JP2011233822A - Flexible circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible circuit board enabling the expansion of life with a simple structure, by reducing possibility of exfoliation and disconnection in a wiring layer and breakage of the flexible circuit board itself, even when the flexible circuit board comes into contact with a peripheral component etc. or a large external force such as vibration or impact acts thereon.SOLUTION: An elastic flexible circuit board 1 includes: an insulating film 7 as a base layer; a wiring layer 4 formed on the insulating film 7; and an insulation layer 8 formed on the wiring layer 4. In the elastic flexible circuit board 1, a curved shape portion 6 is formed in at least one point, and at least the curved shape portion 6 is coated with a resilient member 3.

Description

  The present invention relates to a flexible circuit board. More specifically, it can be used for various electronic devices such as communication / video equipment, connections between components attached to automobiles, aircraft, robots, etc., or mounted circuit boards mounted with mounted parts. Even when a large external force is applied or when rubbing with other parts occurs, the wiring layer of the flexible circuit board can be prevented from being broken or the flexible circuit board itself can be damaged, and the life of the flexible circuit board can be extended. The present invention relates to a flexible circuit board that can prevent disconnection of a wiring layer due to shock or vibration even when external shock or vibration is applied.

  In recent years, the development of robots has been remarkable, and robots with various movements are appearing. In addition, various types of wearable electronic devices that can be worn on the human body and clothes have been developed. These robots and wearable electronic devices use a large number of electric wires for power supply and signal transmission, but in general, the electric wires have a copper wire core and the outer periphery is covered with an insulator. Therefore, there is almost no elasticity in the electric wire itself. For this reason, it is necessary to allow wires to be provided with a margin so as not to hinder the movement of the robot or the human body, and this often becomes an obstacle in device design or practical use.

  In particular, devices such as state-of-the-art humanoid robots and power assist devices that are attached to the human body to assist muscle strength are equipped with wires for moving the motor at the end via multi-degree-of-freedom joints and at the end. Many wires for transmitting signals from various sensors are wired, and in order to increase the degree of freedom of these wires in a multi-degree-of-freedom joint, there is an increasing demand for wires that can be extended and contracted.

  On the other hand, in recent years, arm robots are often used as industrial robots. In this type of arm robot, an electric cable for power supply and signal transmission used for the end effector attached to the tip side of the robot arm and the joint part of the robot arm is connected from the base side to the tip side of the robot arm. Wiring is required. Further, depending on the drive mode of the end effector or the joint portion of the robot arm, it may be necessary to wire an air (pneumatic) hose or a hydraulic hose from the base side to the tip side of the robot arm.

  For this reason, in conventional arm robots, when various cables such as electric cables, air hoses, hydraulic hoses, etc. are wired to the joints, the cables are temporarily placed near the base end of the joints of the robot arm in order to prevent the cables from bending or breaking. A wiring method is adopted in which the cable is placed outside, the cable is arranged in the outer space of the joint, and is introduced into the arm again at a position closer to the tip than the joint. Also known is a configuration in which a support rod is provided at the joint rotation center position in the joint portion of the arm robot and the cable is pre-wound and stored in the robot arm to prevent the cable from being bent or disconnected. (For example, refer to Patent Document 1).

However, in the technique of arranging the cable in the outer space of the robot arm, a space for loosening the cable is required around the joint portion of the robot arm. Furthermore, there is a possibility that the cable may be damaged or disconnected when the cable receives an excessive force during the rotation of the joint portion of the robot arm or interferes with the robot arm. In addition, as disclosed in Patent Document 1, when a support bar is provided at the joint rotation center position, it is necessary to separately provide a support bar, which leads to an increase in manufacturing cost, and further, in the cable storage portion. Since the structure is complicated, there is a problem that it takes much time to route the cable, disassemble it during maintenance, or take out the cable. That is, even in arm robots, there is an increasing demand for an extendable electric wire that can avoid such a problem.

