Imaging unit and imaging device

Abstract

To provide an imaging unit and an imaging apparatus that can reduce a load on a connection part of a flexible wiring board and a printed circuit board without losing flexibility of the flexible wiring board.SOLUTION: An imaging unit has: a printed circuit board that is provided with an image pick-up device and has a first electrode on a surface layer; a flexible wiring board that has a substrate that has a first surface and a second surface, a conductor layer that is provided on the first surface, and an insulating layer that is provided on the conductor layer, in which the conductor layer further has a second electrode not provided with an insulating layer at one leading end; a conductive connection material that connects the first electrode and the second electrode with each other; and a reinforcement material that is provided on the second surface of the substrate. The reinforcement material continuously covers a terminal part of the insulating layer on a side closer to the second electrode and a terminal part of a portion of the conductive connection material connected with the second electrode on a side closer to the insulating layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an imaging unit and an imaging device. [Background technology]

[0002] Patent Document 1 proposes a composite substrate structure having a connection structure between substrates. The composite substrate described in Patent Document 1 has a first flexible wiring board having a reinforcing plate laminated on a first surface thereof, and a second flexible wiring board joined to a second surface of the first flexible wiring board. The reinforcing plate has a portion protruding from an end surface of the first flexible wiring board so as to overlap a joint between the first and second flexible wiring boards. Patent Document 1 describes that the wiring patterns of the first and second flexible wiring boards are electrically connected to each other at the joint, and the reinforcing plate and the second flexible wiring board are fixed with an adhesive, thereby preventing breakage of the exposed portion of the wiring pattern due to bending stress.

[0003] However, when a flexible wiring board is connected to a moving body that moves finely, such as an image stabilization unit, the technology described in Patent Document 1 impairs the flexibility of the flexible wiring board because the entire system is made highly rigid. As a result, the technology described in Patent Document 1 impedes the driving of the moving body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-295821 A Summary of the Invention [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided an imaging unit comprising: a printed wiring board having an imaging element and a first electrode on a surface thereof; a base material having a first surface and a second surface; a conductor layer provided on the first surface; and an insulating layer provided on the conductor layer, the conductor layer further having a second electrode at one end portion thereof not provided with the insulating layer; a conductive connecting material connecting the first electrode and the second electrode; and a reinforcing material provided on the second surface side of the base material, wherein the reinforcing material continuously covers an end portion of the insulating layer close to the second electrode and an end portion of the conductive connecting material connected to the second electrode close to the insulating layer.

[0006] According to another aspect of the present invention, there is provided an imaging device including a housing and an imaging unit inside the housing, the imaging unit being the imaging unit described above. Effect of the Invention

[0007] According to the present invention, it is possible to reduce the load acting on the connection portion between the flexible wiring board and the printed wiring board without impairing the flexibility of the flexible wiring board. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a top view showing a schematic configuration of the imaging unit according to the first embodiment. [Diagram 2] 1 is a schematic cross-sectional view showing a schematic configuration of an imaging unit according to a first embodiment. [Diagram 3] 3 is an enlarged schematic cross-sectional view showing a connection portion between a flexible wiring board and a printed wiring board of the imaging unit according to the first embodiment. FIG. [Figure 4] FIG. 11 is a top view showing a schematic configuration of an imaging unit according to a second embodiment. [Diagram 5] 10 is a schematic cross-sectional view showing a schematic configuration of an imaging unit according to a second embodiment. FIG. [Figure 6]13 is a schematic cross-sectional view showing an enlarged view of a connection portion between a flexible wiring board and a printed wiring board of an imaging unit according to a second embodiment. FIG. [Figure 7] FIG. 13 is a top view showing a schematic configuration of an imaging unit according to a third embodiment. [Figure 8] FIG. 11 is a schematic cross-sectional view showing a schematic configuration of an imaging unit according to a third embodiment. [Figure 9] 13 is a schematic cross-sectional view of a connection portion between a flexible wiring board and a printed wiring board of an imaging unit according to a third embodiment. FIG. [Figure 10] FIG. 13 is an explanatory diagram showing a schematic configuration of an imaging device as an example of an electronic device according to a fourth embodiment. [Figure 11] FIG. 2 is a schematic diagram showing a three-dimensional structural analysis model according to Comparative Example 1. [Figure 12] FIG. 11 is a schematic diagram showing a three-dimensional structural analysis model according to Comparative Example 2. [Figure 13] FIG. 11 is a schematic diagram showing a three-dimensional structural analysis model according to Comparative Example 3. [Figure 14] FIG. 11 is a schematic diagram showing a three-dimensional structural analysis model according to Comparative Example 4. [Figure 15] FIG. 11 is a schematic diagram showing a three-dimensional structural analysis model according to the third embodiment. [Figure 16] FIG. 1 is a diagram showing a comparison of the results of structural analysis of Comparative Examples 1, 2, 3, and 4 and Example 3. [Figure 17] 1 is a graph showing the results of the structure analysis of Examples 4, 5, and 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments, and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the drawings described below, the same reference numerals are used to designate parts having the same functions, and their description may be omitted or simplified.

[0010] [First embodiment] The imaging unit according to the first embodiment will be described with reference to Fig. 1, Fig. 2, and Fig. 3. Fig. 1 is a schematic top view showing the general configuration of an imaging unit 400 according to this embodiment. Fig. 2 is a schematic cross-sectional view showing the general configuration of the imaging unit 400 according to this embodiment, showing a cross section taken along line AA' in Fig. 1.

[0011] FIG. 3 is an enlarged schematic cross-sectional view of a connection portion 19 between a flexible wiring board 4 and a printed wiring board 9 of an imaging unit 400 according to this embodiment, and shows an enlarged cross-section of the connection portion 19 in FIG.

[0012] 1, 2 and 3, imaging unit 400 has an image sensor module 14 having a printed wiring board 9, an image stabilization unit 410, and a flexible wiring board 4. Flexible wiring board 4 is connected to printed wiring board 9 at connection portion 19 via solder 11, as will be described later.

