JP2013008934A - Impedance adjustment sheet and wiring member with shield - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impedance adjustment sheet exhibiting excellent flexibility, capable of reducing the dielectric constant, easily adaptable to various pitch intervals of signal lines and resistant to flexural stress, and capable of shielding unwanted radiation and adjusting the characteristic impedance when used in a wiring member.SOLUTION: A shield layer 32 composed of a conductive material is provided on one surface of an insulator layer formed of a cloth-like body 31 of thermoplastic resin, and an adhesive layer 33 is provided on the other surface to produce an impedance adjustment sheet. When the impedance adjustment sheet is pasted to one or both surfaces of a wiring member by the adhesive layer 33 so as to cover the wiring member, the characteristic impedance is adjusted and the unwanted radiation is shielded.

Description

  The present invention relates to an impedance adjustment sheet and a shielded wiring member, and more particularly, to a flexible and flexible impedance adjustment sheet that adjusts characteristic impedance and shields unwanted radiation, and a shielded wiring member using the same.

  In recent years, with the increase in the speed of digital electrical appliances and electronic devices, transmission of high-frequency high-speed signals corresponding to high-speed interfaces is also required for cables used therefor. Since such a cable is often folded and incorporated in a narrow space in the device casing, generally, a flexible flat cable (hereinafter referred to as FFC) having a structure excellent in flexibility by arranging signal lines in a line. Is frequently used. FFC is required to have uniformity in characteristic impedance and capacitance as the signal speed increases. In particular, impedance and capacitance matching the connected digital appliances and electronic devices are easy. There is a need for a flexible and flexible FFC that can be adjusted to the same level and can shield unwanted radiation.

  In order to increase the signal transmission speed of the cable, it is necessary to reduce the capacitance. Since the capacitance is inversely proportional to the distance between the conductors and proportional to the area of the conductor, in general, the capacitance can be reduced by increasing the distance between the conductors or reducing the area of the conductor.

  Patent Document 1 describes that the characteristic impedance and capacitance are adjusted to desired values by changing the area facing the signal line by adjusting the aperture ratio of the open metal foil layer. By adjusting the aperture ratio of the apertured metal foil layer (increasing the aperture ratio), the area of the apertured metal foil layer changes (decreases), so even if the thickness of the insulator layer between the signal lines is not changed, The electric capacity can be adjusted (smaller). Since the characteristic impedance correlates with the capacitance, the characteristic impedance can be adjusted by adjusting the capacitance.

  However, as the capacitance is reduced to enable high-speed transmission, the aperture ratio of the aperture metal foil layer has to be increased, which makes it difficult to suppress unnecessary radiation and to suppress unnecessary radiation. A shield layer made of a separate non-open metal foil must be provided. As a result, an increase in the number of laminated metal foil layers not only increases the number of manufacturing steps, but the resulting cable becomes rigid and has a problem of lacking in flexibility and flexibility.

  In Patent Document 2, the shield layer is formed in a strip shape (comb shape) and disposed so as to be orthogonal to the signal circuit, thereby reducing the capacitance between the signal circuit and the shield layer. It describes that the stress received by bending stress is reduced.

  In this case as well, the capacitance can be adjusted by appropriately adjusting the strip shape. However, since the shield layer must be formed in a complicated strip shape, there is a problem that the manufacturing becomes complicated. In addition, when bending stress is applied to the cable, the bending stress concentrates on the narrow part between the strips along the length of the cable, so there is a problem in mechanical strength and repeated bending stress is applied. If this happens, the shield layer may be destroyed.

  Furthermore, since the strip-shaped shield layer has a partially open structure, the interval between the strips must be increased as the capacitance is reduced to enable high-speed transmission. Similar to 1, a separate metal foil layer must be laminated in order to suppress unwanted radiation, and there is a problem of stiffening.

  In Patent Document 3, a microballoon foam layer and an adhesive non-foam layer are sequentially formed on a base film, the non-foam layer faces each other, and a plurality of rectangular conductors arranged at a predetermined pitch are sandwiched. It is described that a flat cable having a stable electrostatic capacity can be obtained by laminating the film into a shape and winding a shield tape around the film.

  Since the capacitance is proportional to the dielectric constant of the insulator, the capacitance can be reduced by the low dielectric constant bubbles (air) in the foam layer, which is the insulator, and the cable should be flexible due to the presence of the bubbles. However, since the foamed layer is inferior in mechanical strength, there is a problem that when repeated bending stress is applied, wrinkles are easily generated and the foam layer is eventually destroyed. In particular, the mechanical strength decreases as the bubble content and the expansion ratio are increased in order to decrease the dielectric constant of the foam layer.

  On the other hand, in order not to reduce the mechanical strength, instead of suppressing the bubble content, if the foam layer is made thick and the capacitance is reduced, the foam layer becomes less flexible as the thickness increases. From the standpoint of obtaining a cable that is soft, flexible, and resistant to bending stress, it is not always satisfactory.

  Patent Document 4 describes that an intermediate intervening layer in which an uneven portion for adjusting a dielectric constant is formed by embossing on the front surface or both surfaces of a plastic film is disposed on the front surface or the back surface of an FFC insulating layer. Yes. The intermediate intervening layer has flexibility due to the concavo-convex portion and can achieve a low dielectric constant.

  According to this, it was thought that the problem seen in Patent Document 3 can be solved because flexibility can be imparted without using a foam layer, but the concave portion is formed by compressing a plastic film with an embossing roll. However, as the density increased locally, it became hard, and the expected flexibility was not obtained. In particular, as the concave portion is deepened to reduce the dielectric constant in order to realize high-speed transmission, the concave portion has to be formed more compressed, and there is a problem that the cable becomes more rigid.

