TW201545882A - Multilayer resin sheet for high-speed transmission flexible flat cable, and high-speed transmission flexible cable - Google Patents

Abstract

The present invention addresses the problem of providing a multilayer resin sheet for a high-speed transmission flexible flat cable, the multilayer resin sheet being capable of forming a high-speed transmission flexible flat cable having a desired characteristic impedance and a low dielectric loss. The present invention is a multilayer resin sheet for a high-speed transmission flexible flat cable laminated between a conductor layer installed in a predetermined pattern and a shield layer laminated on at least one of the outer surface sides of the conductor layer, wherein the multilayer resin sheet for a high-speed transmission flexible cable is provided with: a base film; a flame retardant layer laminated on the inner surface side of the base film, the flame retardant layer containing a flame retardant; and a conductor-surrounding layer laminated on the inner surface side of the flame retardant layer, no flame retardant being contained in the conductor-surrounding layer. The flame retardant layer preferably has an average thickness of 10-300 [mu]m. The flame retardant layer preferably has an average thickness of 25%-90% of the overall average thickness.

Description

Multi-layer resin sheet for high-speed transmission of flexible flat cable and high-speed transmission flexible flat cable

The present invention relates to a multilayer resin sheet for high-speed transmission of a flexible flat cable and a high-speed transmission flexible flat cable.

As a wire for internal wiring of an electronic device, a multi-core flat flexible flat cable is used. This flexible flat cable is manufactured by laminating a plurality of strip-shaped conductors in parallel between two sheets of insulating resin sheets, and integrating them by a pressure heating step such as a heat lamination step.

In particular, in a digital machine or the like, a flexible flat cable is used for transmitting a digital signal. In the case of transmitting a digital signal, it is preferable to block electromagnetic noise from the outside. Therefore, a flexible flat cable having a conductive shielding layer in the outer layer of the resin sheet is often used. Moreover, in order to accurately transmit a high frequency signal, it is necessary to integrate a characteristic impedance between a circuit or the like and a flexible flat cable.

Therefore, it has been proposed to increase the characteristic impedance between the conductor and the shield layer by interposing a low dielectric constant layer containing polyolefin as a main component between the insulating resin sheet mainly composed of polyester and the shield layer. (Refer to JP-A-2008-047505).

Further, there is also proposed a resin sheet (insulating tape) for a flexible flat cable which has a characteristic impedance formed by laminating an insulating resin film and an adhesive layer made of a foamed resin next to the conductor (Japanese special Japanese Patent Publication No. 2008-251261).

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-047505

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-251261

Since the industry requires flame retardancy for a flexible flat cable, the resin sheet for a flat cable needs to contain a flame retardant. In the configuration of the resin sheet for a flexible flat cable disclosed in Japanese Laid-Open Patent Publication No. 2008-047505, the resin disposed around the conductor contains a flame retardant material, so that the dielectric constant cannot be sufficiently lowered. When a high frequency signal is transmitted, a dielectric loss is generated.

Further, in the configuration of Japanese Laid-Open Patent Publication No. 2008-251261, the resin of the resin in the vicinity of the conductor is crushed by the thermocompression bonding at the time of forming the flat cable or the bending when the flat cable is used, thereby causing the resin in the vicinity of the conductor. The electric constant changes, so it is not easy to adjust the characteristic impedance of the flat cable.

The present invention has been made in view of the above circumstances, and it is an object of the invention to provide a multilayer resin sheet for a high-speed transmission flexible flat cable capable of forming a high-speed transmission flexible flat cable having a desired characteristic impedance and a small dielectric loss. And high-speed transmission of flexible flat cable.

The invention completed in order to solve the above problems is a multilayer resin sheet for high-speed transmission of a flexible flat cable, which is laminated between a conductor layer and a shield layer which are disposed in a specific pattern, wherein the shield layer is laminated on the conductor At least one outer side of the layer, the resin sheet is provided with a base film; a flame-retardant layer laminated on the inner surface side of the base film and containing a flame retardant; and laminated on the inner surface side of the flame-retardant layer and containing no flame retardant The conductor surrounds the layer.

The multilayer resin sheet for high-speed transmission flexible flat cable of the present invention can form a high-speed transmission flexible with a desired characteristic impedance because the dielectric constant and dielectric loss around the conductor layer are tangentially low and fixed. Flat cable for high dielectric transmission of flexible flat cable with reduced dielectric loss.

1, 1a‧‧‧Multilayer resin sheet for high-speed transmission of flexible flat cable

2‧‧‧ basement membrane

3‧‧‧Next layer

4, 4a‧‧‧ flame retardant layer

5, 5a‧‧‧ conductor surrounding layer

6‧‧‧Conductor layer

6a‧‧‧pattern conductor

7, 7a, 8, 8a‧‧‧ insulation

9‧‧‧Shield (shield)

10‧‧‧ resin film

11‧‧‧Metal evaporation

12‧‧‧ Conductive adhesive layer

Fig. 1 is a schematic cross-sectional view showing a multilayer resin sheet for a high-speed transmission flexible flat cable according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing a high-speed transmission flexible flat cable including a multilayer resin sheet for a high-speed transmission flexible flat cable of Fig. 1.