[0013] Here, the coordinate axes and directions of the X-axis, Y-axis, and Z-axis of the XYZ coordinate system, which is an orthogonal coordinate system used in the following description, are defined. First, the axis perpendicular to the main surface of the printed wiring board 9 is defined as the Z-axis. Also, the axis parallel to the main surface of the printed wiring board 9 and along a pair of parallel end sides of the printed wiring board 9 is defined as the X-axis. Also, the axis perpendicular to the X-axis and Z-axis is defined as the Y-axis. In the XYZ coordinate system in which the coordinate axes are defined in this way, the direction along the X-axis is defined as the X-direction, the direction from one end of the flexible wiring board 4 on the side of the connection portion 19 to the other end is defined as the +X-direction, and the direction opposite to the +X-direction is defined as the -X-direction. Also, the direction along the Y-axis is defined as the Y-direction, the direction from the right side to the left side of the +X-direction is defined as the +Y-direction, and the direction opposite to the +Y-direction is defined as the -Y-direction. The direction along the Z axis is defined as the Z direction, the direction from the imaging sensor element 15 side of the imaging sensor module 14 toward the connecting portion 19 side is defined as the +Z direction, and the direction opposite to the +Z direction is defined as the -Z direction. The rotation direction around the Z axis is defined as the θ direction.

[0014] The flexible wiring board 4 has a flexible base material 1, a flexible wiring layer 2, and a coverlay 3. The flexible wiring board 4 has one or more conductor layers as the flexible wiring layer 2, and is configured by stacking the conductor layers as insulating layers via the flexible base material 1. Note that in this embodiment, a case will be described in which the wiring layer in the flexible wiring board 4 is a single layer, but the present invention is not limited to a single layer, and the wiring layer may be a multiple layer.

[0015] The flexible substrate 1 is an insulating substrate made of resin or the like, for example, in the form of a sheet or film, and has plasticity and flexibility. Therefore, the flexible wiring board 4 can be deformed, such as by bending. The insulator constituting the flexible substrate 1 only needs to have electrical insulation properties. For example, polyimide, polyethylene terephthalate, etc. are used as the insulator constituting the flexible substrate 1. The flexible substrate 1 has a front surface, which is a first surface, and a back surface, which is a second surface. Layers and members are provided on the front surface and back surface of the flexible substrate 1 as follows.

[0016] The flexible wiring layer 2 is a conductor layer made of copper foil, other metal foil, etc. The flexible wiring layer 2 has a wiring pattern. The flexible wiring layer 2 is formed on one or both of the front and back surfaces of the flexible substrate 1. The flexible wiring layer 2 may be formed directly on the front or back surface of the flexible substrate 1, or may be formed on the front or back surface of the flexible substrate 1 via a layer structure such as an insulating layer. The conductor constituting the flexible wiring layer 2 is a material having higher electrical conductivity and thermal conductivity than an insulator, for example, a metal such as copper, silver, or gold. The flexible wiring layer 2 may be formed on at least one surface of the flexible substrate 1. For example, the flexible wiring layer 2 is provided on the surface of the flexible substrate 1 facing the printed wiring board 9.

[0017] The coverlay 3 is an insulating layer that protects the wiring pattern of the flexible wiring layer 2. The coverlay 3 is formed of a cover film, an overcoat, or the like. The coverlay 3 is provided on the surface of the flexible wiring board 4, and is formed on the surface of the flexible base material 1 that includes the flexible wiring layer 2 so as to cover the flexible wiring layer 2. For example, the coverlay 3 is provided on the flexible wiring layer 2 provided on the surface of the flexible base material 1.

[0018] On the side of the coverlay 3 provided on the surface of the flexible base material 1 of the flexible wiring board 4, the coverlay 3 is not formed on one end of the flexible wiring board 4, and the flexible wiring layer 2 is exposed. The exposed part of the flexible wiring layer 2 constitutes the first electrode 5. That is, the flexible wiring layer 2 provided on the surface of the flexible base material 1 has the first electrode 5 on one end where the coverlay 3 is not provided. In addition, the first electrode 5 may be plated with gold or the like. The first electrodes 5 made of the exposed flexible wiring layer 2 are arranged in a row at a predetermined pitch, for example. In this way, the first electrode 5 is formed by the flexible wiring layer 2 exposed at the end of the flexible wiring board 4. One end of the flexible wiring board 4 where the first electrode 5 is formed is an electrode part where the first electrode 5 is exposed. Although not shown, the other end of the flexible wiring board 4 is an insertion terminal on which an electrode is formed.

[0019] In the connection portion 19 between the printed wiring board 9 and the flexible wiring board 4 of the imaging sensor module 14, the first electrode 5 exposed at one end of the flexible wiring board 4 is connected to the second electrode 10 of the printed wiring board 9 via the solder 11. It is preferable that a gap is formed between the coverlay 3 of the flexible wiring board 4 connected to the printed wiring board 9 at the connection portion 19 and the solder 11, and that an exposed portion 24 where the flexible wiring layer 2 is exposed is secured. That is, it is preferable that the flexible wiring layer 2 is exposed between the end portion of the solder 11 on the coverlay 3 side and the end portion of the coverlay 3 on the solder 11 side. The exposed portion 24 is a portion where the first electrode 5 is exposed between the end portion of the coverlay 3 close to the first electrode 5 and the solder 11. When the exposed portion 24 is secured, the end portion of the coverlay 3 close to the first electrode 5 is not in contact with the solder 11. By ensuring the exposed portion 24, the reduction in flexibility of the flexible wiring board 4 caused by the reinforcing material 21 described below can be minimized, while the reinforcing material 21 can reinforce the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9.

[0020] Although not shown in the figure, an insertion terminal at the other end of the flexible wiring board 4 is inserted into a connector mounted on the printed wiring board of the image processing unit. In this way, the flexible wiring board 4 electrically connects the imaging unit 400 and the image processing unit to each other.

[0021] Imaging sensor module 14 has a printed wiring board 9, imaging sensor element 15, a frame 17, and a cover glass 16. Printed wiring board 9 is adhered and fixed to metal frame 22 with an adhesive such as an ultraviolet curable resin. Imaging sensor module 14 is supported by image stabilization unit 410 so as to be movable relative to image stabilization unit 410, as will be described later.

[0022] As described below, a second electrode 10 is provided on the surface layer of one surface of the printed wiring board 9, which is connected to the flexible wiring board 4. A frame 17 is attached and disposed on the peripheral edge of the other surface of the printed wiring board 9. A cover glass 16 is attached to the frame 17 so as to be parallel to the printed wiring board 9.

[0023] The imaging sensor element 15 is an imaging element formed of, for example, a semiconductor element. Specifically, the imaging sensor element 15 is, for example, a solid-state imaging element such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor. The imaging sensor element 15 is attached to the printed wiring board 9 in a hollow portion surrounded by the printed wiring board 9, the cover glass 16, and the frame 17 so as not to come into contact with the cover glass 16. The imaging sensor element 15 is electrically connected to a wire pad 23 of the printed wiring board 9 through a metal wire 18. The wire pad 23 is, for example, Au-plated.

[0024] The image stabilization unit 410 supports the metal frame 22 so that the image sensor module 14 fixed to the metal frame 22 can move in the X and Y directions and rotate in the θ direction. The image stabilization unit 410 can correct camera shake by moving or rotating the image sensor module 14 in response to camera shake. The image stabilization unit 410 has, for example, an L-shape and is configured to support the metal frame 22 having a rectangular outer shape from two adjacent sides of the metal frame 22.

[0025] In this embodiment, the case where frame 17 is attached is described, but the location of the frame 17 is not limited to the peripheral portion of printed wiring board 9. Also, image sensor element 15 may be located in a hollow portion of printed wiring board 9 having a countersunk hole, such as a cavity board.

[0026] The printed wiring board 9 on which the image sensor element 15 is provided has a printed wiring base material 6, a wiring layer 7, and a solder resist layer 8. The printed wiring board 9 is configured by laminating a plurality of wiring layers 7 via the printed wiring base material 6. Unlike the flexible wiring board 4, the printed wiring board 9 is a rigid wiring board.

[0027] For example, the printed wiring board 9 may be made of a glass epoxy material or a ceramic substrate. Alternatively, a printed circuit board may be used in which the image sensor element 15 is disposed on a ceramic substrate and the ceramic substrate and the printed wiring board 9 are connected by a pair of electrodes via solder 11. For example, an LGA (Land Grid Array) type or CLCC (Ceramic Leadless Chip Carrier) type image sensor unit may be used.

[0028] In this embodiment, the wiring layer 7 in the printed wiring board 9 has four layers, but is not limited to four layers. The wiring layer 7 in the printed wiring board 9 may be a single layer or multiple layers, that is, four or less layers or four or more layers.

[0029] Although not shown, the printed wiring board 9 is also equipped with the minimum number of parts necessary for the operation of the imaging unit 400.

[0030] The printed wiring substrate 6 is, for example, a board-shaped insulating substrate made of a hard composite material or the like. The printed wiring substrate 6 is hard, unlike the flexible substrate 1. The insulator constituting the printed wiring substrate 6 only needs to have electrical insulation properties. For example, the printed wiring substrate 6 may be a resin substrate in which a resin such as an epoxy resin is hardened, or a ceramic substrate using ceramics.

[0031] The wiring layer 7 is a conductor layer made of copper foil or other metal foil. The wiring layer 7 has a wiring pattern. The wiring layer 7 is formed on one side or both sides of the printed wiring substrate 6. One or more wiring layers 7 are also formed inside the printed wiring substrate 6. FIGS. 2 and 3 show a case where a total of four wiring layers 7 are formed on both sides and inside the printed wiring substrate 6. Also, vias 13 are formed inside the printed wiring substrate 6 to electrically connect the wiring layers 7. Conductors such as the wiring layer 7 and the vias 13 are materials having higher electrical conductivity and thermal conductivity than insulators, for example, metals such as copper and gold.

[0032] The solder resist layer 8 is an insulating protective film that protects the circuit formed by the wiring layer 7. The solder resist layer 8 is formed of a hardened liquid solder resist, a film-like solder resist, or the like. The solder resist layer 8 is formed on one surface of the printed wiring board 9 on the side to which the flexible wiring substrate 4 is connected so as to cover the wiring layer 7. The solder resist layer 8 is also formed on the other surface of the printed wiring board 9 on the side to which the image sensor element 15 is attached so as to cover the wiring layer 7.

[0033] The solder resist layer 8 has an opening through which the wiring layer 7 is exposed. The exposed portion of the wiring layer 7 forms a second electrode 10. The second electrodes 10 are arranged, for example, in a row at a predetermined pitch. The second electrodes 10 are arranged, for example, in the center of the printed wiring board 9. In this way, the second electrodes 10 made of the wiring layer 7 are provided on the surface layer of the printed wiring board 9. The second electrodes 10 provided on the surface layer are electrically connected to the first electrodes 5 of the flexible wiring board 4 via solder 11, which is a conductive connecting material.

[0034] When the first electrode 5 and the second electrode 10 are connected using the solder 11, the first electrode 5 and the second electrode 10 can be connected by adhering the solder 11 to the connecting material having the solder 11 while the connecting material is heated to a temperature equal to or higher than the melting point of the solder 11. The solder 11 may be, for example, Sn-3.0Ag-0.5Cu solder or Sn-58Bi solder mixed with flux to form a paste. Instead of the solder 11, a conductive adhesive or the like may be used as a conductive connecting material for connecting the first electrode 5 and the second electrode 10.

[0035] A reinforcing material 21 for reinforcing the connection 19 is provided at the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9, where the first electrode 5 and the second electrode 10 are connected as described above. The reinforcing material 21 is provided on the back surface of the flexible substrate 1, which is the surface opposite to the surface on which the first electrode 5 of the flexible wiring board 4 is exposed. The reinforcing material 21 provided on the back surface of the flexible substrate 1 may be provided on the back surface of the flexible substrate 1, or may be provided on the back surface of the flexible substrate 1 via a layer such as a wiring layer or an insulating layer.

[0036] 1, the reinforcing material 21 is provided on both ends in the width direction (short side direction) of the flexible wiring board 4 along the Y direction at the tip end on the connection portion 19 side of the flexible base material 1 of the flexible wiring board 4. Note that the reinforcing material 21 is provided on both ends of the flexible base material 1 in the width direction of the flexible wiring board 4, and may also be provided across the width direction of the flexible wiring board 4 as in a third embodiment described later.

[0037] 3, the reinforcing material 21 is provided on the flexible substrate 1 so as to continuously cover both the end portion of the solder 11 on the coverlay 3 side and the end portion of the coverlay 3 on the solder 11 side via the flexible substrate 1 and the flexible wiring layer 2. That is, the reinforcing material 21 continuously covers the end portion of the coverlay 3 on the side closer to the first electrode 5 and the end portion of the portion of the solder 11 connected to the first electrode 5 on the side closer to the coverlay 3.

[0038] The reinforcing material 21 is not particularly limited, but may be, for example, a cured resin such as an ultraviolet (UV) curable resin, a thermosetting resin, etc. Furthermore, the reinforcing material 21 may be a reinforcing film attached to the same location on the surface of the flexible base material 1, in addition to being a cured resin.

[0039] Here, the flexible wiring board 4 connected to the printed wiring board 9 includes a fixed portion 4a, which is a portion where the first electrode 5 is connected and fixed to the second electrode 10 via the solder 11, and a non-fixed portion 4b, which is a portion other than the fixed portion 4a. The non-fixed portion 4b can bend in a direction away from the printed wiring board 9 with respect to the fixed portion 4a. The reinforcing member 21 provided as described above is provided across the fixed portion 4a and the non-fixed portion 4b. Due to the presence of such reinforcing member 21, the angle θb at which the non-fixed portion 4b bends with respect to the fixed portion 4a is maintained at an obtuse angle. The reinforcing member 21 can be formed with a material, thickness, area, shape, etc. that can be deformed within a range where the angle θb at which the non-fixed portion 4b bends with respect to the fixed portion 4a can be maintained at an obtuse angle. In this manner, the imaging unit 400 according to this embodiment is configured.

[0040] In recent years, digital cameras are equipped with image stabilization units that move the image sensor itself to correct image stabilization. Image stabilization units are subject to not only conventional static loads, but also dynamic loads such as vibrations that occur during image stabilization, which are superimposed in the planar XY directions and the rotational θ direction. For this reason, the flexible wiring board that connects the rigid wiring board mounting the image sensor to the rigid wiring board mounting the image processing LSI is required to have flexibility that does not impede the operation of the image stabilization unit and bonding strength that can withstand repeated loads.

[0041] In contrast, in the imaging unit 400 according to the present embodiment, as described above, the reinforcing material 21 is provided in the connection portion 19 so as to continuously cover both the end portion of the solder 11 on the coverlay 3 side and the end portion of the coverlay 3 on the solder 11 side. The reinforcing material 21 thus provided can locally increase the rigidity of the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9. Therefore, in this embodiment, the deformation behavior in the vicinity of the connection portion 19 caused when the image stabilization unit 410 is driven can be suppressed to a small value. At the same time, in this embodiment, the bending angle θb of the flexible wiring board 4 during driving can be maintained at an obtuse angle, so that the load on the connection portion 19 can be reduced. Furthermore, in this embodiment, the connection portion 19 is only locally increased in rigidity and reinforced, and the entire flexible wiring board 4 is not reinforced, so that the flexibility of the flexible wiring board 4 is not impaired. Therefore, according to this embodiment, the load on the connection portion 19 can be reduced without impeding the operation of the image stabilization unit 410.

[0042] As described above, according to this embodiment, the load acting on the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9 can be reduced without impairing the flexibility of the flexible wiring board 4.

[0043] 1 shows a case where reinforcing material 21 is provided only on both ends in the width direction along the Y direction of flexible wiring board 4, but this is not limited thereto. Reinforcing material 21 may be provided over the entire width direction, or may be provided protruding from flexible wiring board 4 onto printed wiring board 9 in the width direction of flexible wiring board 4.

[0044] 2 and 3 show the case where the reinforcing material 21 is provided so as to cover the end portion of the solder 11 on the coverlay 3 side, but the present invention is not limited to this. The reinforcing material 21 may be provided so as to cover up to one end portion of the flexible wiring board 4, or may be provided so as to extend from the flexible wiring board 4 onto the solder resist layer 8 of the printed wiring board 9.

[0045] [Second embodiment] Next, an imaging unit 400 according to a second embodiment will be described with reference to Figs. 4, 5, and 6. Fig. 4 is a schematic top view showing the schematic configuration of the imaging unit 400 according to this embodiment. Fig. 5 is a schematic cross-sectional view showing the schematic configuration of the imaging unit 400 according to this embodiment, showing a cross section along line BB' in Fig. 4. Fig. 6 is a schematic cross-sectional view showing an enlarged view of a connection portion 19 between the flexible wiring board 4 and the printed wiring board 9 of the imaging unit 400 according to this embodiment, showing an enlarged view of the connection portion 19 in Fig. 5.

[0046] This embodiment differs from the first embodiment in the manner in which the flexible wiring board 4 is disposed relative to the printed wiring board 9. Other configurations are similar to those of the first embodiment, and therefore descriptions of similar configurations will be omitted.

[0047] In the first embodiment, the flexible wiring board 4 was arranged so that it extended without bending in the +X direction on the side of the image processing unit (not shown), which is the connection destination to which one end portion of the flexible wiring board 4 is connected, opposite to one end portion of the flexible wiring board 4 on the connection portion 19 side.

[0048] In contrast, in this embodiment, flexible wiring board 4 is disposed so as to extend in the -X direction opposite to the +X direction on the side of an image processing unit (not shown) which is the connection destination to which the other end portion is connected, with respect to connection portion 19. Furthermore, flexible wiring board 4 extending in the -X direction is bent on printed wiring board 9 in the +X direction on the side of the image processing unit.

[0049] That is, in this embodiment, as shown in Figures 4, 5 and 6, the first electrode 5 of the flexible wiring board 4 is connected to the second electrode 10 via the solder 11 so that one end of the flexible wiring board 4 faces the +X direction opposite to that of the first embodiment, and is then connected to the printed wiring board 9. Furthermore, the flexible wiring board 4 is in a bent state in which it is folded back once from the side opposite the image stabilization unit 410 to the side of the image stabilization unit 410 so that the other end of the flexible wiring board 4 is located on the side of the image stabilization unit 410 and the image processing unit to which it is connected. Thus, in this embodiment, the flexible wiring board 4 is folded back and bent from the side opposite the image stabilization unit 410 and the image processing unit to the side of the image stabilization unit 410 and the image processing unit.

[0050] In this embodiment, the reinforcing material 21 is provided on the flexible wiring board 4 folded back as described above, similarly to the first embodiment. In this manner, in the present embodiment, the flexible wiring board 4 is in a bent state. In the present embodiment, the flexible wiring board 4 in a bent state is provided with the reinforcing material 21 as in the first embodiment. Therefore, according to the present embodiment as well, it is possible to reduce the load acting on the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9 without impairing the flexibility of the flexible wiring board 4.

[0051] 4 shows a case where reinforcing material 21 is provided only on both ends in the width direction along the Y direction of flexible wiring board 4, but the present invention is not limited to this. Reinforcing material 21 may be provided over the entire width direction, or may be provided protruding from flexible wiring board 4 onto printed wiring board 9 in the width direction of flexible wiring board 4.

[0052] 5 and 6 show a case where the reinforcing material 21 is provided so as to cover the end portion of the solder 11 on the coverlay 3 side, but the present invention is not limited to this. The reinforcing material 21 may be provided so as to cover up to one end portion of the flexible wiring board 4, or may be provided so as to extend from the flexible wiring board 4 onto the solder resist layer 8 of the printed wiring board 9.

[0053] In this embodiment, the number of flexible wiring boards 4 is not limited to one, but may be two or more. Furthermore, the connection position between the flexible wiring board 4 and the printed wiring board 9 is not limited to the center of the printed wiring board 9, and may be an edge of the printed wiring board 9. Furthermore, when multiple flexible wiring boards 4 are mounted, their positions may be, for example, one at the center of the printed wiring board 9 and another at an edge of the printed wiring board 9.

[0054] [Third embodiment] Next, an imaging unit 400 according to a third embodiment will be described with reference to Figs. 7, 8, and 9. Fig. 7 is a schematic top view showing the schematic configuration of the imaging unit 400 according to this embodiment. Fig. 8 is a schematic cross-sectional view showing the schematic configuration of the imaging unit 400 according to this embodiment, showing a cross section along line CC' in Fig. 7. Fig. 8 is a schematic cross-sectional view showing an enlarged view of a connection portion 19 between the flexible wiring board 4 and the printed wiring board 9 of the imaging unit 400 according to this embodiment, showing an enlarged view of the connection portion 19 in Fig. 7.

[0055] In this embodiment, the region where the reinforcing material 21 is provided is different from that of the second embodiment. Note that other configurations are similar to those of the second embodiment, and therefore a description of the similar configurations will be omitted.

[0056] 7, in this embodiment, the reinforcing material 21 is provided over the entire width direction (short side direction) of the flexible wiring board 4 along the Y direction, in an area wider than the width of the flexible wiring board 4. In other words, the reinforcing material 21 is provided protruding from above the flexible base material 1 of the flexible wiring board 4 onto above the solder resist layer 8 of the printed wiring board 9 in the width direction of the flexible wiring board 4.

[0057] 7, 8, and 9, in the longitudinal direction of the flexible wiring board 4 along the X direction, the reinforcing material 21 is applied beyond one end of the flexible wiring board 4 on the connection portion 19 side up to the solder resist layer 8. That is, the reinforcing material 21 is provided so as to protrude from the flexible base material 1 of the flexible wiring board 4 up to the solder resist layer 8 of the printed wiring board 9 in the longitudinal direction of the flexible wiring board 4.

[0058] In this embodiment as well, reinforcing material 21 provided as described above can reduce the load acting on connection portion 19 between flexible wiring board 4 and printed wiring board 9 without impairing the flexibility of flexible wiring board 4. By changing the area where reinforcing material 21 is provided, the degree of localized high rigidity of connection portion 19 can be adjusted, and the load acting on connection portion 19 can be reduced in accordance with the flexibility required for flexible wiring board 4.

[0059] In the first embodiment as well, the reinforcing material 21 can be provided in the same region as in this embodiment.

[0060] In addition, the reinforcing material 21 may be provided extending from above the flexible base material 1 of the flexible wiring board 4 to above the solder resist layer 8 of the printed wiring board 9 in either the width direction or the length direction of the flexible wiring board 4.

[0061] [Fourth embodiment] Next, an electronic device according to a fourth embodiment will be described with reference to Fig. 10. Fig. 10 is a schematic diagram showing a schematic configuration of an imaging device as an example of the electronic device according to this embodiment.

[0062] Digital camera (camera) 100 as an imaging device, which is an example of an electronic device according to this embodiment, is, for example, a digital single-lens reflex camera. As shown in Fig. 10, camera 100 includes a camera body 200 and an interchangeable lens 300 (lens barrel) 300 that is detachable from camera body 200. In Fig. 10, interchangeable lens 300 is attached to camera body 200. Below, a case where interchangeable lens 300 is attached to camera body 200 to configure camera 100 as an imaging device will be described.

[0063] Camera body 200 includes a housing 201, and a mirror 222, a shutter 223, an imaging unit 400 which is a printed circuit board, and an image processing circuit 224 which are arranged inside housing 201. Camera body 200 also includes a liquid crystal display 225 which is fixed to housing 201 so as to be exposed to the outside.

[0064] The imaging unit 400 has the configuration described in the first to third embodiments above, and includes an image stabilization unit 410, an imaging sensor module 14 having a printed wiring board 9, and a flexible wiring board 4.

[0065] The interchangeable lens 300 has a housing 301 which is an interchangeable lens housing, and an imaging optical system 311. The imaging optical system 311 is disposed inside the housing 301, and forms an optical image on the imaging sensor module 14 when the housing 301 (interchangeable lens 300) is attached to the housing 201. The imaging optical system 311 is configured to have a plurality of lenses.

[0066] The housing 301 of the interchangeable lens 300 has a lens side mount 301a in which an opening is formed. On the other hand, the housing 201 of the camera body 200 has a camera side mount 201a in which an opening is formed. The interchangeable lens 300 (housing 301) is attached to the camera body 200 (housing 201) by fitting the lens side mount 301a and the camera side mount 201a together. The direction of the arrow X shown in FIG. 10 is the optical axis direction of the imaging optical system 311.