  Therefore, in order to meet the demand for an electric wire configured to be stretchable, a flexible circuit board that can be stretched and formed into a bellows shape has been proposed. By using this flexible circuit board, the degree of freedom of wiring can be increased without unnecessarily extending the length of the wiring, and the robot arm described above requires a space for loosening the cable. It is possible to prevent the cable from being damaged or disconnected.

JP-A-8-57992 Japanese Patent Laid-Open No. 3-220787

  However, the conventional flexible circuit board has the following problems. A conventional flexible circuit board is obtained by forming a wiring layer on an insulating film as a base layer and further covering the wiring layer with an insulating layer. However, although it is possible to obtain a flexible circuit board that can be expanded and contracted by molding into a bellows shape, if the flexible circuit board gets caught or rubbed by peripheral components, the wiring layer may be peeled off or disconnected, The substrate itself may be damaged. For example, when a flexible circuit board is used as a joint part of a robot arm, a large external force such as impact or vibration acts on the flexible circuit board, so that the wiring layer is disconnected or peeled off, or the flexible circuit board itself is damaged. There is a fear.

  In addition to the flexible circuit board formed into a bellows shape, for example, a method of obtaining a corrugated flexible circuit board that can be expanded and contracted by forming the substrate into a corrugated shape in the stacking direction after forming the substrate is also known. However, in this case, since it is necessary to bend the substrate a plurality of times in the manufacturing stage, this bending treatment significantly reduces the adhesion between the layers stacked in the substrate. There is a problem. Even with such a flexible circuit board, there is a possibility that the above-described problems of disconnection and peeling of the wiring layer and damage of the flexible circuit board itself may occur.

  As described above, in the conventional flexible circuit board, there is a possibility that the wiring layer may be disconnected or peeled off or the flexible circuit board itself may be damaged when a large external force such as impact or vibration is applied when contacting with peripheral components. Therefore, there is a risk that the connection reliability of the flexible circuit board may be impaired, and the lifetime of the flexible circuit board cannot be ensured.

  Therefore, the present invention reduces the possibility that the wiring layer is disconnected or peeled off or the flexible circuit board itself is damaged even when it comes into contact with peripheral components or when a large external force such as vibration or impact is applied. An object of the present invention is to provide a flexible circuit board capable of extending the life with a simple structure.

In order to achieve the above object, the present invention provides:
An insulating film as a base layer;
A wiring layer formed on the insulating film;
An insulating layer formed on the wiring layer,
In a stretchable flexible circuit board in which a curved portion is formed in at least one place,
At least the curved shape portion is covered with an elastic member.

  According to this configuration, since the curved shape portion is formed in at least one location of the flexible circuit board, the flexible circuit board can be stretched and deformed in the curved shape portion. Therefore, the external force such as impact and vibration acting on the flexible circuit board can be reduced and it can be expanded and contracted, so that the degree of freedom of wiring can be increased without extending the length of the wiring more than necessary. . Further, by attaching the flexible circuit board in the contracted state, the installation space can be saved, and not only the flexible circuit board but also the electronic device can be miniaturized. Note that a plurality of curved portions may be formed, for example, a flexible circuit board may be formed in a bellows shape. In this case, the stretchability of the flexible circuit board can be further improved.

  Further, according to such a configuration, since at least the curved portion is covered with the elastic member, even when the flexible circuit board comes into contact with peripheral components or the like, or when a large external force such as impact or vibration acts on the flexible circuit board. The flexible circuit board can be protected by the elastic member. That is, it is possible to reduce the possibility that the wiring layer is peeled off or disconnected, or the flexible circuit board itself is damaged. In addition, the heat resistance of the elastic member improves the thermal durability of the flexible circuit board, and the flexible circuit board can be used even at high temperatures. That is, it is possible to improve connection reliability and extend the life of the flexible circuit board.

