JP4183691B2 - Shielded cable and manufacturing method thereof - Google Patents

Description

  The present invention relates to a shielded cable having excellent bending resistance used as an electric cable and a method for manufacturing the same. The shielded cable provided by the present invention, for example, in addition to an industrial robot, in particular, an information signal for control or the like via a movable part (bent part or the like) in an information communication device such as a notebook PC or a mobile phone. It is preferably used when manufacturing an electric cable for transmission.

  In recent years, in the field of the electronics industry, for example, electronic devices are rapidly becoming smaller, lighter, and higher performance, and accordingly, electrical cables used for connecting electronic devices are also made ultra-thin. There is a demand for space saving.

  Here, a flexible printed circuit (FPC) substrate, which is one of electric cables, is, for example, a connection portion (bent portion) between a personal computer body of a notebook personal computer and a liquid crystal display, a bent portion of a folding type mobile phone, or the like. In order to extend its life, a great durability against bending is required.

  In addition, with signal transmission cables, with the miniaturization and high functionality of electrical equipment, it has become an important issue to prevent the negative effects of external electromagnetic noise. A braid or laterally wound shield formed by braiding or laterally winding a linear member is used. Since such a shield is generally located immediately under the sheath which is the outermost peripheral member of the cable, it receives a large expansion force and bending deformation force when the cable is bent.

  By the way, recently, a coaxial cable has been used in a connection portion that cannot be handled by a film-like FPC board, such as a rotary cellular phone. As such a coaxial cable, for example, an insulator is formed on the outer periphery of the central conductor, and an outer conductor is provided on the outer periphery of the insulator by braiding a thin metal wire, lateral winding, winding of a metal foil, etc. The thing which provided the protective coating layer in the outer periphery of this is known (for example, refer patent document 1). And for such a coaxial cable, the ultra-thin cable outer diameter is progressing, but on the other hand, there are problems such as easy disconnection, and a cable having sufficient bending resistance has been proposed. The fact is not.

Japanese Patent Laid-Open No. 7-272553 (Prior Art, FIG. 6)

  An object of the present invention is to provide a shielded cable having very excellent bending resistance and a method for manufacturing the same.

  A first aspect of the present invention that solves the above-described problem comprises at least a center conductor, an insulator layer provided around the center conductor, and a shield provided around the insulator layer, In the shielded cable, the insulator layer is made of ABS resin.

  In the first aspect, since the insulator layer is made of ABS (acrylonitrile-butadiene-styrene) resin, a shielded cable having very excellent bending resistance can be realized.

  According to a second aspect of the present invention, there is provided a shielded cable according to the first aspect, wherein the cable outer diameter is 0.3 mm or less.

  In the second aspect, it is possible to realize a shielded cable having a very fine cable outer diameter of 0.3 mm or less and having very excellent bending resistance.

  A third aspect of the present invention is the shielded cable according to the first or second aspect, wherein the insulator layer has a thickness of 0.09 mm or less.

  In the third aspect, the bending resistance can be further improved by using an insulator layer having a thickness of 0.09 mm or less.

  A fourth aspect of the present invention is the shielded cable according to any one of the first to third aspects, wherein the shield is made of a metal plating layer having a thickness of 4 μm or less.

  In the fourth aspect, by setting the thickness of the shield to 4 μm or less, the bending resistance of the shield itself is increased, and as a result, the bending resistance of the cable is further increased while maintaining the desired electromagnetic shielding performance. be able to.

  A fifth aspect of the present invention is the shielded cable according to the fourth aspect, wherein the shield is made of a metal plating layer having a thickness of 2 μm or less.

  In the fifth aspect, by setting the thickness of the shield to 2 μm or less, the bending resistance of the shield itself is enhanced, and as a result, the bending resistance of the cable is further enhanced while maintaining the desired electromagnetic shielding performance. be able to.

  According to a sixth aspect of the present invention, in the first or second aspect, the insulator layer has a thickness of 0.09 mm or less, and the shield is a metal plating layer having a thickness of 4 μm or less. There is a shielded cable to do.

  In the sixth aspect, by making the thickness of the insulator layer and the shield within a predetermined range, the flex resistance of the insulator layer and the shield can be improved, and as a result, the flex resistance of the cable can be further improved. Can do.

  According to a seventh aspect of the present invention, in the first or second aspect, the insulator layer has a thickness of 0.09 mm or less, and the shield is a metal plating layer having a thickness of 2 μm or less. There is a shielded cable to do.

  In the seventh aspect, by making the thickness of the insulator layer and the shield within a predetermined range, the flex resistance of the insulator layer and the shield can be improved, and as a result, the flex resistance of the cable can be further improved. Can do.

  According to an eighth aspect of the present invention, in any of the fourth to seventh aspects, the metal plating layer is formed by electroless plating or a combination of electroless plating and electroplating. It is in the shielded cable.

  In the eighth aspect, a metal plating layer (shield) having a desired thickness can be manufactured relatively easily on the outer periphery of the insulator layer made of ABS resin.

  A ninth aspect of the present invention is the shielded cable according to any one of the first to eighth aspects, wherein an outer covering layer made of polyurethane is provided on an outer periphery of the shield.

  In the ninth aspect, since the outer coating layer is made of polyurethane, it is possible to effectively prevent scorching (discoloration) from occurring on the surface of the outer coating layer during laser processing when exposing the central conductor.

  According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the central conductor is made of a tin-containing copper alloy, a chromium-zirconium-containing copper alloy, or an in situ fiber-reinforced copper alloy. On shielded cable.

  In the tenth aspect, it is possible to realize a shielded cable in which the bending resistance of the center conductor is remarkably improved.

  An eleventh aspect of the present invention is the shielded cable according to the tenth aspect, wherein the central conductor is made of an in-situ fiber reinforced copper alloy.

  In the eleventh aspect, since the center conductor is made of an in-situ fiber reinforced copper alloy, it is possible to realize a shielded cable in which the tensile strength is increased and the center conductor is difficult to break.

  The twelfth aspect of the present invention comprises at least a first step of forming an insulator layer on the outer periphery of the central conductor and a second step of forming a shield on the outer periphery of the insulator layer. In the method of manufacturing a shielded cable, the insulator layer made of ABS resin is formed on an outer periphery of the center conductor by extrusion molding.

  In the twelfth aspect, an insulator layer having a substantially uniform thickness made of ABS resin can be surely formed on the outer periphery of the center conductor, and a highly shielded cable having excellent bending resistance can be produced at high production. It can be manufactured with sex.

  A thirteenth aspect of the present invention is the manufacture of a shielded cable according to the twelfth aspect, characterized in that, in the first step, the drawing direction of the central conductor at the time of extrusion molding is a horizontal direction or a vertical direction downward. Is in the way.

  In the thirteenth aspect, an insulator layer made of ABS resin can be satisfactorily formed on the outer periphery of the center conductor.

  According to a fourteenth aspect of the present invention, in the thirteenth aspect, in the first step, the insulator layer is formed by attaching an ABS resin larger than the MFR 10 and having an MRF of 50 or less to the outer periphery of the center conductor by extrusion molding by pulling down. The method of manufacturing a shielded cable is characterized in that the cable is continuously formed.

  In the fourteenth aspect, by using an ABS resin that is larger than MFR10 having a relatively high fluidity and having an MFR of 50 or less, an insulator layer having a substantially uniform thickness is reliably formed on the outer periphery of the central conductor by extrusion molding. Therefore, an ultra-fine shielded cable can be manufactured with high productivity.

  A fifteenth aspect of the present invention is the shielded cable according to any one of the twelfth to fourteenth aspects, wherein the surface of the insulator layer is subjected to surface treatment by chromic acid etching before the second step. It is in the manufacturing method.

  In the fifteenth aspect, the adhesion of the shield (metal plating layer) to the insulator layer is improved.

  In a sixteenth aspect of the present invention, in any one of the twelfth to fifteenth aspects, in the second step, a metal plating layer is formed as the shield by using electroless plating or a combination of electroless plating and electroplating. The present invention is directed to a method for manufacturing a shielded cable.

  In the sixteenth aspect, a metal plating layer (shield) having a desired thickness can be manufactured relatively easily on the outer periphery of the insulator layer made of ABS resin.

  A seventeenth aspect of the present invention is the manufacture of a shielded cable according to any one of the twelfth to sixteenth aspects, wherein an outer covering layer made of polyurethane is formed on an outer periphery of the shield after the second step. Is in the way.

  In the seventeenth aspect, it is possible to realize a shielded cable that effectively prevents the surface of the outer coating layer from being burnt (discolored) during laser processing for exposing the central conductor.

  According to an eighteenth aspect of the present invention, in the seventeenth aspect, in the step of forming the outer covering layer, the covered electric wire having the shield formed on the outer periphery is passed through a die from the polyurethane tank in which the polyurethane is accommodated. It exists in the manufacturing method of the cable with a shield characterized by performing by drawing out.

  In such an eighteenth aspect, the covered electric wire having a shield formed on the outer periphery is drawn out in the vertical direction to form an outer covering layer, so that the die can be easily set at the axial center of the central conductor. The outer coating layer can be formed with a substantially uniform film thickness by finishing.

  The shielded cable of the present invention has very excellent bending resistance because the insulator layer is made of ABS resin. In particular, the shielded cable of the present invention is a very fine coaxial cable having a cable outer diameter of 0.3 mm, preferably 0.2 mm, and more preferably 0.1 mm, and has very excellent bending resistance. When the shielded cable of the present invention is a coaxial cable having a characteristic impedance of 50Ω, the shield inner diameter is preferably about three times the outer diameter of the central conductor.

  Here, the central conductor (conductive wire) included in the shielded cable of the present invention may be a single wire having a predetermined diameter, for example, a single wire having a diameter of about 30 μm to 0.1 mm, or a multi-core wire. For example, a plurality of ultrafine wires having a diameter of about 10 to 80 μm may be assembled. Moreover, as a structure of the covered electric wire which provided the insulator layer around the center conductor, a structure in which an insulator layer is covered on a single wire or a structure in which an insulator layer is covered on a multi-core wire may be used.

  In the present invention, examples of the center conductor include a tin-containing copper alloy, a chromium-zirconium-containing copper alloy, or an in-situ fiber reinforced copper alloy. It is preferable in terms of bending resistance. Further, when the center conductor is a single wire made of an in-situ fiber reinforced copper alloy, the tensile strength of the center conductor is increased, and as a result, a shielded cable in which the center conductor is hard to break can be realized.

  Here, the conducting wire made of the in-situ fiber reinforced copper alloy is a copper matrix reinforced with fibers, and particularly refers to a wire formed in situ, that is, in a step of forming a wire. For example, it refers to a wire rod containing in-situ formed fibrous silver having a maximum diameter of 2.5 μm or less and an average diameter of 1.0 μm or less in a copper matrix.

  For example, the in-situ fiber reinforced copper alloy is formed by swaging an alloy material made of copper with a silver content of 1 to 25% by weight and the balance substantially, and then performing a first cold drawing. Applying wire processing, then solution treatment, and then applying a second cold wire drawing to form a wire silver in situ in a copper matrix to obtain a wire, using at least one wire It is obtained by forming a conducting wire. In addition, as an alloy material used as a material, it is not limited to what was mentioned above, For example, silver content rate is 1 to 25 weight%, zirconium content rate is 0.01 to 8 weight%, and remainder is substantially copper. An alloy material can also be used.

  The wire made of such a composite material can ensure high conductivity when current flows through the copper matrix, and mechanical strength can be ensured by fiber reinforcement, and has contradictory characteristics of high mechanical strength and high conductivity. It will have both.

  In the present invention, the insulating layer made of ABS resin is preferably formed to be relatively thin, for example, 0.09 mm or less, and more preferably 0.03 mm or less. That is, if the insulating layer is formed relatively thick, when the cable is bent, the surface of the cable (insulator layer) is whitened, and the cable is easily broken from the whitened portion. However, the thickness of the insulator layer is not limited to the above-described one, and the cable outer diameter may be 0.3 mm or less, and may be appropriately determined in consideration of the thickness and material of the center conductor and shield. Good.

  Here, the ABS resin is not particularly limited as long as an insulator layer having a predetermined thickness can be formed on the outer periphery of the center conductor, but for example, by extrusion in the horizontal direction. When forming, it is preferable to use an ABS resin having a relatively low fluidity, for example, an ABS resin having a melt flow rate (MFR) of 20 [g / 10 min] or less. On the other hand, when using a highly fluid ABS resin, there is a risk of cable deformation due to the occurrence of resin sag, and therefore, it is desirable to perform extrusion molding in the vertical direction. In this case, a highly fluid ABS resin, for example, an ABS resin having an MFR greater than 20 and 50 or less, preferably an ABS resin having an MFR of 30 to 40, may be used. However, in the case of a cable having an outer diameter of 0.3 mm, the resin itself becomes light, the cable is not deformed, and can be sufficiently extruded even in the horizontal direction. Such an insulator layer may be used alone as an ABS resin. However, in addition to this ABS resin, for example, various resins, specifically, polystyrene (PS), polycarbonate (PC), etc. are added. In addition to this, what added various additives, such as a hardening | curing agent and a thickener, may be used.

  In the present invention, for example, a metal plating layer is provided as a shield on the outer periphery of the insulator layer. However, before the metal plating layer is formed, the surface of the insulator layer is subjected to a predetermined surface treatment. preferable. Here, the predetermined surface treatment is not particularly limited as long as it roughens the surface, improves the wettability of the surface, and improves the adhesion of the shield to the insulator layer. For example, chromic anhydride is used. It is preferable to perform the surface treatment by the chromic acid etching used. Thereby, the wettability of the surface of the insulator layer made of ABS resin is increased, and the adhesion with the metal plating layer (shield) formed thereon is improved.

  In the present invention, it is preferable to form a metal plating layer as such a shield. The metal plating layer may be formed only by electroless plating, or may be formed by combining electroless plating and electroplating. Examples of the metal plating layer include copper, silver, nickel, gold, etc., or composite plating or alloy plating thereof.

  Furthermore, the thickness of such a metal plating layer is preferably 4 μm or less, more preferably 2 μm or less. This is because if it is thicker than this, there is a problem in bending resistance.

  In the present invention, preferably, the thickness of the insulator layer is 0.09 mm or less (or 0.03 mm or less), and the thickness of the metal plating layer is 4 μm or less. The thickness is preferably 0.09 mm or less (or 0.03 mm or less), and the thickness of the metal plating layer is preferably 2 μm or less. This is because the bending resistance of the insulator layer and the shield is increased, and as a result, the bending resistance of the cable can be further increased.

  The shielded cable of the present invention has an outer coating layer (sheath) outside the shield. Examples of the material for the outer coating layer include fluorine resins, olefin resins, polyesters, polyurethanes, ABS resins, and polyimides. Among these materials, polyurethane is used as the material of the outer coating layer, so that, for example, the surface of the outer coating layer is burned (discolored) during laser processing when exposing the central conductor from the end of the shielded cable. Can be effectively prevented.

  Thus, as a method of forming an outer coating layer made of polyurethane, for example, dipping or the like can be mentioned. In the present invention, a shield is formed on the outer periphery through a die from the inside of a polyurethane tank containing polyurethane. It is preferable to form the coated wire by pulling out the so-called die finish. In addition, for example, by forming the outer coating layer by pulling out the covered electric wire in the vertical direction, it is easy to set the die at the center of the axis of the central conductor, and the outer coating layer is formed with a substantially uniform film thickness by die finishing. can do.

  Hereinafter, the shielded cable of the present invention will be described in detail based on one embodiment.

(Example 1)
FIG. 1 is a cross-sectional view of a shielded cable according to the first embodiment. 2 and 3 are enlarged cross-sectional views of the main part of the extrusion molding apparatus used when the shielded cable shown in FIG. 1 is manufactured.

  As shown in FIG. 1, the shielded cable 10 of the present embodiment is provided with a shield 14 on a covered electric wire 13 in which an insulating layer 12 made of ABS resin is applied to a single-wire central conductor 11, and polyurethane is formed on the shield 14. The outer coating layer 15 is formed to have a cable outer diameter of about 0.1 mm.

  Here, the covered electric wire 13 is formed on the outer periphery of the center conductor 11 made of an in-situ silver fiber reinforced copper alloy (silver content of about 10%) from the ABS resin by an extrusion molding apparatus shown in FIG. An insulating layer 12 is formed, and the outer diameter is 0.08 mm.

  Specifically, as shown in FIGS. 2 and 3, the extrusion molding apparatus 100 includes a tip member 110 provided with an insertion hole 111 through which the center conductor 11 is inserted and a tip member 110 that engages with the tip member 110. The die member 120 is provided with a joint hole 121 and a fixing member 130 to which the die member 120 is fixed.

  Further, a predetermined gap is provided between the chip member 110 and the die member 120, and this gap is filled with ABS resin. Furthermore, a nozzle opening 140 that is constituted by the insertion hole 111 and the engagement hole 121 and through which the covered electric wire 13 is led out is provided on the end surface of such an extrusion molding apparatus in the vertically downward direction (downward in the figure). Yes.

  And in such an extrusion molding apparatus 100, it installs so that a nozzle direction may become a substantially horizontal direction, and while the center conductor 11 is pulled out through the insertion hole 111 of the chip member 110 from the nozzle opening 140, it is ABS resin 12A. Is pulled down along the outer periphery of the center conductor 11 from the gap between the chip member 110 and the die member 120, and the covered electric wire 13 in which the insulator layer 12 made of the ABS resin 12A is formed on the outer periphery of the center conductor 11 is led out.

  In this example, as the ABS resin, MFR36 [g / 10 min] (test standard: ASTM D1238, temperature: 220 ± 0.2 ° C., load: 2160 g, sample: pellet approximately 10 g, test apparatus: melt indexer, orifice : 0.9φ × 8 L (mm)) ABS resin was used.

  Moreover, in the extrusion molding by the above-mentioned drawing, the outer diameter of the covered wire 13 can be formed with a desired thickness by setting the drawing rate (DDR) shown in the following formula 1 to a desired value. .

[Formula 1] Withdrawal rate (DDR) = (D _D ² −D _T ² ) / (D _CW ² −D _BW ² )

Here, with respect to the symbols used in Formula 1, _DD is the inner diameter (mm) of the engagement hole 121 on the nozzle opening side, D _T is the outer diameter (mm) of the tip of the tip member 110, and D _CW is a final outer diameter of the covered wire 13 _(mm), an outer diameter of _{D BW} center conductor 11 (mm) (see FIG. 3).

  In addition, the outer peripheral surface of the covered electric wire 13 formed in this way is subjected to surface treatment by chromic acid etching with a solution containing chromic anhydride or the like in this embodiment, and from that, electroless A shield 14 (metal plating layer) made of copper and having a thickness of 2 μm is formed by plating.

  Further, in the present embodiment, an outer covering layer 15 made of polyurethane is formed on the outer periphery of the covered electric wire 13 on which the shield 14 is formed by die finishing as shown in FIG. FIG. 4 is a schematic cross-sectional view illustrating a process of forming an outer coating layer by die finishing. Specifically, a die 21 is provided at the lower end of the polyurethane tank 20 in which a polyurethane solution dissolved in a urethane-soluble solvent such as dimethylformamide (DMF), methyl ethyl ketone (MEK), and toluene is provided. The heater 22 is disposed on the lower side in the vertical direction (lower side in the figure). Then, the coated electric wire 13 is pulled out from the die 21 through the polyurethane tank 20 and continuously heated by the heater 22, thereby forming the outer coating layer 15 made of polyurethane on the outer periphery of the coated electric wire 13. In this case, the die 21 can be easily set at the axial center of the central conductor 11, and the outer coating layer 13 can be formed with a substantially uniform film thickness by die finishing. Thereby, the cable 10 with a shield of a present Example is manufactured.

  In the present embodiment, the covered electric wire 13 on which the shield 14 is formed is drawn from the vertical upper side to the lower side through the polyurethane tank 20, and the outer coating layer 15 is formed by die finishing. Of course, the present invention is not limited to this. For example, although not shown, the outer covered layer may be formed by die drawing by drawing the covered electric wire on which the shield is formed from below in the vertical direction.

