JP2009135191A - Substrate connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate connection structure which controls cracking at a portion corresponding to the outer edge of a joint in the conductive part of a flexible printed board. <P>SOLUTION: A substrate connection structure includes a key substrate 50 on which a conductive part 57 on the side of the key substrate is formed, a flexible printed board 90 on which a conductive part 91 on the side of FPC is formed, and an anisotropic conductive film 100 constituting a joint 95. The flexible printed board 90 includes a portion 94 curved around a curve axis Y such that the inner surface 90b becomes the inside, and the joint 95 is formed such that the outer edge 96 in the joint 95 is not parallel with a projection line Y1 obtained by projecting the curve axis Y onto a plane Z including the second surface 50b in the key substrate 50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a substrate connection structure using an anisotropic conductive film.

  A board connection structure in which a board and an FPC (Flexible Printed Circuit) are connected to each other, and an ACF (Anisotropic Conductive Film) is arranged between the board and the FPC is known. (For example, refer to Patent Document 1).

  In the substrate connection structure using ACF, the conductive portion in the FPC is formed by removing the insulating layer as the surface layer and exposing a part of the conductive layer as the inner layer. This conductive part is connected to the substrate by a connection part made of ACF. Here, when a curved portion is formed to connect one end of the FPC to another opposing substrate, bending stress concentrates on a portion corresponding to the outer edge of the connecting portion. For this reason, the conductive portion (layer) may break at a portion corresponding to the outer edge of the connection portion in the conductive portion (generally, the boundary with the insulating layer).

On the other hand, in order to prevent the conductive part (layer) from cracking in the FPC, a connection structure has been proposed in which a UV curable bond is poured and fixed between the FPC and the substrate.
JP 2003-264353 A

  However, in order to prevent cracking of the conductive part (layer) in the FPC, when adopting a connection structure in which a UV curing bond is poured and fixed between the FPC and the substrate, the burden on the manufacturing process increases, and the material and There was a problem that the manufacturing cost increased.

  An object of this invention is to provide the board | substrate connection structure by which the part corresponding to the outer edge of the connection part in the electroconductive part of a flexible printed circuit board was suppressed.

  The present invention includes a first substrate formed by exposing a first conductive portion on one surface, a conductive layer and an insulating layer stacked on both sides of the conductive layer, and the insulating layer is stacked. A flexible printed circuit board on which a second conductive portion formed by exposing a part of the conductive layer is formed, and the first conductive portion is disposed between the first conductive portion and the second conductive portion. An anisotropic conductive film constituting a connecting portion that connects a conductive portion and the second conductive portion, wherein the flexible printed board has a surface opposite to the first substrate side. The connecting portion has a bending portion that is bent about a predetermined bending axis so as to be inside, and the connection portion is not parallel to a projection line that projects the bending axis on the bending portion side onto a plane including the surface on the one side. The present invention relates to a substrate connection structure formed with an outer edge portion.

  In addition, it is preferable that the first printed circuit board includes a second board disposed to face the one surface of the first board, and the flexible printed board electrically connects the first board and the second board. .

  Further, it is preferable that the outer edge portion has a first region where an intersection point with the moved projection line becomes 2 or more when the projection line is moved in a direction perpendicular to the projection line on the plane. .

  Moreover, it is preferable that the said flexible printed circuit board arrange | positions the said insulating layer in all or one part of the area | region which does not cross | intersect the said 1st area | region in the said projection line moved on the surface at the said 1st board | substrate side.

  Moreover, it is preferable that the said outer edge part has an oblique line-shaped part where the outer edge by the side of the said curved part cross | intersects the said moved projection line.

  Further, it is preferable that the outer edge portion has a substantially V shape in which the outer edge on the bending portion side is in a direction perpendicular to the moved projection line and protrudes toward the bending portion side.

