JP2019040902A - Circuit board - Google Patents

Abstract

To provide a circuit board capable of achieving high density of a wiring pattern while improving strength of a rigid part and heat radiation property.SOLUTION: A circuit board comprises a flexible wiring base material and a reinforcement part. The flexible wiring base material has: a first end part that has a first principal surface and a second principal surface that are orthogonal to a thickness direction; and a second end part provided on an opposite side to the first end part. The reinforcement part has: a first resin layer that selectively covers the first principal surface of the first end part; a second resin layer that selectively covers the second principal surface of the first end part; a first mounting surface that has a first wiring layer provided on the first resin layer and electrically connected with the flexible wiring base material; a second mounting surface that has a second wiring layer provided on the second resin layer and electrically connected with the flexible wiring base material; and a plate-like or frame-like metal reinforcement member buried in the first end part. The first end part is arranged closer to the first mounting surface than the second mounting surface.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a circuit board having a flexible portion and a rigid portion.

  The needs for electronic devices are diversified with the expansion of the information and communication industry, and the needs for the early start of development and mass production are also increasing. In particular, in smartphones, in addition to basic functions as a telephone, various functions such as the Internet, e-mail, camera, GPS, wireless LAN, and 1Seg TV are added, and the number of models is increasing. In high-performance smartphones, improving battery capacity is an issue, and high-density mounting of main boards, miniaturization and thinning, and modularization of functional blocks are being promoted. Above all, modules mounted on smartphones are required to be thin, including the method of joining the main board.

  Module boards used in mobile devices such as smartphones are required to be further thinner in order to realize multi-functional and thin parts. In particular, when using a flexible board or the like for connecting the main board and the module, a technique using a connector and a technique for pasting the module board and the flexible board together are known. Increasing is a problem. Therefore, the adoption of a composite circuit board (rigid-flexible board) in which a rigid part is provided on a flexible board is advancing.

  For example, Patent Document 1 includes a deformable flexible part, an insulating base and an electric circuit formed on the insulating base, formed on the rigid part to which the flexible part is connected, and the peripheral part of the insulating base, A circuit board is disclosed that includes an internal stress applied to an insulating base material and a reinforcing member formed of an insulating resin having higher rigidity than the insulating base material.

JP 2011-108929 A

  In recent years, for example, in a field where further thinning is required, such as a camera module, there is a demand for the development of a circuit board that has a rigid portion with high strength, excellent heat dissipation, and high wiring pattern density. However, in the configuration in which the reinforcing portion is provided at the peripheral portion of the rigid portion, there is a problem that the strength of the in-plane center portion of the rigid portion is weaker than the peripheral portion of the rigid portion, and the heat dissipation is not good.

  In view of the circumstances as described above, an object of the present invention is to provide a circuit board capable of increasing the density of a wiring pattern while improving the strength and heat dissipation of a rigid portion.

In order to achieve the above object, a circuit board according to an embodiment of the present invention includes a flexible wiring substrate and a reinforcing portion.
The flexible wiring substrate includes a first end portion having a first main surface and a second main surface orthogonal to a thickness direction, and a second end opposite to the first end portion. Part.
The reinforcing portion includes a first resin layer, a second resin layer, a first mounting surface, a second mounting surface, and a metal plate-like or frame-like reinforcing member. The first resin layer selectively covers the first main surface of the first end. The second resin layer selectively covers the second main surface of the first end portion. The first mounting surface includes a first wiring layer provided on the first resin layer and electrically connected to the flexible wiring substrate. The second mounting surface includes a second wiring layer provided on the second resin layer and electrically connected to the flexible wiring substrate. The reinforcing member is embedded in the first end.
The first end is disposed closer to the first mounting surface than the second mounting surface.

  In the above circuit board, the reinforcing portion has a plate-like or frame-like reinforcing member embedded in the first end portion, so that the strength and heat dissipation of the reinforcing portion can be improved while satisfying the thickness requirement. Can be planned. In addition, since the first end portion of the flexible wiring substrate is arranged closer to the first mounting surface than the second mounting surface, the interlayer of the second wiring layer that communicates with the first end portion It becomes possible to make the length and diameter of the connecting portion relatively small, and this makes it possible to increase the density of the wiring pattern.

The first end portion may have a bottomed or bottomless concave portion, and the reinforcing member may be disposed in the concave portion.
Thereby, a reinforcement member can be easily embed | buried under the 1st edge part of a flexible wiring base material.