  The shielded cable 10 of the present embodiment described above has a characteristic impedance of 46Ω and an electromagnetic wave shielding characteristic of 25 dB.

(Test Example 1)
Here, the durability test of the shielded cable of the above-described embodiment was performed. FIG. 5 is a schematic diagram illustrating a cable durability test. As shown in FIG. 5, the shielded cable 10 of the present embodiment is sandwiched between a pair of support rods 30 having a radius of 5 mm, and a predetermined load is applied to one end of the shielded cable 10. From the left and right sides, it was bent repeatedly at positions B and C that were bent 90 ° from side to side. As a result, the durability (flexibility) against bending of the shielded cable of this example was 100,000 times or more. In addition, although not shown, in a durability test in which the cable is twisted ± 180 ° around its axis in a state where one end of the shielded cable 10 of this embodiment is fixed, a durability of 200,000 times or more is shown. It was.

1 is a cross-sectional view of a shielded cable according to Example 1. FIG. It is a principal part expanded sectional view of the extrusion molding apparatus used when manufacturing the shielded cable of FIG. It is a principal part expanded sectional view of the extrusion molding apparatus used when manufacturing the shielded cable of FIG. It is a schematic sectional drawing explaining the process of forming an outer coating layer by die finishing. It is the schematic explaining the bending resistance test of the cable which concerns on the test example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cable with shield 11 Center conductor 12 Insulator layer 13 Covered electric wire 14 Shield 15 Outer coating layer

Claims (15)

A central conductor; an insulator layer provided directly around the central conductor; and a shield provided around the insulator layer, wherein the insulator layer is made of ABS resin and has a thickness. A shielded cable , wherein the shield is 0.09 mm or less and the shield is made of a metal plating layer having a thickness of 4 μm or less . The shielded cable according to claim 1, wherein the outer diameter of the cable is 0.3 mm or less. The shielded cable according to claim 1 or 2, wherein the insulator layer has a thickness of 0.03 mm or less. The shielded cable according to claim 1, wherein the shield is made of a metal plating layer having a thickness of 2 μm or less. In any one of claims 1 to 4, wherein the metal plating layer, electroless plating, or shielded cable which is characterized in that one formed by combining electroless plating and the electroplating. 6. The shielded cable according to claim 1 , wherein an outer coating layer made of polyurethane is provided on an outer periphery of the shield. 7. The shielded cable according to claim 1, wherein the central conductor is made of a tin-containing copper alloy, a chromium-zirconium-containing copper alloy, or an in situ fiber-reinforced copper alloy. 8. The shielded cable according to claim 7 , wherein the central conductor is made of an in-situ fiber reinforced copper alloy. At least a first step of forming an insulator layer directly on the outer periphery of the central conductor, and a second step of forming a shield on the outer periphery of the insulator layer . In the first step, the outer periphery of the central conductor A method for producing a shielded cable, comprising forming the insulator layer made of an ABS resin and having a thickness of 0.09 mm or less by extrusion molding. 10. The method of manufacturing a shielded cable according to claim 9 , wherein, in the first step, a drawing direction of the center conductor at the time of extrusion molding is set to a horizontal direction or a vertical direction downward. In claim 10 , in the first step, the insulator layer is continuously formed by attaching ABS resin larger than MFR10 and lower than MFR50 to the outer periphery of the center conductor by extrusion molding by pulling down. A method for manufacturing a shielded cable. 12. The method of manufacturing a shielded cable according to claim 9 , wherein a surface treatment is performed on the surface of the insulator layer by chromic acid etching before the second step. The manufacturing of a shielded cable according to any one of claims 9 to 12 , wherein, in the second step, a metal plating layer is formed by combining electroless plating or electroless plating and electroplating as the shield. Method. 14. The method for producing a shielded cable according to claim 9 , wherein an outer covering layer made of polyurethane is formed on an outer periphery of the shield after the second step. 15. The step of forming the outer covering layer according to claim 14 , wherein the covered electric wire having the shield formed on the outer periphery thereof is pulled out from the polyurethane tank containing the polyurethane through a die. A method of manufacturing a shielded cable.

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