  In order to make the dielectric constant uniform, it is desirable that the concave and convex portions be present in accordance with the pitch intervals of the FFC signal lines. However, concave portions having a pitch suitable for each type of FFC (pitch intervals of the signal lines) are required. Embossing rolls for forming had to be prepared, and there was a problem in terms of manufacturing adaptability to various types of FFCs.

JP 2006-24824 A JP-A-5-235495 Japanese Patent Application Laid-Open No. 8-212434 JP 2010-129475 A

  As a result of intensive studies in view of the above-described problems of the prior art, the present inventor is flexible and excellent in flexibility, can achieve a low dielectric constant, and can easily be applied to various pitch intervals of signal lines. The present inventors have found a new insulator layer structure that can be applied and is resistant to bending stress, and has reached the present invention.

  In other words, the present invention is soft and excellent in flexibility, can have a low dielectric constant, can be easily adapted to various pitch intervals of signal lines, is strong in bending stress, and is used for a wiring member. An object of the present invention is to provide an impedance adjustment sheet that can shield unwanted radiation and adjust characteristic impedance.

  In addition, the present invention can shield unwanted radiation, is soft and flexible, can have a low dielectric constant, and can be easily applied to various pitch intervals of signal lines. It is an object of the present invention to provide a shielded wiring member having an adjusted characteristic impedance having a structure strong against bending stress.

  Furthermore, the other subject of this invention becomes clear by the following description.

  The above problems are solved by the following inventions.

(Claim 1)
A shield layer made of a conductive material is provided on one surface of an insulator layer formed of a cloth-like body of thermoplastic resin, and a pressure-sensitive adhesive layer is provided on the other surface. An impedance adjustment sheet characterized in that the characteristic impedance is adjusted by adhering to one side or both sides and covering the wiring member and shielding unwanted radiation.

(Claim 2)
2. The impedance adjusting sheet according to claim 1, wherein the cloth-like body is formed of a woven cloth or a cross-bonded cloth formed by a linear body obtained by uniaxially stretching a thermoplastic resin.

(Claim 3)
A wiring member body in which signal lines are arranged in parallel;
A shield layer made of a conductive material is provided on one surface of an insulator layer formed by a cloth-like body of thermoplastic resin, and an impedance adjustment sheet having an adhesive layer provided on the other surface.
With the shield, the characteristic impedance of the wiring member main body is adjusted and unnecessary radiation is shielded by attaching the impedance adjusting sheet to one side or both sides of the wiring member main body and covering the same. Wiring member.

(Claim 4)
4. The shielded wiring member according to claim 3, wherein the cloth-like body is made of a woven cloth or a cross-bonded cloth formed by a linear body obtained by uniaxially stretching a thermoplastic resin.

  According to the present invention, it is flexible and excellent in flexibility, can have a low dielectric constant, can be easily adapted to various pitch intervals of signal lines, is strong in bending stress, and used for wiring members. Thus, it is possible to provide an impedance adjustment sheet that can shield unwanted radiation and adjust the characteristic impedance.

  Further, according to the present invention, unnecessary radiation can be shielded, flexible and excellent in flexibility, low dielectric constant can be achieved, and easily adapted to various pitch intervals of signal lines. It is possible to provide a shielded wiring member having a characteristic impedance that is adjustable and has a structure that is resistant to bending stress.

The perspective view of FFC with a shield formed by laminating the impedance adjustment sheets according to the present invention Plan view showing partially cut off FFC with shield (A) Cross-sectional view of a cloth-like body formed of a woven fabric, (b) Cross-sectional view of a cloth-like body formed of a cross-bonded cloth Partial plan view of cloth-like body The top view which shows another aspect of FFC with a shield partly broken and shows (A) is a cross-sectional view of a striate body made of a single layer, (b) is a cross-sectional view of a striate body having a bonding layer on one side of the base layer, and (c) is a striated body having a bonding layer on both sides of the base layer. Cross section (A) is a cross-sectional view of a shielded FFC in which an impedance adjustment sheet is laminated on both sides of the FFC main body, and (b) is a cross-sectional view of a shielded FFC in which an impedance adjustment sheet is wound around and coated around the FFC main body. (A) (b) is sectional drawing which shows the grounding aspect of the shield layer of an impedance adjustment sheet The figure explaining the relationship between the flexibility of a shielded FFC and the signal transmission speed

  The impedance adjustment sheet according to the present invention is provided with a shield layer made of a conductive material on one surface of an insulator layer formed of a cloth-like body of a thermoplastic resin and an adhesive layer on the other surface. Thus, the characteristic impedance is adjusted and unnecessary radiation is shielded by adhering to one or both sides of the wiring member with an adhesive layer and covering the wiring member.

  Although the cloth-like body is excellent in softness and flexibility and will be described in detail later, it can achieve a lower dielectric constant than a resin sheet having the same material and the same thickness. In addition, since it is not necessary to contain air bubbles as in the foamed layer, it is difficult to be destroyed even when repeated bending stress is applied, and it has excellent mechanical strength. It is possible to finely adjust the characteristics by appropriately adjusting.

  Therefore, a cloth-like body is used as the insulator layer, and a shield layer made of a conductive material is provided on one surface of the insulator layer, so that it is soft and flexible, has a low dielectric constant, and various signal lines. Therefore, it is possible to provide an impedance adjustment sheet that can be easily adapted to a large pitch interval and is resistant to bending stress.

  The capacitance (characteristic impedance) can be adjusted by adjusting the thickness of the cloth-like body serving as the insulator layer. However, as described above, the cloth-like body has flexibility and flexibility. Even if the thickness is increased in order to reduce the capacity, sufficient flexibility and flexibility can be maintained.

