JP4775127B2 - Flat cable electroplating method and flat cable manufacturing method - Google Patents

Description

  The present invention relates to a method of electroplating a long flat cable having a plurality of exposed conductor portions in the longitudinal direction, in which both surfaces of a plurality of conductors arranged on a plane are covered with an insulating material, and a flat using the same The present invention relates to a method for manufacturing a cable.

  Flat cables used for electrical wiring in small communication devices such as mobile phones and video cameras are required to have high density and high reliability in a limited space in the device. As a wiring member for this purpose, a flat cable in which a plurality of flat conductors are arranged on a plane, both surfaces of the arrangement surface are covered with an insulating resin film, etc., and terminals for electrical connection are formed at both ends is often used. Yes. This type of flat cable uses a flat copper conductor with excellent flexibility and conductivity. However, when used as a bare copper conductor, migration tends to occur in high temperature and high humidity environments. The electrical insulation between them is lowered, and an electrical short circuit is likely to occur. Also, bare copper conductors are easily oxidized and their adhesion to the insulating film is reduced. For this reason, the surface of a flat copper conductor with tin plating is usually used.

Further, in a flat cable in which a copper conductor is tin-plated by electroplating, needle-like crystals (whiskers) are generated due to the end portions at both ends receiving compressive stress for electrical contact. In order to suppress the occurrence of whiskers in the terminal portion and to improve the reliability of electrical connection between the terminal conductor and the electrical connector, it is disclosed that the terminal conductor is plated with gold (for example, see Patent Document 1). ).
JP 2006-49185 A

  Although the method of applying gold plating to the terminal conductor of the flat cable is not specifically disclosed in the above-mentioned Patent Document 1, a method as shown in FIG. 3A is usually used. That is, a flat cable having terminal portions at both ends has conductor exposed portions 3 provided at predetermined intervals on an insulator 2 of a long flat cable 1 that is continuously formed. The conductor 4 of the conductor exposed portion 3 is sequentially plated by being intermittently sent to the bath 5 and immersed therein and applying an electric field to the plating solution by the plating power source 8. Then, the conductor 4 exposed at the conductor exposed portion 3 is divided to form a short single-unit flat cable.

  In this case, the conductor 4 exposed at the conductor exposed portion 2 of the long flat cable 1 is brought into contact with the power supply electrode such as the electrode roller 6 at a portion outside the plating solution tank 5 to give a negative potential of the plating power source 8. A positive potential is applied to the plated metal material 7. The plurality of conductors 4 are formed so as to be in electrical contact with a power feeding electrode such as an electrode roller 6 as shown in FIG. However, depending on the cable drawing tension and the laminated state of the resin film of the insulator 2, the arrangement of the conductors 4 is curved as shown in FIG. 3C and is not in contact with the power supply electrode such as the electrode roller 6. Conductors may occur. In addition, when the exposed area of the conductor exposed portion 3 is small, the feeding electrode such as the electrode roller 6 may not be in contact with the conductor 4.

  In order to avoid the above problem, a method of arranging the electrode rollers 6 on both upper and lower surfaces of the conductor 4 so as to sandwich the conductor 4 is also conceivable. However, if the support shaft of the electrode roller 6 is inclined, A conductor that does not come into contact with the electrode roller 6 may be generated, which is not perfect. If there is a conductor that does not come into contact with the electrode roller 6, a conductor that is not plated is generated, and an electrical short circuit due to poor connection with the electrical connector or whisker generation is likely to occur.

  The present invention has been made in view of the above-described situation, and a plurality of conductors exposed at a conductor exposed portion of a long flat cable are securely connected to a plating power source, and no electric leakage of a plating cable is generated. It aims at providing the plating method and the manufacturing method of a flat cable.

  The method for electroplating a flat cable according to the present invention includes a plurality of conductors arranged on a plane, and a plurality of conductors arranged at predetermined intervals in the longitudinal direction of a long flat cable in which both surfaces of the conductor are covered with an insulating resin. The conductor exposed portion is provided, and the conductor of the exposed conductor portion is electroplated. A plurality of exposed conductors are connected and integrated by a conductive member at at least one conductor exposed portion of a long flat cable, and the flat cable is immersed in a plating solution. Further, the exposed conductor of the exposed conductor portion has a cutting allowance for cutting and removing a portion integrated and connected by the conductive member.