  Moreover, according to this structure, since the curved shape part is coat | covered with the elastic member, it becomes possible to maintain a curved shape more reliably with the shape maintenance force of an elastic member. For example, when a large external force is applied to the flexible circuit board, the curved shape portion may be extended (cannot return to the original shape), and the wiring layer may be peeled off or disconnected. In addition, since the curved shape of the curved portion is easily maintained by the covered elastic member, it is possible to more reliably prevent the wiring layer from being peeled off or disconnected. That is, it is possible to improve connection reliability and extend the life of the flexible circuit board.

  In addition, according to such a configuration, it is possible to easily form a curved shape portion by covering the flexible circuit board, which is difficult to mold the base layer, the wiring layer, and the insulating layer into a curved shape, by covering the elastic layer. it can. That is, since the selection range of materials that can be used for the base layer, the wiring layer, and the insulating layer is widened, the manufacturing cost can be reduced.

In the present invention,
The elastic member is
It is preferable that it is any of silicone rubber, acrylic elastomer, or urethane elastomer.

  According to such a configuration, it is possible to suppress the manufacturing cost of the flexible circuit board by using relatively inexpensive silicone rubber, acrylic elastomer, or urethane elastomer as the elastic member. Silicone rubber, in particular, has excellent heat resistance, cold resistance, water repellency, and electrical insulation, so if it is used as an elastic member, it will expand the range of environmental conditions such as temperature and humidity where the flexible circuit board can be used. Is possible. Further, since the acrylic elastomer is excellent in oil resistance, if it is used as an elastic member, it is possible to widen the usage environment of the flexible circuit board. Furthermore, when using a urethane-based elastomer, the abrasion resistance of the flexible circuit board is improved, so even when it comes into contact with peripheral parts or the like, or when a large external force such as vibration or impact acts, It becomes possible to suppress disconnection more reliably. That is, it is possible to improve connection reliability and extend the life of the flexible circuit board.

In the present invention,
It is preferable that the curved shape portion is configured to be extendable and contractible in a state where the curvature radius R (mm) is maintained.

  According to such a configuration, since the expansion and contraction are performed in a state where the curvature radius R (mm) of the curved shape portion is maintained, there is no possibility that the wiring layer is peeled or disconnected in the curved shape portion when the flexible circuit board expands or contracts. Therefore, excellent connection reliability can be maintained, and the life of the flexible circuit board can be extended.

  As described above, according to the present invention, even when a contact is made with peripheral components or when a large external force such as vibration or impact is applied, the wiring layer is peeled off or disconnected, or the flexible circuit board itself is damaged. It is possible to provide a flexible circuit board capable of reducing the possibility and extending the life with a simple configuration.

1 is a schematic configuration diagram of a flexible circuit board according to the present invention. The figure for demonstrating the manufacturing method of the flexible circuit board based on this invention. The figure for demonstrating the manufacturing method of the flexible circuit board based on this invention. The figure for demonstrating the manufacturing method of the flexible circuit board based on this invention. Schematic configuration diagram of a flexible circuit board according to the present invention

  DETAILED DESCRIPTION Exemplary embodiments for carrying out the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

<1: Schematic configuration of flexible circuit board>
With reference to FIG.1 (d), the schematic structure of the flexible circuit board 1 which concerns on this embodiment is demonstrated. FIG. 1D is a schematic cross-sectional view of the flexible circuit board 1 according to this embodiment.

  As shown in FIG. 1D, the flexible circuit board 1 according to this embodiment includes an insulating film 7 as a base layer, a wiring layer 4 formed on the insulating film 7 with an adhesive layer 9 interposed therebetween, and a wiring layer 4. It has an insulating layer 8 formed thereon. In this embodiment, although the adhesive layer 9 is provided, the wiring layer 4 may be directly formed on the insulating film 7 without providing the adhesive layer 9. Furthermore, in this embodiment, the upper surface of the insulating layer 8 and the lower surface of the insulating film 7 are each covered by the elastic member 3, and although not shown in FIG. 1 (d), the insulating film 7, the adhesive layer 9, the wiring The side surfaces of the layer 4 and the insulating layer 8 are also covered with the elastic member 3. Hereinafter, the insulating film 7, the adhesive layer 9, the wiring layer 4, and the insulating layer 8 are collectively referred to as “flexible circuit body 2”. Next, each layer mentioned here will be described in more detail.