  In the present invention, the cloth-like body is preferably made of a woven cloth or a cross-bonded cloth formed by a linear body obtained by uniaxially stretching a thermoplastic resin. By uniaxially stretching, it is possible to obtain a cloth-like body having superior mechanical strength, and by adjusting the width and the number of driven wires, a desired cloth-like body having flexibility and flexibility can be easily obtained. Can be formed.

  The shielded wiring member according to the present invention includes a wiring member main body in which signal lines are arranged in parallel and the above-described impedance adjustment sheet, and the impedance adjustment sheet is attached to one side or both sides of the wiring member main body and covered. Thus, the characteristic impedance of the wiring member body is adjusted and unnecessary radiation is shielded.

  The wiring member in the present invention is not particularly limited as long as the signal lines are arranged in parallel and an electric signal is transmitted through the signal lines, but a flat and flexible member is particularly preferable. Such a wiring member may be an FPC (flexible printed circuit) or the like in addition to FFC, and may be a wiring member that has to adjust characteristic impedance and capacitance and shield unwanted radiation. The present invention can be applied.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an example of a shielded wiring member formed by laminating an impedance adjustment sheet according to the present invention, and shows an end portion in section. FIG. 2 is a plan view of the shielded wiring member, partially broken away. Here, FFC is illustrated as the wiring member.

  The shielded FFC 1 includes an FFC main body 2 and an impedance adjustment sheet 3 laminated on the upper surface side of the FFC main body 2.

  The FFC main body 2 is a flat and flexible cable in which a large number of signal lines (including ground lines) 21 are arranged in parallel at a predetermined pitch, and these signal lines 21 are covered with an insulating resin layer 22. .

  In the impedance adjustment sheet 3, an insulating layer is formed by a cloth-like body 31 made of a thermoplastic resin, and a shield layer 32 made of a conductive material is provided on one surface of the cloth-like body 31. An adhesive layer 33 is provided on the other surface. Further, a surface layer 34 for insulating and protecting the shield layer 32 is provided on the surface of the shield layer 32. Then, the adhesive layer 33 is laminated so as to be in contact with the upper surface of the FFC main body 2, and the FFC 1 with shield is configured by being adhered to the FFC main body 2 by the adhesive layer 33.

  In the impedance adjustment sheet 3 according to the present invention, the cloth-like body 31 is formed by a linear body made of a thermoplastic resin. In particular, as shown in FIG. 3 (a), uniaxially stretched thermoplastic resin filaments 31a and 31b are used as warps and wefts to form a woven fabric, or as shown in FIG. 3 (b). In addition, a large number of thermoplastic resin filaments 31b are arranged in parallel on the thermoplastic resin filaments 31a so as to be orthogonal to the filaments 31a, and the intersections thereof are joined. A cross-bonded cloth (soft) is preferred.

  The filaments 31a and 31b may be monofilaments, flat yarns, split yarns, short fibers, long fibers, etc., among which flat yarns are preferred.

  In the present invention, the reason why the dielectric constant can be reduced by using such a cloth-like body 31 as the insulator layer of the impedance adjustment sheet 3 is considered to be as follows.

  FIG. 4 shows a partial plan view of a cloth-like body 31 made of a woven fabric woven with the filaments 31a and 31b as warps and wefts, respectively. As shown in FIG. Slight gaps S are formed between the linear bodies 31a to be formed, between the linear bodies 31b to be the wefts, and between the linear bodies 31a to be the warps and the linear bodies 31b to be the wefts. The cloth-like body 31 has such a space S, and a portion where the striates overlap each other and a portion where the other striates pass between the adjacent striates and the surface is uneven as a whole. Therefore, compared to a resin sheet having the same thickness (total thickness of the filaments 31a and 31b), it exhibits an effect that is excellent in flexibility and flexibility. In this case, the voids S are regularly and uniformly distributed, so that there are portions where the linear bodies 31a and 31b are partially absent. The same can be said for the cloth-like body 31 made of the cross-bonded cloth shown in FIG.

  For this reason, in the insulator layer made of the cloth-like body 31, the region made of the thermoplastic resin filaments 31a and 31b and the region of the void S where the filaments 31a and 31b do not exist are regularly mixed. In other words, the presence of air in the void S, or the absence of the resin constituting the filaments 31a and 31b in the void S, indicates that the dielectric constant of the insulating layer as the entire cloth-like body 31 is present. It is thought that it contributes to lowering. As a result, the cloth-like body 31 using the linear bodies 31a and 31b is lower than the insulating layer which is simply formed into a flat resin sheet using the same thermoplastic resin as the linear bodies 31a and 31b. The dielectric constant can be increased.

  As a result, the shielded FFC 1 formed by laminating the impedance adjustment sheet 3 can be made more flexible and have a lower capacitance. Therefore, as shown in FIG. 9, the insulator layer is a non-cloth body. Compared to FFC (broken line), when the flexibility is the same, the signal transmission speed can be further increased, and when the signal transmission speed is the same, the FFC can be more flexible.

  Moreover, the cloth-like body 31 made of thermoplastic resin is resistant to bending stress, can flexibly follow even when subjected to repeated bending stress, and has superior durability compared to an insulating layer made of a conventional foamed layer. It can be.

  The capacitance of the shielded FFC 1 can be adjusted by adjusting the thickness of the cloth-like body 31 of the impedance adjustment sheet 3, but the thickness of the cloth-like body 31 is the linear body 31a used. , 31b can be easily adjusted by appropriately adjusting the thickness. By using the cloth-like body 31, the surface has an uneven shape. Therefore, strictly speaking, it is considered that the thickness is different between the concave portion and the convex portion, and the capacitance is slightly changed. Since the distribution is regularly and uniformly over the entire area 31, the capacitance of the shielded FFC 1 as a whole can be made substantially uniform.

