JP2006173274A - Flexible printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed board electrically connecting a plurality of mutual FPCs or a plurality of places of one bent FPC efficiently and having an excellent maintenance after connection. <P>SOLUTION: A first exposure 25 is formed at the end 24 of a first board 21, on which a base layer 21a, a conductive layer 21b, and a protective layer 21c are laminated. A second exposure 26 is formed to a second board 22 constituted in the same manner as the first board 21. A conductive member 23 is formed near the first and second exposure sections 25 and 26. The flexible printed board 20 is connected electrically by forming a soldering section 27 by soldering and treating the first exposure section 25, the second exposure section 26, and the conductive member 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flexible printed circuit board.

  Electronic devices, particularly portable electronic devices, have been reduced in size and thickness in order to improve portability. As the equipment becomes smaller and thinner, the space in the equipment provided for wiring tends to become smaller and more complicated, so flexible printed boards (hereafter referred to as fixed wiring boards) , Which may be abbreviated as FPC).

  The FPC has a structure in which at least three layers of a base layer (base film), a conductive layer (mostly formed of copper foil), and a protective layer (coverlay film) are laminated and have flexibility. Such conduction between the FPC and a contacted body made of a conductive material (hereinafter referred to as a conductive member) is performed by opening a hole in a protective layer at a position where the FPC is brought into contact with the conductive member to expose the conductive layer. This is realized by soldering the exposed portion of the electrode and the conductive member.

  6 and 7 are diagrams showing an outline of connection between a conventional FPC and a conductive member. FIG. 6 shows a connection structure in which one FPC 1 and another FPC 2 are electrically connected to the conductive member 3. In the connection structure shown in FIG. 6, first, in one FPC 1 in which the base layer 1a, the conductive layer 1b, and the protective layer 1c are laminated, the conductive layer 1b is exposed at a predetermined portion of the protective layer 1c to form an exposed portion 4 In another FPC 2 that forms the portion 5 and is formed by laminating the base layer 2a, the conductive layer 2b, and the protective layer 2c, the opening 7 that forms the exposed portion 6 by exposing the conductive layer 2b to a predetermined portion of the protective layer 2c. Form. Next, positioning is performed so that the exposed portion 4 of the conductive layer 1b formed on one FPC 1 and the exposed portion 6 of the conductive layer 2b formed on the other FPC 2 correspond to each other, and the conductive member 3 is disposed at this position. To do. Further, the exposed portion 4 of the conductive layer 1b and the conductive member 3 are soldered to form a first soldered portion 8, and the exposed portion 6 of the conductive layer 2b and the conductive member 3 are soldered to form a second soldering portion 8. Conduction is enabled by forming the soldering portion 9.

  Since the outline of the conventional connection shown in FIG. 7 is similar to that shown in FIG. 6, the corresponding parts are denoted by the same reference numerals. FIG. 7 shows a connection structure in which one FPC 1 is bent and the conductive layers 1 b included in one FPC 1 are electrically connected to the conductive member 3. In FIG. 7, since one FPC 1 is partially inverted by bending, the conductive layer 1b is exposed on the base layer 1a side of the inverted portion, and the opening 11 forming the exposed portion 10 is formed. Therefore, the second soldering portion 9 is formed so that the exposed portion 10 of the conductive layer 1b formed by removing the base layer 1a and the conductive member 3 can conduct.

  However, in the conventional connection structure shown in FIGS. 6 and 7, each of the exposed portions and the corresponding portions of the conductive member 3 as in the first and second soldering portions 8 and 9 are soldered. Therefore, there is a problem that soldering is required as many as the number of places where the exposed portion of the conductive layer and the conductive member are electrically connected, and a long time is required for the soldering operation. In addition, since the first soldering portion 8 is hidden by the FPC (inverted portion of FPC1 or FPC2) located on the side where the second soldering portion 9 is formed, the solder bonding of the first soldering portion 8 is performed. There is also a problem that it is difficult to confirm the situation. Further, the FPC protruding from the second soldering portion 9 may be cracked due to being pulled in a direction away from the first soldering portion 8 due to, for example, hooking.

Many prior arts related to conduction of conductive layers of FPC have been proposed.
For example, a through hole is formed in the first printed wiring board, and the first printed wiring board is provided. The first electrode portion circumscribing the through hole and the second printed wiring board are overlapped with the first printed wiring board. In this state, it is proposed to connect the second electrode part located at the part facing the through hole by filling the through hole with solder (see Patent Document 1).