  ADVANTAGE OF THE INVENTION According to this invention, the board | substrate connection structure by which the part corresponding to the outer edge of the connection part in the electroconductive part of a flexible printed circuit board was suppressed can be provided.

The best mode for carrying out the present invention will be described below with reference to the drawings.
With reference to FIG. 1, a basic structure of a mobile phone 1 as an electronic device will be described. FIG. 1 is an external perspective view in a state where the mobile phone 1 is opened.

  As shown in FIG. 1, the mobile phone 1 includes an operation unit side body 2 and a display unit side body 3 as a housing. The operation unit side body 2 and the display unit side body 3 are connected so as to be openable and closable via a connecting part 4 having a hinge mechanism. Specifically, the upper end portion of the operation unit side body 2 and the lower end portion of the display unit side body 3 are connected via a connecting portion 4. Thereby, the mobile phone 1 is configured to be able to relatively move the operation unit side body 2 and the display unit side body 3 connected via the hinge mechanism. That is, in the mobile phone 1, the operation unit side body 2 and the display unit side body 3 are opened (open state), and the operation unit side body 2 and the display unit side body 3 are folded. (Closed state). Here, the closed state is a state in which both housings are arranged so as to overlap each other, and the open state is a state in which both housings are arranged so as not to overlap each other.

  The outer surface of the operation unit side body 2 includes a front case 2a and a rear case 2b. The operation unit side body 2 exposes the operation key group 11 and the voice input unit 12 as a microphone to which the voice uttered by the user of the mobile phone 1 is input on the front case 2a side. Composed.

  The operation key group 11 includes a function setting operation key 13 for operating various functions such as various settings, a telephone book function, and a mail function, and an input operation key 14 for inputting a telephone number and characters such as mail. And a determination operation key 15 as an operation member for performing determination in various operations, scrolling in the vertical and horizontal directions, and the like. Each key constituting the operation key group 11 has a predetermined function according to the open / close state of the operation unit side body 2 and the display unit side body 3, various modes, or the type of the activated application. Assigned (key assignment). Then, when the user presses each key, an operation corresponding to the function assigned to each key is executed.

  The voice input unit 12 is disposed on the outer end side opposite to the connection unit 4 side in the longitudinal direction of the operation unit side body 2. That is, the voice input unit 12 is arranged on one outer end side when the mobile phone 1 is in the open state.

  An interface (not shown) for communicating with an external device (for example, a host device) is disposed on one side surface of the operation unit side body 2. A side key to which a predetermined function is assigned and an interface (not shown) through which an external memory is inserted and removed are arranged on the other side surface of the operation unit side body 2. The interface is covered with a cap. Each interface is covered with a cap when not in use.

  The outer surface of the display unit side body 3 includes a front panel 3a, a front case 3b, a rear case 3c, and a rear panel 3d. The front case 3b in the display unit side body 3 is disposed so as to expose a display unit 21 for displaying various types of information and a voice output unit 22 as a receiver for outputting the voice of the other party of the call. The Here, the display unit 21 includes a liquid crystal panel, a drive circuit that drives the liquid crystal panel, and a light source unit such as a backlight that emits light from the back side of the liquid crystal panel.

  Next, the internal structure of the operation unit side body 2 and the display unit side body 3 will be described with reference to FIGS. FIG. 2 is an exploded perspective view of members built in the operation unit side body 2. FIG. 3 is an exploded perspective view of members built in the display unit side body 3. 4 is a cross-sectional view taken along the line DD in FIG. FIG. 5 is a diagram for explaining the positional relationship between the key substrate 50 and the flexible printed circuit board 90. FIG. 6 is an enlarged plan view of region X in FIG. FIG. 7 is a diagram for explaining the relationship between the projection line Y1 obtained by projecting the curved axis Y onto the plane Z and the connection portion 95. In FIG. 8 is a cross-sectional view taken along the line CC in FIG. FIG. 9 is a cross-sectional view taken along the line SS in FIG.