  Examples of the insulating film 7 and the insulating layer 8 include polyimide, polyester, polyamide, polycarbonate, polyarylate, polyphenylene ether, polyphenylene sulfide, polyethersulfone, polyetherimide, liquid crystal polymer, polyetheretherketone, cyclic polyolefin, and polyamideimide. , A film made of one kind selected from thermoplastic polyimide, polyethylene terephthalate, and cycloolefin polymer, or a laminated film in which a plurality of resin films are laminated.

  In addition, the thickness of the insulating film 7 and the insulating layer 8 is preferably 5 to 200 μm, particularly 5 to 100 μm. The materials used for the insulating film 7 and the insulating layer 8 may be the same material or different materials. In addition, among the materials listed above, a thermoplastic resin is recommended when moldability is particularly required, and liquid crystal polymers (for example, trade names “Lordlan” (manufactured by Unitika), “EPE” (manufactured by Mitsubishi Chemical) , “Idemitsu LCP” (manufactured by Idemitsu Petrochemical Co., Ltd.), “Econol” (manufactured by Sumitomo Chemical Co., Ltd.), “Zider” (manufactured by Nippon Petrochemical Co., Ltd.), “LCP” (manufactured by Tosoh Corporation), “Vectra” (Hoechst-Celanese) "SRP" (manufactured by ICI), "Bexter" (manufactured by Kuraray), "Biac" (manufactured by Japan Gore-Tex), "Sumika Super LCP" (manufactured by Sumitomo Chemical)), polyamideimide ( For example, polyamideimide obtained from trimellitic acid and aromatic diamine such as diaminodiphenylmethane, diaminodiphenyl ether, m- or p-phenylenediamine) Plastic polyimide (for example, trade name “Aurum” (manufactured by Mitsui Chemicals)), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), cycloolefin polymer (COP, for example, trade name “ZEONEX” (manufactured by Nippon Zeon), “ZEONOR” "(Manufactured by Nippon Zeon Co., Ltd.)). As described above, when a thermoplastic resin is used for the insulating film 7 and the insulating layer 8, the flexible circuit body 2 having an integral structure is subjected to a molding process by heating and pressurization before the elastic member 3 is covered. At a stage, the curved circuit portion 6 can be provided on the flexible circuit body 2 (details will be described later).

  The wiring layer 4 (also referred to as a wiring pattern) is formed by attaching a known metal foil such as a rolled copper foil and an electrolytic copper foil to the insulating film 7 with the adhesive layer 9. Alternatively, the wiring layer 4 is formed on the surface of the insulating film 7 (or the surface of the adhesive layer 9 formed on the insulating film 7) by using a metal such as copper or silver by a method such as vapor deposition or sputtering. You can also.

  The adhesive layer 9 is made of a known thermoplastic resin such as polyimide, or a cyanate ester resin, a polyphenylene ether resin, a phenol resin, a naphthalene resin, a urea resin, an amino resin, an alkyd resin, a silicon resin, a furan resin, or an unsaturated polyester. It is formed using a known thermosetting resin such as a resin, an epoxy resin, and a polyurethane resin. Alternatively, the adhesive layer 9 may be made by dispersing an inorganic filler such as silica or alumina in the organic resin described above.

  As the elastic member 3, silicone rubber, acrylic elastomer, urethane elastomer, fluororubber, ethylene-propylene-diene terpolymer, ethylene-propylene rubber, butyl rubber, butadiene-styrene copolymer, natural rubber, isoprene rubber Chloroprene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, acrylonitrile butadiene rubber, butadiene rubber, styrene thermoplastic elastomer, olefin thermoplastic elastomer, vinyl chloride thermoplastic elastomer, ester thermoplastic elastomer, amide thermoplastic elastomer, 1,2-BR type thermoplastic elastomer, fluorine type thermoplastic elastomer, etc. can be used. Among them, silicone rubber and oil resistance excellent in heat resistance, cold resistance, water repellency, and electrical insulation. Excellent acrylic elastomer transparency or mechanical strength, it is preferable to use a good urethane elastomer abrasion resistance. In addition to the materials mentioned here, the above-described materials applicable to the insulating film 7 and the insulating layer 8 can also be used as the elastic member 3.

