 51, it is desirable to absorb the reflected radiation by the reflective material and to suppress the accumulation of radiant energy.

(Objective of the Invention) In view of the above two points, the present invention has a structure in which a resistor layer is formed on one surface of a composite ferrite having good workability, and the amount of transmission of input I radio waves is sufficiently reduced. The present invention aims to provide an electromagnetic shielding material that absorbs reflected waves in a composite ferrite portion and prevents the accumulation of radiated energy.

(Structure of the Invention) The structure of the electromagnetic shielding material of the present invention is as shown in FIG. It has a three-layer structure including an insulating layer, and the magnetic layer 1 is preferably set to satisfy the following conditions in order to reduce the amount of radio wave reflection to -6 dB or less.

(1) The magnetic layer is made of various rubber and polymer materials of various resin chopsticks.
This is a composite ferrite with dispersed ferrite particles.

(2) Ferrite 1 has a spinel structure of MFe and Ol. However, M is Fe+Ni, CoJ(n, Mg+Cu, Z
Consists of one type or a combination of two or more types of ne.

(3) The average particle size of 7elite is 1.0 to 50
It is in the range of 0 μm.

(4) The imaginary class μr'' of the complex relative magnetic permeability (,ur-μr'-jμr'') of ferrite is 2.0
It must be 'ni'.

(5) 11; Waist thickness 511 in consideration of use as f body
1m side, 1ζ.

(6) 7 Eli 1's 1 Fukika sweat? , the combined ratio is 1ilvo
1% to 65vo1%.

In addition, the resistance layer 21 preferably has a radio wave transmission amount of −3+1
In order to keep it below 1 dB, settings are made to satisfy the following conditions.

(1) The resistor layer is made of either conductive fiber M1 cloth or conductive composite I4 material (complete 1''': does not need to be reflective wood).

(2) For example, the proprietary electric fiber fabric is made of acrylic or nylon fiber with copper sulfide CFIX S (strength X = 1~
2) Form and weave the fibers to make cloth [Product name:
Sangouron S S -N: Nippon Kasuke Dyeing Co., Ltd.” or by depositing N1 or Ckl on the surface of polymer fiber IT.
There are fabrics made from the same fibers (trade name: Nimeta, Kusu: manufactured by (Hayashi) Takase Dyeing Factory). The sheet resistance of the conductive yarn 1 cloth shall be less than 10Ω/roll.

(3) Conductive composite abrasive materials include various rubbers and various 4.44 fats.
For example, carbon black (Ketjen Black EC, manufactured by Nilion Akzo Co., Ltd.) is dispersed in the polymeric material No. 9. Its thickness should be 0.3 to 3 mm, and its resistivity should be less than ]OΩ-clll.

(Embodiments of the Invention) Hereinafter, embodiments of the electromagnetic shielding material of the present invention will be described in detail.

Example 1 60 Mn-Zn Fe7z lights with an average particle size of 2 μmo
The magnetic layer is composed of composite ferrite B, which is a mixture of VO1% and epoxy resin at a ratio of 40VO1%, and has a sheet resistance of 3.7Ω.
/A conductive blue fiber (Cu-deposited metal) was composited as a resistor layer on one side of the magnetic layer (for example, molded simultaneously with the magnetic layer). In this case, the material constants of composite ferrite B are as shown in Table 1 below. The shielding characteristics at frequency 100100O are transmission amount -35dB, anti-IJ star is -6dB
It became.

6 Mu-ZnFe7x lights with a particle size of 150μIll
The magnetic layer was composed of a composite ferrite C mixed at a ratio of 0vo'1% and chloroprene rubber/LOvo1%, and a conductive fiber with a sheet resistance of 3.7Ω/mouth was composited as a resistor layer on one side of the magnetic layer. . In this case, the material constants of the composite 7 element C are as shown in Table 1 below.

The shielding characteristic at frequency 100100O is transmission amount -35d
B, the reflection amount is -8 dB, and the solid line shows the frequency characteristic of the reflection amount, and the dotted line shows the frequency characteristic of the transmission ζ.

Example 3 4n Z++ -Fc・7x with a particle size of 150 μIn
Light 60vo1%, Chloroprentum 1. ('
, IV (l) Composite ferrite C mixed at a ratio of 1%
23vo1 of magnetic resistance] is formed on one side of the magnetic field.
%, chloroprene rubber 77vo1%? ! +l] conductive composite (・I1, 1 were combined into one. In this case, frequency]t) 00 lV・] 11/, the seal l' 46 property is the amount of transparency jD -30d 13, Reflection-Fij
I: t +E d B It's gone.

Table 1 Here, εr′ is the complex dielectric constant jr (n real term, εr″
indicates the isoimaginary term.

Table 2 below shows 11) OOmu 4l of Examples 1 and 2.3.
This shows a comparison of the amount of transmission and the amount of reflection at -1z.For reference, the composite ferrite shown in Table 1)/\(μr" or smaller than 2) and the conductivity of sheet resistance 3.7Ω/mouth are shown. As a comparative example, the case of combination with sexual fiber is shown.

Table 2 (Effects of the Invention) As explained below, the electromagnetic shield 44 of the present invention can bring about the following effects.

(1) In addition to counteracting incident radio waves such as radiated noise,
It's all about destroying the foul wave. Therefore, when used as a housing, it is possible to prevent DJ'/chair energy from being accumulated in the substitute.

(2) The magnetic layer is made of composite ferrite made by combining 71941 particles with polymer A/A material (IX7, resistance 1A (layer is made of conductive fiber 1 cloth or conductive mesh, composite 4/4 material). 4-1
Since it is made of +, can it be molded into any shape?
, Easy and Asu Nikei 7I: Excellent strength and durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of the electromagnetic shield shrine of the present invention,
FIG. 2 is a graph showing the frequency characteristics of the amount of reflection and amount of transmission in the case of Example 2. 1... Magnetic layer, 2... Resistor layer. Takashi Kikai, patent attorney and agent for patent applicant TDC Co., Ltd.

Claims (1)

[Claims] (1) An electromagnetic shielding material characterized in that a resistor layer made of conductive fiber cloth or a conductive composite material is provided on the negative side of (1) a composite ferrite obtained by mixing ferrite particles with a polymeric material.