JPH09307263A - Electromagnetic wave shielding gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave shielding gasket having excellent contact property with a conductive member. SOLUTION: An electromagnetic wave shielding gasket 20 is provided with a core material 22 made of silicone rubber formed in a quadrangular prism sectional shape, a damping layer 24 formed to cover the surface of the core material 22 and a shielding layer 26 provided around the damping layer 24. The damping layer 24 made of a soft and fluid silicone base damping material is transformable into various shapes corresponding to the surface shapes of the contacted members, so that the contact area between the shielding layer 26 and the contacted members may be increased, resulting in lessening the contact resistance between the elements for assuring the excellent shielding property. Besides, the damping material forming the damping layer 24 converts the applied oscillation to heat and discharges for damping the oscillation so that, even if a conductive member is applied with continuous oscillation, the fluctuation in the contact resistance between the shielding layer 26 and the contacted member may be lowered, thereby enabling the stable electromagnetic shielding performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding gasket which is used at a portion where a plurality of conductive members are in contact with each other and shields electromagnetic waves passing between these conductive members.

[0002]

2. Description of the Related Art Conventionally, as a gasket for electromagnetic wave shielding of this type, for example, one having a shield layer provided on the surface of a core material made of an elastic material such as elastomer has been known. It is formed by forming a conductive coating film on the surface of the core material by vapor deposition, vapor deposition or the like, or by covering the core material with a conductive knitted fabric or sheet.

The electromagnetic wave shielding gasket thus constructed is attached, for example, to the periphery of the opening of the housing and shields electromagnetic waves passing through the space between the housing and the lid that closes the opening. Used in cases etc.

[0004]

However, in the conventional electromagnetic wave shielding gasket as described above, when continuous vibration is applied to the casing to which the gasket is attached, the core material also responds to the vibration. Vibrate together,
As a result, the contact state between the shield layer and the lid, and thus the contact resistance, fluctuates, and there is a problem that stable shield performance cannot be obtained.

Further, since the elastic material forming the core material is wholly deformed by a pressing force from the outside, when the contact surface of the housing is partially uneven, it is flexible according to its shape. However, there is a problem in that the contact area between the shield layer and the housing becomes small, and the shield performance deteriorates as compared with the case where the contact surface is a flat surface.

The present invention has been made to solve the above problems.
An object of the present invention is to provide a gasket for electromagnetic wave shielding, which has good contact with a conductive member.

[0007]

The electromagnetic wave shielding gasket according to claim 1 of the present invention, which has been made to achieve the above object, is used at a portion where a plurality of conductive members come into contact with each other, and the gasket is provided by the elasticity of the main body. The shield layer formed on the surface adheres to the conductive members and shields electromagnetic waves passing between the conductive members.

The surface of the core material made of an elastic material is covered with a damping layer made of a damping material, and since the damping material is soft and has fluidity, it partially covers the surface of the conductive member. Even if the surface has irregularities and has a complicated shape, the shield layer is flexibly deformed accordingly and the shield layer is brought into close contact with the surface of the conductive member, so that the contact area between them is large, that is, the contact resistance is small. it can.

Further, since the vibration damping material absorbs the vibration by converting the vibration into heat and diverging when the vibration is applied, the vibration damping material has a shield layer and a conductive member which are different from those of the conventional gasket. Since the contact state is good, the variation in contact resistance is small. Further, since the vibration damping material has airtightness and watertightness, the airtightness and watertightness of the gasket will not be deteriorated even if a material that allows moisture or air to pass through is used as the core material.

As the damping material for forming the damping layer, silicone-based, butyl rubber-based, polyurethane-based, acrylic-based, PVC-based, polyolefin-based, polyester-based materials and the like are known. These are designed to increase the internal loss of vibration transmission by, for example, bringing the glass transition point to a temperature near the operating temperature by copolymerization or addition of a filler, and control the energy of vibration into heat. Shake.

As the elastic material forming the core material,
Any of synthetic rubber, natural rubber, silicone rubber, solid and foam made of thermoplastic curable elastomer can be used, and the shape of the core material is tube-shaped or column-shaped, and its cross-sectional shape Also, various shapes such as a circle, an ellipse, a polygon, an Ω shape, a T shape, and an L shape can be used.

Furthermore, the shield layer is made of aluminum,
A metal coating may be formed on the surface of the core material by performing vapor deposition, thermal spraying, electrolytic or electroless plating using a metal having good conductivity such as titanium, silver, nickel or copper,
Alternatively, a metal foil made of the above metal or stainless steel, a plated fiber obtained by plating a synthetic fiber with the above metal, or a conductive knitted woven fabric or non-woven fabric using carbon fiber, or polyvinyl chloride (PVC) or polyethylene terephthalate ( PET)
Alternatively, the surface of the core material may be covered with a conductive sheet obtained by laminating a foil made of the above metal on a resin sheet made of, for example.