  As shown in FIG. 2, the operation unit side body 2 includes a front case 2a, a key structure 40, a key substrate 50 as a first substrate, a case body 60, a reference potential pattern layer 75, and a cellular phone. A circuit board 70 as a second board having various electronic components such as an RF (Radio Frequency) module, a rear case 2b having a battery lid 2c, and a battery 80. The key board 50 and the circuit board 70 are electrically connected by a flexible printed board 90. In other words, the mobile phone 1 is configured to have a connection structure that electrically connects the key substrate 50 and the flexible printed circuit board 90.

  The front case 2a and the rear case 2b are disposed such that the concave inner surfaces face each other, and are joined so that the outer peripheral edges thereof overlap each other. In addition, the key structure 40, the key board 50, the case body 60, the circuit board 70, and the flexible printed board 90 are built in between the front case 2a and the rear case 2b. .

  In the front case 2a, key holes 13a, 14a, and 15a are formed on the inner surface of the front case 2a facing the display unit 21 of the display unit side body 3 in a state in which the cellular phone 1 is folded. From each of the key holes 13a, 14a, 15a, the pressing surface of the function setting operation key member 13b constituting the function setting operation key 13, the pressing surface of the input operation key member 14b constituting the input operation key 14, and the determination operation key 15 The pressing surface of the determination operation key member 15b that constitutes is exposed. By pressing the exposed function setting operation key member 13b, the input operation key member 14b, and the determination operation key member 15b so as to depress, the metal dome described later is provided in each corresponding key switch 51, 52, 53. The apex of (saddle-like shape) is pressed and comes into electrical contact with the switch terminal.

  The key structure unit 40 includes an operation member 40A, a key frame 40B as a reinforcing member, and a key sheet 40C as a sheet member.

  The operation member 40A is composed of a plurality of key operation members. Specifically, it is configured by a function setting operation key member 13b, an input operation key member 14b, and a determination operation key member 15b. Each operation key member constituting the operation member 40A is bonded to the key sheet 40C with a key frame 40B described later interposed therebetween. As described above, the pressing surface of each operation key member bonded to the key sheet 40C is disposed so as to be exposed to the outside from each of the key holes 13a, 14a, 15a.

  The key frame 40B is a metallic plate-like member having a plurality of holes 14c. The key frame 40B is a reinforcing member for preventing adverse effects on the circuit board 70 and the like due to the pressing of the input operation key member 14b. The key frame 40B is a conductive member, and also functions as a member for releasing static electricity from the input operation key member 14b. The plurality of holes 14c formed in the key frame 40B are arranged so that convex portions 14d formed in the key sheet 40C described later are fitted. The input operation key member 14b is bonded to the convex portion 14d.

  The key sheet 40C is a flexible sheet-like member made of silicon rubber. As described above, a plurality of convex portions 14d are formed on the key sheet 40C. The plurality of convex portions 14d are formed on the surface of the key sheet 40C on the side where the key frame 40B is disposed. Each of the plurality of convex portions 14d is formed at a position corresponding to a key switch 52 described later.

  The key substrate 50 includes a plurality of key switches 51, 52, and 53 disposed on a first surface 50a that is a surface on the key sheet 40C side. The plurality of key switches 51, 52, 53 are arranged at positions corresponding to the respective operation members 40A. The key switches 51, 52 and 53 arranged on the key substrate 50 have a structure having a metal dome of a metal plate which is curved in a bowl shape and is three-dimensionally formed. The metal dome is configured to be electrically connected to a switch terminal formed on an electric circuit (not shown) printed on the surface of the key substrate 50 when the apex of the bowl-shaped shape is pressed. Is done. The key board 50 is obtained by sandwiching wiring between a plurality of insulating layers (insulating films).

