JP2002279831A - Shield material for flat cable and flat cable with shield - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat cable with shield in which the shield layer and adhesive layer of the shield material are improved, and conduction of the shield layer and a ground wire is easy and can be done stably, and which has fire- resistance and excellent shield characteristics. SOLUTION: A conductive and fire-resistant adhesive layer 13 is formed on the insulating substrate 11 made of PET or the like using a heat seal resin composite containing a conductive filler 14 and a fire-resistant filler 15, and, thereby, a flexible shield material for a flat cable 1 of film shape is manufactured. The shield material 1 obtained has conductivity in its adhesive layer, and, thus, by overlapping the shield material on the flat cable and by heating and pressurizing, the shield layer and the ground wire can be conducted, hence, the work efficiency is much improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat cable shield material (such as an electromagnetic wave shielding film) and a shielded flat cable using the same. In particular, it is an object of the present invention to provide a shielded flat cable excellent in shield characteristics by improving a shield layer and an adhesive layer of a shield material so that conduction between the shield layer and a ground line can be easily and stably performed. .

[0002]

2. Description of the Related Art Recently, flat cables have been used in place of horizontal shielded wires and coaxial wires for signal transmission in interfaces between devices such as communication devices, computers and peripheral devices and between devices. However, in an environment where various radio waves, electromagnetic waves, and the like are generated as in today, the flat cable is affected by these factors and often causes a malfunction of the computer.

For this reason, various shield technologies have been developed for protecting the flat cable from electromagnetic waves and for shielding electromagnetic waves generated from the flat cable so as not to affect other devices. For example, a metal foil is used in which an insulating adhesive layer is provided on the surface of a metal foil in order to adhere the metal foil to a flat cable by using a metal foil for a shield layer of the shield material. Also,
Shielding materials in which an adhesive containing a conductive substance such as metal powder is applied to a plastic film and the conductive adhesive layer is used as a shielding layer are also being studied. In addition, a shield material formed as a shield layer by forming a conductive adhesive layer in which a conductive substance such as a metal powder is added to a metal foil has been studied.

Further, as a material having good sliding properties, an electromagnetic wave shielding film in which a metal thin film is formed on a base fill and then an adhesive resin layer containing silver particles and / or copper particles is formed has been proposed. (JP-A-7-9403
6). Since this shield tape has a metal thin film,
It is excellent in conductivity and has good electromagnetic wave shielding properties. However, if the adhesive resin layer contains silver particles, it becomes expensive, and if copper particles are used, there is a problem that the shielding characteristics with time deteriorate.

Further, there has been proposed an electromagnetic wave shielding film in which a silver vapor-deposited film is formed as a metal thin film on a base film and a nickel filler is contained in an adhesive resin layer (JP-A-11-120831). This shield tape is also expensive because the base film is a flame-retardant engineering plastic and the metal thin film is a silver deposited film. Further, in order to make the plastic film flame-retardant, a film using a flame-retardant engineering plastic such as polyphenylene sulfide, polyamide imide, polyether imide, or polyarylate is disclosed as the plastic film.

[0006]

A shielding material having an insulating adhesive layer provided on the surface of a metal foil is used to make a part of the insulating adhesive layer conductive between the shield layer and the ground wire of the flat cable. Excision to expose the ground line,
It was necessary to cut off a part of the shield material to expose the metal foil, and to connect the exposed ground line and the metal foil (shield layer) by a special processing method such as spot welding.
Further, when a metal foil is used, the flexibility is inferior, so that the mounting of the flat cable is restricted, and the shape of the electronic member is restricted.

