JPH01165200A - Laminated board for shielding electromagnetic wave - Google Patents

Abstract

PURPOSE:To improve the closely adhering property between the two, and to increase the mechanical working feasibility, by giving minute roughness with a base material made of nonwoven cloth to metal foil in time of thermal pressing, by the use of the base material made of resin-impregnated nonwoven cloth put on at least one side of the metal foil such as cupper foil etc. CONSTITUTION:Base materials impregnated with a thermosetting resin composite are laminated on both sides of metal foil, and they are formed in one body. In this case, an at least one-side base material in contact with the metal foil is formed with nonwoven cloth. The material and thickness of the metal foil are selected by considering the use. As a thermosetting resin, such resins as epoxy, polyimide, unsaturated polyester and phenol etc., are named, and the best is selected by considering the use, in other words, the heat resistance, weather resistance, elasticity, workability, and mechanical strength etc. As nonwoven cloth, an inorganic fiber life a filament mat, a chopped strand mat, or a continuous strand mat etc., is favorable in the respect of strength, and in the respects of close adhesion and better scattering characteristics against an electric wave because of the enough roughness of the metal foil after the press forming. In that case, the heat resistance, mechanical strength and weather resistance etc., of the laminated board obtained become better.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention is directed to an electromagnetic shielding laminate suitable for use as an electromagnetic shielding plate used in electrical/electronic equipment, wiring boards, etc., or as a backing material for an electromagnetic wave absorber. It's about the board.

(b) Conventional technology In recent years, electrical and electronic devices such as personal computers have become widespread not only in the industrial world but also in ordinary households, but these devices cannot coexist in a limited space. Moreover, an environment has been created in which high-power equipment and extremely weak electrical signal equipment are placed next to each other, and unnecessary electromagnetic energy that is unnecessarily generated or leaked from these equipment can interfere with the operation of peripheral equipment or cause malfunctions. This has led to many problems related to so-called electromagnetic interference (EMI), and there has been a strong call for regulation or countermeasures against it.

Electromagnetic wave shielding materials for the power supply parts of these combiator equipment and office equipment vary in size and shape depending on their use, but from the perspective of space saving, insulation treatment is applied to one or both of the metal foil materials such as copper, iron, or aluminum. Shielding materials have been proposed.

For example, as proposed in Japanese Utility Model Application Publication No. 57-168297, glass cloth prepreg using a thermosetting resin composition is laminated on both sides of an electrolytic copper foil or rolled copper foil, and this is integrally molded. Structural shielding materials have been proposed.

(,) Problems that the invention attempts to solveHowever, the actual lff1! The following shielding material was formed based on Publication No. 57-168297, and when this shielding material was cut into a predetermined size using a rotary diamond cutter, the smooth surface of the electrolytic copper foil and the glass cloth base material were cut. A situation occurred where separation occurred at the interface and cutting powder entered.Furthermore, when creating a grounding part, a hole of 6 mm diameter was punched with a punching die, but separation occurred on the punched cross section, and pars occurred on the punched cross section. did.

Such peeling at the edges of the material easily spreads when the material is bent, resulting in a significant reduction in the mechanical strength of the material itself.

Furthermore, during the above-mentioned punching process, cracks may be formed or minute cutting powder may be mixed into one part of the peeling W, and if such a shielding material is used for a combination false-taper, other operations may occur during assembly. This may result in particles hitting between parts, etc., or minute cutting powder entering the peeled area, causing damage to the parts, causing operational failure or malfunction, or foreign matter entering the peeled area. There are problems such as the insulation is thick (there is a risk of damage), and the reliability is poor and it cannot be used.

(d) Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that a thermosetting method that is laminated on both sides of a metal foil such as an electrolytic copper foil or a metal foil such as pressure*rtsm. By using a non-woven fabric as a base material to be laminated on one side of the metal foil, the copper foil and the base material (non-woven fabric) can be laminated on one side of the metal foil.
It was discovered that an electromagnetic shielding laminate with extremely good adhesion and excellent machinability for cutting and punching could be obtained. We discovered that the minute irregularities of the foil not only improve adhesion, but also can be used as a backing material for ideal resistance-type radio wave absorbers, which can disperse and scatter radio waves during radio wave reflection and reduce energy intensity. This has led to the completion of the present invention.

That is, the electromagnetic shielding laminate of the present invention is a laminate in which a base material impregnated with a thermosetting resin composition is laminated on both sides of a metal foil such as an electrolytic copper foil or a rolled copper foil, and this is integrally molded. The base material on at least one side surface in contact with the metal foil is formed of a nonwoven fabric.

The present invention will be explained in detail below.

The metal foil used in the present invention is not particularly limited, but specifically includes, for example, electrolytic foil, rolled copper foil,
Examples include electrolytic iron foil, galvanized iron foil, copper-plated iron foil, aluminum foil, etc., and the material and thickness of these may be selected according to the shielding purpose and use.

The preferable range of the thickness of the metal foil is usually as follows:
It is 10 to 100 μ-.

Further, thermosetting resins used in the present invention include epoxy resins, polyimide resins, unsaturated polyester met,
Examples include phenol resins, and these resins may be selected depending on the intended use, such as heat resistance, weather resistance, elasticity, workability, and mechanical strength.

Furthermore, it is necessary to select and add an appropriate curing agent and curing catalyst to the thermosetting resin for curing the resin, thereby forming the thermosetting resin composition used in the present invention. There is no need to use special ones, and known ones can also be used.

For the above-mentioned epoxy resin, known ones such as amines, acid anhydrides, and imiguzole compounds can be used, and for the above-mentioned unsaturated polyester resin, for example, peroxide catalysts such as tert-butyl perbenzoate, etc. can be used. , a publicly known one is used.

Furthermore, a coupling agent may be used in the thermosetting resin composition, and for the purpose of flame retardation, for example, a brominated epoxy resin may be used, or a flame retardant such as antimony dioxide may be added.

The present invention is characterized in that the base material used is formed of a non-woven fabric with a small amount of metal foil (laminated on one side). Examples of the non-woven fabric include glass fiber non-woven fabric, ceramic am Examples include nonwoven fabrics made of polyester fibers, nonwoven fabrics made of polyester fibers, nonwoven fabrics made of amide fibers, etc., but preferably glass or ceramic filament mats,
It is preferable to use inorganic fibers such as Chi, Tsubuto Strand Mat, and Conteier 1 Fussushi Land Mat.

When a non-woven fabric base material is used in this way, the outer layer is harder than the conventional one using a woven fabric due to the unevenness of the gold R foil after press molding, but it is easier to make the base material stronger and easier to form when the base material is made of inorganic fibers. ,
The stronger the unevenness, the better the adhesion and scattering of radio waves.
Moreover, it is preferable because the heat resistance, mechanical strength, weather resistance, etc. of the obtained electromagnetic shielding laminate are improved.

Commercially available nonwoven fabric substrates used in the present invention include, for example, MF30P-104, MF60P-104, MS3
00A-186, MC300A (all manufactured by Nittobo Co., Ltd.), ERM-450 (Unitika Co., Ltd. g1), Kao Wool Paper (Isolite Kogyo Co., Ltd.), SC Paper 870
, SC Paper 1260 (manufactured by Nippon Steel Chemical Industry Co., Ltd.) F
C-55, 0R-210 (manufactured by Nippon Vilene Co., Ltd.), and the like.

Further, the electromagnetic shielding laminate of the present invention is one in which a nonwoven fabric substrate impregnated with the thermosetting resin composition is laminated on at least one side of the metal foil, but preferably on both sides. This is desirable because it tends to cause unevenness in the metal foil.

By the way, in the present invention, when considering the mechanical strength and surface smoothness of the shielding laminate, it is preferable to laminate a base material made of stock cloth such as glass cloth on the outer layer of the laminate. is desirable.

The electromagnetic wave shielding laminate of the present invention can be produced by, for example, dissolving the above-mentioned thermosetting resin composition in a suitable organic solvent, impregnating it into a nonwoven fabric G1 base material, drying this, and then laminating it together with a shielding metal insulating material. It can be created by a normal method such as heating and curing using a hot press.

(e) Effect The electromagnetic shielding laminate of the present invention has the above-mentioned implantation,
By using a nonwoven fabric base material with a small amount of metal foil such as body foil (both sides impregnated with a thermosetting resin composition (Tamabe impregnated nonwoven fabric base material), the nonwoven fabric base material is The base material gives the metal foil a minute uneven shape, and this change in shape significantly improves the adhesion between the metal foil and the resin-impregnated nonwoven fabric base material, and it peels off on the cut surface using a rotary diamond cutter or the like. 1Iit, etc., without causing any external abnormalities, and furthermore, during punching, there is extremely little burr, and it has excellent machinability.

Furthermore, since the metal foil of the electromagnetic wave shielding laminate of the present invention has an uneven shape, it has an effect that it is also effective as a backing shielding material for a resistive electromagnetic wave absorber.

In other words, the back side of the radio wave absorber is combined with a shielding material, but according to radio wave absorption theory, radio waves are scattered by geometric shapes, and the incident energy is dispersed to reduce the energy density. It is effective to absorb (published by CMC Co., Ltd., T eeh
nical Report No.

51 Basics of electromagnetic shielding! Third collected wave absorption theory 198
4), the incident waves that could not be converted into thermal energy by the absorber are scattered again by the unevenness of the foil in the electromagnetic shielding laminate of the present invention, reducing the reflected and transmitted energy density. It has the function of being an effective radio wave absorber.

(f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

In addition, in the following, part or % means tt part or! !
! means fi%.

Example 1 Bisphenol A type epoxy resin (epoxy fl 480 g/eq, softening point 7) was used as a thermosetting resin composition.
0°C) and 30 parts of anhydrous Flimellitic acid were dissolved in 200 parts of methyl ethyl ketone to prepare a face.