  Further, a part of the copper foil of the first flexible substrate is exposed, a hole is formed by bending a part of the exposed copper foil in the direction of the base member, and the bent copper foil and the second flexible substrate It is proposed to make a connection by bringing the exposed copper foil into contact with each other and filling the hole with solder (see Patent Document 2).

  Also, the copper foil of one flexible printed circuit board is protruded from the end of the base film, and the copper foil protruding from one printed circuit board is inserted into the hole provided adjacent to the copper foil on the other printed circuit board, It is proposed to solder (see Patent Document 3).

  Also, a through hole is formed in the solder land of one flexible printed circuit board, a convex solder layer is formed in advance on the solder land of the other flexible printed circuit board, and the tip of the solder layer is engaged with the through hole. It is proposed to connect by melting the solder by heating (see Patent Document 4).

  It is also proposed to expose the lands on the first substrate, expose the pair of connection terminals provided on the second substrate at different lengths from the end portions, and connect the lands and the connection terminals by soldering. (See Patent Document 5).

  However, all of the techniques disclosed in Patent Documents 1 to 5 disclose only the connection method between the upper FPC and the lower FPC, and the configuration for connecting the conductive layer of the FPC and the conductive member is completely different. Not mentioned.

  Note that Patent Document 5 is a proposal for the purpose of preventing disconnection failure of a connection portion of stress concentration due to soldering, and is a solution technique paying attention to the tensile strength at this position. Further, since this disconnection failure occurs because the lengths of the front and back connection portions coincide with each other, this proposed technique has a problem that the length of each connection terminal on the front and back exposed from one end portion of the second substrate must be changed. Therefore, there is a need for a technology that enables connection without having to be aware of the lengths of the connecting portions on the front and back sides.

  As a prior art for conducting FPC using a conductive member, there is a connection structure in which a bump made of a conductive metal provided through a relay FPC and connected to a conductor pattern of the relay FPC is used as a conductive member. A configuration is proposed in which a pre-solder layer formed in advance on the surface and a pre-solder layer formed on the surface of the connection pad where the main FPC is exposed are brought into contact with each other by heating and melting (see Patent Document 6). ).

  However, in the technique disclosed in Patent Document 6, since the soldered portion of the main FPC is hidden by the relay FPC, there remains a problem that it is difficult to confirm the solder adhesion state of the soldered portion.

Japanese Patent Laid-Open No. 61-8987 Japanese Utility Model Publication No. 61-183565 Japanese Utility Model Publication No. 2-146865 JP 2002-368370 A JP 2002-151823 A JP-A-10-256688

  An object of the present invention is to provide a flexible printed circuit board in which a plurality of FPCs or a plurality of bent FPCs are electrically connected efficiently and are excellent in maintenance manageability after connection.

In the present invention, at least a conductive layer provided on one substrate on which a base layer, a conductive layer, and a protective layer are stacked, and at least a conductive layer on another substrate on which the base layer, the conductive layer, and the protective layer are stacked are interposed via a conductive member. In a flexible printed circuit board in which the conductive layers are electrically connected to each other via a conductive member by bending one substrate or bending one substrate,
A first exposed portion of a conductive layer formed on an edge of one substrate;
A second exposed portion of the conductive layer formed on another substrate or a second exposed portion of the conductive layer formed on a portion other than an end portion of one bent substrate;
A conductive member provided at a position in contact with the first and second exposed portions of the conductive layer or in the vicinity of the first and second exposed portions of the conductive layer;
A flexible printed circuit board including a soldering portion provided so as to electrically connect the first and second exposed portions of the conductive layer and the conductive member.

  In the invention, it is preferable that the first exposed portion is formed by partially peeling the protective layer.

  In the invention, it is preferable that the first exposed portion is formed by partially peeling the base layer.

  In the invention, it is preferable that the first exposed portion is formed by partially peeling the protective layer and the base layer.

Moreover, the present invention provides any of the flexible printed circuit boards,
A light emitting element that emits laser light;
A light receiving element that receives light and converts it into an electrical signal;
A lead pin electrically connected to the light emitting element and the light receiving element;
A protective cover covering the light emitting element and the light receiving element;
A hologram laser comprising: a hologram element mounted on a laser light emitting surface of a protective cover.

  The present invention is also an optical pickup device comprising any one of the flexible printed boards.

  According to another aspect of the present invention, there is provided a disk drive device comprising the optical pickup device.

  According to the present invention, the flexible printed circuit board has a first exposed portion of the conductive layer formed on the end portion of one substrate and a second exposed portion of the conductive layer formed on the other substrate or bent. A second exposed portion of the conductive layer formed on a portion other than the end portion of one substrate, and a position contacting the first and second exposed portions of the conductive layer or the first and second exposed portions of the conductive layer The first and second exposed portions of the conductive layer and the conductive member are soldered so as to be electrically connected. As a result, at least two electrical connection portions can be integrated into one place, so that the working time can be shortened. In addition, the first exposed portion is formed on the end portion of one substrate, and the end portion is soldered so that one substrate does not protrude from the soldered portion. Therefore, the occurrence of cracks can be prevented. In addition, since the first exposed portion and the second exposed portion are soldered at one place, it is easy to confirm the connection state of the soldered portion, and the ease of maintenance such as removal of the solder is improved. Furthermore, the location of the soldering portion is saved, and the space can be reduced by effectively using the space of the saving portion.

  According to the present invention, since the first exposed portion is formed by partially peeling the protective layer and / or the base layer, the first exposed portion can be easily formed and can contribute to an improvement in product yield.

  Further, according to the present invention, the hologram laser can be thinned by using any one of the flexible printed boards as the hologram laser.

  According to the present invention, the optical pickup device can be made compact by including any one of the flexible printed boards.

  According to the present invention, the disk drive device can be made compact by including the optical pickup device.

  FIG. 1 is a diagram showing a simplified configuration of a flexible printed circuit board 20 according to an embodiment of the present invention. In the FPC 20 of this embodiment, at least a base layer, a conductive layer, and a protective layer are stacked, and at least a base layer, a conductive layer, and a protective layer are stacked. The second conductive layer 22 b of the second substrate 22, which is another substrate, is electrically connected through the conductive member 23.

  The FPC 20 includes a first exposed portion 25 of the first conductive layer 21 b formed on the end portion 24 of the first substrate 21, and a second exposed portion 26 of the second conductive layer 22 b formed on the second substrate 22. The conductive member 23 provided in the vicinity of the first and second exposed portions 25 and 26 of the first and second conductive layers 21b and 22b, and the first and second exposed portions 25 and 26 and the conductive member 23 are electrically connected. And a soldering portion 27 provided so as to be connected.

  As described above, the first substrate 21 has a configuration in which the first base layer 21a (also referred to as a base film), the first conductive layer 21b, and the first protective layer 21c are laminated in three layers, and has flexibility. Have. The first base layer 21a is a film made of, for example, polyimide. The first conductive layer 21b is formed of, for example, copper foil or copper plating, and constitutes a conductive circuit. The first protective layer 21c (also called a coverlay film) is a film made of, for example, polyimide, and is formed by being laminated on the first conductive layer 21b to protect the conductive circuit from scratch damage.

  In the first substrate 21, the first exposed portion 25 is formed by partially removing the first protective layer 21 c at the end portion 24 to be electrically connected. The formation of the first exposed portion 25 is realized by, for example, a photoetching method. The first substrate 21 is also a flexible printed circuit board.

  The second substrate 22 is configured in the same manner as the first substrate 21 and has a configuration in which the second base layer 22a, the second conductive layer 21b, and the second protective layer 21c are laminated in three layers, and is flexible. Have. A second exposed portion 26 is formed on the second substrate 22 at a predetermined location for electrical conduction. The second exposed portion 26 is formed by removing the second protective layer 22 c of the second substrate 22 at the above-described location and forming an opening 28. The removal of the second protective layer 22c is also realized by, for example, a photoetching method. The second substrate 22 is also a flexible printed circuit board, and the flexible printed circuit board 20 (FPC 20) of the present embodiment is a flexible printed circuit board (FPC) having a composite structure in which a plurality of flexible printed circuit boards are electrically connected by a conductive member 23. ).

  The material of the conductive member 23 is not particularly limited, and a material or a component suitable for establishing electrical continuity between the FPCs is selected in an apparatus or device that uses a composite structure FPC as a circuit board. The conductive member 23 is provided in the vicinity of a portion positioned so that the first exposed portion 25 and the second exposed portion 26 correspond to each other.