Further, the shield layer further comprises Ni--Fe.
A foil made of a highly magnetically permeable material such as alloys such as permalloy, various amorphous alloys such as Co—Ni—Fe, 4.5% silicon iron alloy, and ferrite may be laminated. Also,
You may form the coating film of these metals on the surface of a core material by methods, such as plating.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a perspective view including a partially cutaway view showing the overall configuration of a housing to which the electromagnetic shielding gasket of this embodiment is applied.

As shown in FIG. 2, a casing (case) 1 for accommodating electronic parts is formed in a rectangular parallelepiped shape, and a case body 3 is provided with an opening 4 for accommodating the electronic parts.
And a case lid 5 which is attached to the case body 3 via a hinge 7 and which can open and close the opening 4.

A conductive thin film layer 6 formed by vapor deposition of aluminum is formed on the inner surfaces of the case body 3 and the case lid 5. Then, when the case lid 5 is closed, the electromagnetic shielding gasket 20 is attached to the edge portion 9 of the opening 4 that comes into contact with the case lid 5 with a conductive adhesive. Further, a lid body tightening portion 11 for fastening the case body 3 and the case lid body 5 with the electromagnetic wave shielding gasket 20 sandwiched so that the inside of the case body 3 is sealed when the case lid body 5 is closed. Are provided on the case body 3 and the case lid 5. A waterproof connector 13 is attached to the side surface of the case body 3 for taking out signal lines (not shown) of electronic components housed in the case body 3 to the outside.

Here, the electromagnetic wave shielding gasket 20 is used.
As shown in FIG. 1, a core member 22 made of a silicone rubber tube having a rectangular cross section and a core member 2 are provided.
The vibration damping layer 24 is formed so as to cover the surface of the second vibration layer 2, and the shield layer 26 is provided around the vibration damping layer 24.

The damping layer 24 is made of silicone rubber, and since the silicone rubber damping material has an adhesive property, it is directly attached to the surface of the core material 22. The damping layer 24 is formed to have a thickness of 1.0 mm and has a hardness of 18 degrees in the ASKER F type.

The shield layer 26 is made of polyvinyl chloride (PV
C), polyethylene terephthalate (PET), and an aluminum foil are sequentially laminated, and a conductive sheet is wound around the vibration damping layer 24 with the aluminum foil on the outside and bonded. In the electromagnetic wave shielding gasket 20 configured as described above, when the case lid 5 is closed and tightened by the lid tightening portion 11, the soft and fluid damping layer 24 forms the case lid. 5 and the edge portion 9 are flexibly deformed according to the surface shape, and the shield layer 26 is brought into close contact with the case body 3 and the case lid 5 in a wide range.

Therefore, according to the electromagnetic wave shielding gasket 20 of this embodiment, the shield layer 26 and the case body 3 are provided.
Also, since the contact resistance with the case lid 5 becomes small, it is possible to reliably block the electromagnetic waves that try to pass through the gap between the case body 3 and the case lid 5, and obtain good shielding performance.

When the housing 1 is continuously vibrated, the damping layer 24 absorbs the vibration by converting the vibration into heat and releasing the heat. Therefore, as compared with the conventional gasket without the damping layer 24, the contact state between the shield layer 26 and the case body 3 or the case lid 5, that is, the fluctuation of the contact resistance is suppressed to be small, so that an extremely stable shield performance is obtained. Therefore, the reliability of the shield performance can be improved.

Further, according to the electromagnetic wave shielding gasket 20 of the present embodiment, since it is excellent in the adhesion to the case body 3 and the case lid 5, the moisture and the air from the outside are surely shut off and the case 1 is hermetically sealed. And the watertightness can be sufficiently maintained.
Next, the electromagnetic wave shielding gasket 30 of the second embodiment will be described.

The electromagnetic wave shielding gasket 3 of this embodiment
As shown in FIG. 3, 0 represents a core material 32 made of silicone rubber having a cross section of Ω and a butyl rubber damping material provided around the core material according to the shape of the core material 32. The damping layer 34 having a thickness of 0.5 mm and a shield layer 36 formed by coating the surface of the damping layer 34 with a nylon fabric silver-coated by electroless plating.

According to the electromagnetic wave shielding gasket 30 of this embodiment, the flat leg portion 3 is arranged along the axial direction.
Since 0a and 30b are formed, the case body 3 and the like can be easily attached. Next, the electromagnetic wave shielding gasket 40 of the third embodiment will be described.

The electromagnetic wave shielding gasket 4 of this embodiment
As shown in FIG. 4, 0 is a core material 42 made of sponge rubber having a cylindrical cross section, a damping layer 44 made of polyurethane damping material and having a thickness of 1.0 mm, and a high magnetic material. The shield layer 46 is formed by depositing a copper coating having a thickness of 1 μm on the surface of a flexible sheet material having a thickness of 50 μm and made of an amorphous alloy of Co—Ni—Fe.