[0067] Light traveling in the direction of the arrow X by the imaging optical system 311 is guided into the housing 201 through an opening of the lens side mount 301a in the housing 301 and an opening of the camera side mount 201a in the housing 201. Inside the housing 201, a mirror 222, a shutter 223, etc. are provided along the direction of the arrow X in front of the imaging unit 400 in the direction of the arrow X.

[0068] The imaging sensor element 15 in the imaging sensor module 14 is a solid-state imaging element such as a CMOS image sensor or a CCD image sensor that photoelectrically converts the optical image formed by the imaging optical system 311 .

[0069] The camera 100, which is an image capturing device including the imaging unit 400, is configured as described above.

[0070] As described above, according to this embodiment, even when the digital single-lens reflex camera 100 is dropped or otherwise subjected to an impact, the load generated at the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9 can be reduced, thereby improving performance.

[0071] In this embodiment, the case where the interchangeable lens 300 is attached to the camera body 200 has been described, but the present invention is not limited to this. When there is only the camera body 200 without the interchangeable lens 300 attached, the camera body 200 is the imaging device.

[0072] Furthermore, in this embodiment, the camera 100 is described as being divided into the camera body 200 and the interchangeable lens 300, but the camera 100 may be an integrated type in which the lens is built into the camera body 200.

[0073] Furthermore, in this embodiment, the camera 100 has been described as an imaging device that is an electronic device, but the present invention is not limited to this.

[0074] [Example 1] As the imaging unit of Example 1, an imaging unit 400 according to the first embodiment shown in Figures 1, 2, and 3 was manufactured. In the imaging unit 400 of Example 1, the frame 17 was made of resin and had a thickness of 2 mm. The imaging sensor element 15 was a CMOS image sensor having a rectangular planar shape of 30 mm x 20 mm. The cover glass 16 was a rectangular planar shape of 28 mm x 38 mm.

[0075] The flexible wiring board 4 used had a flexible base material 1 and a coverlay 3 made of polyimide, and a flexible wiring layer 2 and a first electrode 5 made of Cu. The flexible base material 1 had a thickness of 25 μm, the coverlay 3 had a thickness of 12 μm, and the flexible wiring layer 2 had a thickness of 18 μm.

[0076] The printed wiring board 9 had a rectangular outer shape of 30 mm×40 mm, the printed wiring base material 6 was made of glass epoxy material, and the wiring layer and the second electrode 10 were made of Cu. The thickness of the wiring layer 7 and the second electrode 10 was about 30 μm, and the thickness of the solder resist layer 8 was about 25 μm. A UV-curable resin was used as an adhesive for fixing the printed wiring board 9 to the metal frame 22. The metal frame 22 had an outer shape of 50 mm×60 mm.

[0077] The first electrodes 5 of the flexible wiring board 4 and the second electrodes 10 of the printed wiring board 9 were connected by solder 11. The second electrodes 10 had a pitch of 0.2 mm, an electrode width of 0.15 mm, and 80 wires. The opening of the solder resist layer 8 through which the second electrodes 10 were exposed had a size of 1.1 mm×20 mm. On the other hand, the first electrodes 5 had a pitch of 0.2 mm, an electrode width of 0.15 mm, and 80 wires. The width of the flexible wiring board 4 was 22 mm, which is larger than the opening width of the solder resist layer 8 (20 mm). The electrode pitch, electrode width, width between electrodes, and number of electrodes were appropriately set according to the specifications of the imaging sensor module 14.

[0078] The length in the X direction of exposed portion 24 in the gap between coverlay 3 and solder 11 was set to 1 mm. Solder 11 was made of Sn-3.0-Ag-0.5Cu material. Image stabilization unit 410 was an L-shaped unit with a 70 mm x 55 mm rectangle cut out from a 85 mm x 70 mm rectangle.

[0079] A UV-curable resin was used as the reinforcing material 21. The reinforcing material 21 had a thickness of 0.5 mm. The reinforcing material 21 was provided at both ends in the width direction of the flexible wiring board 4 when viewed from above. The reinforcing material 21 covered the gap between the coverlay 3 and the solder 11, and was provided so as to cover 0.5 mm from the end of the coverlay 3 in the direction opposite to the connection part 19 of the flexible wiring board 4. The reinforcing material 21 was further provided so as to cover 0.5 mm from the joint part between the flexible wiring layer 2 and the solder 11 in the direction of the connection part 19.

[0080] The completed imaging device incorporating the imaging unit 400 of the first embodiment was able to fully guarantee the optical performance of the built-in CMOS image sensor.

[0081] [Example 2] As the imaging unit of Example 2, an imaging unit 400 according to the third embodiment shown in Figs. 7, 8 and 9 was manufactured. In the imaging unit 400 of Example 2, the flexible wiring board 4 is pulled out to the side opposite the image stabilization unit 410 as shown in Fig. 7, and folded back once. Also, as shown in Fig. 8, the reinforcing region where the reinforcing material 21 is provided is a region wider than the width of the flexible wiring board 4. Furthermore, as shown in Fig. 9, the reinforcing material 21 is applied beyond the tip of the connection portion 19 of the flexible wiring board 4 and onto the solder resist layer 8.

[0082] The flexible wiring board 4 used was the same as that in Example 1. The printed wiring board 9 used was the same as that in Example 1. The reinforcing material 21 used was the same UV-curable resin as that in Example 1.

[0083] The completed imaging device equipped with the imaging unit 400 of Example 2 was able to fully guarantee the optical performance of the built-in CMOS image sensor. Moreover, in Example 2, even in a bent state, the flexibility of the flexible wiring board 4 was maintained, and the load generated on the connection portion 19 between the flexible wiring board 4 and the printed wiring board 9 was reduced. Furthermore, in Example 2, the reinforcing material 21 was provided in an area wider than the width of the flexible wiring board 4, so that the load generated on not only the connection portion 19 but also the flexible base material 1 was reduced.

[0084] [Evaluation by structural analysis] In order to confirm the effect of the present invention, an example will be shown in which a structure including flexible wiring board 4 and printed wiring board 9 was simplified and subjected to a structural analysis.