On the other hand, CEGP, which is a glass nonwoven fabric, is used as a nonwoven fabric base material.
PE-1-100 (manufactured by Nippon Sheet Glass Co., Ltd.) and 116T-VL-110-J (manufactured by Unitika Um Glass Co., Ltd.), which is a glass cloth, were used as the woven fabric base material, and the resin content was determined for each base material. Impregnated and adjusted so that it is 45%,
Drying was performed at a temperature of 100°C for 10 minutes to obtain a resin-impregnated base material for each base material.

Furthermore, an electrolytic copper foil with a thickness of 35 μm was used as a metal foil for shielding, and two sheets of the previously obtained resin-impregnated lath nonwoven fabric were laminated on each side of the foil, and four sheets of glass cloth base material were laminated on each side of the foil. Then, hot pressing was performed for 3 hours at a temperature of 165°C and a pressure of 50 kg/am'', and then after cooling for 1 hour, the laminate was taken out from the press to obtain a laminate for electromagnetic shielding of the present invention.

Examples 2 to 7 Laminated plates for electromagnetic shielding of the present invention of Examples 2 to 7 were prepared in the same manner as in Example 1 using thermosetting resin compositions having the compositions shown in Table tjS1.

Comparative Examples 1 to 7 In Examples 1 to 7, the same glass cloth as in Example 1 and the same glass cloth as in Example 1 were used in place of the nonwoven fabric substrates used in each of them.

A: Bisphenol A type epoxy resin (EEW=480
g/eq, softening point 70°C) B: Anhydrous trinolyte acid C: Unsaturated polyester resin u-8601 (manufactured by Nippon U-Pica) D: Peroxide catalyst tertiary-butyl perbenzoate E: Polyimide resin Kelimide 601 (manufactured by Rhone Poulenc) F: γ-glycidoxypropyltrimethoxysilane G: lath nonwoven fabric CEGPPE-1-100 (manufactured by Nippon Sheet Glass Co., Ltd.) l! : Ceramic non-woven fabric GT-6X (manufactured by Donami Paper Co., Ltd.) ■: Polyester non-woven fabric 0R-210 (manufactured by Nippon Vilene Co., Ltd.) JAW lath fiber fabric AS-7628-450 (Asahi Schoebel Co., Ltd. SRIK: ,lr?X Woven fabric 116T-VL-110-J (
a Manufactured by Ethica CM Glass Co., Ltd.) L: Kepler woven fabric K-120 (manufactured by Kanebo Glass Fiber Co., Ltd.) M: 18 μ-pressure 1Lt14M N: 35 μ-electrolytic copper foil 0: 30 μ-electrolytic iron whistle Each example product and each comparison above The results of the characteristic tests of the example products are shown in Tables 1 and 2.

(Margin below) In addition, in the column of nonwoven fabric base material in the Pt51 table, W
The number L (A/mouth) indicates the number of laminated sheets of the resin-impregnated nonwoven fabric base material stretched on the front and back sides of the metal foil; A indicates the front side, and opening indicates the back side. A) means that two resin-impregnated nonwoven fabric 91 base materials were stretched on each of the front and back sides of the metal foil.

Further, the number in the column of woven fabric substrates in Table 1 indicates the number of laminated resin-impregnated woven fabric substrates stretched over the resin-impregnated nonwoven fabric substrates on both the front and back sides.

Note 1) Evaluation of machinability Each example and each comparative example were cut using a rotary diamond cutter, and the peeling width generated on the cut surface was 0.
．． 5aI11 or less was rated ○, and those wider than 0.51 were rated ×.

Furthermore, when punching a hole of 6 mwφ with a punching die, check for peeling and cracking! ! Shita.

Note 2) Evaluation of unevenness of metal foil A release agent was applied to the smooth surface of the metal foil, and one side of the base material was peeled off at the interface after molding under the same conditions, and the surface roughness of the metal foil surface was measured. 25μ- larger than 0. Anything less than that was designated as X.

As is clear from the results shown in Table Pls1 and Table V2,
It can be seen that in the examples, the metal foil and the resin-impregnated nonwoven fabric base material adhered tightly to each other due to their uneven shapes, and were excellent in machinability such as cutting and punching.

Furthermore, the unevenness of this metal foil has excellent radio wave scattering properties, and can be used as a good backing material for resistive radio wave absorbers.

(g) Effects of the Invention The present invention has the above structure, and has the effect that the metal foil and the resin-impregnated nonwoven fabric base material are tightly adhered to each other due to their uneven shape, and have excellent machinability in cutting, punching, etc. be.

Furthermore, the electromagnetic wave shielding laminate of the present invention has an excellent radio wave scattering property due to the unevenness of the metal foil constituting it, and as a result, it has the effect of being able to be used as a good backing material for a resistive radio wave absorber. be.

Claims (2)

[Claims] (1) A laminate in which a base material impregnated with a thermosetting resin composition is laminated on both sides of a metal foil such as an electrolytic copper foil or a rolled copper foil, and these are integrally molded, and the at least one part in contact with the metal foil is A laminate for electromagnetic shielding, characterized in that the base material on one side is made of nonwoven fabric. (2) The electromagnetic shielding laminate according to claim 1, wherein the nonwoven fabric is made of glass fiber or ceramic fiber.