  Moreover, the cloth-like body 31 can adjust the magnitude | size and pitch of the space | gap S easily by adjusting the width | variety and the pitch (the number of driving-in) of the linear bodies 31a and 31b suitably. In particular, the size and pitch of the gaps S greatly affect the flexibility and flexibility of the cloth-like body 31. For example, the thickness of the filaments 31a and 31b itself increases, or the filaments When the resin itself of the bodies 31a and 31b is relatively poor in flexibility, and the flexibility and flexibility are reduced, the size and pitch of the voids S are appropriately adjusted, so that the desired flexibility and possible Flexibility can be maintained.

The specific size of the gap S is finely adjusted as appropriate depending on the required dielectric constant, capacitance, flexibility, and the like, but is 15 μm × 15 μm to 2000 μm × 2000 μm. Moreover, the ratio of the space | gap S in the impedance adjustment sheet 3 whole, ie, the porosity calculated by the following formula, is 0.1 to 80%, preferably 1 to 75%, and more preferably 3 to 50%. If the size and the porosity of the gap S are both smaller than the above range, it is difficult to sufficiently reduce the electrostatic capacity only by adjusting the gap S and the porosity, and if the gap S is larger than the above range, the mechanical strength is increased. It becomes insufficient.

  The dielectric constant of the cloth-like body 31 adjusted by the size of the gap S is very small. In other words, the dielectric constant of the cloth-like body 31 can be adjusted by appropriately adjusting the size and pitch of the gap S. It can be said that the flexibility and flexibility can be appropriately adjusted without greatly changing.

  FIG. 2 shows a mode in which one of the warp or the weft of the cloth-like body 31 is laminated on the FFC main body 2 so that one of the warps or the weft is along the length direction of the signal line 21 and the other is perpendicular to the length direction of the signal line 21. However, by making the width and pitch of the linear bodies 31a and 31b coincide with the width and pitch of the signal lines 21, for example, the intersections of the linear bodies 31a and 31b and the gaps S are connected to each signal line 21. It is easy to make the cloth-like body 31 adjusted so as to be uniformly distributed. Therefore, according to the impedance adjustment sheet 3, even when the gap S is arranged in accordance with the width and pitch of the signal line 21 of the FFC main body 2, various types of FFC main bodies 2 having different widths and pitch intervals of the signal lines 21 are provided. It can be easily adapted to.

  In addition, the cloth-like body 31 in the impedance adjustment sheet 3 is not limited to the mode shown in FIG. 2, and as shown in FIG. 5, the linear bodies 31 a and 31 b are in the length direction of the signal line 21 of the FFC main body 2. It is good also as an aspect arrange | positioned so that it may become diagonal.

  As the linear bodies 31a and 31b of the thermoplastic resin used for the cloth-like body 31, as shown in FIG. 6 (a), a single layer of crystalline resin may be used, or FIG. 6 (b). As shown in FIG. 6, a low melting point bonding layer 311 may be laminated on one side of the base layer 310, and as shown in FIG. 6C, the low melting point bonding layer 311 is formed on both sides of the base layer 310. May be laminated.

  As the synthetic resin constituting the single layer body of the linear bodies 31a and 31b of the thermoplastic resin or the base layer 310 of the laminated body, a resin having a large stretching effect, generally a crystalline resin is used, and high density polyethylene, polypropylene, Polyolefins such as ethylene / propylene copolymers, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, and the like can be used.

  Among these, polyolefins such as polyethylene, polypropylene, and polyethylene terephthalate having a low dielectric constant and good workability and economy are preferable. In particular, polyethylene is preferable, and high density polyethylene is most preferable.

The high density polyethylene has a density of 0.930 to 0.970 g / cm ³ , preferably 0.940 to 0.960 g / cm ³ , and an MFR of 0.2 to 10.0 g / 10 minutes, preferably 0.3. The thing of -3.0 g / 10min is preferable.

  The joining layer 311 joins the filaments 31a and 31b after being formed into a cloth by the filaments 31a and 31b, and has a lower melting point than the synthetic resin constituting the base layer 310 and excellent thermal fusion properties. A synthetic resin is used.

  Specifically, polyolefins such as polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinyl acetate copolymer, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides of nylon 6, nylon 66, and the like can be used. A synthetic resin having a lower melting point than the base layer 310 is selected.

  Various additives can be added to the synthetic resin used as the base layer 310 or the bonding layer 311 depending on the purpose.

  Specifically, organic phosphorus-based, thioether-based antioxidants; hindered amine-based light stabilizers; benzophenone-based, benzotriazole-based, benzoate-based ultraviolet absorbers; anti-static agents; bisamide-based, wax-based, Dispersants such as organic metal salts; lubricants such as amides and organic metal salts; flame retardants such as bromine-containing organic, phosphoric acid and antimony trioxide; organic pigments; inorganic pigments; inorganic fillers and organic fillers An inorganic or organic antibacterial agent such as a metal ion type.

  These additives are appropriately combined and blended in any process for producing the material composition of the base layer 310 and the bonding layer 311. The blending of the additive may be prepared by mixing at a predetermined ratio using a kneading device such as a conventional known twin screw extruder, Banbury mixer, kneader, mixing roll, and melt-kneading the mixture. A so-called master batch having a high concentration may be prepared and used after being diluted.