  One end 90 </ b> A of the flexible printed circuit board 90 is connected to the second surface 50 b which is the surface opposite to the first surface 50 a of the key substrate 50. Specifically, as shown in FIG. 4, the flexible printed circuit board 90 is connected to the key board 50 by the anisotropic conductive film 100 on the outer surface 90 a side at one end 90 </ b> A. The flexible printed circuit board 90 is attached to a connector 77 whose other end 90 </ b> B is mounted on the second surface 70 b of the circuit board 70. As a result, the flexible printed circuit board 90 has a curved portion 94 that is curved around the curved axis Y with the inner surface 90b opposite to the outer surface 90a on the inside between the one end 90A and the other end 90B. Is done. Here, the flexible printed circuit board 90 includes a gold plating layer 193 and a copper pattern layer 195 as conductive layers, and coverlays 191 and 197 as insulating layers disposed on both surfaces of the conductive layer.

  Specifically, a key board side conductive portion 57 as a first conductive portion is formed on the second surface 50 b of the key substrate 50. On the outer surface 90a of one end 90A of the flexible printed circuit board 90, an FPC side conductive portion 91 is formed as a second conductive portion that is disposed so as to face the key substrate side conductive portion 57. The FPC-side conductive portion 91 is formed by removing the first coverlay 191 as an insulating layer. The FPC side conductive portion 91 is formed by exposing a part of the gold plating layer 193. Further, in the FPC side conductive portion 91, a gold plating layer 193 is disposed outside one side of the copper pattern layer 195, and a second cover 197 is disposed outside the other side. For this reason, when it deform | transforms so that it may curve with the 2nd coverlay 197 side (inner surface 90b side) inside, it becomes easy to produce a crack in the copper pattern layer 195.

  The flexible printed circuit board 90 is attached to a connector 77 disposed on a circuit board 70 disposed at the other end 90 </ b> B so as to face the key substrate 50 across the case body 60. As described above, the flexible printed circuit board 90 is configured to have the curved portion 94 that is curved about the curved axis Y with the inner surface 90b being the inner side at a portion between the one end 90A and the other end 90B. The bending portion 94 is disposed so as to surround the outer edges of the outer edge of the case body 60 and the outer edge of the circuit board 70.

  A force that separates from the key substrate 50 is applied to the one end 90 </ b> A side that is continuous with the bending portion 94, particularly when the bending portion 94 is formed or when the mobile phone 1 is disassembled. When this force is concentrated on the portion of the FPC side conductive portion 91 that is located in the vicinity of the outer edge 96 on the curved portion 94 side of the connecting portion 95 described later, the copper pattern layer 195 constituting the FPC side conductive portion 91 is cracked. There is. Specifically, this force may cause a crack in a corresponding portion between the outer edge 96 of the connection portion and the outer edge 93 of the cover 191 in the copper pattern layer 195. In the present embodiment, the copper pattern layer 195 is prevented from being cracked by forming the connecting portion 95 that connects the flexible printed circuit board 90 and the key board 50 in the following shape or the like.

  The connection part 95 is configured by an anisotropic conductive film 100 disposed between the FPC side conductive part 91 formed on the flexible printed circuit board 90 and the key board side conductive part 57 formed on the key board 50. . The connecting portion 95 is formed by subjecting the anisotropic conductive film 100 disposed between the FPC side conductive portion 91 and the key board side conductive portion 57 to a thermocompression treatment.

  As shown in FIGS. 6 and 7, the outer edge 96 of the connecting portion 95 is formed in a substantially V-shape that protrudes toward the outer edge of the key substrate 50 in a direction perpendicular to a projection line Y <b> 2 described later. In other words, the connecting portion 95 is configured to include a substantially triangular first region 95A formed on the outer edge side of the key substrate 50 and a substantially rectangular second region continuous with the first region 95A.

  Here, as shown in FIGS. 6 to 9, the FPC side conductive portion 91 is formed by removing the coverlay 191 corresponding to the shape of the outer edge 96 of the connecting portion 95. The outer edge of the FPC-side conductive portion 91 (the outer edge 93 of the cover lay 191) is formed in a V shape that is substantially the same shape as the outer edge 96 of the connecting portion 95 with a gap.

  The anisotropic conductive film 100 is formed corresponding to the shape of the connecting portion 95. The anisotropic conductive film 100 has one surface fixed to the FPC side conductive portion 91 and the other surface fixed to the key substrate side conductive portion 57. In other words, the anisotropic conductive film 100 physically and electrically connects the FPC side conductive part 91 and the key board side conductive part 57.

  Further, as shown in FIGS. 5 and 7, the connecting portion 95 has a projection line Y1 whose outer edge 96 projects the curved axis Y onto the plane Z including the first surface 50a of the key substrate 50, and is perpendicular to the projection line Y1. The first region 95A is a region intersecting the projection line Y2 moved in the direction at two points. An outer edge 96 that intersects the projection line Y2 at the two points in the first region 95A has a substantially V-shape projecting toward the outer edge side of the key substrate 50. In other words, the outer edge 96 is configured to have oblique lines 96a and oblique lines 96b that intersect the projection line Y2.

  In addition, the connection portion 95 is a first region 95A that is an area where the outer edge 96 intersects a line obtained by translating a line perpendicular to the bending direction of the bending portion 94 along the inner surface 90b of the flexible printed circuit board 90 at two points. It can be said that it has. Further, it can be said that the connecting portion 95 has a first region 95A in which the outer edge 96 is a region intersecting at two points with a line extending in the width direction W of the flexible printed circuit board 90.

  A coverlay 191 is disposed outside the width direction W in the first region 95A. That is, in the direction of the projection line Y2, the first region 95A and the coverlay 191 in the connecting portion 95 are arranged side by side. Further, in the direction of the projection line Y2, there is no portion where neither the connection portion 95 nor the cover 191 exists. Specifically, the projection line Y2 is configured so that there is no portion in the vicinity of the outer edge (the outer edge 93 of the cover lay 191) in the FPC side conductive portion 91 that is not covered by the cover lay 191.

  Here, since the key substrate 50 is placed on the flat plate portion 61 of the case body 60, the pressure and the deflection caused by pressing each of the operation members 40 </ b> A are transmitted to the circuit board 70 disposed below the case body 60. It is hard to be done.

  The case body 60 is a conductive member having a shape in which one wide surface of a thin rectangular parallelepiped is opened. The case body 60 includes ribs 62 that are formed substantially perpendicular to the opening-side surface of the flat plate portion 61. The rib 62 is formed to be equal to or sufficiently higher than the height of the tallest electronic component among the various electronic components mounted on the circuit board 70. The rib 62 is formed so as to correspond to the reference potential pattern layer 75 constituting the reference potential portion on the periphery and inside of the flat plate portion 61. Specifically, the rib 62 is formed so as to be disposed on the reference potential pattern layer 75 in a state where the case body 60 is placed on the circuit board 70. Note that the case body 60 may be formed of a metal, a skeleton formed of a resin, and a conductor film formed on the surface thereof.

  The case body 60 is electrically connected to the reference potential pattern layer 75 by contacting the bottom surface of the rib with the reference potential pattern layer 75. The case body 60 is electrically connected to the reference potential pattern layer 75 and has the same potential as the reference potential pattern layer 75. That is, the case body 60 functions as a shield case. The case body 60 serves as a shield case to suppress external noise such as high frequency from acting on various electronic components disposed on the circuit board 70, and to emit from an RF (Radio Frequency) circuit, a CPU circuit, a power supply circuit, and the like. This prevents the generated noise from acting on other electronic components and a receiving circuit connected to the antenna. Specifically, the bottom surface of the rib 62 in the case body 60 is disposed on the reference potential pattern layer 75, so that each circuit described later is surrounded by the rib 62 and covered with a part of the flat plate portion 61. The rib 62 functions as a partition wall in each circuit, and shields each circuit together with a part of the flat plate portion 61.

  On the circuit board 70, various electronic components and circuits (not shown) including a signal processing unit that processes signals transmitted and received by the antenna 108 are arranged. Various electronic components form a plurality of circuit blocks by a predetermined combination. For example, various circuit blocks including an RF (Radio Frequency) circuit, a power supply circuit, and the like are formed.

  In addition to the various electronic components described above, a reference potential pattern layer 75 constituting a reference potential portion is formed on the first surface 70a of the circuit board 70 on the case body 60 side. The reference potential pattern layer 75 is formed so as to partition each circuit block described above. The reference potential pattern layer 75 is formed by printing a conductive member in a predetermined pattern on the surface of the first surface 70a of the circuit board 70.

  A detachable battery lid 2c is provided on one end side (in FIG. 2) of the rear case 2b. After the battery 80 is stored from the outside of the rear case 2b, the battery case 2b is attached to the rear case 2b. In addition, an audio input unit 12 (not shown) for inputting the user's voice is accommodated at one end of the rear case 2b.

  As shown in FIG. 3, the display unit side body 3 includes a front panel 3a, an audio output unit 22, a front case 3b, an audio output unit 22, a display unit 21, and a print to which the display unit 21 is connected. A substrate 85, a rear case 3c, and a rear panel 3d are provided.

  The display unit side body 3 includes a front panel 3a, a front case 3b, a display unit 21, a printed circuit board 85, a rear case 3c, and a rear panel 3d that are stacked. Specifically, the front case 3b and the rear case 3c are arranged so that the inner surfaces of the concave shapes face each other, and are joined so that the outer peripheral edges thereof overlap each other.

  A printed circuit board 85 to which the display unit 21 is connected is sandwiched between the front case 3b and the rear case 3c. A speaker connected to an amplifier (not shown) is connected to the printed board 85.

  Next, the operation of the substrate connection structure of the present embodiment will be described with reference to FIGS. FIG. 10 is a diagram for explaining the rigidity in the board connection structure of the present embodiment. FIG. 11 is a diagram for explaining the rigidity in the conventional board connection structure.

  First, the rigidity in the conventional board connection structure will be described with reference to FIG. As shown in FIG. 11, in the conventional board connection structure, the outer edge 296 of the connection portion 295 is formed in a straight line extending in the width direction W. The connection part 295 is formed by disposing the rectangular anisotropic conductive film 100 on the FPC side conductive part 291 formed by removing the cover 191.

  As shown in FIG. 11, in the conventional board connection structure, the outer edge 296 of the connection portion 295 is formed in a straight line extending in the width direction W, so the rigidity G in the vicinity of the outer edge 296 in the FPC side conductive portion 291 is low. Specifically, the rigidity G of the region between the outer edge 293 of the cover lay 191 and the outer edge 296 of the connecting portion 295 is lowered.

  Specifically, the rigidity G is constant at the rigidity G2 between the position P0 and the position P1 where the coverlays 191 and 197 are laminated on both surfaces of the flexible printed circuit board 90.

  Then, between the position P1 and the position P2 where the coverlay 197 is laminated and disposed on only one surface of the flexible printed circuit board 90, the rigidity G is significantly reduced to the rigidity G1.

  In addition, the rigidity G is significantly higher from the position P2 to the position P3, which is a portion connected to the key substrate 50 by the connection portion 295, to the rigidity G3. This is because the flexible printed circuit board 90 is fixed to the key board 50 by the connecting portion 295, and this portion of the flexible printed circuit board 90 has the same degree of rigidity as the key board 50.

  Here, due to the operation of bending the flexible printed circuit board 90 when the bending portion 94 is formed, the above-described force is concentrated on the portion between the position P1 and the position P2 where the rigidity G is low. The intermediate portion is bent and cracking is likely to occur.

Next, the rigidity in the board connection structure of the present embodiment will be described with reference to FIGS.
As shown in FIG. 10, in the substrate connection structure of the present embodiment, the outer edge 96 of the connection portion 95 is formed in a substantially V shape so as not to overlap in the width direction W. Thereby, in the board | substrate connection structure in this embodiment, the part which rigidity G becomes low unlike the conventional board | substrate connection structure does not exist. Specifically, since the outer edge 96 of the connecting portion 95 is formed so as to intersect the projection line Y2 extending in the width direction W at two points and not so as to overlap linearly, there is a portion where the rigidity G is greatly reduced. not exist.

  Specifically, the rigidity G12 is constant between the position P10 and the position P11 where the coverlays 191 and 197 are laminated on both surfaces of the flexible printed circuit board 90.

  Then, the rigidity G is slightly reduced to the rigidity G11 between the position P11 and the position P12 partially including a portion where the cover lay 197 is laminated on only one surface of the flexible printed circuit board 90. In addition to the fact that the number of the cover lays 197 stacked on only one surface is smaller than in the conventional case, the part where the cover lays 191 and 197 are stacked on both sides is arranged outside the width direction W in this part. Therefore, the rigidity G of the flexible printed circuit board 90 is suppressed from being significantly lowered.

  In addition, the rigidity G changes from the position P12 to the position P13, which is a portion connected to the key substrate 50 by the first region 95A in the connecting portion 95, to the rigidity G3 so that the rigidity is significantly increased. This is because the flexible printed circuit board 90 is fixed to the key board 50 by the first region 95A in the connection portion 95, and thus approaches the rigidity G of the key board 50 corresponding to the area of the connected portion. Here, in the substrate connection structure of the present embodiment, a region where the portion between the outer edge 96 of the connection portion 95 and the outer edge of the cover lay 191, which is the portion having the lowest rigidity G in the conventional substrate connection structure, continuously exists. In contrast, the rigidity G is increased without decreasing the rigidity G.

  Further, the rigidity G maintains a high rigidity G3 between the position P13 and the position P4, which are portions connected to the key substrate 50 by the second region 95B in the connection portion 95. This is because the flexible printed circuit board 90 is fixed to the key board 50 by the connecting portion 95 as described above, and thus has the same degree of rigidity as the key board 50.

  Here, by the operation of bending the flexible printed circuit board 90 when the bending portion 94 is formed, the above-described force is concentrated on a portion between the position P11 and the position P12 where the rigidity G is low, but from the position P11 to the position P12. In this portion, the rigidity G11 that is not bent by the above-described force is maintained, so that the portion is hardly cracked.

  According to the present embodiment, the key substrate 50 on which the key substrate side conductive portion 57 is formed, the flexible printed circuit board 90 on which the FPC side conductive portion 91 is formed, the key substrate side conductive portion 57 and the FPC side conductive portion 91, And an anisotropic conductive film 100 that constitutes a connecting portion 95 that connects the key board side conductive portion 57 and the FPC side conductive portion 91, and is connected to the FPC side conductive portion. It is possible to provide a substrate connection structure in which a portion corresponding to the outer edge 96 of the portion 95 is suppressed from being broken. Moreover, according to this embodiment, the mobile telephone 1 as an electronic device containing such a board | substrate connection structure can be provided.

  Moreover, according to this embodiment, the crack which arises near the outer edge 96 of the connection part 95 in the FPC side electroconductive part 91, without using adhesives, such as a bond required in order to suppress that the above-mentioned crack generate | occur | produces. Can be suppressed. Thereby, while being able to suppress the burden in a manufacturing process, manufacturing cost can be reduced.

  As mentioned above, although preferred embodiment was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above. For example, in the present embodiment, the mobile phone 1 is described as an electronic device. However, the present invention is not limited to this, and is not limited to this. A PHS (registered trademark), a personal digital assistant (PDA), a portable navigation device, and a laptop computer. Etc.