Fig. 3 is a schematic cross-sectional view showing a high-speed transmission flexible flat cable of an embodiment different from that of Fig. 2.

[Description of Embodiments of the Present Invention]

The present invention relates to a multilayer resin sheet for high-speed transmission of a flexible flat cable, which is laminated between a conductor layer and a shielding layer which are disposed in a specific pattern, wherein the shielding layer is laminated on at least one outer side of the conductor layer, the resin The sheet includes: a base film; a flame-retardant layer laminated on the inner surface side of the base film and containing a flame retardant; and a conductor surrounding layer laminated on the inner surface side of the flame-retardant layer and containing no flame retardant.

In the multilayer resin sheet for a high-speed transmission flexible flat cable, when a high-speed transmission flexible flat cable is formed on the outer surface side of the conductor layer, the conductor surround adjacent to the conductor layer Since the winding layer does not contain a flame retardant, the dielectric constant and the dielectric loss tangent become substantially uniform, and the characteristic impedance of the formed high-speed transmission flexible flat cable can be easily adjusted to a desired value. Further, in the multilayer resin sheet for a high-speed transmission flexible flat cable, as described above, the conductor surrounding layer does not contain a flame retardant, and therefore the dielectric constant and dielectric loss tangent of the layer are small. Thereby, the distance between the conductor layer and the shielding layer can be reduced, so that the high-speed transmission flexible flat cable can be thinned, and the formed high-speed transmission flexible flat cable can be dielectrically transmitted when the conductor layer transmits a high-frequency signal. The loss will not increase.

The average thickness of the flame-retardant layer is preferably 10 μm or more and 300 μm or less. As described above, by setting the average thickness of the flame-retardant layer to the above range, it is possible to ensure sufficient flame retardancy and sufficient flexibility.

The average thickness of the flame-retardant layer is preferably 25% or more and 90% or less of the average thickness of the whole. By setting the average thickness of the flame-retardant layer to the above range, sufficient flame retardancy can be ensured, and a sufficient thickness of the base film and the conductor surrounding layer can be ensured.

Preferably, the main resin component of the base film is polyethylene terephthalate or polyphenylene sulfide, and the main resin component of the flame retardant layer is polypropylene. By setting the main component of the resin of the base film and the flame retardant layer to the above materials, good workability and economy can be obtained.

Preferably, the adhesive layer is further provided between the base film and the flame retardant layer. By providing the adhesive layer in this way, the adhesion between the base film and the flame-retardant layer is improved, and reliability can be improved.

Preferably, the above adhesive layer does not contain a flame retardant. Thus, by not blending the flame retardant with the adhesive layer, the characteristic impedance between the conductor layer and the shield layer can be further reduced, and the adhesion between the base film and the flame retardant layer can be further improved. Further, in the case of extrusion molding the subsequent layer, the dross of the flame retardant is not accumulated in the opening of the mold, so that productivity can be improved.

The main resin component of the above-mentioned adhesive layer may be an acid-modified polypropylene. By setting the main resin component of the adhesive layer to the acid-modified polypropylene in this manner, the adhesion between the base film and the flame-retardant layer can be further improved.

Furthermore, the present invention includes a high-speed transmission flexible flat cable having a conductor layer disposed in a specific pattern, a shielding layer laminated on at least one outer side of the conductor layer, and a laminated layer on the conductor layer and the shielding layer In the insulating layer, the insulating layer is a multilayer resin sheet for a high-speed transmission flexible flat cable, and the conductor surrounding layer is in contact with the conductor layer.

In the high-speed transmission flexible flat cable, since the multilayer resin sheet for the high-speed transmission flexible flat cable has a fixed and small dielectric constant, the error of the characteristic impedance is small, and the dielectric loss when the high-frequency signal is transmitted is small.

The average thickness of the conductor surrounding layer between the specific patterns of the conductor layer is preferably 50% or more of the average thickness of the conductor layer. By setting the average thickness of the conductor surrounding layer to the above lower limit or more, the conductor surrounding layer is filled between the conductors of the conductor layer, so that the dielectric loss can be further reduced.

The flame-retardant layer of the multilayer resin sheet for high-speed transmission flexible flat cable may not be filled between specific patterns of the conductor layer. Thereby, the dielectric constant in the vicinity of the conductor layer becomes small, and the dielectric loss can be prevented more effectively.

Here, the "outer side" and "inner side" refer to the side of the high-speed transmission flexible flat cable that is close to the conductor layer as the "inner side" and the opposite side as the "outer side". In addition, the term "main resin component" means a resin component having the highest mass content in the resin component, and is preferably contained in the resin component in an amount of 50% by mass or more. Moreover, the "filling of the flame-retardant layer between the specific patterns of the conductor layer" means a state in which the flame-retardant layer exists in the space between the pattern conductors of the conductor layer. Also, "the conductor layer The average thickness of the conductor surrounding layer between the particular patterns is the average thickness of the conductor surrounding layer between the patterned conductors of the body layer.

[Details of Embodiments of the Present Invention]

Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[Multi-layer resin sheet for high-speed transmission of flexible flat cable]

The multilayer resin sheet 1 for high-speed transmission of a flexible flat cable of FIG. 1 includes a base film 2, an adhesive layer 3 laminated on the inner surface of the base film 2, and a laminate of the inner surface of the adhesive layer 3 and containing a flame retardant. The fuel layer 4; and a conductor layer which is laminated on the inner surface of the flame-retardant layer 4 and which does not contain a flame retardant surrounds the layer 5.

<base film>

As the base film 2, a film mainly composed of an insulating resin is used. Examples of the insulating resin of the base film 2 include polyester, polyphenylene sulfide, and polyamidene. Among them, polyester or polyphenylene sulfide which is versatile is preferable. Here, the main component means a component having the highest mass content, and preferably contains 50% by mass or more.

Examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. Polybutylene naphthalate), polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethylterephthalate, and the like. Among the polyesters, polyethylene terephthalate is preferred from the viewpoints of electrical properties, mechanical properties, cost, and the like.

The base film 2 may be a surface treated surface to improve the adhesion. As the surface treatment, for example, corona treatment can be mentioned. By performing such corona treatment, hydroxyl groups, A polar functional group such as a carbonyl group is introduced to the inner surface side of the base film 2 to impart hydrophilicity. Corona treatment is effective when polyphenylene sulfide is used as the insulating resin. The surface treatment can also be carried out by other methods such as chemical treatment. Of course, the surface treatment such as corona treatment is not limited to the case where polyphenylene sulfide is used as the insulating resin, and may be arbitrarily carried out when other insulating resin is used. Further, in order to improve the adhesion, a known anchor coat agent may be applied to the inner surface side of the base film 2.

The length dimension and the width dimension of the base film 2 may be appropriately set depending on the use and the like. The lower limit of the average thickness of the base film 2 is preferably 6 μm, more preferably 9 μm, still more preferably 12 μm. On the other hand, the upper limit of the average thickness of the base film 2 is preferably 75 μm, more preferably 50 μm, still more preferably 40 μm. If the average thickness does not reach the above lower limit, there is a possibility that sufficient rigidity cannot be ensured. When the average thickness exceeds the above upper limit, sufficient flexibility cannot be ensured.

<Next layer>

Next, layer 3 contains a resin component. The main resin component of the adhesive layer 3 is, for example, a polyolefin. Examples of the polyolefin include a homopolymer of each olefin such as ethylene, propylene, butene, and hexene, or a copolymer of the monomers or a monomer and a non-olefin monomer. Specific examples of the polyolefin include a low-density polyethylene, a linear polyethylene (ethylene-α-olefin copolymer), an ethylene resin such as high-density polyethylene, and an acrylic resin such as polypropylene or an ethylene-propylene copolymer. , poly(4-methylpentene-1), poly(butene-1), ethylene-vinyl acetate copolymer, and acid-modified polycondensation obtained by modifying (treating) maleic anhydride An olefin resin or the like. In particular, as the main resin component of the adhesive layer 3, in order to increase the adhesion between the base film 2 and the flame-retardant layer 4, an acid-modified polyolefin is preferable, and among them, an acid-modified polypropylene is more preferable. Further, the entire resin component may be composed only of the main resin component.

The lower limit of the average thickness of the adhesive layer 3 is preferably 1 μm, more preferably 2 μm. On the other hand, the upper limit of the average thickness of the adhesive layer 3 is preferably 50 μm, more preferably 30 μm. When the average thickness of the adhesive layer 3 is less than the above lower limit, it is difficult to form a uniform layer, and the effect of joining the underlying film 2 and the flame-retardant layer 4 cannot be sufficiently exhibited. When the average thickness of the adhesive layer 3 exceeds the above upper limit, the multilayer resin sheet 1 for high-speed transmission flexible flat cable may be unnecessarily thickened.

Layer 3 may then contain other additives as desired, but preferably does not contain a flame retardant. Then, the layer 3 does not contain a flame retardant, whereby the dielectric constant in the vicinity of the surface of the multilayer resin sheet 1 for the high-speed transmission flexible flat cable can be made small, and the multilayer resin sheet 1 for flexible transmission of the flexible flat cable can be used. When the high-speed transmission flexible flat cable is formed, the characteristic impedance of the conductor layer and the shield layer can be made small. Moreover, when the adhesion layer 4 is formed by the co-extrusion and the flame-retardant layer 4 and the conductor surrounding layer 5, since the flame retardant is not exposed on the surface of the film, the adhesion to the base film 2 becomes high. Further, at the time of extrusion molding, the dross of the flame retardant is not accumulated in the opening of the mold, so that productivity can be improved.

<flammable layer>

The flame-retardant layer 4 contains a resin component and a flame retardant.

(resin component)

The resin component of the flame-retardant layer 4 is, for example, a polyolefin. Examples of the polyolefin include a homopolymer of each olefin such as ethylene, propylene, butene, and hexene, or a copolymer of the monomers or a monomer and a non-olefin monomer. Specific examples of the polyolefin include a low-density polyethylene, a linear polyethylene (ethylene-α-olefin copolymer), an ethylene resin such as high-density polyethylene, and an acrylic resin such as polypropylene or an ethylene-propylene copolymer. Poly(4-methylpentene-1), Poly(butene-1), an ethylene-vinyl acetate copolymer, and an acid-modified polyolefin resin obtained by modifying (treating) maleic anhydride. In particular, when polypropylene is used as the main resin component of the flame-retardant layer 4, it is preferable in terms of heat resistance, low dielectric constant, and cost.

(flammable agent)

Examples of the flame retardant contained in the flame-retardant layer 4 include a metal hydrate-based flame retardant, a halogen-based flame retardant, and a lanthanum-based flame retardant. These may be used alone or in combination of two or more.

Examples of the metal hydrate-based flame retardant include magnesium hydroxide [Mg(OH) ₂ ], aluminum hydroxide [Al(OH) ₃ ], and hydrotalcite. These may be used alone or in combination of two or more.

Examples of the halogen-based flame retardant include chlorinated compounds such as chlorinated paraffin, chlorinated polyethylene, chlorinated polyphenyl, perchloropentacyclodecane, chloro bridge anhydride, and chlorendic acid, and tetrabromo. Halogen-containing compounds such as ethane, tetrabromobisphenol A, hexabromobenzene, decabromodiphenyl ether, tetrabromophthalic anhydride, polydibromophenyl ether, hexabromocyclododecane, ammonium bromide, etc. The organic or inorganic compound may be used alone or in combination of two or more.

Examples of the antimony-based flame retardant include antimony trioxide, antimony trichloride, antimony pentoxide, antimony borate, and antimony molybdate. These may be used alone or in combination of two or more.

The lower limit of the content of the flame retardant is preferably 20 parts by mass, more preferably 40 parts by mass, per 100 parts by mass of the resin component of the flame-retardant layer 4. On the other hand, the upper limit of the content of the flame retardant is preferably 200 parts by mass, more preferably 150 parts by mass, per 100 parts by mass of the resin component of the flame-retardant layer 4. If the content of the flame retardant does not reach the above lower limit, there is a possibility that sufficient flame retardancy cannot be imparted. When the content of the flame retardant exceeds the above upper limit, the strength of the flame retardant layer 4 may become insufficient, or the cost may become excessive.

In the flame-retardant layer 4, in order to improve the effect of the flame retardant, a flame retardant auxiliary may be contained. Examples of the flame retardant auxiliary agent include cerium oxide and the like.

The lower limit of the average thickness of the flame-retardant layer 4 is preferably 10 μm, more preferably 20 μm. On the other hand, the upper limit of the average thickness of the flame-retardant layer 4 is preferably 300 μm, more preferably 200 μm. When the average thickness of the flame-retardant layer 4 is less than the above lower limit, sufficient flame retardancy cannot be imparted to the multilayer resin sheet 1 for high-speed transmission of the flexible flat cable. When the average thickness of the flame-retardant layer 4 exceeds the above upper limit, the flexibility of the multilayer resin sheet 1 for the high-speed transmission flexible flat cable becomes insufficient.

Moreover, the lower limit of the ratio of the average thickness of the flame-retardant layer 4 to the average thickness of the entire multilayer resin sheet 1 for high-speed transmission flexible flat cable 1 is preferably 25%, more preferably 40%. On the other hand, the upper limit of the ratio of the average thickness of the flame-retardant layer 4 is preferably 90%, more preferably 80%. When the ratio of the average thickness of the flame-retardant layer 4 is less than the above lower limit, sufficient flame retardancy cannot be imparted to the multilayer resin sheet 1 for high-speed transmission of the flexible flat cable. When the ratio of the average thickness of the flame-retardant layer 4 exceeds the above upper limit, the dielectric constant in the vicinity of the conductor in the high-speed transmission flexible flat cable becomes high and the dielectric loss increases.

<Conductor surrounding layer>

The conductor surrounding layer 5 is mainly composed of a resin and does not substantially contain a flame retardant. The resin which becomes the main resin component of the conductor surrounding layer 5 is, for example, a polyolefin. Examples of the polyolefin include a homopolymer of each olefin such as ethylene, propylene, butene, and hexene, or a copolymer of the monomers or a monomer and a non-olefin monomer. Specific examples of the polyolefin include a low-density polyethylene, a linear polyethylene (ethylene-α-olefin copolymer), an ethylene resin such as high-density polyethylene, and an acrylic resin such as polypropylene or an ethylene-propylene copolymer. Poly(4-methylpentene-1), Poly(butene-1), ethylene-vinyl acetate copolymer, and acid-modified polyolefin resin, epoxy modified polyolefin, and decane modified by the modification (treatment) of maleic anhydride Polyolefins, etc. In particular, as the main component of the conductor surrounding layer 5, it is preferably an acid-modified polyolefin or an epoxy-modified polyolefin in terms of adhesion to a conductor, low dielectric constant, and cost, and more preferably Acid modified polypropylene and epoxy modified polyolefin.

The lower limit of the average thickness of the conductor surrounding layer 5 is preferably 1 μm, more preferably 3 μm. On the other hand, the upper limit of the average thickness of the conductor surrounding layer 5 is preferably 100 μm, more preferably 50 μm. If the average thickness of the conductor surrounding layer 5 does not reach the above lower limit, there is a possibility that the dielectric loss of the high-speed transmission flexible flat cable becomes large due to the proximity of the flame retardant conductor layer. When the average thickness of the conductor surrounding layer 5 exceeds the above upper limit, the flexibility of the multilayer resin sheet 1 for high-speed transmission flexible flat cable becomes insufficient.

<Manufacturing method>

The method for producing a multilayer resin sheet 1 for a high-speed transmission flexible flat cable includes the steps of: preparing a resin composition for separately forming the adhesive layer 3, the flame-retardant layer 4, and the conductor surrounding layer 5; Forming a film constituting the adhesive layer 3, the flame-retardant layer 4, and the conductor surrounding layer 5; laminating the film constituting the adhesive layer 3, the flame-retardant layer 4, and the conductor surrounding layer 5 on the base film 2 and integrating by thermocompression bonding The steps.

(Resin composition preparation step)

The resin composition for forming the adhesive layer 3, the flame-retardant layer 4, and the conductor surrounding layer 5, respectively, can be prepared by kneading a composition in which other components such as a resin component and a flame retardant are blended by a kneading machine. Examples of the kneading machine include an open roll, a kneader, a 2-axis mixing extruder, and the like.

(film forming step)

Next, the formation of the layer 3, the flame-retardant layer 4, and the conductor surrounding layer 5 can be performed by a melt extrusion method such as a T-die method or an inflation method. Next, the layer 3, the flame-retardant layer 4, and the conductor surrounding layer 5 may be formed into separate films, or may be formed into an integrated three-layer film by co-extrusion.

(hot crimping step)

The three-layer film or the three-layer film formed in the above manner is laminated on the base film 2, and integrated by thermocompression bonding, whereby the multilayer resin sheet 1 for high-speed transmission flexible flat cable can be formed. The thermocompression bonding can be performed, for example, by using a heating laminator having a heating roll, a heating press, or the like. The heating temperature is, for example, about 80 ° C to 200 ° C.

[High-speed transmission flexible flat cable]

The high-speed transmission flexible flat cable of FIG. 2 includes: a conductor layer 6 disposed in a stripe pattern; an insulating layer 7 laminated on the surface of the conductor layer 6, and an insulating layer 8 laminated on the back surface of the conductor layer 6; A shielding layer 9 laminated on the outside of the insulating layer 7 on the front side.

The average thickness of the high-speed transmission flexible flat cable can be, for example, 200 μm or more and 900 μm or less.

<conductor layer>

The conductor layer 6 is formed in a layered shape, and has a stripe pattern in which a plurality of strip-shaped pattern conductors 6a are arranged in parallel with each other. The conductor layer 6 is made of a conductive metal such as copper, tin-plated soft copper, or nickel-plated soft copper. The conductor layer 6 is preferably formed of a foil-shaped conductive metal.

The lower limit of the average thickness of the conductor layer 6 is preferably 10 μm, more preferably 20 μm. On the other hand, the upper limit of the average thickness of the conductor layer 6 is preferably 100 μm, more preferably 50 μm. If the average thickness of the conductor layer 6 does not reach the above lower limit, the mechanical strength of the conductor layer 6 is insufficient to break. If the average thickness of the conductor layer 6 exceeds the above upper limit, the speed is high. The transmission of the flexible flat cable becomes unnecessarily thick, or the flexibility becomes insufficient.

The average thickness of the conductor surrounding layer 5 between the pattern conductors 6a of the conductor layer 6 of the multilayer resin sheet 1 for high-speed transmission of the flexible flat cable is preferably 50% or more, more preferably 70% of the average thickness of the conductor layer 6. %the above. If the average thickness of the conductor surrounding layer 5 does not reach the above lower limit, it is impossible to fill the pattern conductor 6a of the conductor layer 6 only by the conductor surrounding layer 5, and the flame retardant layer 4 containing the flame retardant enters between the pattern conductors 6a. Therefore, the dielectric constant between the pattern conductors 6a becomes high and the loss of the high-frequency signal transmission of the pattern conductor 6a becomes large.

<insulation layer>

The insulating layers 7 and 8 are each formed of the multilayer resin sheet 1 for a high-speed transmission flexible flat cable of Fig. 1 . The two multilayer resin sheets 1 for high-speed transmission flexible flat cable are laminated on both sides of the conductor layer 6 so that the conductor surrounding layer 5 abuts against the conductor layer 6, and are thermocompression bonded. By the thermocompression bonding, the conductor surrounding layers 5 of the multilayer resin sheets 1 for the high-speed transmission flexible flat cable 1 are filled between the pattern conductors 6a, and are welded and integrated. As described above, the two multilayer resin sheets 1 for the high-speed transmission flexible flat cable constituting the insulating layers 7 and 8 may be the same, or the materials or thicknesses of the respective layers may be different from each other.

<shield layer>

The shielding layer 9 is used to reduce electromagnetic interference and noise, and may be formed into a layered material. Such a shielding layer 9 can be formed, for example, by attaching a commercially available shielding tape.

For example, the inner surface of the insulating resin film 10 such as a polyethylene terephthalate resin having a thickness of 9 μm can be used, for example, by vapor-depositing a conductive metal such as silver to form a metal. On the inner surface of the metal deposition layer 11, the vapor deposition layer 11 is coated with a conductive adhesive such as silver paste to a thickness of 20 μm to form a conductive adhesive layer 12. Replace the party The shielding layer 9 can also be formed by coating a conductive coating or a metal foil.

<Manufacturing method>

The method for manufacturing the high-speed transmission flexible flat cable can be manufactured by a manufacturing method comprising the steps of forming the insulating layer 7 on the both sides of the conductor layer 6 by the high-speed transmission of the multilayer resin sheet 1 for a flexible flat cable. Step 8; and a step of forming a shielding layer 9 by attaching a shielding tape to the outer surface of the insulating layer 7 on the front side.

(insulation layer forming step)

In the insulating layer forming step, the multilayer resin sheet 1 for high-speed transmission of the flexible flat cable is laminated on the front and back surfaces of the conductor layer 6, and the laminated body is thermocompression bonded. The multilayer resin sheet 1 for high-speed transmission flexible flat cable is laminated so that the conductor surround layer 5 abuts against the conductor layer 6, and the conductor surround layer 5 is filled between the pattern conductors 6a of the conductor layer 6 by thermocompression bonding. Further, the conductors of the multilayer resin sheet 1 for the high-speed transmission flexible flat cable of the high-speed transmission are welded to each other around the layer 5. Thereby, the insulating layer 7 on the front side and the insulating layer 8 on the back side are integrated with the conductor layer 6. The thermocompression bonding can be performed, for example, by using a heating laminator having a heating roll, a heating press, or the like. The heating temperature is set to, for example, about 80 ° C to 200 ° C.

(Shield layer forming step)

In the shield layer forming step, the shield layer 9 is formed by attaching a shield tape to the outer surface of the insulating layer 7 on the surface side.

[Advantage]

When the high-speed transmission flexible flat cable is formed by using the multilayer resin sheet 1 for a high-speed transmission flexible flat cable, the flame-retardant layer 4 and the conductor surrounding layer 5 can be laminated on the multilayer resin sheet for the high-speed transmission flexible flat cable. 1 between the shielding layer 9 on the outer surface side and the conductor layer 6 laminated on the inner side, An insulating layer 7 having a small dielectric constant is formed. Therefore, the characteristic impedance of the high-speed transmission flexible flat cable can be set to a desired value without laminating other films or the like.

Further, in the high-speed transmission flexible flat cable of the multilayer resin sheet 1 for high-speed transmission of a flexible flat cable, a conductor surrounding layer 5 having a particularly small dielectric constant is disposed around the conductor layer 6, so that when a high-frequency signal is transmitted The dielectric loss is small.

[Different embodiments of high-speed transmission flexible flat cable]

The high-speed transmission flexible flat cable of Fig. 3 includes a conductor layer 6, an insulating layer 7a, 8a laminated on the front and back surfaces of the conductor layer 6, and a shield layer 9 laminated on the outer surface of the insulating layer 7a on the front side. In the high-speed transmission flexible flat cable of Fig. 3, the conductor layer 6 and the shield layer 9 are the same as those of the conductor layer 6 and the shield layer 9 of the high-speed transmission flexible flat cable of Fig. 2, and therefore, the same reference numerals will be given thereto, and the description thereof will be omitted.

The insulating layers 7a and 8a are formed of a multilayer resin sheet 1a for high-speed transmission of a flexible flat cable.

The multilayer resin sheet 1a for high-speed transmission of a flexible flat cable includes a base film 2, an adhesive layer 3 laminated on the inner surface of the base film 2, and a flame-retardant layer 4a laminated on the inner surface of the adhesive layer 3 and containing a flame retardant. And a conductor layer 5a laminated on the inner surface of the flame-retardant layer 4a and containing no flame retardant.

The base film 2 and the adhesive layer 3 of the multilayer resin sheet 1a for high-speed transmission of the flexible flat cable are the same as the base film 2 and the adhesive layer 3 of the multilayer resin sheet 1 for high-speed transmission flexible flat cable of FIG. Label the same symbols and omit the description. In addition, the flame-retardant layer 4a and the conductor-surrounding layer 5a of the multilayer resin sheet 1a for a flexible flat cable are transported at high speed, and the flame-retardant layer of the multilayer resin sheet 1 for high-speed transmission of the flexible flat cable of FIG. 4 and the conductor is the same around layer 5.

In the high-speed transmission flexible flat cable of FIG. 3, the average thickness of the conductor surrounding layer 5a in the multilayer resin sheet 1a for high-speed transmission flexible flat cable laminated in front of the conductor layer 6 is less than 50% of the average thickness of the conductor layer 6, The conductor surrounding layer 5a is not filled in the entire space between the specific patterns of the conductor layer 6. That is, the average thickness of the conductor surrounding layer 5a between the pattern conductors 6a of the high-speed transmission flexible flat cable of FIG. 3 becomes smaller than 50% of the average thickness of the conductor layer 6. As described above, in the case where the thin layered portion which is in direct contact with the pattern conductor 6a and which causes dielectric loss does not contain the flame retardant, the multilayer resin sheet 1 for high-speed transmission of the flexible flat cable can be used as shown in FIG. The dielectric loss is similarly reduced.

[Other Embodiments]

It is to be understood that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the above-described embodiments, and all modifications within the meaning and scope of the claims are intended to be included within the scope of the claims.

For example, in the multilayer resin sheet for high-speed transmission of a flexible flat cable, the subsequent layer may be omitted.

The high-speed transmission flexible flat cable does not have a shielding layer on only one surface, and may have a shielding layer on both sides.

The method for producing a multilayer resin sheet for a high-speed transmission flexible flat cable can be formed by dissolving a resin composition constituting an adhesive layer, a flame-retardant layer, and a conductor surrounding layer in a solvent, and sequentially coating the resin composition. The inner surface of the base film is laid and dried.

[Examples]

Hereinafter, the present invention will be described based on examples. Furthermore, the present invention is not limited to the embodiments, and modifications and changes may be made to the embodiments based on the gist of the present invention. The modifications and changes are not to be construed as limiting the scope of the invention.

<Multilayer Resin Sheet for High Speed Transmission of Flexible Flat Cable>

In order to verify the present invention, multilayer resin sheets No. 1 to 10 for high-speed transmission of flexible flat cables were produced.

First, in order to form an adhesive layer of a multilayer resin sheet No. 1 to 10 for high-speed transmission of a flexible flat cable, a flame-retardant layer, and a conductor surrounding layer, the following materials A to F were prepared.

(Material A)

To 100 parts by mass of the acid-modified polypropylene, 1 part by mass of an antioxidant was added.

(Material B)

40 parts by mass of the flame retardant, 10 parts by mass of the flame retardant auxiliary, and 1 part by mass of the antioxidant were added to 100 parts by mass of the acid-modified polypropylene.

(Material C)

110 parts by mass of a flame retardant, 30 parts by mass of a flame retardant auxiliary, and 1 part by mass of an antioxidant were added to 100 parts by mass of the polypropylene.

(Material D)

80 parts by mass of a flame retardant, 10 parts by mass of a flame retardant auxiliary, and 1 part by mass of an antioxidant were added to 100 parts by mass of the polypropylene.

(Material E)

To 100 parts by mass of the polypropylene, 1 part by mass of an antioxidant was added.

(Material F)

To 100 parts by mass of the resin composition composed of 90 parts by mass of the epoxy-modified polyolefin and 10 parts by mass of the olefin-based elastomer, 1 part by mass of an antioxidant was added.

As the acid-modified polypropylene, "Admer QE060" from Mitsui Chemicals Co., Ltd. was used as the above-mentioned polypropylene, and "WELNEX RFG4VA" from Japan Polypropylene Co., Ltd. was used as the epoxy-modified polyolefin. As a olefin-based elastomer, "Dynaron 6200P" from JSR Corporation is used as the olefin-based elastomer. As a flame retardant, Albemarle's "SAYTEX 8010" is used as the above-mentioned flame retardant. For the above-mentioned antioxidant, cerium oxide was used, and "Irganox 1076" of BASF Corporation was used.

The subsequent layer, the flame-retardant layer, and the conductor surrounding layer are simultaneously formed by co-extrusion using a plurality of T-dies by a material selected from the above materials A to F, and a three-layer film in which the layers are integrated is obtained. Then, the above-mentioned three-layer film was attached by applying a tackifier to the base film, thereby obtaining a multilayer resin sheet No. 1 to 10 for high-speed transmission of a flexible flat cable.

As the base film, a film made of polyethylene terephthalate having an average thickness of 12 μm was used. Further, as a tackifier, a mixture of "Takelac A-310" and "Takenate A-3" from Mitsui Chemicals Co., Ltd. was used.

The adhesive layer of the multilayer resin sheet No. 1 to 10 for high-speed transmission of the flexible flat cable, the flame-retardant layer, and the conductor-surrounding layer were respectively adjusted to have the average thickness shown in Table 1 using the materials shown in Table 1. The amount.

<High-speed transmission flexible flat cable>

Then, as shown in Table 2, one or two types of the multilayer resin sheets No. 1 to 10 for the high-speed transmission flexible flat cable are used to form an insulating layer, and a high-speed transmission flexible flat cable No. 11 is manufactured. 18. In addition, the high-speed transmission flexible flat cable No. 11 to 18 has a target value of the characteristic impedance of 100 Ω, and the thickness of each layer is selected.

As the conductor layer, a rolled copper foil having a thickness of 35 μm and a width of 0.3 mm was used. The multilayer resin sheet for high-speed transmission flexible flat cable is placed on the front and back of the metal foil and thermocompression bonded so that the conductor surrounding layer abuts against the conductor layer. For thermocompression bonding, a hot roller with a temperature of 140 ° C to 160 ° C is used. By the thermocompression bonding, the conductors of the multilayer resin sheet for the high-speed transmission flexible flat cable of the front and back are softened around the layer and filled in the gaps between the conductors of the conductor layer to be joined to each other.

The vertical burning test was performed on the high-speed transmission flexible flat cables No. 11 to 18 obtained in this manner. Here, the "vertical burning test" refers to the vertical burning test specified in the UL (National Insurer Safety Test) specification. The test results are summarized in Table 2. The test In the test results, the benchmark that satisfies the vertical burning test defined by UL's VW-1 is expressed as good (G), and those who do not satisfy the above criteria are indicated as poor (NG).

Next, the high-speed transmission flexible flat cables No. 11 to 15, 17 and 18 are attached to the outer surface of the insulating layer on the front side, and the high-speed transmission flexible flat cable No. 16 is provided on both sides of the front and back. A shield tape is attached to the outside.

As the above-mentioned shielding tape, silver was vapor-deposited on the inner surface side of a polyethylene terephthalate film having a thickness of 9 μm, and silver paste was applied to the silver vapor deposition surface to a thickness of 20 μm.

The results of measuring the characteristic impedance between the conductor layer of the high-speed transmission flexible flat cable No. 11 to 18 and the surface side shield layer to which the shield tape is attached as described above are collectively shown in Table 2. Here, the characteristic impedance is measured using Agilent Technologies' "Network Analyzer E8362B" and Agilent Technologies' "S-Parameter Test Set N4419B".

As described above, the high-speed transmission flexible flat cable is a high-speed transmission flexible flat cable No. 17 of a multilayer resin sheet No. 9 for high-speed transmission of a flexible flat cable having a small thickness of a flame-retardant layer. It has a flame retardancy comparable to that of the UL specification VW-1. Furthermore, the above-mentioned UL standard VW-1 test is performed without attaching a shield tape, so the above test knot It is different from the flame retardancy under the state of actual use (the state in which the shielding tape is attached).

For the characteristic impedance error, the high-speed transmission flexible flat cables of No.11~18 are within 5% and are within the allowable range.

Further, these high-speed transmission flexible flat cables of No. 11 to 18 each have a conductor surrounding layer which does not contain a flame retardant around the conductor layer, so that the dielectric loss when transmitting a high-frequency signal is small. For example, the No. 15 high-speed transmission flexible flat cable has a loss of about 12 dB at a high frequency of 8 GHz, which is sufficiently low compared to the loss of the previous flexible flat cable (17 to 25 dB).

Claims (10)

A multilayer resin sheet for high-speed transmission of a flexible flat cable, which is laminated between a conductor layer disposed in a specific pattern and a shielding layer, wherein the shielding layer is laminated on at least one outer side of the conductor layer, the resin sheet having: a base film; a flame-retardant layer laminated on the inner surface side of the base film and containing a flame retardant; and a conductor surrounding layer laminated on the inner surface side of the flame-retardant layer and containing no flame retardant. The multilayer resin sheet for a high-speed transmission flexible flat cable according to the first aspect of the invention, wherein the flame-retardant layer has an average thickness of 10 μm or more and 300 μm or less. The multilayer resin sheet for a high-speed transmission flexible flat cable according to the first aspect of the invention, wherein the flame-retardant layer has an average thickness of 25% or more and 90% or less of the entire average thickness. The multilayer resin sheet for a high-speed transmission flexible flat cable according to the first aspect of the invention, wherein the base resin component of the base film is polyethylene terephthalate or polyphenylene sulfide, the flame retardant layer The main resin component is polypropylene. A multilayer resin sheet for a high-speed transmission flexible flat cable according to the first aspect of the invention, further comprising an adhesive layer which is laminated between the base film and the flame-retardant layer. A multilayer resin sheet for a high-speed transmission flexible flat cable according to claim 5, wherein the adhesive layer does not contain a flame retardant. A multilayer resin sheet for high-speed transmission of a flexible flat cable according to claim 5 or 6, wherein the main resin component of the adhesive layer is an acid-modified polypropylene. A high-speed transmission flexible flat cable comprising: a conductor layer arranged in a specific pattern; a shielding layer laminated on at least one outer side of the conductor layer; and an insulating layer laminated between the conductor layer and the shielding layer, the insulating layer being a multilayer resin for high-speed transmission flexible flat cable according to claim 1 a sheet, the conductor surrounding layer is in contact with the conductor layer. A high-speed transmission flexible flat cable according to claim 8 wherein the average thickness of the conductor surrounding layer between the specific patterns of the conductor layer is 50% or more of the average thickness of the conductor layer. The high-speed transmission flexible flat cable according to claim 9, wherein the flame-retardant layer of the multilayer resin sheet for the high-speed transmission flexible flat cable is not filled between the specific patterns of the conductor layer.