<2: Position where the elastic member is provided>
FIG. 1A shows a schematic side view of the flexible circuit board 1 according to the present embodiment. As shown in the figure, the flexible circuit board 1 according to the present embodiment has a curved portion 6 formed at least at one location, and is thus configured to be able to expand and contract as a whole. (FIG. 1A shows a form in which a plurality of curved shape portions 6 are provided, but it may be a substantially U shape in which only one curved shape portion 6 is provided). And in this embodiment, at least the curved shape part 6 of the flexible circuit board 1 comprised in this way is covered with the elastic member 3 mentioned above, It is characterized by the above-mentioned.

  Although FIG. 1A shows a case where almost the entire flexible circuit board 1 is covered with the elastic member 3, the elastic member 3 only needs to cover at least the curved portion 6. Moreover, although it is desirable that all of the upper surface, the lower surface, and the side surface of the curved shape portion 6 are covered with the elastic member 3, if any one surface is covered with the elastic member 3, compared to the conventional case. It is possible to obtain a sufficient effect. FIG. 1B shows a schematic top view of the flexible circuit board 1 according to the present embodiment. A connection terminal 5 is provided at an end of the flexible circuit board 1, and electrical connection with an electric device or the like is provided. In order to secure a general connection, at least this portion needs to be exposed without being covered with the elastic member 3.

  In this way, by covering at least the curved shape portion 6 with the elastic member 3, the flexible circuit body 2 is not exposed in the curved shape portion 6, so when the flexible circuit board 1 comes into contact with peripheral components or the like, or Even when a large external force such as vibration or impact acts on the flexible circuit board 1, the elastic member 3 functions as a protective layer, so that the wiring layer 4 may be disconnected or peeled off, or the flexible circuit body 2 may be damaged. Can be reduced. In particular, the curved shape portion 6 is likely to be the most protruding portion in the flexible circuit body 2, and thus is a portion that is likely to come into contact with peripheral components and the like, so that disconnection and peeling of the wiring layer 4 and damage to the flexible circuit body 2 are prevented. It is effective in terms.

  Further, if a material having excellent heat resistance is selected for the elastic member 3, the thermal durability of the flexible circuit board 1 is improved, and use at high temperatures is possible. In addition, if a portion other than the curved shape portion 6 that has a lot of contact with peripheral parts or the like is known in advance, the durability of the flexible circuit board 1 is improved by covering the portion with the elastic member 3. On the other hand, since the elastic member 3 is not covered on a portion that is not particularly necessary, the manufacturing cost and weight of the flexible circuit board 1 can be reduced.

  Further, by covering the curved shape portion 6 with the elastic member 3, there is an effect that the shape of the curved shape portion 6 can be more reliably maintained by the shape maintaining force of the elastic member 3. That is, when a large external force such as a sudden tensile stress acts on the flexible circuit board 1, for example, the curved shape portion 6 may be extended, and the wiring layer 4 may be disconnected or peeled off. Since the curved shape of the curved portion 6 can be more reliably maintained by the elastic member 3 that is covered, the curved portion 6 is easily maintained even when the flexible circuit board 1 is repeatedly expanded and contracted due to a large external force. It is easy to return to the original shape when stretched). Therefore, disconnection and peeling of the wiring layer 4 and damage to the flexible circuit board 1 can be prevented more reliably.

<3: Configuration of the curved portion>
FIG. 1C shows a schematic enlarged view of the curved portion 6. The curved portion 6 has a radius of curvature R (mm) as shown. By providing the curved shape portion 6 in this way, the flexible circuit board 1 can be expanded and contracted in the curved shape portion 6. In particular, in the case of the bellows-like flexible circuit board 1 provided with a plurality of curved portions 6, the entire flexible circuit board 1 can be expanded and contracted, so that external forces such as vibration and impact acted on the flexible circuit board 1. Also in this case, it is possible to prevent stress from being concentrated locally on the flexible circuit board 1. Therefore, peeling of the wiring layer 4, disconnection, and breakage of the flexible circuit body 2 can be prevented. Further, by attaching the flexible circuit board 1 in a contracted state, the installation space can be reduced, and not only the flexible circuit board 1 but also the electronic device can be miniaturized.

  The curvature radius R (mm) is more preferably 0.3 mm or more. According to the earnest study by the inventors, if the radius of curvature R (mm) is 0.3 mm or more, the disconnection layer 4 may be disconnected or peeled off even if a fine and complicated wiring pattern is formed. It has been found that can be further reduced.

  Furthermore, according to the flexible circuit board 1 according to the present embodiment, the flexible circuit board 1 can be stretched and deformed with the shape maintaining force of the elastic member 3 while the curvature radius R (mm) in the curved shape portion 6 is maintained. Is possible. That is, even when the flexible circuit board 1 expands and contracts (dotted line portion in FIG. 1C), the curved shape, that is, the radius of curvature R (mm) hardly changes. Therefore, there is no possibility that the wiring layer 4 is peeled off or disconnected in the curved portion 6, and excellent connection reliability can be obtained.

<4: Manufacturing method of flexible circuit body>
With reference to Fig.2 (a)-FIG.2 (c), the manufacturing method of the flexible circuit body 2 in this embodiment is demonstrated.

  First, as shown in FIG. 2A, a metal-clad film 10 is prepared. The metal-clad film 10 can be formed by forming the adhesive layer 9 on the surface of the insulating film 7, laminating the metal foil 4A on the surface of the adhesive layer 9, and integrating the three layers by thermocompression bonding. As another method for forming the metal-clad film 10, a varnish that is a precursor of a base film is applied on a metal foil and the precursor is dried, and a metal layer is deposited or sputtered on the base film. And a method of forming a metal layer by electrolytic plating on a base film coated with a conductive paste.

  Next, as shown in FIG. 2B, the wiring layer 4 is formed by etching the metal layer (metal foil 4A) into a desired pattern. Next, as shown in FIG. 2C, the flexible circuit body 2 is obtained by thermocompression bonding the insulating layer 8 on the wiring layer 4. As described above, the single-sided flexible circuit body 2 having the insulating layer 8 is obtained by the steps shown in FIGS. 2 (a) to 2 (c).

  The flexible circuit body 2 according to the present embodiment can employ not only the above-described single-side structure but also a multilayer structure described below. With reference to FIG. 3, the manufacturing method of the multilayer flexible circuit body 2 which has a three-layer structure is demonstrated.

  First, as shown in FIG. 3A, the above-described metal-clad film 10, single-sided flexible circuit body 2, and metal foil 11 are prepared, and two adhesive sheets 12 for bonding these three sheets are prepared. prepare. As the adhesive sheet 12, the above-described adhesive layer 9 formed into a sheet shape is used. These are laminated as shown in the figure, and the laminated ones are integrated by heating and pressing.

  Next, as shown in FIG. 3B, a through hole 13 is formed at a desired position using a drill or a laser, and through-hole plating 13a is performed, and each layer of the metal foil 4A, the wiring layer 4, and the metal foil 11 is formed. Is electrically connected. FIG. 3B shows a form in which the wiring layers are connected by plating. As another method, the layers can be electrically connected by filling the through holes 13 with a conductive paste and curing the conductive paste.

Next, as shown in FIG.3 (c), metal foil 4A, 11 provided in each surface is processed into the wiring pattern which has a desired pattern by methods, such as an etching. Thereafter, the insulating layer 8 is formed on both surfaces in the same manner as described above (see FIG. 2C). Thereby, the multilayer flexible circuit body 2 having a three-layer structure can be manufactured. In addition, although the form which has a 3 layer structure is demonstrated here, the structure of the multilayer flexible circuit body 2 is not restricted to a 3 layer structure.