The reinforcing member may be electrically connected to the circuit unit.
In this case, the reinforcing member can be used as a part of the wiring.

The reinforcing part may further include a third resin layer. The third resin layer is provided between the second main surface and the second resin layer and is made of a resin material having a smaller coefficient of thermal expansion than the second resin layer.
Thereby, the curvature of a reinforcement part can be suppressed and the flatness of a rigid part can be improved.

The circuit board may further include an image sensor. The imaging element is mounted on the first mounting surface and is electrically connected to the circuit unit.
Since the first end portion is arranged so as to be biased toward the first mounting surface, it is possible to realize a high-density wiring pattern that can correspond to the terminal arrangement pitch of the image sensor.

  The reinforcing member may be disposed closer to the first mounting surface than the second mounting surface. Thereby, the thermal radiation efficiency of the electronic component mounted in the 1st mounting surface can be improved.

  As described above, according to the present invention, it is possible to increase the density of the wiring pattern while improving the strength and heat dissipation of the rigid portion.

1 is a schematic plan view showing a configuration of a circuit board according to a first embodiment of the present invention. It is the sectional view on the AA line direction in FIG. It is a schematic sectional drawing which shows the structural example of the electronic device which incorporated the said circuit board. It is a schematic sectional side view which shows the structure of the circuit board which concerns on the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic plan view showing the configuration of a circuit board according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG.
In each figure, the X axis, the Y axis, and the Z axis indicate three axial directions orthogonal to each other, and the Z axis direction corresponds to the thickness direction of the circuit board.

[Circuit board]
The circuit board 100 according to the present embodiment includes a first substrate body 10 and a second substrate body 20. The circuit board 100 is typically configured integrally with the control board 30, but may be configured as a separate component from the control board 30.

(First board body)
The first board body 10 is composed of a flexible wiring base 11 that connects the second board body 20 and the control board 30, and constitutes a flexible portion in the circuit board 100. The flexible wiring substrate 11 typically has a longitudinal direction in the X-axis direction and a width direction in the Y-axis direction, and a central portion in the longitudinal direction corresponding to the first substrate body 10 is formed narrow. Is done. A reinforcing portion 12 is provided at one end portion (first end portion 11a) in the longitudinal direction of the flexible wiring substrate 11, and a control board 30 is provided at the other end portion (second end portion 11b).

  As shown in FIG. 2, the flexible wiring substrate 11 includes a resin core 110, wiring layers 111 and 112 provided on both surfaces thereof, and insulating layers 113 and 114 covering the wiring layers 111 and 112. Consists of a laminate.

  The resin core 110 is composed of a single-layer or multilayer flexible plastic film such as polyimide or polyethylene terephthalate. The wiring layers 111 and 112 are typically made of a metal material such as copper or aluminum. A part of the wiring layers 111 and 112 are electrically connected to each other through through holes or vias provided at appropriate positions of the resin core 110. The wiring layer of the flexible wiring substrate 11 is not limited to the illustrated two layers, and may be one layer or three or more layers. The insulating layers 113 and 114 are made of a flexible plastic film such as polyimide having an adhesive layer.

  The insulating layers 113 and 114 form two main surfaces orthogonal to the thickness direction of the flexible wiring substrate 11. In FIG. 2, the insulating layer 113 forms the first main surface S <b> 11 (the lower surface in FIG. 2) of the flexible wiring substrate 11, and the insulating layer 114 forms the second main surface S <b> 12 of the flexible wiring substrate 11. (The upper surface in FIG. 2) is formed.

(Second board body)
The second substrate body 20 includes first and second resin layers 211 and 212 that selectively cover the first end 11 a of the flexible wiring substrate 11, and first and second resin layers 211. , 212 includes a reinforcing portion 12 having a circuit portion 22 (first wiring layer 221 and second wiring layer 222) and a metal reinforcing member 23 embedded in the first end portion 11a. . The second substrate body 20 (or the reinforcing portion 12) constitutes a rigid portion in the circuit board 100.

  The second substrate body 20 is configured by a laminated body of the first end portion 11 a of the flexible wiring substrate 11 and the reinforcing portion 12. That is, the first end portion 11 a of the flexible wiring substrate 11 constitutes a core material (core) of the second substrate body 20 together with the reinforcing member 23.