Further, in order to solve the above-mentioned problems, a shielding material in which a conductive adhesive layer is provided on a plastic film has improved flexibility, so that the problem of workability and the problem of the shape of an electronic member can be solved. There is a problem that the shielding characteristics are inferior to the shielding material using a metal foil. Furthermore, in order to make the shielding material flame-retardant, when a flame-retardant engineering plastic such as polyphenylene sulfide, polyamide imide, polyether imide, or polyarylate is used, these flame-retardant engineering plastics are expensive. As a result, the cost of the shield material increases, and an economic problem arises.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the structure of a flat cable shielding material and a shielded flat cable using the same are as follows. That is, a flat cable shielding material is formed by forming a metal thin film layer on one side of an electrically insulating base material, and conducting a heat-sealing resin composition mainly containing a thermoplastic resin on the metal thin film layer. A shielding material for flat cables, characterized in that an adhesive layer having conductivity and flame retardancy was formed using a resin composition containing a conductive filler and a flame retardant filler. Further, the conductive layer and the flame-retardant adhesive layer formed on the electrically insulating base material may contain 10 to 30% by weight of a conductive filler and 2% of a flame-retardant filler.
A shielding material for flat cables characterized by containing 0 to 50% by weight. The conductive filler is made of spherical or granular carbon particles.

In the flat cable shielding material, the electrically insulating substrate is a polyethylene terephthalate film, and the metal thin film layer has a thickness of 0.04 to 0.04 mm.
A flat cable shield material characterized by being a 0.2 μm aluminum vapor-deposited film.

Further, the shield material for a flat cable having the above-mentioned structure was integrated by heating and pressurizing the flat cable to obtain a flat cable with a shield, wherein the flat cable had a shielding function.

That is, the flat cable shielding material of the present invention comprises a metal thin film layer such as an aluminum vapor-deposited film formed on one surface of an electrically insulating substrate such as a polyethylene terephthalate (hereinafter abbreviated as PET) film or a polyimide film. On the metal thin film layer, a thermoplastic resin having a heat sealing property, for example, a resin composition containing polyethylene, polypropylene, polyester or the like as a main component, a metal powder, a conductive filler such as a carbon powder, and a hydroxide. Aluminum, using a resin composition to which a flame-retardant filler such as magnesium hydroxide is added, forming an adhesive resin layer by coating or the like, that is, an adhesive layer having conductivity and flame retardancy, and having flexibility. This is a shield material for flat cables.

The conductive layer and the flame-retardant adhesive layer contain 10 to 30% by weight of a conductive filler and 20 to 50% by weight of a flame-retardant filler.
The adhesive layer of the flat cable shield material is provided with conductivity and is provided with flame retardancy. Further, by using spherical or granular carbon particles as the conductive filler, a shield material for a flat cable can be manufactured at low cost. Therefore, the ground wire of the flat cable and the shield layer (metal thin film layer) of the shield material can be conducted only by superposing the adhesive layer of the flat cable shield material on the flat cable and applying heat and pressure. Therefore, when the shield material for a flat cable of the present invention is used, the operation process of manufacturing a flat cable with a shield is simplified and can be made at a high speed.
Manufacturing costs are reduced. Further, since the adhesive layer contains a flame-retardant filler, the shielded flat cable manufactured using the shield material of the present invention can pass the UL standard flame-retardant test.

The flat cable shielding material of the present invention is bonded to the surface of a flat cable to provide a shielded flat cable in order to impart a shielding function to the flat cable. That is, the flat cable is folded in two so that the adhesive layer of the shield material for the flat cable is inside, the flat cable is inserted into the inside of the folded shield material, and the flat cable is heated and pressed from above the shield material. Shield material and flat cable are integrated to produce a shielded flat cable with excellent shielding characteristics.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the flat cable shielding material of the present invention. FIG. 2 is a schematic plan view showing an example of the shielded flat cable of the present invention. 3A and 3B are schematic cross-sectional views of a shielded flat cable according to the present invention. FIG. 3A is a cross-sectional view taken along line X-Y in FIG. 2, and FIG. 3B is a schematic cross-sectional view illustrating a layer configuration. FIG. 4 is a schematic cross-sectional view showing a layer configuration of a shielded flat cable manufactured using a conventional flat cable shield material.

The shield material 1 for a flat cable according to the present invention.
As shown in FIG. 1, a metal thin film layer 12 such as an aluminum vapor-deposited film is formed on one surface of an electrically insulating base material 11 such as a PET film, and has a heat sealing property on the metal thin film layer 12. A conductive filler 14 such as a metal powder or a carbon powder is added to a resin composition mainly composed of a thermoplastic resin.
And a resin composition to which a flame-retardant filler 15 such as aluminum hydroxide or magnesium hydroxide is added, and by coating or the like, an adhesive resin layer, that is, an adhesive layer 13 having conductivity and flame retardancy (hereinafter referred to as a conductive layer). And flame retardant adhesive layer 1
3) to form a flexible flat cable shield material 1.

The conductive / flame-retardant adhesive layer 13
By containing 10 to 30% by weight of the conductive filler 14 and 20 to 50% by weight of the flame retardant filler 15,
The conductive / flame-retardant adhesive layer 13 of the flat cable shield material 1 is provided with conductivity and also has flame retardancy. Therefore, the conductive / flame-retardant adhesive layer 13 of the flat cable shield material 1 is superposed on the flat cable, and only by heating and pressurizing, the ground wire 21 of the flat cable 2 and the metal thin film layer 12 of the shield material 1 are conductive. It can be easily conducted through the adhesive / flame-retardant adhesive layer 13.
Therefore, when a shielded flat cable is manufactured using this shield material, work efficiency is extremely improved as compared with a conventional flat cable shield material, and a high-speed and stable product can be manufactured.

That is, when producing a shielded flat cable using the flat cable shield material of the present invention, the flat cable shield material 1 is folded in two with the conductive / flame retardant adhesive layer 13 inside. As shown in FIG. 2, the flat cable 2 is inserted into the flat cable 2, and the flat cable 2 is wrapped around the flat cable 2 except for the terminal portion, and the flat cable 2 is heated and pressed from the flat cable shield 1 side. Thereby, the flat cable shield material 1 and the flat cable 2 are integrated to produce the shielded flat cable 3.

In this case, it is necessary to connect the ground wire 21 of the flat cable 2 and the metal thin film layer 12 of the flat cable shielding material 1 to ground. Therefore, as shown in FIG. 3A, a portion of the flat cable insulating layer 23 of the flat cable 2 is cut off to cut off the conductive cutout portion 24.
Is formed. That is, as shown in FIG. 3B, the flat cable insulating layer 23 is composed of the PET film 23a and the insulating adhesive layer 23b. Form. Next, the flat cable shielding material 1 is overlaid on the flat cable 2 with a part of the ground wire exposed, and heated and pressurized to form a conductive and flame-retardant resin as shown in FIG. Since the layer 13 enters the cutout portion 24 for conduction, the ground line 21 and the metal thin film 12 are conducted through the conductive and flame-retardant resin layer 13 having conductivity.

In the case of a conventional shield material, as shown in FIG. 4, a metal foil is attached to the electrically insulating base material 11 and the insulating adhesive layer 13a is provided on the metal foil. When a conventional flat cable 3a with a shield is manufactured by bonding the flat cable 2 to the flat cable 2, the ground wire 21 of the flat cable 2 and the metal foil 12a of the shield material are electrically connected to each other by the flat cable insulating layer 23 (see FIG. 3B). P
Both the ET film 23a and the insulating adhesive layer 23b) and the insulating adhesive layer 13a of the shield material 1 need to be provided with the cutout portion 24 for conduction and the cutout portion 24a for conduction. In addition, since the ground wire 21 and the metal foil 12a of the shield material are electrically connected by spot welding using the cutout portions 24 and 24a for electrical connection, the operation process becomes complicated, and there is a problem in the workability. That is, since the work efficiency is poor, the productivity has not been increased, and the production cost has been increased.

The shield material 1 for a flat cable of the present invention
Is that the conductive / flame-retardant adhesive layer 13 of the electrically insulating substrate 11 such as a PET film contains a flame-retardant filler, so that not only the adhesive property but also the entire flat cable shielding material 1 Become flame retardant. Therefore, when a flat cable with a shield is manufactured using the shield material 1 for a flat cable, a product that passes the UL standard flame retardancy test is obtained as the flat cable with the shield.

Examples of the thermoplastic synthetic resin having heat sealing properties used in the flat cable shielding material of the present invention include hot melt adhesives such as polystyrene, polyolefin, polyester, and polyamide, rubber, and acrylic. Examples thereof include polyvinyl ether-based and silicone-based adhesives. These adhesives need to adhere to both the metal thin film layer and the outer insulating layer of the flat cable while containing the conductive filler and the flame retardant filler. As an adhesive suitable for this purpose, a hot melt adhesive using a polyester resin is preferable. The hot melt adhesive using the polyester resin is a saturated copolymerized polyester resin, and among them, the glass transition point is −50 to 80 ° C.,
A resin composition containing a polyester resin having a weight average molecular weight of 7,000 to 50,000 as a main component is preferable.

The conductive filler used in the flat cable shielding material of the present invention includes carbon particles, metal powders such as nickel, copper, and silver, alloy powders such as solder, metal whiskers, metal-plated glass fibers, and the like. Is mentioned. In the case of carbon filler, the length (or diameter) of the filler is used in the range of 0.1 to 20 μm, and among them, 0.1 to 5 μm, which is easy to disperse, is desirable. Examples of the carbon particles include spheres, granules, flakes, needles, fibers, and the like. In the present invention, spheres or granules that are inexpensive are preferable. And, since the conductive adhesive layer containing these conductive fillers needs to be bonded to both the metal thin film layer and the outer insulating layer of the flat cable, as a heat-sealable thermoplastic resin, The heat-sealable thermoplastic resin is selected. The content of the conductive filler is preferably from 10 to 30% by weight in the resin solid content when the conductive adhesive layer was formed.

Examples of the flame retardant used as the flame retardant filler of the present invention include chlorine-based and bromine-based halogenated flame retardants. Examples of chlorine-based materials include chlorinated paraffin, chlorinated polyethylene, chlorinated polyfel, perchlorocyclopentadecane, heptic anhydride, chlorendic acid, and the like. As bromine compounds, tetrabromoethane, tetrabromobutane, tetrabromobisphenol A (TBBA), decabromodiphenyl oxide (D
BDPO), hexabromocyclododecane (HBC
D), octabromodiphenyl oxide (OBDP)
O), bistribromophenoxyethane (BTBP)
E), tribromophenol (TBP), ethylene bis tetrabromo phthalimide, TBA polycarbonate oligomer, brominated polystyrene, TBA epoxy oligomer, TBA bis dibromopropyl ether, ethylene bis pentabromo diphenyl, polybromophenyl oxide, hexabromobenzene And organic compounds or inorganic compounds such as decabromo diphenyl ether, tetrabromophthalic anhydride, hexabromocyclodecane and ammonium bromide.

Phosphorus-based flame retardants include red phosphorus, triallyl phosphate, alkyl allyl phosphate, alkyl phosphate, dimethyl methyl phosphate, phosphate, halogen-containing condensed phosphoric ester, trimethyl phosphate, triethyl phosphate, Tributyl phosphate, resolediyl bisphosphate, trioctyl phosphate, tribubutoxyethyl phosphate, 2ethylhexyldiphenyl phosphate, tricresyl phosphate, cresyl phenyl phosphate, triphenyl phosphate (TPP), tris (chloroethyl) ) Phosphate,
Tris-β-chloropropyl phosphate, tris (2,3-dichloropropyl) phosphate, tris (2,3-dibromopropyl) phosphate, tris (bromochloropropyl) phosphate, bis (2
3-dibromopropyl) 2,3-dichloropropyl phosphate, bis (chloropropyl) monooctyl phosphate, polyphosphonate, polyphosphate, aromatic phosphate, aromatic condensed phosphate, dibromoneopentyl glycol And the like.

Other organic flame retardants include polyol compounds such as phosphonate polyols, phosphate polyols, and halogen-containing polyols. Examples of inorganic flame retardants include hydrated metal compounds such as aluminum hydroxide and magnesium hydroxide, antimony oxides such as antimony trioxide, antimony tetroxide, and antimony pentoxide, zinc borate, zinc stannate, antimony borate, and borate. Acids: molybdenum compounds such as antimony molybdate, molybdenum oxide, molybdenum oxide, calcium-aluminum-silicate, zirconium compounds, tin compounds, dawsonite, calcium aluminate hydrate, zinc sulfide, iron oxide,
Copper oxide, copper powder, calcium carbonate, metal salts of ferrosense sulfonic acid such as barium ferrocene metaborate, metal nitrates, hydroxyquinoline Mn complex salts, vanadium chloride, silicone polymers and the like. In addition, various flame retardants such as guanidine compounds, triazine compounds, melamine cyanurates, nitrogen-containing compounds such as phosphorus-nitrogen compounds, fumaric acid, maleic acid, isocyanurate, and urea can be used.