The sponge rubber constituting the core material 42 is produced by blowing air into uncured latex strongly or adding a foaming material such as sodium bicarbonate to the elastomer which has been strongly masticated. Is. According to the electromagnetic wave shielding gasket 40 of the present embodiment configured in this way, not only the same effects as in the first embodiment are obtained, but also the shield layer 46 is a layer made of a high magnetic material,
Since it is formed of a layer made of a highly conductive material,
It is possible to effectively absorb electromagnetic waves in a wide frequency range.

Further, since the damping layer 44 is excellent in watertightness and airtightness, the watertightness and airtightness of the gasket are impaired even if a sponge rubber that allows water or air to pass therethrough is used as the core material 42. Never be next,
As shown in FIG. 5, the electromagnetic wave shielding gasket 50 of the fourth embodiment has a core member 52 made of sponge rubber having a T-shaped cross section and a thickness of 0. It is composed of a 5 mm vibration damping layer 54 and a shield layer 56 made of a wire mesh braided with stainless metal fibers.

Further, as shown in FIG. 6, the electromagnetic wave shielding gasket 60 of the fifth embodiment comprises a core material 62 made of sponge rubber having an L-shaped cross section and a polyester damping material. Damping layer 6 with a thickness of 1.0 mm
4 and a 35 μm thick shield layer 66 formed on the surface of the damping layer 64 by a nickel-deposited polyester film. The electromagnetic wave shielding gasket 60 of the present embodiment is used by being attached to, for example, the upper end corner portion of the case wall surface 68.

In the above embodiment, the core members 22, 32, 42,
Although silicone rubber and sponge rubber have been used as the material for forming 52 and 62, the material is not limited to these, and various resins such as elastomer can be used.
Further, as for the shape, other than the above-described embodiment, various irregular cross-sections such as Y-shape and anchor-shape can be used.

[0030]

As described above, according to the gasket for electromagnetic wave shielding of the present invention, the surface of the core material is covered with the damping layer made of the soft and fluid damping material. The layer flexibly deforms according to the surface shape of the conductive member, and improves the adhesion between the shield layer formed on the surface of the vibration damping layer and the conductive member, so that the contact area between them becomes large. As a result, the contact resistance between the shield layer and the conductive member is reduced, so that good electromagnetic wave shielding performance can be obtained.

According to the electromagnetic wave shield material of the present invention,
Since the damping layer absorbs vibration, even if continuous vibration is applied to the conductive member, fluctuations in the contact state between the shield layer and the conductive member, that is, fluctuations in contact resistance, are small, and stable shield performance is obtained. You can

Further, since the vibration damping material is excellent in watertightness and airtightness, even if a sponge rubber that allows water or steam to pass through is used as the core material, the watertightness and airtightness of the gasket will be improved. The core material can be appropriately selected from a wide range of materials without deterioration.

[Brief description of drawings]

FIG. 1 is a perspective view including a partially broken surface of a gasket for electromagnetic wave shielding of a first embodiment.

FIG. 2 is a perspective view showing the overall configuration of a housing to which the electromagnetic wave shielding gasket of the first embodiment is applied.

FIG. 3 is a perspective view including a partially broken surface of the electromagnetic wave shielding gasket of the second embodiment.

FIG. 4 is a perspective view including a partially broken surface of an electromagnetic wave shielding gasket of a third embodiment.

FIG. 5 is a perspective view including a partially broken surface of an electromagnetic wave shielding gasket of a fourth embodiment.

FIG. 6 is a perspective view including a partially broken surface of an electromagnetic wave shielding gasket of a fifth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing | casing (case) 3 ... Case main body 4 ... Opening part 5 ... Case lid body 6 ... Thin film layer 7 ... Hinge
9 ... Edge 11 ... Lid tightening part 13 ... Waterproof connector 20, 30, 40, 50, 60 ... Electromagnetic wave shielding gasket 22, 32, 42, 52, 62 ... Core material 24, 34, 44, 54, 64 ... Damping layer 26, 36, 46, 56, 66 ... Shield layer 30a, 30b ... Leg part 68 ... Case wall surface

Claims (1)

[Claims] 1. A main body which is elastically deformed in response to an external pressure, and a shield layer which is provided on the surface of the main body and has at least conductivity. The main body is used in a portion where a plurality of conductive members are in contact with each other. In an electromagnetic wave shielding gasket that shields electromagnetic waves passing between conductive members, the main body has a core material made of an elastic material, and a damping material that converts vibration into heat and dissipates the surface of the core material. A gasket for electromagnetic wave shielding, comprising: