JP2010147061A - Inter-printed board connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inter-printed board connection structure with split printed boards stacked inside an enclosure and interconnected with a flexible board, which reduces the mounting area of the printed board and prevents damage to the flexible board interconnecting the printed boards. <P>SOLUTION: The inter-printed board connection structure 10 includes a first printed board 1, a second printed board 2, and the flexible board 3 electrically interconnecting the back surfaces of the first and second printed boards 1 and 2. The edge 2a of the second printed board 2 is provided with a cutout 6 that allows a bent portion 5, at which the flexible board 3 bends, to go around inside the edge 2a to reach the back surface of the printed board 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printed circuit board connection structure in which a plurality of rigid printed boards are disposed in a casing in a stacked state with a predetermined interval, and the rigid printed boards are electrically connected by a flexible board.

  For example, liquid crystal display devices and portable terminal devices for personal computers are being reduced in size, weight, and functionality in response to consumer needs. For this reason, the number of electronic components housed inside these devices has increased. Accordingly, the area of a rigid printed circuit board (hereinafter simply referred to as “substrate” in the present specification) on which electronic components are mounted is inevitably increased.

  Usually, in these apparatuses, the mounting area is increased by dividing the board on which the electronic component is mounted into two or more instead of one because of the limitation of the mounting space of the apparatus housing on which the board is mounted. There are many cases. The board-to-board connection when the board is divided is implemented by using, for example, a connector. However, if the connector is used, a necessary component mounting area of the board is reduced. Therefore, in many cases, two substrates are connected by a flexible printed circuit (hereinafter simply referred to as “flexible substrate”) formed in a flexible film shape.

  For example, when the two substrates are mounted inside the apparatus housing so as to be stacked in a stacked manner with a predetermined interval, the connection with the flexible substrate is U-shaped at one edge of the two substrates. It is bent and connected. Thereby, the mounting area of the substrate on the plane in the housing can be made smaller than that in the case where the substrate is mounted in the apparatus housing.

  FIG. 4 is a schematic side sectional view showing a conventional substrate connection structure. In this case, two substrates 41 and 42 are arranged in a stacked manner in the housing 40 so as to be separated from each other in the vertical direction. The back surfaces of the substrates 41 and 42 (the lower surfaces of the substrates in FIG. 4) are joined and electrically connected to each other by a single flexible substrate 43. The flexible substrate 43 is bent at a bent portion 44 that is bent and protruded in a U shape at one side edge portions 41 a and 42 a of both the substrates 41 and 42. An electronic component 45 is mounted on the surface of both the substrates 41 and 42 (the upper surface side of both substrates in FIG. 4).

  In FIG. 4, the flexible substrate 43 is bonded to the back side of the two substrates 41 and 42. As another example, the flexible substrate is bonded to the back side and the lower substrate is bonded to the front side. And the case where the insulation part extended in a part of flexible substrate joined to the back surface side of the upper board | substrate is provided is also disclosed (for example, refer patent document 1).

Also disclosed is a structure in which two substrates joined by a flexible substrate are arranged at right angles (horizontal and vertical), and the substrates arranged vertically in a recess provided on the side of the housing are stored. (For example, see Patent Document 2).
JP 2003-264353 A JP 2008-112070 A

  However, as described in FIG. 4 and Patent Document 1 described above, when two substrates are arranged in a stacked manner apart from each other in the vertical direction, the two flexible substrates are connected to each other by flexible substrates. It is formed by bending at a bent portion protruding by bending in a U shape at one edge of the substrate. In this state, the two substrates are mounted inside the apparatus casing so as to overlap each other. Therefore, the bent part of the flexible substrate remains protruding from the edges of both substrates.

  In this case, since the bent portion of the flexible board protrudes from the edge of the board, it is easy to come into contact with a tool or other parts when mounting, etc. The probability of. In order to prevent this, it is necessary to reinforce the bent portion.

  In addition, if the bent portion of the flexible board protruding from the edge of the board is forced to be stored between the stacked boards, the flexible board will be bent and a crack will occur, causing a breakage. As a countermeasure, it is structurally necessary to devise a sufficient storage space when the substrate is stored in the housing.

  The present invention has been made on the basis of these circumstances, in a case where the divided substrates are arranged in a stacked manner inside the housing, and a printed circuit board connection structure when a flexible substrate is used to connect the mutual substrates. An object of the present invention is to provide a printed circuit board connection structure capable of reducing the mounting area of a circuit board and preventing damage to a flexible circuit board connected between the circuit boards.

  According to one aspect of the present invention, the first printed circuit board disposed in the housing and the first printed circuit board are stacked on the back surface of the first printed circuit board with the front surface facing and spaced apart from the first printed circuit board. Printed circuit board connection comprising a second printed circuit board arranged in a shape, and a flexible circuit board electrically connecting the back surface side of the first printed circuit board and the back surface side of the second printed circuit board In the structure, a cutout portion is provided at an edge of the second printed circuit board so that a bent portion of the flexible printed circuit board wraps around the back surface side of the second printed circuit board inside the edge. A printed circuit board connection structure is provided.

  In the printed circuit board connection structure of the present invention, a third printed circuit board is disposed on the back surface side of the second printed circuit board so as to face and separate from the second printed circuit board, and is laminated with the second printed circuit board. The edge of the third printed circuit board is provided with a notch for allowing the bent portion of the flexible circuit board to wrap around to the back side of the third printed circuit board inside the edge. To do.

  In the printed circuit board connection structure according to the present invention, the edge portion of the first printed circuit board corresponding to the notched portion of the second printed circuit board is formed outside at least the bottom of the notched portion. It is characterized by being.

  According to the present invention, the printed circuit board connection structure when the divided printed circuit boards are arranged in a stacked manner inside the housing and the flexible printed circuit board is used to connect the printed circuit boards to each other is reduced. In addition, it is possible to prevent damage to the flexible substrate connecting the printed circuit boards.

  The best mode for carrying out the printed circuit board connection structure of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic side sectional view showing an example of an embodiment of a connection structure between printed circuit boards according to the present invention.

  The basic structure of the inter-print board connection structure 10 is as follows. The first board 1 and the second board 2 arranged in a stacked manner with a predetermined interval inside the housing 20 and the two boards 1 and 2 are mutually connected. And a flexible substrate 3 electrically connected to the substrate.

  As for the 1st board | substrate 1, the electronic component 4 is mounted in the surface (upper side of a board | substrate in FIG. 1), and the one end side of the flexible substrate 3 is electrically joined to the back surface (lower side of a board | substrate in FIG. 1). In addition, the second substrate 2 arranged to face the lower side of the first substrate 1 has an electronic component 4 mounted on the surface (the upper side of the substrate in FIG. 1), similarly to the first substrate 1. Yes. In addition, a flexible portion is formed on the back surface (the lower side of the substrate in FIG. 1) by forming a bent portion 5 that is bonded to the first substrate 1 and bent into a U shape at the edge 1a of the first substrate 1 and folded back. The other end side of the substrate 3 is joined.

  At that time, the bent portion 5 bent in a U shape at the edge 1a of the first substrate 1 turns around the second substrate 2 from the front surface side to the back surface side. It penetrates through the notch 6 formed in the edge 2a. That is, the first substrate 1 and the second substrate 2 are electrically connected via the flexible substrate 3 in which the bent portion 5 penetrates through the cutout portion 6.

  In addition, the first substrate 1 and the second substrate 2 are overlapped with the positions of the edges 1a and 2a of the substrates 1 and 2 being substantially coincident. That is, when viewed downward from the upper surface of the first substrate 1, the second substrate 2 is substantially hidden, and conversely, when viewed downward from the lower surface of the second substrate 2, 1 substrate 1 is almost hidden.

  Note that the edge 1 a corresponding to the notch 6 of the second substrate 2 in the first substrate 1 is formed outside at least the bottom 6 a of the notch 6.

  FIG. 2 is an explanatory diagram showing a state in which the flexible substrate 3 enters the back surface side of the second substrate 2 when viewed from the front surface side of the second substrate 2. That is, a notch portion 6 is formed in a portion of the second substrate 2 where the bent portion 5 of the flexible substrate 3 enters, and the bent portion 5 of the flexible substrate 3 penetrates through the notched portion 6 and is second. It wraps around the back surface of the substrate 2. In this state, the other end of the flexible substrate 3 is bonded to the second substrate 2.

  That is, the bent portion 5 of the flexible substrate 3 penetrates through the cutout portion 6 and wraps around the back surface side of the second substrate 2 inside the edge portion 1 a of the first substrate 1. Therefore, the bent portion 5 of the flexible substrate 3 cuts in the thickness direction of the second substrate 2 in the cutout portion 6 from the front surface side and goes around the back surface side of the second substrate 2. Thereby, the bent portion 5 of the flexible substrate 3 is located inside the edge portion 1a of the first substrate 1 and the edge portion 2a of the second substrate 2, and does not protrude from both the edge portions 1a and 2a.

  As described above, since the bent portion 5 of the flexible substrate 3 does not protrude from the edge portions 1a and 2a of both the substrates 1 and 2, the flexible substrate 3 is mounted when the inter-printed substrate connection structure 10 is attached to the inside of the housing 20 or the like. It is possible to prevent occurrence of disconnection due to contact with the housing 20 or the mounting tool and receiving an impact. In addition, since the entire printed circuit board connection structure 10 is easy to handle, it is not necessary to reinforce the bent portion 5 of the flexible substrate 3 and the cost can be reduced.

  The structures of both the substrates 1 and 2 are not particularly shown because they can adopt a well-known structure of a rigid printed circuit board, but a Cu (copper) foil pattern is formed on a rigid base material, and Cu ( A solder resist is formed on the (copper) foil pattern.

  In addition, since a well-known structure can be adopted as the structure of the flexible substrate 3, the structure is not particularly illustrated. For example, an insulating sheet, for example, an insulating resin material such as polyimide (polyimide) is used. A Cu (copper) foil pattern is formed as signal lines arranged in a large number on the thin film base material formed in (1). The film substrate has a thickness of 40 μm or less, more preferably 25 μm to 40 μm, and has sufficient flexibility.

  Further, a solder resist as an insulating protective layer is laminated on the Cu (copper) foil pattern. This solder resist is made of a material such as polyimide, and functions as a protective film that insulates the Cu (copper) foil pattern from the outside and protects the Cu (copper) foil pattern from corrosion such as generation of rust. And plays a role of increasing the bending resistance of the flexible substrate 3. In particular, the solder resist is formed such that the end portion of the Cu (copper) foil pattern is exposed so that the end portion of the Cu (copper) foil pattern can be used as an electrode.

  In addition, the inter-substrate connection is performed through the anisotropic conductive adhesive layer in a state where the pattern terminal portion of the flexible wiring substrate and the pattern terminal portion formed on the substrate face each other.

  Next, a modification of the above embodiment will be described.

  In the above-described embodiment, the case where two substrates are stacked has been described. In this modification, a case where three or more substrates are stacked will be described.

  FIG. 3 is a schematic side sectional view showing an example of a modified embodiment of the printed circuit board connection structure 10 of the present invention. In FIG. 3, the same functional parts as those in FIG.

  In the modified printed circuit board connection structure 10a of the modified example, the first substrate 1, the second substrate 2, and the third substrate 7 are arranged in a stacked manner at a predetermined interval inside the housing 20.

  Since the relationship between the first substrate 1 and the second substrate 2 is the same as that described in the above embodiment, the description thereof is omitted.

  The third substrate 7 arranged to face the lower side of the second substrate 2 has the electronic component 4 mounted on the front surface (the upper side of the substrate in FIG. 3) and the second substrate 7 on the rear surface (the lower side of the substrate in FIG. 3). The other end side of the flexible substrate 3 that is joined to the second substrate 2 and formed with a bent portion 5a that is bent and bent in a U shape at the edge 2b of the second substrate 2 is joined.

  Further, the second substrate 2 and the third substrate 7 overlap each other with the positions of the edge portions 2b and 7a of the respective substrates substantially coincident with each other.

  In addition, the second substrate 2 and the third substrate 7 are similar to the first substrate 1 and the second substrate 2 in the same manner as the structure shown in FIG. A cutout portion 8 is formed at a portion where the bent portion 5a of the flexible substrate 3 enters. The bent portion 5 a of the flexible substrate 3 penetrates through the notch 8 and wraps around the back surface of the third substrate 7, and the other end of the flexible substrate 3 is joined to the back surface side of the third substrate 7. That is, the bent portion 5 a of the flexible substrate 3 penetrates through the cutout portion 8 and wraps around the back side of the third substrate 7 inside the edge portion 2 b of the second substrate 2.

  Therefore, the bent portion 5 a of the flexible substrate 3 is cut around the thickness direction of the third substrate 7 in the cutout portion 8 from the front surface side and wraps around the back surface side of the third substrate 7. The bent portion 5a is located inside the edge 2b of the second substrate 2 and the edge 7a of the third substrate 7, and does not protrude from both the edges 2b, 7a.

  In addition, when viewed downward from the upper surface of the first substrate 1, the second substrate 2 and the third substrate 7 are substantially hidden, and conversely, above the lower surface of the third substrate 7. When viewed in the direction, the second substrate 2 and the first substrate 1 are substantially hidden.

  Note that the edge 2 b of the second substrate 2 corresponding to the notch 8 of the third substrate 7 is formed outside at least the bottom 8 a of the notch 8.

  Further, the flexible substrate 3 may be formed integrally with the third substrate 7 from the first substrate 1 through the second substrate 2, or may be separated by the second substrate 2. However, in the case of integration, the electrical connection between the first substrate 1 and the second substrate 2 and the electrical connection between the second substrate 2 and the third substrate 7 are different in circuit configuration. What is necessary is just to isolate | separate and form the corresponding copper foil pattern.

  As described above, the bent portion 5a of the flexible substrate 3 does not protrude from the edge portions 1a, 1b, 2a, 2b, and 7a of the respective substrates 1, 2, and 7, so that the printed circuit board connection structure 10a is attached to the housing 20. For example, it is possible to prevent the flexible substrate 3 from coming into contact with the casing 20 or the mounting tool and receiving an impact and breaking. In addition, since the entire printed circuit board connection structure 10a can be easily handled, it is not necessary to reinforce the bent portion 5a of the flexible substrate 3, and the cost can be reduced.

  In this modification, three substrates have been described, but the same structure can be used for four or more substrates. Further, when the flexible substrate is separated from the intermediate substrate, the cutout portion can be provided in a direction perpendicular to the bent portion of the flexible substrate.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is a schematic diagram of the side cross section which shows an example of embodiment of the connection structure between printed circuit boards which concerns on this invention. It is explanatory drawing which shows the state which a flexible substrate penetrates into the back surface side of a 2nd board | substrate seeing from the surface side of the 2nd board | substrate in the connection structure between printed circuit boards of this invention. It is a schematic diagram of the side cross section which shows the modification of embodiment of the connection structure between printed circuit boards which concerns on this invention. It is a schematic diagram of the side cross section which shows the connection structure of the conventional printed circuit board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st printed circuit board, 1a, 1b ... Edge part, 2 ... 2nd printed circuit board, 2a, 2b ... Edge part, 3 ... Flexible substrate, 4 ... Electronic component 5, 5a ... Bending part, 6 ... Notch Part, 6a ... bottom, 7 ... third substrate, 7a ... edge, 8 ... notch, 8a ... bottom, 10, 10a ... printed circuit board connection structure, 20 ... housing.

Claims (3)

A first printed circuit board disposed inside the housing;
A second printed circuit board disposed in a laminated manner with the first printed circuit board, with the front surface side facing and separated from the back surface side of the first printed circuit board;
A printed circuit board connection structure constituted by a flexible substrate that electrically connects a back surface side of the first printed circuit board and a back surface side of the second printed circuit board,
The edge of the second printed circuit board is provided with a notch for turning the bent portion of the flexible printed circuit board to the inner side of the edge to the back side of the second printed circuit board. Characteristic printed circuit board connection structure.   A third printed circuit board is disposed on the rear surface side of the second printed circuit board with the front surface facing and spaced apart from the second printed circuit board. The third printed circuit board is disposed at the edge of the third printed circuit board. 2. The inter-print board connection according to claim 1, wherein a cutout portion is provided for the bent portion of the flexible board to wrap around to the back surface side of the third print board inside the edge portion. Construction.   2. The edge portion of the first printed board corresponding to the cutout portion of the second printed circuit board is formed at least outside a bottom portion of the cutout portion. Printed circuit board connection structure.

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