<5: Manufacturing method of flexible circuit board>
4 (a) to 4 (c), the flexible circuit board 1 having the curved shape portion 6 is obtained by covering the flexible circuit body 2 manufactured by the above-described manufacturing method and covering the elastic member 3. A manufacturing method for this will be described.

  In the present embodiment, a urethane elastomer is used as the elastic member 3, but the material usable as the elastic member 3 is not limited to the urethane elastomer as described above. That is, the material for the elastic member 3 may be appropriately selected according to the environmental conditions in which the flexible circuit board 1 is used. For example, when the flexible circuit board 1 is used for the wiring of the robot, a material having high wear resistance and high hardness may be used, and when the purpose is to absorb impact or vibration, the material having low hardness is used. Should be used. Furthermore, it is more effective to use a material having a high elongation at break.

  When forming the curved shape portion 6, as shown in FIG. 4A, first, the flexible circuit body 2 is arranged so as to be along the guide pin 15, and in this state, tension is applied to both ends of the flexible circuit body 2. multiply. The magnitude of the tension may be set as appropriate depending on the material, thickness, etc. of the flexible circuit body 2.

  Next, as shown in FIG. 4B, a mold (upper mold) 14a and a mold (lower mold) 14b having curved portions are used, and the flexible circuit body 2 is formed by the pair of molds 14a and 14b. The urethane elastomer before curing is poured into the mold except for the connection terminals 5. As a casting method for a mold, various casting methods such as cast molding which are generally used can be adopted. By casting with such a mold, the elastic member 3 can be provided integrally with the flexible circuit body 2, and the flexible circuit board 1 can be obtained (FIG. 4C).

  According to this manufacturing method, the curved shape portion 6 can be easily provided by covering the elastic member 3 even on the flexible circuit body 2 where it is difficult to provide the curved shape portion 6 by a molding process such as heating and pressing. It becomes possible. In FIG. 4C, the flexible circuit body 2 is almost entirely covered with the elastic member 3, but a mold is installed only in the vicinity of the portion where the guide pin 15 is in contact with the urethane elastomer. Only the curved portion 6 may be covered with the elastic member 3 by molding.

  In this embodiment, the elastic member 3 is covered with the flexible circuit body 2 that does not have the curved portion, but the flexible circuit body 2 made of thermoplastic resin is heated and pressurized. The manufacturing method which coat | covers the elastic member 3 to the curved shape part 6 after giving the curved shape part 6 previously may be sufficient. In this case, it is possible to more reliably maintain the curved shape of the already-curved curved shape portion 6.

  In addition, according to the above-described manufacturing method, the covering position by the elastic member 3 can be appropriately changed by changing the position where the mold is installed, so that the elastic member 3 can be covered only at a necessary position. Thus, the flexible circuit board 1 can be reduced in weight as compared with the case where almost the entire flexible circuit body 2 is covered with the elastic member 3. A flexible circuit in which the entire flexible circuit board 1 is covered with the elastic member 3 and the curved portion 6 is formed, and then the elastic member 3 other than the necessary portion is shaved to cover only the desired portion. A method of obtaining the substrate 1 may be used.

<6: Effects of this embodiment>
According to the flexible circuit board 1 according to the present embodiment, the following effects can be mainly obtained.
Since the flexible circuit board 1 can be expanded and contracted by having the curved shape portion 6, even when an external force such as vibration or impact is applied, the flexible circuit board 1 is expanded or deformed to cause peeling or disconnection of the wiring layer 4. In addition, damage to the flexible circuit board 1 can be prevented, connection reliability can be improved, and the life of the flexible circuit board 1 can be extended.
Since at least the curved portion 6 is covered with the elastic member 3, the flexible circuit body 2 can be protected by the elastic member 3. In other words, it is possible to prevent disconnection and peeling of the wiring layer 4 and damage to the flexible circuit board 1 due to contact with peripheral parts and the like, the action of external force, etc., thereby improving connection reliability and flexible circuit board. 1 lifespan can be extended.
-Since the curved shape part 6 is coat | covered with the elastic member 3, the shape of the curved shape part 6 can be more reliably maintained with the shape maintenance force of the elastic member 3. FIG. Therefore, even when a large external force such as impact or vibration acts, the possibility of disconnection and peeling of the wiring layer 4 in the curved portion 6 can be reduced, so that connection reliability is improved and a flexible circuit board is provided. 1 lifespan can be extended.