[0085] As shown in Figures 11 to 15, structural analysis was performed on Comparative Example 1, in which reinforcing material 21 was not arranged on the flexible substrate 1, and on Comparative Examples 2, 3, 4 and Example 3, in which reinforcing material 21 was arranged in different locations on the flexible substrate 1.

[0086] That is, FIG. 11 is a schematic diagram showing a structure in which a flexible wiring board 4 is connected to a printed wiring board 9 using solder 11 as Comparative Example 1. FIG. 12 is a schematic diagram showing a structure in which, in addition to Comparative Example 1, a reinforcing material 21 is arranged at a location including an end portion of the solder 11 on the coverlay 3 side and not including an end portion of the coverlay 3 on the solder 11 side. FIG. 13 is a schematic diagram showing a structure in which, in addition to Comparative Example 1, a reinforcing material 21 is arranged at a location including an end portion of the solder 11 on the coverlay 3 side and not including an end portion of the coverlay 3 on the solder 11 side. FIG. 14 is a schematic diagram showing a structure in which, in addition to Comparative Example 1, a reinforcing material 21 is arranged intermittently at a location including an end portion of the solder 11 on the coverlay 3 side and at a location including an end portion of the coverlay 3 on the solder 11 side.

[0087] On the other hand, Figure 15 is a schematic diagram showing a structure of Example 3 in which, in comparison with Comparative Example 1, reinforcing material 21 is continuously arranged at a location including the end portion of solder 11 on the coverlay 3 side and at a location including the end portion of coverlay 3 on the solder 11 side.

[0088] The structural analysis method used in the evaluation is explained below. The structural analysis software used was ANSYS Mechanical Enterprise Version 19.1. The structural analysis was performed in three dimensions.

[0089] The dimensions used in the structural analysis will be described. The printed wiring board 9 was 2.5 mm long, 1 mm wide, and 0.8 mm thick. The solder 11 was 1 mm long from a point 0.75 mm from the end face of the printed wiring board 9 in the X direction, and 0.1 mm long from a point 0.45 mm from the end face of the printed wiring board 9 in the Y direction, and the solder height in the Z direction was 50 μm. The flexible wiring board 4 was modeled for each layer. The flexible wiring layer 2 was 2 mm long from the end face of the solder 11 in the X direction, and the length in the Y direction was 0.1 mm like the solder 11, and the thickness in the Z direction was 20 μm. The flexible base material 1 was laminated in the +Z direction with respect to the flexible wiring layer 2, and the thickness in the Z direction was 20 μm. The coverlay 3 was laminated in the -Z direction with respect to the flexible wiring layer 2, had a length of 0.9 mm from a point 1.1 mm from the end face of the flexible wiring layer 2 in the X direction, and had a thickness of 20 μm in the -Z direction. That is, the length in the X direction of the exposed portion 24 of the flexible wiring layer 2, which is the gap between the solder 11 and the coverlay 3, was 0.1 mm.

[0090] The reinforcing material 21 is a cured product of epoxy resin, laminated on the flexible substrate 1, and has a thickness of 20 μm. In Comparative Example 2, the length of the reinforcing material 21 in the X direction is 10 μm in each of the ±X directions, totaling 20 μm, with the end of the solder 11 on the coverlay 3 side as the center, and the length in the Y direction is the same as that of the solder 11. In Comparative Example 3, the length of the reinforcing material 21 in the X direction is 10 μm in each of the ±X directions, totaling 20 μm, with the end of the solder 11 on the coverlay 3 as the center, and the length in the Y direction is the same as that of the solder 11. In Comparative Example 4, the reinforcing material 21 is disposed at the same location as Comparative Examples 2 and 3 at the same time. In Example 3, the length of the reinforcing material 21 in the X direction is 0.12 mm from a position 10 μm in the −X direction from the end of the solder 11 on the coverlay 3 side to a position 10 μm in the +X direction from the end of the solder 11 on the coverlay 3 side, and the length in the Y direction is the same as that of the solder 11.

[0091] The conditions for the structural analysis are as follows. In the printed wiring board 9, the nodal displacement on the back surface, which is the surface in the -Z direction that is not connected to the flexible wiring board 4, was set to 0 in all of the X, Y, and Z directions. Furthermore, the end portion opposite to the connection portion 19 of the flexible wiring board 4 was set to Area A, and the plane of Area A was set to a displacement of 0.1 mm in the +Z direction. The structural analysis was performed under the above conditions for all of Comparative Examples 1, 2, 3, and 4 and Example 3.

[0092] The evaluation standard was the maximum value of equivalent stress in the non-covered area of ​​the flexible wiring layer 2, which is an area where the solder 11 and the coverlay 3 are not connected. A structural analysis was performed under the above conditions, and the stress values ​​generated in the flexible wiring layer 2 were compared. Figure 16 shows the results of the stress analysis by the structural analysis. In Figure 16, the evaluation axis is the stress ratio, with the stress value of Comparative Example 1 being 100% of the reference value.

[0093] As shown in Fig. 16, in Example 3, the stress can be reduced by about 20% compared to Comparative Examples 1, 2, 3, and 4. From the results shown in Fig. 16, it can be seen that if the reinforcing material 21 is arranged in a location including only the end portion of the solder 11 on the coverlay 3 side as in Comparative Example 2, the reinforcing material 21 does not have a reinforcing effect. It can also be seen that if the reinforcing material 21 is arranged in a location including only the end portion of the coverlay 3 on the solder 11 side as in Comparative Example 3, the reinforcing material 21 does not have a reinforcing effect. Furthermore, it can be seen that even if the reinforcing material 21 is arranged in a location including both end portions as in Comparative Example 4, the reinforcing material 21 is arranged intermittently, the reinforcing material 21 does not have a reinforcing effect.

[0094] Next, in order to confirm the effect of the covering length of the reinforcing material 21 of the present invention, the longitudinal length L1 of the coverlay 3 and the covering length L2 of the reinforcing material 21 in Fig. 15 were changed and structural analysis was performed. The longitudinal length L1 of the coverlay 3 is the length from one end of the coverlay 3 on the solder 11 side to the opposite other end in the longitudinal direction of the flexible wiring board 4 along the X direction. The covering length L2 of the reinforcing material 21 is the length of the portion covering the coverlay 3 in the +X direction from one end of the coverlay 3 on the solder 11 side, of the reinforcing material 21 which continuously covers the end portion of the solder 11 on the coverlay 3 side and the end portion of the coverlay 3 on the solder 11 side in the longitudinal direction.