  According to the present invention, all the conductors exposed to the conductor exposed portion can be electrically connected, and all the conductors can be reliably connected to the plating power source, thereby preventing the plating conductor from being unplated. be able to. In addition, by providing a conductor with a cutting margin, connecting a conductive member to the conductor, and removing the conductive member by removing the cutting margin, the total number of flat cables cut in a short length can be reduced without wasting the product. Can be usable.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1A is a diagram for explaining a state in which a flat cable is electroplated in a plating bath, and FIGS. 1B and 1C show a state in which the conductors of the conductor exposed portions are connected and integrated by a conductive member. FIG. In the figure, 1 is a long flat cable, 2 is an insulator, 3 is a conductor exposed portion, 4 is a conductor, 5 is a plating bath, 7 is a plating metal material, 8 is a plating power source, 9 is a terminal reinforcing tape, 10 Indicates a conductive member, and 11 indicates a soldering agent.

  In the flat cable electroplating method according to the present invention, as shown in FIG. 1 (A), a long flat cable 1 is intermittently fed and immersed in a plating bath 5 to expose a conductor exposed portion 3 of the flat cable 1. The conductor exposed in this part is electroplated. In order to attach the plated metal to the exposed conductor, at least one conductor exposed portion 3 is connected and integrated by the conductive member 10 intersecting with all the exposed conductors to be electrically connected. When the conductive member 10 comes out of the plating solution when the flat cable 1 is immersed in the plating solution, the conductive member 10 is connected to the negative potential side of the plating power source 8 with an electric clip or the like, and the plating metal immersed in the plating solution The material 7 is connected to the positive potential side of the plating power source 8. When the conductive member 10 is immersed in the plating solution, one of the conductors outside the plating solution is connected to the negative potential side of the plating power source 8.

  As shown in FIG. 1 (B) or FIG. 1 (C), the long flat cable 1 is usually a flat copper whose cross section is flattened by crushing a plurality of conductors 4 (for example, round copper wire). Conductors) are arranged in a line on a plane, and both surfaces (upper and lower surfaces) of the arrangement surface are covered with an insulator 2 such as an insulating resin. Further, when the conductor 4 is used as bare copper, migration is likely to occur under high temperature and high humidity, and the insulation resistance between adjacent conductors is lowered, and an electrical short circuit is likely to occur. Further, bare copper is easily oxidized, and if it is oxidized before being coated with the insulator 2, its adhesion to the insulator 2 is lowered. For this reason, a conductor surface that is tin-plated is usually used.

  The insulator 2 that covers and insulates the plurality of conductors 4 is obtained by, for example, laminating an insulating film having an adhesive resin layer from the upper and lower surfaces of the arrangement surface of the conductors 4 or by molding the insulating film on the conductors by an extruder. It is formed. The short flat cable has a conductor exposed portion 3 in which the conductor 2 is exposed by removing the insulator 2 of the long flat cable 1 at a predetermined interval. It is formed by dividing the conductor 4 of the portion 3. In this way, a flat cable with the conductor 4 exposed at both ends is obtained. For example, the conductor exposed portion 3 is formed by removing the insulator on one surface side and leaving the insulator on the opposite surface side as the insulating end portion 2a, to which the terminal reinforcing tape 9 is joined.

  The conductive member 10 is formed of, for example, a rod-shaped body having a round or rectangular cross section, has a sufficient length that intersects all the conductors 4 exposed from the conductor exposed portion 3, and uses a soldering agent or a conductive adhesive. It is connected to the conductor 4 and electrically shorts all conductors. The conductive member 10 may not be provided in all the conductor exposed portions 3, but may be provided in the conductive exposed portions 3 at arbitrary positions of the long flat cable 1. For example, as shown in FIG. 1A, the conductive exposed portions 3 (every two in the drawing) are provided for each flat cable length that can be immersed in the plating solution tank 5 at one time.

  Moreover, in this invention, the space d is provided between the terminal reinforcement tapes 9 adjoined adjacently, the insulating film of both surfaces is removed in this space part, and the electrically-conductive member 10 is the terminal reinforcement tape side part of the space d. You may make it fix with soldering or a conductive adhesive. The space d is cut and removed when the conductor exposed portion 3 is divided later, and is formed as a cutting allowance. According to this configuration, the solder agent 11 for fixing the conductive member 10 tends to flow along the longitudinal direction of the conductor 4, but the flow of the solder agent 11 is stopped by the edges of the terminal reinforcing tape 9 on both sides of the space d. It is done. And the part to which the soldering agent 11 adheres can maintain the state as a terminal conductor used as an electrical connection surface by cutting and removing later, and can be used as a product without discarding.