  That is, according to the present embodiment, the possibility that the wiring layer is disconnected or peeled off or the flexible circuit board itself is damaged even when it comes into contact with peripheral components or when a large external force such as impact or vibration is applied. And it becomes possible to provide the flexible circuit board which can extend a lifetime with a simple structure.

<7: Other embodiments>
The form of the flexible circuit board 1 according to the present invention is not limited to the form described above. Hereinafter, other embodiments that can be adopted by the flexible circuit board 1 according to the present invention will be described.

  In addition to the bellows shape shown in FIG. 1A, the flexible circuit board 1 can also take a shape as shown in FIGS. 5A to 5C, for example. Fig.5 (a) is a schematic top view of the flexible circuit board 1 which concerns on other embodiment, FIG.5 (b) is a schematic side view.

  The flexible circuit board 1 may have not only a meandering shape in which the curved shape portion 6 is formed in at least one place, but also a “horse-shoe shape” or an “Ω shape”, for example. Even in this case, the same effect as described above can be obtained by covering at least the curved portion 6 with the elastic member 3.

  In the meandering shape shown in FIG. 5A, when a tensile stress acts on the flexible circuit board 1, the curved portion 6 of the flexible circuit board 1 may rise in the Z direction in FIG. 5B. . In this case, an installation space in consideration of this rising amount is required. On the other hand, according to the present embodiment, since the curved shape portion 6 is covered with the elastic member 3, it is possible to suppress the rising of the curved shape portion 6 and to save the installation space. it can.

Moreover, the flexible circuit board 1 of the present invention can also adopt the form shown in FIG. FIG. 5C shows a case where almost the entire flexible circuit body 2 is covered in a rectangular parallelepiped shape with the elastic member 3. In this case, since the flexible circuit body 2 can be covered with the elastic member 3 using a mold having a simple structure, an improvement in production efficiency and a reduction in manufacturing cost can be expected. 5C, the flexible circuit board 1 can be stretched and deformed if a material having a high elongation rate (low hardness) is selected as the elastic member 3 to be coated. Further, by providing a slit in the vicinity of the curved portion 6, it can be expanded and contracted.

  As described above, according to the other embodiments described here, even when a large external force such as vibration or impact is applied when contacting with a peripheral component or the like, the wiring layer is disconnected or peeled off, or the flexible circuit board itself is It is possible to provide a flexible circuit board capable of reducing the possibility of breakage and extending the life with a simple configuration.

DESCRIPTION OF SYMBOLS 1 ... Flexible circuit board 2 ... Flexible circuit body 3 ... Elastic member 4 ... Wiring layer 5 ... Connection terminal 6 ... Curve-shaped part 7 ... Insulating film (base layer) 8 ... Insulating layer 9 ... Adhesive layer

Claims (3)

An insulating film as a base layer;
A wiring layer formed on the insulating film;
An insulating layer formed on the wiring layer,
In a stretchable flexible circuit board in which a curved portion is formed in at least one place,
A flexible circuit board, wherein at least the curved portion is covered with an elastic member. The elastic member is
The flexible circuit board according to claim 1, wherein the flexible circuit board is any one of silicone rubber, acrylic elastomer, and urethane elastomer.   3. The flexible circuit board according to claim 1, wherein the flexible circuit board is configured to be extendable and contractable in a state in which a curvature radius R (mm) of the curved shape portion is maintained.

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