  The first resin layer 211 selectively covers the first main surface S11 of the first end portion 11a of the flexible wiring substrate 11. The second resin layer 212 selectively covers the second main surface S12 of the first end portion 11a of the flexible wiring substrate 11. The first and second resin layers 211 and 212 constitute the outer shape of the second substrate body 20, and the planar shape thereof is typically a rectangular shape that is long in the X-axis direction as shown in FIG. Although formed, it may be formed in a rectangular shape that is long in the Y-axis direction.

  The size of the first and second resin layers 211 and 212 is not particularly limited. For example, the long side is 10 to 30 mm, the short side is 10 to 20 mm, and the thickness is 0.2 to 0.5 mm. Typically, the thicknesses of the first and second resin layers 211 and 212 are the same, but are not limited thereto. As shown in FIG. 1, the first end portion 11 a of the flexible wiring substrate 11 is formed in the same shape and size as the second substrate body 20. It may be formed larger or smaller than the substrate body 20.

  The synthetic resin material constituting the first and second resin layers 211 and 212 is not particularly limited, and typically, a general-purpose thermosetting resin material such as an epoxy resin, a phenol resin, or a BT resin is used. These synthetic resin materials may contain fillers (fillers) such as glass fibers, glass cloth, and oxide particles in order to impart desired mechanical strength. The first and second resin layers 211 and 212 may be made of the same resin material, or may be made of different resin materials. Hereinafter, the first and second resin layers 211 and 212 may be collectively referred to as the resin layer 21 except for a case where they are individually described.

  The circuit unit 22 includes a first wiring layer 221, a second wiring layer 222, and an interlayer connection unit 223 that connects the wiring layers 221 and 222. The first and second wiring layers 221 and 222 are electrically connected to the flexible wiring substrate 11 (wiring layers 111 and 112) constituting the first substrate body 10 via, for example, vias V1 and V2. Connected. The vias V1 and V2 are formed by filling a hole passing through the first and second resin layers 211 and 212 with a conductive paste or metal plating. The hole is formed by laser processing, etching processing, or the like.

  The first and second wiring layers 221 and 222 are formed on the surfaces of the first and second resin layers 211 and 212, respectively, and some of them are appropriately formed on the first and second resin layers 211 and 212. It is electrically connected to the reinforcing member 23 through a via formed at the position. The reinforcing member 23 may be configured as a part of the wiring layer, and is used as a part of the ground wiring, for example. Further, the reinforcing member 23 may be used as a heat radiating component of an electronic component mounted on the second substrate body 20.

  The first and second wiring layers 221 and 222 are typically made of a metal material such as copper or aluminum or a cured product of a metal paste. The first and second wiring layers 221 and 222 mainly connect the connection lands of electronic components mounted on the surface of the second substrate body 20 and electrically connect the electronic components to the flexible wiring substrate 11. A rewiring layer or the like is configured. On the surfaces of the first and second wiring layers 221 and 222, an insulating protective layer 25 such as a solder resist having an opening (not shown) exposing a part of the surface of the circuit unit 22 at an appropriate position, respectively. Provided.

  The surface of the insulating protective layer 25 that covers the first wiring layer 221 forms the first mounting surface S21 (the lower surface in FIG. 2) of the reinforcing portion 12, and the insulating protective layer that covers the second wiring layer 222. The surface 25 forms a second mounting surface S22 (upper surface in FIG. 2) of the reinforcing portion 12. The first and second mounting surfaces S21 and S22 are typically configured as mounting surfaces for electronic components.

  The first and second wiring layers 221 and 222 are not limited to a single layer structure, and may be a multilayer structure, and are not limited to the case where both the first and second wiring layers 221 and 222 are provided. Only one of them (for example, the first wiring layer 211) may be provided.

  The reinforcing member 23 is for imparting desired strength to the second substrate body 20. In the present embodiment, the reinforcing member 23 is configured by a plate material disposed inside the first end portion 11 a of the flexible wiring substrate 11. The reinforcing member 23 is composed of a good conductor of electricity and heat, and is typically composed of copper (Cu), but may be composed of other metal materials such as aluminum.