[0095] As shown in Table 1 below, the effect of reinforcement when the length L1 and the covering length L2 were changed was verified by structural analysis. The units of the length L1 and the covering length L2 in Table 1 are mm. Table 1 also shows the coverage ratio L2 / L1, which is the ratio of the covering length L2 to the length L1. The structural analysis method and evaluation criteria are the same as those of the above-mentioned conditions. In addition, when comparing the stress values, the stress value when the reinforcing material 21 was not placed in Examples 4, 5, and 6 was set to 100% of the reference value. The results are shown in FIG. 17. As a result of performing the structural analysis under these conditions, in Examples 4, 5, and 6, the effect of reinforcement was obtained regardless of the value of the coverage ratio L2 / L1, but a particularly remarkable effect of reinforcement was obtained when the coverage ratio L2 / L1 was less than 0.4.

[0096] TIFF0007657614000001.tif60107

[0097] From the above, it has been confirmed that according to the present invention, the load acting on connection portion 19 between flexible wiring board 4 and printed wiring board 9 can be reduced without impairing the flexibility of flexible wiring board 4. [Explanation of symbols]

[0098] 1. Flexible substrate 2. Flexible wiring layer 3. Coverlay 4. Flexible wiring board 5. First electrode 6 Printed wiring substrate 7...Wiring layer 8. Solder resist layer 9 Printed wiring board 10...Second electrode 11. Solder 13. Via 14 Imaging sensor module 15. Imaging sensor element 16...Cover glass 17... Frame 18 Metal wire 19... Connection 21... Reinforcement material 22 Metal frame 23 Wire pad 24...Exposed part 400···Imaging unit

Claims

1. a printed wiring board on which an imaging element is provided and which has a first electrode on a main surface; a flexible wiring board having a base material having a first surface and a second surface, a conductor layer provided on the base material on the side of the first surface, and an insulating layer provided on the conductor layer, the conductor layer having a first region between the base material and the insulating layer, the conductor layer further having a second electrode that is not provided between the base material and the insulating layer; a conductive connecting member connecting the first electrode and the second electrode and contacting a second region of the second electrode; a reinforcing member provided on the base material on the second surface side, the reinforcing material continuously covers a first portion of the flexible wiring board and a second portion of the flexible wiring board, the first portion includes the second region of the second electrode, and the second portion includes the first region of the conductor layer; The first portion and the second portion overlap the main surface of the printed wiring board in a direction perpendicular to the main surface, and the second portion is bent in a direction away from the printed wiring board with respect to the first portion. The imaging unit is characterized by:

2. The angle at which the second portion bends with respect to the first portion is an obtuse angle.

2. The imaging unit according to claim 1.

3. The second electrode is exposed between the end of the insulating layer close to the second electrode and the conductive connecting material.

3. The imaging unit according to claim 1, wherein the imaging unit is a first imaging unit.

4. The reinforcing material is provided on both ends of the base material in the short-side direction of the flexible wiring board.

4. The imaging unit according to claim 1, wherein the first and second lenses are arranged in a first direction.

5. The reinforcing material is provided so as to protrude from the base material onto the printed wiring board in the longitudinal direction of the flexible wiring board.

5. The imaging unit according to claim 1, wherein the first and second lenses are arranged in a first direction.

6. The reinforcing material is provided so as to protrude from the base material onto the printed wiring board in the short-side direction of the flexible wiring board.

6. The imaging unit according to claim 1, wherein the imaging unit is a first imaging unit.

7. The ratio of the length of the portion of the reinforcing material that covers the insulating layer to the length of the insulating layer in the longitudinal direction is smaller than 0.

4.

7. The imaging unit according to claim 1, wherein the first and second lenses are arranged in a first direction.

8. an image sensor module having the printed wiring board; an image stabilization unit that movably supports the image sensor module; The imaging unit according to claim 1 , further comprising:

9. The flexible wiring board extends in a second direction opposite to a first direction on a connection destination side to which the other end portion is connected with respect to a connection portion where the first electrode and the second electrode are connected by the conductive connecting material, and then is bent in the first direction.

9. The imaging unit according to claim 1, wherein the first and second lenses are arranged in a first direction.

10. The reinforcing material is a cured product of an epoxy resin, an ultraviolet curable resin, or a thermosetting resin.

10. The imaging unit according to claim 1, wherein the first and second lenses are arranged in a first direction.

11. The insulating layer has a portion located between the reinforcing material and the printed wiring board.

11. The imaging unit according to claim 1,

12. The reinforcing material covers an end portion of the insulating layer close to the second electrode and an end portion of the conductive connecting material close to the insulating layer.

12. The imaging unit according to claim 1, wherein the imaging unit is a first imaging unit.

13. The reinforcing material is a resin that contacts the base material.

10. The imaging unit according to claim 1, wherein the first and second lenses are arranged in a first direction.

14. The reinforcing material is in contact with the conductive connecting material.

14. The imaging unit according to claim 1, wherein the imaging unit is a first imaging unit.

15. The conductive connecting material is solder.

15. The imaging unit according to claim 1, wherein the imaging unit is a lens.

16. The printed wiring board has a solder resist layer on the main surface, and the reinforcing material is in contact with the solder resist layer.

16. The imaging unit according to claim 1,

17. The first portion of the flexible wiring board is disposed between the third portion of the flexible wiring board and the main surface of the printed wiring board.

17. The imaging unit according to claim 1,

18. The third portion includes the first region of the conductor layer, and the third portion is not disposed between the reinforcing material and the main surface of the printed wiring board.

18. The imaging unit according to claim 17.

19. An imaging device including a housing and an imaging unit inside the housing, 19. An imaging device, wherein the imaging unit is an imaging unit according to claim 1.

20. The imaging device described in Claim 19, wherein the flexible wiring board has a portion that does not overlap the main surface in a direction perpendicular to the main surface of the printed wiring board.

Images