  In the soldering portion 27, an amount of solder that can contact the first exposed portion 25, the second exposed portion 26, and the conductive member 23 is electrically connected to the first exposed portion 25, the second exposed portion 26, and the like. It is formed by being supplied to a connecting portion with the member 23. The solder used for forming the soldering portion 27 may be either tin (Sn) -lead (Pb) solder or lead-free solder. Moreover, it may be soldered by a method of filling with molten solder, or may be soldered by a method of heating and melting after supplying solid state solder to the connecting portion.

  The FPC 20 of the present embodiment adopts a configuration having two connection portions that connect the first conductive layer of the first substrate and the conductive member and connect the second conductive layer of the second substrate and the conductive member. Since the first conductive layer 21b, the second conductive layer 22b, and the conductive member 23 are electrically connected by one soldering portion 27, it is possible to consolidate the electrical connection portions. Time savings are achieved. Further, since the end portion 24 of the first substrate 21 does not protrude outward from the soldering portion 27, the end portion 24 is not caused by hooking, and the generation of cracks can be prevented. Further, since the first and second exposed portions 25 and 26 are soldered at one place, it is easy to confirm the connection state of the soldered portion 27 and the ease of maintenance such as removal of the solder is improved.

  In the present embodiment, the first substrate 21 and the second substrate 22 are separate substrates, and the first exposed portion 25 is formed facing upward. However, the present invention is not limited to this. The second substrate 22 is bent, that is, bent in a U-shape, the end of the second substrate 22 is positioned above the second exposed portion 26, and the first exposed portion faces the second substrate 22 and the second substrate 22 faces the second substrate 22. It may be configured to be formed on two substrates 22.

  FIG. 2 is a diagram showing a simplified configuration of the FPC 30 according to the second embodiment of the present invention. The FPC 30 of the present embodiment is similar to the FPC 20 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  It should be noted in the FPC 30 that the first exposed portion 31 of the first conductive layer 21b in the first substrate 21 is formed by partially peeling the first base layer 21a. Since the formation of the soldering portion 27 is performed in the same manner as the FPC 20 of the first embodiment, the description thereof is omitted.

  In the present embodiment, the first substrate 21 and the second substrate 22 are separate substrates, and the first exposed portion 31 is formed at a position facing the second substrate 22. However, the present invention is limited to this. The second substrate 22 is bent, that is, bent into a U-shape, the end of the second substrate 22 is positioned above the second exposed portion 26, and the first exposed portion faces upward. You may be comprised so that.

  FIG. 3 is a diagram showing a simplified configuration of the FPC 35 according to the third embodiment of the present invention. The FPC 35 of the present embodiment is similar to the FPC 20 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  It should be noted in the FPC 35 that the first exposed portions 36a and 36b of the first conductive layer 21b in the first substrate 21 partially peel the first protective layer 21c and the first base layer 21a, and the first conductive layer It is to be formed on both front and back surfaces of 21b. Since the formation of the soldering portion 27 is performed in the same manner as the FPC 20 of the first embodiment, the description thereof is omitted.

  As described above, the connection portion of the first substrate 21 may be the end portion of the second substrate 22 bent in a U-shape.

  FIG. 4 is a diagram showing a simplified configuration of a hologram laser 40 according to another embodiment of the present invention. The hologram laser 40 of this embodiment is electrically connected to a flexible printed circuit (FPC) 41, a light emitting element that emits laser light, a light receiving element that receives light and converts it into an electrical signal, and a light emitting element and a light receiving element. A plurality of lead pins 42 connected to each other, a protective cover 43 covering the light emitting element and the light receiving element, and a hologram element 44 attached to the laser light emitting surface of the protective cover 43.

  The light emitting element is, for example, a semiconductor laser. The light receiving element is, for example, a photodiode. Since the light emitting element and the light receiving element are mounted on the island 45, and the protective cover 43 is provided on the island 45 so as to cover the light emitting element and the light receiving element, they are not shown in FIG. The protective cover 43 is a bottomed cylindrical container made of resin, for example, and is attached with the opening side facing the island 45, and houses the light emitting element and the light receiving element in the internal space. A window (not shown) is formed at the bottom of the protective cover 43 opposite to the island 45, and the hologram element 44 is attached to the window.

  A plurality of lead pins 42 are provided as input / output terminals electrically connected to the light emitting element and the light receiving element mounted on the island 45 so as to protrude from the island 45 to the opposite side of the protective cover 43. The island 45 and the plurality of lead pins 42 are integrally held by the resin molding portion 46. The resin molding portion 46 is provided so as to be continuous with the protective cover 43, and constitutes a package 47 that fixes the island 45 on which the light emitting element and the light receiving element are mounted together with the protective cover 43. The resin molding portion 46 also integrally holds the lead pins 42 that protrude from the island 45, and the resin molding portion 46 and the lead pins 42 that protrude from the island 45 constitute a socket portion 48.