  Further, in the present embodiment, the mobile phone 1 that can be folded by the connecting portion 4 is described. However, it is not such a foldable type, and the operation unit side body 2 and the display unit side body 3 are overlapped. One of the cases is slid in one direction from the closed state, and one case is rotated around an axis along the overlapping direction of the operation unit side case 2 and the display unit side case 3 A rotation (turn) type, or a type (straight type) in which the operation unit side body 2 and the display unit side body 3 are arranged in one housing and do not have a connecting portion may be used. The mobile phone 1 may be a so-called biaxial hinge type that can be opened and closed and rotated.

  In the present embodiment, the outer edge 96 of the connecting portion 95 is substantially V-shaped, but is not limited to this, and is substantially U-shaped, substantially W-shaped, zigzag-shaped, wave-shaped, etc. Also good.

FIG. 3 is an external perspective view in a state where the mobile phone 1 is opened. FIG. 6 is an exploded perspective view of members built in the operation unit side body 2. FIG. 5 is an exploded perspective view of members built in the display unit side body 3. It is DD sectional drawing in FIG. It is a figure explaining the positional relationship of the key board | substrate 50 and the flexible printed circuit board 90. FIG. FIG. 6 is an enlarged plan view of a region X in FIG. 5. It is a figure explaining the relationship between the projection line Y1 which projected the curved axis Y on the plane Z, and the connection part 95. FIG. It is CC sectional drawing in FIG. It is SS sectional drawing in FIG. It is a figure explaining the rigidity in the board | substrate connection structure of this embodiment. It is a figure explaining the rigidity in the conventional board | substrate connection structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile phone 2 Operation part side housing | casing 3 Display part side housing | casing 50 Key board | substrate (1st board | substrate)
50b 2nd surface 57 Key board side conductive part 60 Case body 70 Circuit board 90 Flexible printed circuit board 91 FPC side conductive part 94 Curved part 95 Connection part 96 Outer edge 100 Anisotropic conductive film 191 Coverlay 193 Gold plating layer 195 Copper pattern layer 197 Coverlay Y Curved axis Y1 Projection line Y2 Projection line Z Plane

Claims (6)

A first substrate formed by exposing the first conductive portion on one surface;
A conductive layer and an insulating layer stacked on both sides of the conductive layer are formed, and a second conductive portion is formed in which the insulating layer is not stacked and formed and a part of the conductive layer is exposed. A flexible printed circuit board;
An anisotropic conductive film that is disposed between the first conductive part and the second conductive part and that constitutes a connection part that connects the first conductive part and the second conductive part. There,
The flexible printed circuit board has a bending portion that curves around a predetermined bending axis so that a surface opposite to the first substrate side is inside,
The connection part is a substrate connection structure formed so as to have an outer edge part that is non-parallel to a projection line obtained by projecting the bending axis onto a plane including the one side surface on the bending part side. A second substrate disposed to face the one surface of the first substrate;
The board connection structure according to claim 1, wherein the flexible printed board electrically connects the first board and the second board.   The said outer edge part has a 1st area | region where the intersection with this moved projection line becomes two or more when the said projection line is moved to the direction perpendicular | vertical to this projection line on the said plane. The board connection structure described in 1. 4. The flexible printed circuit board according to claim 3, wherein the flexible printed circuit board has the insulating layer disposed in all or part of a region that does not intersect the first region in the moved projection line on the surface on the first substrate side. Board connection structure.   5. The substrate connection structure according to claim 3, wherein the outer edge portion has a hatched portion in which an outer edge on the curved portion side intersects the moved projection line. 6.   6. The substrate according to claim 3, wherein the outer edge portion has a substantially V shape in which the outer edge on the curved portion side is in a direction perpendicular to the moved projection line and protrudes toward the curved portion side. Connection structure.

Images