  When the laminated body of the base layer 310 and the bonding layer 311 is used as the filaments 31a and 31b, as a means for forming a laminated film as a molding material, a film to be the base layer 310 and a film to be the bonding layer 311 are formed in advance. Then, a means for forming a multilayer by using a dry laminating method or a thermal laminating method, a method of coating a synthetic resin to be the bonding layer 311 on the surface of the film to be the base layer 310, a bonding layer to the film to be the base layer 310 previously formed 311 can be appropriately selected from known means such as extrusion lamination or extrusion molding as a laminated film by multilayer coextrusion. Among these, in terms of ease of molding, cost, and adhesiveness between each layer of the product, a method of obtaining a laminated body of the base layer 310 and the bonding layer 311 in a single step by a multilayer coextrusion method is preferable.

  In addition, as a means for stretching and forming the filaments 31a, 31b, it can be performed by a known method in the case of a single layer, and in the case of a laminate, after stretching the film to be the base layer 310 in a uniaxial direction, A synthetic resin to be the bonding layer 311 may be laminated and slit in a tape shape, or before or after slitting the laminated film in which the base layer 310 and the bonding layer 311 are laminated, It can also be obtained by stretching. The draw ratio is usually about 3 to 10 times.

  The uniaxially stretched flat yarn obtained in this way can be made into a split yarn by making small cuts in the longitudinal direction. Moreover, as the filaments 31a and 31b, monofilaments stretched uniaxially can be used.

  As shown in FIG. 3A, the filaments 31a and 31b are woven fabrics such as plain weave and twill, and as shown in FIG. 3B, a large number of filaments 31a are arranged in one direction. The cloth-like body 31 is formed by arranging a large number of linear bodies 31b in a direction orthogonal thereto and forming a cross-bonded cloth (soft) joining the intersections.

  The cloth-like body 31 is joined at the intersection of the line bodies 31a and 31b as necessary. As a method of joining the intersections of the linear bodies 31a and 31b, it can be bonded with a hot melt adhesive, and the linear bodies 31a and 31b are bonded to the bonding layer 311 shown in FIGS. 6B and 6C. Can be bonded by melting and bonding the bonding layer 311 by thermocompression using a heat roll.

  There are no restrictions on the thickness and width of the filaments 31a and 31b. The width and pitch of the signal line 21 of the FFC main body 2 to be laminated, the capacitance required for the shielded FFC 1 (characteristics) Impedance), flexibility, flexibility, etc., can be arbitrarily set. Generally, it is preferable that the range is 50 to 10,000 dt (decitex) and the yarn width is 0.3 to 10 mm.

  As shown in FIG. 3, a thermoplastic resin layer 31 c can be further laminated on the cloth-like body 31 of the impedance adjustment sheet 3. In FIG. 3, the thermoplastic resin layers 31 c are laminated on both sides of the cloth-like body 31, but only one side may be used. By laminating the thermoplastic resin layer 31c, prevention of misalignment of the linear bodies 31a and 31b can be further ensured.

  Even when the thermoplastic resin layers 31c are laminated on both surfaces of the cloth-like body 31, the gap S remains between the filaments 31a and 31b, and the gap S has the filaments 31a and 31b. Therefore, the function of the gap S described above is not completely lost.

  As a material used as the thermoplastic resin layer 31c, polyolefin such as polyolefin, polyethylene terephthalate, polybutylene terephthalate, and the like, polyamide such as nylon 6, nylon 66, and the like can be used. Of these, polyolefin is preferable. A homopolymer such as ethylene, propylene, butene-1, hexene-1, octene-1, and decene-1, or a copolymer containing these as a main component can be used.

  In particular, it is preferable to use a polyolefin polymerized using a metallocene catalyst, preferably polyethylene, polypropylene, or ethylene-α-olefin copolymer.

  The bonding of the cloth-like body 31 and the thermoplastic resin layer 31c can be performed by a publicly known means, and a method of superimposing the thermoplastic resin layer 31c on the cloth-like body 31 and thermocompression bonding using a hot roll, A method of extruding and laminating a resin that becomes the thermoplastic resin layer 31c on the cloth-like body 31 to form a film, and adhering the thermoplastic resin layer 31c to the cloth-like body 31 with an adhesive such as a hot melt agent. You can also.

  Although the thickness of the thermoplastic resin layer 31c can be arbitrarily selected according to the purpose, in general, each layer is preferably 10 to 100 μm, and more preferably 15 to 40 μm.

  The thickness of the cloth-like body 31 is a factor for prescribing the electrostatic capacity (characteristic impedance) when the shielded FFC 1 is configured, is appropriately adjusted to obtain a desired value, and is not limited at all. Although not intended, it can be 10 μm to 1000 μm. If it is this range, it will be soft and excellent in flexibility rather than making it the resin sheet of equivalent thickness, and can be used conveniently as an impedance adjustment sheet. When the thermoplastic resin layer 31c is provided, the thickness of the cloth-like body 31 includes the thickness of the thermoplastic resin layer 31c.

  When the cloth-like body 31 becomes thinner than the lower limit value of the thickness, the capacitance becomes large and becomes unsuitable for high-speed transmission. When the upper limit value of the thickness is exceeded, the size and porosity of the gap S are increased. Even if the adjustment is made, the impedance adjustment sheet 3 tends to become rigid. More preferably, it is 50 μm to 300 μm.

  In the impedance adjustment sheet 3, the shield layer 32 does not need to be formed with an opening for adjusting the capacitance as in the prior art, and a layered body made of a conductive material having a flat surface is used to shield unwanted radiation. It takes on the (shielding) function. Such a conductive material is not particularly limited as long as it is a conductive material capable of shielding unwanted radiation. For example, a metal such as copper, silver, nickel, aluminum, and stainless steel; conductive zinc oxide, conductive indium oxide, conductive Metal oxides such as titanium oxide and conductive tin oxide; conductive carbon such as acetylene black, oil furnace black, thermal black, graphite, and carbon nanotube; one or more conductive polymers such as polypyrrole and polyaniline Can be used in combination. Among these, copper, silver, and aluminum are preferable because they are excellent in conductivity and flexibility.

  The shield layer 32 can be attached to the cloth-like body 31 via a pressure-sensitive adhesive layer (not shown) formed in a thin film shape with a conductive material. In addition, a thin film made of a conductive material may be provided on one surface of the cloth-like body 31 by vapor deposition or sputtering.

  The thickness of the shield layer 32 can be 0.1 μm to 2,000 μm. If the thickness is lower than the lower limit value, it becomes difficult to adjust the shield for unnecessary radiation and the capacitance, and if the upper limit value is exceeded, it becomes over spec and causes rigidity. More preferably, it is 0.4 μm to 200 μm.

  The pressure-sensitive adhesive layer 33 is laminated on the other surface of the cloth-like body 31 (the surface opposite to the shield layer 32). The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 33 has tackiness at room temperature, and is different from a material that exhibits an adhesive function by being cured by a curing process like an adhesive.

The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 33 has a storage elastic modulus measured using a dynamic viscoelasticity measuring device having a conical / disk-shaped measuring surface at a temperature of 23 ° C. and a frequency of 1 Hz, preferably 10 ³ Pa. The range is 10 ⁷ Pa or less, more preferably 10 ⁴ Pa or more and 10 ⁶ Pa or less. If it is in said range, since adhesiveness will not become insufficient and the appropriate balance of adhesive force and cohesion force is maintained, it is preferable as the impedance adjustment sheet 3 stuck on the FFC main body 2. FIG.

  The glass transition temperature of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 33 is preferably −20 ° C. or lower, more preferably −30 ° C. or lower. If it is the glass transition temperature below this value, since it has the outstanding adhesiveness and the adhesion to the FFC main body 2 becomes easy, it is preferable as the impedance adjustment sheet 3 stuck on the FFC main body 2.

  The weight average molecular weight of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 33 is preferably 50,000 or more, more preferably 150,000 to 1,500,000, and most preferably 200,000 to 1,000. , 000. If it is above this lower limit value, the adhesive force and cohesive force of the obtained pressure-sensitive adhesive layer 33 have a good balance, so it is preferable as the impedance adjustment sheet 3, and if it is below the upper limit value, the pressure-sensitive adhesive layer 33 In the application of the pressure-sensitive adhesive solution at the time of forming a suitable coating viscosity can be obtained without reducing the solid content so much, the pressure-sensitive adhesive layer 33 can be formed by drying in a relatively short time, Since the amount of the organic solvent to be volatilized can also be suppressed, the impedance adjustment sheet 3 is preferable both economically and environmentally.

  That is, the impedance adjustment sheet 3 is adhered to the wiring member such as the FFC main body 2 to be laminated by the adhesive layer 33 and is not cured, so that the wiring member is the FFC main body 2. Even in such a flexible case, the flexibility is not impaired.

  Specific adhesives used for the adhesive layer 33 include, for example, acrylic resin adhesives, rubber adhesives such as natural rubber and synthetic rubber, styrene-butadiene-styrene block copolymers, and styrene-isoprene-styrene blocks. Examples include copolymers and block copolymer adhesives such as hydrogenated products, ethylene-vinyl acetate copolymer adhesives, polyvinyl ether resin adhesives, silicone resin adhesives, among others, durability and weather resistance. An acrylic resin-based pressure-sensitive adhesive that is excellent in properties and has little dirt during handling is preferably used. These pressure-sensitive adhesives may be used alone or in combination of two or more.

  As the acrylic resin adhesive, for example, an acrylic polymer obtained by polymerizing a carboxyl group-containing monomer and a (meth) acrylic acid alkyl ester monomer is used. The number of carbon atoms of the alkyl group of the (meth) acrylic acid alkyl ester monomer is preferably about 4 to 12, and specifically, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-octyl (meth) acrylate. , Isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and the like. Examples of the carboxyl group-containing monomer include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid; dicarboxylic acids such as fumaric acid and maleic acid, and monoesters thereof.

  The polymerization method of the acrylic resin-based pressure-sensitive adhesive is not particularly limited, and a known method such as solution polymerization, emulsion polymerization, suspension polymerization or the like can be adopted, but it is preferable to employ solution polymerization having excellent durability.

  In addition, the form of these pressure-sensitive adhesives is not particularly limited. For example, a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a hot-melt-type pressure-sensitive adhesive, a reactive pressure-sensitive adhesive, a photopolymerizable monomer-type pressure-sensitive adhesive, etc. Either form may be sufficient. There is no restriction | limiting in a coating means and a drying method, A well-known method is employable.

  The pressure-sensitive adhesive layer 33 is preferably crosslinked with a crosslinking agent such as a polyvalent isocyanate compound, a polyvalent epoxy compound, an amino resin, or a polyvalent metal chelate compound in order to improve cohesion. Among these crosslinking agents, the use of polyvalent isocyanate compounds is preferred for reasons such as the pot life of the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer and the speed of crosslinking.

  In addition, these pressure-sensitive adhesives may be provided with a tackifier, a coupling agent, a filler, a softener, a plasticizer within the range that does not impair the object or purpose of the present invention, in particular, the range that does not impair flexibility. Agent, surfactant, antioxidant (anti-aging agent), heat stabilizer, light stabilizer, ultraviolet absorber, colorant, antifoaming agent, flame retardant, antistatic agent (metal powder such as copper powder, nickel powder) 1 type, or 2 or more types of additives such as carbon (excluding conductive fillers such as carbon) may be added.

  However, in the present invention, the adhesive layer 32 does not require electrical conductivity. Therefore, a conductive filler such as metal powder such as copper powder and nickel powder and carbon is not added to the pressure-sensitive adhesive layer 33. These cause a loss of flexibility.

  As a method for forming the pressure-sensitive adhesive layer 33, a conventionally known method such as applying a pressure-sensitive adhesive can be appropriately employed. The thickness of the pressure-sensitive adhesive layer 33 is not particularly limited, but is preferably 1 μm to 0.5 mm, and more preferably 10 to 200 μm. If the thickness of the pressure-sensitive adhesive layer 33 is less than 1 μm, the adhesion to the wiring member such as the FFC main body 2 and the unevenness followability become insufficient, which is not preferable for maintaining the flexibility as the impedance adjustment sheet 3. If the thickness exceeds 0.5 mm, the adhesive force is no longer improved, but the cost becomes high.

  The surface layer 34 in the impedance adjustment sheet 3 is a layer for protecting and insulating the shield layer 32. The material of the surface layer 34 is not particularly limited as long as the flexibility and flexibility of the impedance adjustment sheet 3 are not impaired. For example, cellophane, celluloid, synthetic paper, art paper, retroreflective sheet, thermoplasticity Resin or the like can be used.

  Among them, a thermoplastic resin is preferable, and an ethylene-based polymer such as a high-pressure method low-density polyethylene, high-density polyethylene, linear low-density polyethylene, or ethylene-vinyl acetate copolymer, or propylene-α mainly composed of polypropylene or propylene. -A thermoplastic resin such as a propylene polymer such as an olefin copolymer, polyvinyl chloride, polyester, polyamide, polyimide, or an acrylic resin can be used.

  The thickness of the surface layer 34 can be 0.5 μm to 300 μm. When it becomes thinner than the lower limit value, the protective function of the shield layer 32 is lowered, and when the upper limit value is exceeded, it becomes over-spec and causes stiffening. More preferably, the thickness is 5 μm to 100 μm.

  The surface layer 34 can be laminated on the surface of the shield layer 32 by a known method.

  Although the impedance adjusting sheet 3 configured as described above is not shown in the drawing until it is laminated on the wiring member, the adhesive surface is protected by providing a release sheet on the surface of the adhesive layer 33. Then, the impedance adjustment sheet 3 is placed so that the adhesive layer 33 is in contact with the surface of the FFC main body 2 that is a target for adjusting characteristic impedance and shielding unwanted radiation by peeling the release sheet. By sticking with the agent layer 33, the shielded FFC1 is obtained.

  In the shielded FFC 1 shown in FIG. 1, the impedance adjustment sheet 3 is attached and laminated only on one side of the FFC main body 2, but as shown in FIG. 7A, the impedance adjustment sheet 3 is attached to the FFC main body 2. You may stick and laminate on both sides. Moreover, as shown in FIG.7 (b), you may laminate | stack so that the impedance adjustment sheet | seat 3 may be wound around the FFC main body 2, and may be coat | covered.

  As shown in FIG. 8A, the shielded FFC 1 in which the impedance adjustment sheet 3 is laminated has the other end side of the conductive line 21 b that is electrically connected to the ground line 21 a of the FFC main body 2 at the end of the impedance adjustment sheet 3. Is bent and sandwiched between the cloth-like body 31 and the shield layer 32, thereby making the shield layer 32 and the ground line 21a conductive. As a result, the shield layer 32 of the impedance adjustment sheet 3 is electrically connected to the ground line 21a of the signal line 21 of the FFC main body 2 via the conductive line 21b and maintained at the ground potential, and the shield layer 32 and the signal line 21 are thus connected. The characteristic impedance is defined by the capacitance between and. The conductive line 21b may be formed by bending the ground line 21a itself.

  Further, as shown in FIG. 8B, an exposed portion 32a where the shield layer 32 is exposed is formed by removing a part of the surface layer 34 at the end portion of the impedance adjustment sheet 3, and this exposed portion. In 32a, the shield layer 32 of the impedance adjustment sheet 3 may be maintained at the ground potential by conducting with a ground line or ground electrode on the connector side (not shown) to which the shielded FFC 1 is connected.

  The effects of the present invention are illustrated below by examples.

Example 1
Using a high-density polyethylene flat yarn having a yarn width of 1.2 mm and a fineness of 300 dt as a warp and weft, a flat yarn woven fabric of 50 μm in thickness was obtained by plain weaving at a rate of 14 per 25.4 mm.

  Low-density polyethylene was extruded and laminated on both sides of the obtained woven fabric to obtain a polyethylene cloth (insulator layer) in which a low-density polyethylene layer (thermoplastic resin layer) was laminated on both sides. The total thickness of the obtained polyethylene cloth was 90 μm.

  The surface of the low-density polyethylene layer of this polyethylene cloth was subjected to corona discharge treatment to a wetting tension of 440 μN / cm.

  Next, a 9 μm aluminum foil was joined to one surface of the low density polyethylene layer via a polyurethane adhesive to obtain a laminate having an aluminum foil layer (shield layer).

  Next, an acrylic pressure-sensitive adhesive composition “COPONIL NK-631 (manufactured by Nippon Synthetic Chemical Co., Ltd.) / Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) = 100 parts by weight / 1 part by weight is applied to the release-treated surface of the release sheet. The solution was applied to a coating thickness (solid content basis) of 20 μm. After drying with a circulation dryer at 100 ° C. for 1 minute, the above laminate was bonded as a base sheet and crosslinked at 23 ° C. and 65% RH for 7 days to obtain an impedance adjustment sheet.

  The obtained impedance adjustment sheet was affixed to a 25-core FFC “Sumicard SML2CD-25BD (manufactured by Sumitomo Electric Industries)”, and the aluminum foil layer was connected to the ground wire to obtain a wiring member.