  The FPC 41 is one in which a single board bent in a U-shape is connected to lead pins 42 which are also conductive members at a plurality of locations. Strictly speaking, the FPC 41 and the lead pins 42 constitute the FPC having the composite structure of the present invention. To do.

  FIG. 5 is a diagram for explaining the outline of connection of the FPC 41 shown in FIG. 5A shows the FPC 41 before connection, and FIG. 5B shows the FPC 41 after connection. The FPC 41 is provided with an insertion hole 49 for inserting and connecting the socket portion 48. A plurality of second exposed portions 50 formed by removing the protective layer and exposing the conductive layer so as to correspond to the arrangement of the lead pins 42 of the socket portion 48 are formed on the peripheral portion facing the insertion hole 49 of the FPC 41. The Further, at the end portion 52 of the bent substrate, the base layer is removed and the second exposed portion 51 is formed.

  The board is bent in a U-shape and positioned so that the first exposed portion 51 and the second exposed portion 50 correspond to each other, the socket portion 48 is inserted into the insertion hole 49, and the lead pin 42, which is a conductive member, is attached. The first and second exposed portions 51 and 50 and the lead pin 42 are brought into contact with each other by bringing the first and second exposed portions 51 and 50 into contact with each other and performing a soldering process to form a soldered portion. Electrical connection by soldering. In addition to the portion corresponding to the bent end portion 52 of the substrate, the FPC 41 is mounted by electrically connecting the second exposed portion 50 and the lead pin 42 by soldering. Therefore, the hologram laser 40 provided with the FPC 41 does not require an unnecessary space for circuit wiring, and thus can be reduced in size.

It is a figure which simplifies and shows the structure of the flexible printed circuit board 20 which is one Embodiment of this invention. It is a figure which simplifies and shows the structure of FPC30 which is 2nd Embodiment of this invention. It is a figure which simplifies and shows the structure of FPC35 which is the 3rd Embodiment of this invention. It is a figure which simplifies and shows the structure of the hologram laser 40 which is another embodiment of this invention. It is a figure explaining the outline | summary of the connection of FPC41 shown in FIG. It is a figure which shows the outline | summary of the connection of the conventional FPC and an electroconductive member. It is a figure which shows the outline | summary of the connection of the conventional FPC and an electroconductive member.

Explanation of symbols

20, 30, 35, 41 Flexible printed circuit board 21 First board 22 Second board 23 Conductive member 25, 31, 36, 51 First exposed part 26, 50 Second exposed part 27 Soldering part 40 Hologram laser 42 Lead pin 43 Protective cover 44 Hologram element

Claims (7)

At least a conductive layer provided on one substrate on which a base layer, a conductive layer, and a protective layer are stacked, and at least a conductive layer on another substrate on which the base layer, the conductive layer, and the protective layer are stacked are electrically connected via a conductive member. Or a flexible printed circuit board in which one substrate is bent and the conductive layers are electrically connected via a conductive member,
A first exposed portion of a conductive layer formed on an edge of one substrate;
A second exposed portion of the conductive layer formed on another substrate or a second exposed portion of the conductive layer formed on a portion other than an end portion of one bent substrate;
A conductive member provided at a position in contact with the first and second exposed portions of the conductive layer or in the vicinity of the first and second exposed portions of the conductive layer;
A flexible printed circuit board comprising: a soldering portion provided to electrically connect the first and second exposed portions of the conductive layer and the conductive member. The first exposed part is
2. The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board is formed by partially peeling the protective layer. The first exposed part is
The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board is formed by partially peeling the base layer. The first exposed part is
The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board is formed by partially peeling the protective layer and the base layer. The flexible printed circuit board according to any one of claims 1 to 4,
A light emitting element that emits laser light;
A light receiving element that receives light and converts it into an electrical signal;
A lead pin electrically connected to the light emitting element and the light receiving element;
A protective cover covering the light emitting element and the light receiving element;
A hologram laser, comprising: a hologram element mounted on a laser light emitting surface of a protective cover.   An optical pickup device comprising the flexible printed circuit board according to claim 1.   A disk drive device comprising the optical pickup device according to claim 6.

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