When the flame-retardant filler and the conductive filler are added together in the adhesive layer, the content of the flame-retardant filler is preferably 20 to 50% by weight in the solid content of the resin. By adding the flame-retardant filler in the adhesive layer, even when using an electrically insulating substrate such as PET,
In the oxygen index (JIS K7201-2), flame retardancy of 21 or more can be provided. The oxygen index is preferably set to 25 to 35. When the oxygen index is less than 25, the thickness of the flat cable base material is large, and when the PET has a thickness of 38 μm or more, the flame retardancy may be insufficient. It is necessary to increase the amount to be added, and the adhesive strength to the flat cable decreases, which is problematic. Therefore, a flat cable with a shield manufactured using a shield material for a flat cable is a UL standard flame retardant test (UL15810).
80 VW-1).

In the present invention, other additives can be arbitrarily added in order to adjust physical properties such as suitability for coating of the thermoplastic resin composition as described above. As other additives, for example, fillers, stabilizers, plasticizers, ultraviolet absorbers, lubricants, antistatic agents, coloring agents, and the like can be used. Specifically, extenders such as magnesium carbonate, aluminum oxide, titanium oxide, and zinc oxide, or white pigments, powders of other inorganic compounds, glass frit, fluorine resin powder, polyolefin resin powder, and the like are used. be able to.

As the electrically insulating substrate used in the present invention, those having flexibility and electrical insulation, for example, various synthetic resin films, can be used, and especially, those having heat resistance are preferable. Examples of such a material include polyethylene terephthalate, polyimide, polyamide imide, polyester imide, polyphenylene sulfide, and polyethylene naphthalate. In the present invention, a polyethylene terephthalate film is particularly preferred in view of cost and workability. The thickness of the film of the electrically insulating substrate is usually 4 to 25 μm, preferably 6 to 1 μm.
2 μm.

In the present invention, as the metal thin film provided on the surface of the electrically insulating substrate, one having high conductivity when the thin film is formed can be used. A deposited film of aluminum, silver, copper, nickel, or the like is preferable. Among them, an aluminum vapor-deposited film which is particularly inexpensive is desirable. Note that the metal thin film may be a metal foil, but in the case of a foil, the cost is high. In the present invention, the vapor deposition film has a greater merit. The thicker the metal thin film layer, the higher the shielding properties. However, if the metal thin film layer is too thick, the flexibility is reduced, and the bending suitability and slidability are deteriorated. In addition, in order to increase the thickness of the deposited film, satisfactory results cannot be obtained by one or two depositions, and three or more depositions are required, which is disadvantageous in cost. As a method for forming the deposited film, vacuum deposition, sputtering, CVD, or the like can be used, but vacuum deposition excellent in mass productivity is preferable. The thickness of the metal thin film can be used in the range of 0.04 to 0.2 μm, preferably 0.8 to 0.15 μm. If the thickness of the deposited film is less than 0.04 μm, the shielding effect as a shielding material is insufficient, and the thickness of the deposited film is 0.2 μm.
If it exceeds m, vapor deposition processing must be performed three times or more, which is disadvantageous in cost.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. Example 1 As shown in FIG. 1, a 12 μm thick polyethylene terephthalate (PE)
T) On the film, a metal thin film layer 12 having a thickness of 0.1
An aluminum vapor-deposited film having a thickness of μm is formed, and a conductive / flame-retardant adhesive layer 13 (having a thickness of 33 μm after drying) is formed on the aluminum vapor-deposited film using a hot melt adhesive having the following composition.
To form a film-shaped shield material 1 for a flat cable. Hereinafter, this film-shaped flat cable shielding material 1 is simply referred to as a shielding film 1.