  The planar shape of the reinforcing member 23 is not particularly limited. For example, the reinforcing member 23 is formed in a rectangular plate shape having a size that can be accommodated in the first end portion 11a of the flexible wiring substrate 11. The shape of the reinforcing member 23 is not limited to a plate shape, and may be another shape such as a frame shape or a lattice shape. The magnitude | size of the reinforcement member 23 is not specifically limited, For example, the length of each side is 5-20 mm, and thickness is 0.1-1 mm. The thickness of the reinforcing member 23 is not particularly limited, and in this embodiment, the reinforcing member 23 is formed with a thickness equal to or less than that of the flexible wiring substrate 11.

  As shown in FIG. 1, the reinforcing member 23 is formed in a size that can cover substantially the entire region of the first end portion 11 a of the flexible wiring substrate 11. Thereby, the reinforcing member 23 can effectively fulfill the function as the core material of the second substrate body 20. Further, since the entire reinforcing member 23 is accommodated in the first end portion 11a, the reinforcing member 23 is prevented from being exposed from the peripheral edge portion of the first end portion 11a, and the second substrate body 20 The insulating property of the peripheral edge can be ensured. Since both surfaces of the reinforcing member 23 are covered with the first and second resin layers 211 and 212, the reinforcing member 23 is prevented from being exposed from both surfaces of the second substrate body 20.

  The reinforcing member 23 is built in the accommodating portion 213 formed in the plane of the first end portion 11a of the flexible wiring substrate 11. The accommodating portion 213 is a bottomed or bottomless recess having a size capable of accommodating the reinforcing member 23, and in the present embodiment, is constituted by a rectangular opening penetrating the first end portion 11a. Thereby, the reinforcing member 23 can be easily embedded in the first end portion 11 a of the flexible wiring substrate 11.

  In the present embodiment, the reinforcing member 23 includes the first insulating material 241 filled in the groove portion 231 formed so as to penetrate the surface thereof, and the outer peripheral surface of the reinforcing member 23 and the inner portion of the accommodating portion 213. It is being fixed inside the 1st end part 11a via the 2nd insulating material 242 with which it filled between peripheral surfaces. The lower surface of the reinforcing member 23 is adjacent to the first resin layer 211, and the upper surface of the reinforcing member 23 is connected to the second resin layer 212 via the third resin layer 233 made of the first insulating material 241. Opposite.

  The flexible wiring substrate 11 and the reinforcing member 23 are arranged closer to the first mounting surface S21 than the second mounting surface S22 of the reinforcing portion 12. In the present embodiment, the reinforcing member 23 has a thickness equivalent to that of the flexible wiring substrate 11. Therefore, the center C2 in the thickness direction of the reinforcing member 23 and the center C3 in the thickness direction of the flexible wiring base material 11 coincide with each other, and the center C2 in the thickness direction of the reinforcing member 23 and the flexible wiring base material 11 respectively. , C3 are located closer to the first mounting surface S21 than the center C1 of the reinforcing portion 12 in the thickness direction. As a result, as shown in FIG. 2, the distance H1 between the first main surface S11 of the flexible wiring substrate 11 and the first mounting surface S21 of the reinforcing portion 12 is the same as that of the flexible wiring substrate. It is set to be smaller than H2 between the second main surface S12 and the second mounting surface S22 of the reinforcing portion 12.

  The reinforcing member 23 has one or a plurality of through-hole portions 232 for forming the interlayer connection portion 223. The through-hole portion 232 is formed at an appropriate position within the surface of the reinforcing member 23, and is provided, for example, between the peripheral portion of the reinforcing member 23 and the formation region of the groove portion 231. The through hole portion 232 is formed as a round hole having a size that can accommodate the interlayer connection portion 223. The interlayer connection portion 223 is typically configured by copper plating formed on an inner peripheral surface of the through hole portion 232 with an insulating layer interposed therebetween. The insulating layer is made of, for example, a first insulating material 241.

  The reinforcing portion 12 further includes a third resin layer 233 provided between the upper surface S12 of the first end portion 11a of the flexible wiring substrate 11 and the second resin layer 212. The third resin layer 233 is composed of the first insulating material 241. The first insulating material 241 is made of a resin material having a smaller coefficient of thermal expansion than the resin material that forms the resin layer 21. In the present embodiment, the first insulating material 241 is further made of a resin material having a higher elastic modulus than the resin material constituting the resin layer 21.

  By configuring the first insulating material 241 with a resin material having a smaller thermal expansion coefficient than that of the resin layer 21, it is possible to ensure adhesion between the first end portion 11a and the first resin layer 212, It is possible to suppress warpage of the second substrate body 20. In addition, since the first insulating material 241 is made of a resin material having a higher elastic modulus than the resin layer 21, the rigidity of the first insulating material 241 is increased, and the strength of the second substrate body 20 is improved. Can be planned.

  The material which comprises the 1st insulating material 241 is not specifically limited, For example, the same kind of material as the resin material which comprises the resin layer 21 may be sufficient. In this case, by increasing the filler content rather than the resin layer 21, it is possible to configure the first insulating material 241 having a smaller coefficient of thermal expansion than the resin layer 21 and a higher elastic modulus.

  On the other hand, the second insulating material 242 is made of a material having a lower elastic modulus than the resin material constituting the resin layer 21. Thereby, since the bending stress applied to the peripheral portion of the second substrate body 20 is relaxed by the second insulating material 242, it is possible to suppress the peeling of the reinforcing member 23 from the housing portion 213. The second insulating material 242 may be made of a material having a lower water absorption rate than the resin layer 21. Thereby, volume expansion or swelling due to water absorption of the second insulating material 242 is suppressed.

  Although the material which comprises the 2nd insulating material 242 is not specifically limited, A material with high affinity with the flexible wiring base material 11 is preferable, for example, an epoxy, a polyimide, a liquid crystal polymer, BT resin, PPS etc. are mentioned. .

  As described above, the second insulating material 242 is filled between the outer peripheral surface of the reinforcing member 23 and the inner peripheral surface of the housing portion 213. The second insulating material 242 need not be provided over the entire circumference of the outer peripheral surface of the reinforcing member 23, and may be provided at least at one end of the flexible wiring substrate 11 on the second end 11 b side. . Thereby, for example, the tensile stress from the first substrate body 10 can be absorbed or alleviated by the second insulating material 242 and the second substrate body 20 is broken or the reinforcing portion 12 is detached from the first end portion 11a. Can be suppressed.

  Further, the present invention is not limited to the case where the entire region of the one end portion between the reinforcing member 23 and the accommodating portion 213 is filled with the second insulating material 242, and as shown in FIG. A laminated portion 243 with two insulating materials 242 may be provided. In this case, the region can be provided with appropriate rigidity and appropriate elasticity, so that the connection reliability between the flexible wiring substrate 11 and the reinforcing portion 12 can be increased.

  Note that the second insulating material 242 may be omitted depending on required characteristics, specifications, and the like, and the first insulating material 241 is replaced with the reinforcing member 23, the housing portion 213, and the second insulating material 242. It may be filled in between. In addition, the stacked portion 243 may be omitted as necessary, and the entire region of the one end portion may be filled with the first insulating material 241 or the second insulating material 242.

(Control board)
The control board 30 corresponds to a main board on which an integrated circuit such as an IC and its peripheral components are mounted, and is electrically connected to the second board body 20 via the first board body 10. The control board 30 is typically composed of a double-sided board having an area equivalent to or larger than that of the second board body 20.

  The control board 30 is configured by a laminate of the second end portion 11b of the flexible wiring substrate 11 and the multilayer wiring portions 31 and 32 provided on both surfaces thereof. The multilayer wiring portions 31 and 32 are typically manufactured by a build-up method. The interlayer insulating film constituting the multilayer wiring portions 31 and 32 may be made of a glass epoxy type rigid material. In this case, the control board 30 is constituted as a rigid board.

  In the circuit board 100 of the present embodiment configured as described above, the second board body 20 has a plate-like reinforcing member 23 embedded in the first end portion 11a of the flexible wiring substrate 11. Therefore, the strength can be improved by the thickness of the first end portion 11a. Therefore, according to the present embodiment, it is possible to improve the strength of the second substrate body 20 while satisfying the thickness requirement of the second substrate body 20.

  Furthermore, according to the circuit board 100 of the present embodiment, since the reinforcing member 23 made of metal is embedded in the reinforcing portion 12, it is possible to improve the heat dissipation of the electronic components mounted on the second substrate body 20. it can. Moreover, since the reinforcing member 23 is disposed close to the first mounting surface S21 of the second substrate body 20, the heat dissipation efficiency of the electronic components mounted on the first mounting surface lower surface S21 can be increased.

  FIG. 3 is a schematic cross-sectional view illustrating a configuration example of the electronic device 1 in which the circuit board 100 is built.