  The conductive member 10 is connected to a plating power source outside the plating solution tank 5, and is adapted to perform electroplating on the conductor exposed portion 3 in the portion immersed in the plating solution. In consideration of resistance, it is preferable to connect to the plating power source 8 as close to the plating bath 5 as possible. Moreover, although the example which connects the plating power supply 8 only to one conductor exposed part 3 of the cable part immersed in plating liquid was shown, it plating on the conductor exposed part 3 of the both sides of the cable part immersed in plating liquid A power supply 8 may be connected. In addition, the long flat cable 1 may be divided into a length that can be accommodated in the plating solution tank 5 in addition to being continuously fed into the plating solution tank and immersed therein.

  The plating applied to the exposed conductor portion 3 is for suppressing the generation of whiskers at the terminal portion, or for improving the reliability of the electrical connection between the terminal conductor and the electric connector, and is preferably plated with gold. . However, if gold plating is directly applied on tin plating, electrolytic corrosion due to contact with dissimilar metals may occur and it may not be able to withstand long-term use. For this reason, gold plating may be applied after nickel plating as the base metal.

  FIG. 2 is a diagram for explaining an example in which the above-described long flat cable is cut at each conductor exposed portion to form a short single flat cable 1 ′ having connection terminals 12 on both sides. The connection terminal 12 is formed by cutting the conductor exposed portion 3 electroplated by the method of FIG. 1 (A) into two. Specifically, the conductive member 10 of FIG. 1 (C) is soldered. It is formed by removing the cut margin (space d portion). In addition, the conductor exposed portion 3 to which the conductive member 10 is not actually connected is also cut and removed in the same manner if it has a cutting allowance.

  The connection terminal 12 of the unitary flat cable 1 ′ removes one side of the insulator 2 covering the arrangement surface of the conductors 4 to expose one side of the conductors 4, and connects the insulating end 2 a on the opposite side. It leaves and becomes the shape which affixed the terminal reinforcement tape 9 on this part. The exposed surfaces of the plurality of conductors 4 whose one side is exposed are formed of terminal conductors that have been reliably plated by the electroplating method described above. The connection terminal 12 can be inserted into the elastic contact 13a of the electrical connector 13 to obtain a reliable and good electrical connection. Note that the exposed surface of the conductor 4 may be on the same side in the connection terminals at both ends, but may be on a different side.

It is a figure explaining the outline of the present invention. It is a figure explaining an example of the unitary flat cable produced by this invention. It is a figure explaining a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Long flat cable, 1 '... Single-piece | unit flat cable, 2 ... Insulator, 2a ... Insulation end part, 3 ... Conductor exposure part, 4 ... Conductor, 5 ... Plating bath, 6 ... Electrode roller, 7 DESCRIPTION OF SYMBOLS ... Metal plating material, 8 ... Plating power supply, 9 ... Terminal reinforcement tape, 10 ... Conductive member, 11 ... Solder agent, 12 ... Connection terminal, 13 ... Electrical connector, 13a ... Elastic contactor.

Claims (3)

A plurality of conductor exposed portions are provided at predetermined intervals in a longitudinal direction of a long flat cable in which a plurality of conductors are arranged on a plane and both surfaces of the conductor arrangement surface are covered with an insulating resin. A flat cable electroplating method for electroplating a conductor of
A flat cable characterized in that a plurality of conductors exposed at a conductor exposed portion of at least one portion of the long flat cable are connected and integrated by a conductive member to be electrically connected, and the flat cable is immersed in a plating solution. Electroplating method.   2. The method of electroplating a flat cable according to claim 1, wherein the conductor exposed at the conductor exposed portion has a cutting allowance for cutting and removing a portion electrically connected and integrated by the conductive member. . A plurality of conductor exposed portions are arranged at predetermined intervals in the longitudinal direction of a long flat cable in which a plurality of conductors are arranged on a plane and both surfaces of the conductor arrangement surface are covered with insulating resin, A method of manufacturing a flat cable, after electroplating the conductor of the part, cutting the conductor of the exposed conductor part,
The exposed conductors in at least one portion of the long flat cable are electrically connected by connecting and integrating the exposed conductors with a conductive member, and the flat cable is immersed in a plating solution to expose the conductor. A method for producing a flat cable, characterized in that electroplating is applied to the conductor of the cable.

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