Composition of hot melt adhesive 60% by weight of polyester resin 15% by weight of granular carbon (particle diameter: 0.1 to 1.0 μm) 10% by weight of brominated flame retardant 5% by weight of antimony trioxide 10% by weight of aluminum hydroxide 40 parts by weight of resin solid content and 60 parts by weight of solvent (mixed solvent of 50% methyl ethyl ketone and 50% toluene)
A mixture of

The surface resistance of the conductive / flame retardant adhesive layer 13 of the obtained shield film was 5 Ω / □. Also,
The flame retardancy was 28. The thus produced shield film could be wound up in a roll and transferred. Using this shield film, the shield film is folded in two with the conductive / adhesive layer 13 inside, and a flat cable 2 provided with a ground line is inserted inside the folded shield film 1,
By heating and pressing from the surface of the shield film using a hot plate, the conductive / flame-retardant adhesive layer 13 is applied to the ground line.
, And the shield film 1 and the flat cable 2 were heat-sealed and integrated to produce a shielded flat cable 3 as shown in FIG. The obtained shielded flat cable exhibited a complete shielding effect. In addition, it passed the UL standard flame retardancy test.

[0033]

According to the flat cable shield material of the present invention, when a flat cable with a shield is manufactured using this shield material, since the adhesive layer of the shield material has conductivity, the flat wire has a ground line and a shield. Conduction of the shield layer (metal thin film) of the material can be easily achieved by heating and pressing the shield material on the flat cable, so that the working process is simplified and the production speed is improved, so that the manufacturing cost is reduced. Become cheap. In addition, since the adhesive layer also contains a flame retardant filler together with the conductive filler, the obtained shield material has flame retardancy, and a flat cable with a shield manufactured using this shield material is UL. It can pass the standard flame retardancy test. Furthermore, the flat cable shielding material of the present invention is:
The use of a PET film for the electrically insulating base material and the use of an aluminum vapor-deposited film for the shield layer make it extremely flexible, and shielded flat cables using this shield material have excellent sliding characteristics. It will be.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one example of a flat cable shielding material of the present invention.

FIG. 2 is a schematic plan view showing an example of the shielded flat cable of the present invention.

3 is a schematic cross-sectional view of a shielded flat cable according to the present invention, and FIG. 3 (a) is a schematic cross-sectional view taken along line XY in FIG. (B) is a schematic cross-sectional view showing the layer configuration of (a).

FIG. 4 is a schematic sectional view of a shielded flat cable manufactured using a conventional flat cable shield material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield material for flat cables 2 Flat cable 3 Flat cable with shield 11 Electrically insulating base material 12 Metal thin film 12a Metal foil 13 Conductive / flame retardant adhesive layer 13a Insulating adhesive layer (of shielding material) 14 Conductive filler 15 Flame-retardant filler 21 Ground wire 22 Conductor 23 Flat cable insulating layer 23a PET film 23b Insulating adhesive layer (of flat cable) 24 Conductive cutout (of flat cable insulating layer) 24a Conductive cutout (of insulating adhesive layer) )

Claims (5)

[Claims] 1. A metal thin film layer is formed on one surface of an electrically insulating base material, and a resin composition mainly composed of a thermoplastic resin having heat sealing properties is added to the metal thin film layer by adding a conductive filler and a conductive filler. A shielding material for a flat cable, wherein an adhesive layer having conductivity and flame retardancy is formed using a resin composition containing a flammable filler. 2. The adhesive layer having conductivity and flame retardancy contains 10 to 30% by weight of a conductive filler and 20 to 50% by weight of a flame retardant filler. The shielding material for flat cables described in the above item. 3. The flat cable shielding material according to claim 1, wherein the conductive filler comprises spherical or granular carbon particles. 4. The electric insulating base material is a polyethylene terephthalate film, and the metal thin film layer is a 0.04 to 0.2 μm-thick aluminum vapor-deposited film. Item 4. The flat cable shielding material according to any one of Items 3. 5. A flat cable with a shield, wherein the flat cable shield material according to claim 1 is integrated by heating and pressurizing the flat cable shield material, and a flat cable is provided with a shielding function. .