  The characteristic impedance of the obtained wiring member was 100Ω.

(Example 2)
An impedance adjusting sheet was obtained in the same manner as in Example 1 except that a flat yarn woven fabric of 50 μm thick high density polyethylene that was plain woven at a rate of 16 per 25.4 mm in Example 1 was used. The obtained impedance adjustment sheet was attached to the FFC in the same manner as in Example 1 to obtain a wiring member.

  The characteristic impedance of the obtained wiring member was 100Ω.

(Example 3)
In Example 1, a flat yarn woven fabric using a polypropylene flat yarn having a yarn width of 1.2 mm and a fineness of 310 dt as warp and weft was used. An impedance adjustment sheet was obtained in the same manner as in Example 1 except that the thickness was 90 μm. The obtained impedance adjustment sheet was attached to the FFC in the same manner as in Example 1 to obtain a wiring member.

  The characteristic impedance of the obtained wiring member was 100Ω.

(Comparative Example 1)
An impedance adjusting sheet was obtained in the same manner as in Example 1 except that a polyethylene sheet (thickness 90 μm) was used instead of the polyethylene cloth in Example 1. The obtained impedance adjustment sheet was attached to the FFC in the same manner as in Example 1 to obtain a wiring member.

  The characteristic impedance of the obtained wiring member was 50Ω.

(Comparative Example 2)
Example 1 except that a polyethylene foam sheet (foaming magnification 1.1 times, thickness 90 μm) mixed with a microballoon “ADVANCEL EMH201 (manufactured by Sekisui Chemical)” was used instead of using a polyethylene cloth in Example 1. In the same manner as in Example 1, an impedance adjustment sheet was obtained. The obtained impedance adjustment sheet was attached to the FFC in the same manner as in Example 1 to obtain a wiring member.

  The characteristic impedance of the obtained wiring member was 100Ω.

<Measurement and evaluation method>
Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated for porosity, adhesive strength, shield characteristics, and bending test. The results are shown in Table 1.

1. Porosity The porosity was calculated by the following formula.

2. Adhesive strength Conforms to JIS-Z0237.

3. Shielding characteristics Measured sequentially at 1 GHz following the copper pipe method.

4). Bending test In accordance with JIS-P8115, the surface state after bending 10,000 times was observed to observe the shape of wrinkles and cracks, and evaluated according to the following criteria.
○: No wrinkles or cracks on the surface.
Δ: There are slight wrinkles on the surface and no cracks.
X: Wrinkles are clearly seen on the surface and cracks are generated.

  As can be seen from the comparison between Examples 1 and 2 and Comparative Example 1, even when polyethylene having the same thickness is used as the insulator layer, Examples 1 and 2 formed by cloth-like bodies have a characteristic impedance of 100Ω, Comparative Example 1 was 50Ω. This is because the capacitance of the wiring member was reduced in Examples 1 and 2 as compared with Comparative Example 1 in which the insulating layer had a cloth-like structure.

  Moreover, since Examples 1 and 2 are cloth-like bodies, they are excellent in flexibility and flexibility. In the bending test, no wrinkles or cracks were observed on the surface. Cracks occurred. In general, the relationship between the insulator layer, the capacitance, and the characteristic impedance is such that when the insulator layer is thickened and the capacitance is reduced, the characteristic impedance increases. In order to achieve the same 100Ω as in the first and second embodiments by using an insulator layer, the insulator layer must be formed thicker, which is more rigid.

  Furthermore, in Comparative Example 2 in which the same thickness of the foamed resin layer was used as the insulator layer, wrinkles and cracks were observed on the surface in the bending test.

  Accordingly, by using a thermoplastic resin cloth as the insulator layer as in the present invention, the impedance adjustment sheet can be soft and excellent in flexibility, resistant to bending stress, and having a low dielectric constant. And the wiring member with a shield by which the impedance was adjusted by this impedance adjustment sheet | seat was able to be provided.

  Further, even when a polypropylene cloth was used as the insulator layer as in Example 3, the same performance as in Examples 1 and 2 was obtained.

1: FFC with shield
2: FFC main body 21: Signal line 21a: Ground line 21b: Conductive line 22: Insulating resin layer 3: Impedance adjustment sheet 31: Cloth-like body 31a, 31b: Linear body 31c: Thermoplastic resin layer 310: Base layer 311: Joining Layer 32: Shield layer 33: Adhesive layer 34: Surface layer S: Void

Claims (4)

  A shield layer made of a conductive material is provided on one surface of an insulator layer formed of a cloth-like body of thermoplastic resin, and a pressure-sensitive adhesive layer is provided on the other surface. An impedance adjustment sheet characterized in that the characteristic impedance is adjusted by adhering to one side or both sides and covering the wiring member and shielding unwanted radiation.   2. The impedance adjusting sheet according to claim 1, wherein the cloth-like body is formed of a woven cloth or a cross-bonded cloth formed by a linear body obtained by uniaxially stretching a thermoplastic resin. A wiring member body in which signal lines are arranged in parallel;
A shield layer made of a conductive material is provided on one surface of an insulator layer formed by a cloth-like body of thermoplastic resin, and an impedance adjustment sheet having an adhesive layer provided on the other surface.
With the shield, the characteristic impedance of the wiring member main body is adjusted and unnecessary radiation is shielded by attaching the impedance adjusting sheet to one side or both sides of the wiring member main body and covering the same. Wiring member. 4. The shielded wiring member according to claim 3, wherein the cloth-like body is made of a woven cloth or a cross-bonded cloth formed by a linear body obtained by uniaxially stretching a thermoplastic resin.