  The electronic device 1 is composed of a mobile information terminal with a camera such as a smartphone, a mobile phone, and a notebook personal computer. The circuit board 100 is disposed inside the housing 40 of the electronic device 1. A controller (not shown) of the electronic device 1 is connected to the control board 30 of the circuit board 100, and an image sensor 41 such as a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD) is connected to the second board body 20. Installed. A lens barrel 42 is disposed on the light receiving surface of the image sensor 41, and an opening 401 for exposing the lens barrel 42 to the outside is provided in the housing 40. The imaging device 41 is mounted on the first mounting surface S21 side of the reinforcing portion 12 (second substrate body 20) of the circuit board 100 by a face-up method, and the first imaging layer 221 and a plurality of bonding wires W are interposed therebetween. Are electrically connected.

  In the present embodiment, the reinforcing member 23 is disposed closer to the first mounting surface S21 than to the second mounting surface S22. For this reason, the distance D1 between the first mounting surface S21 that is the mounting surface of the imaging element 41 and the reinforcing member 23 is smaller than the distance D2 between the second mounting surface S22 and the reinforcing member 23. Therefore, compared to the case where the image pickup device 41 is mounted on the second mounting surface S22, the heat dissipation of the image pickup device 41 is enhanced, so that deterioration of device characteristics due to heat can be suppressed even under long-time camera operation. The image quality of the period can be secured stably.

  The size of the distance D1 between the imaging element 41 and the reinforcing member 23 is not particularly limited as long as it is larger than the distance D2, and is, for example, 15 to 100 μm. The first resin layer 211 and the insulating protective layer 25 are not limited. It can be set as appropriate according to the thickness and the like. An insulating intermediate layer having excellent heat conductivity may be provided between the reinforcing member 23 and the first resin layer 211. Thereby, it is possible to secure desired electrical insulation and heat dissipation while reducing the thickness of the first resin layer 211.

  In addition, since the reinforcing member 23 is disposed close to the mounting surface of the image sensor 41, the flatness (flatness) of the mounting surface is easily ensured. Thereby, since the image pick-up element 41 can be mounted in the reinforcement part 12 with the stable attitude | position, the dispersion | variation in the optical axis of the image pick-up element 41 can be suppressed.

  Furthermore, since the flexible wiring substrate 11 is arranged closer to the first mounting surface S21 than the second mounting surface S22, as shown in FIG. 1, the first mounting surface S21 side first side is arranged. The via V1 that electrically connects the wiring layer 221 and the wiring layer 111 on the first main surface S1 side of the flexible wiring substrate 11 is formed on the second wiring layer on the second mounting surface S22 side. It can be formed shallower than the via V2 that electrically connects 222 and the wiring layer 112 on the second main surface S1 side of the flexible wiring substrate 11. For this reason, the diameter of the via V1 is smaller than the diameter of the via V2, and the via V1 can be formed at a higher density than the via V2. Thereby, when the first mounting surface S21 is configured as the mounting surface of the image sensor 41 as shown in FIG. 3, it is possible to sufficiently cope with the electrode pitch of the image sensor 41.

  For example, when the aspect ratio (via diameter / depth) of the vias V1 and V2 is 0.5 to 1, when the depth of the via V1 is 50 μm, the via diameter is 50 to 100 μm, and the pad Part clearance and space are added. On the other hand, when the depth of the via V2 is 100 μm, the via diameter is 100 to 200 μm. Therefore, the via V1 can be formed with a wiring density approximately twice that of the via V2.

  In order to arrange the flexible wiring substrate 11 close to the first mounting surface S <b> 21, in the present embodiment, between the second main surface S <b> 12 of the first end portion 11 a and the second resin layer 212. However, the present invention is not limited to this, and the second resin layer 212 is formed thicker than the first resin layer 211, whereby the flexible wiring substrate 11 is mounted on the first mounting layer. You may make it approach the surface S21.

<Second Embodiment>
FIG. 4 is a schematic sectional side view showing the configuration of the circuit board according to the second embodiment of the present invention. Hereinafter, the configuration different from the first embodiment will be mainly described, and the same configuration as the first embodiment will be denoted by the same reference numeral, and the description thereof will be omitted or simplified.

  The circuit board 200 of the present embodiment is common to the first embodiment in that it includes a first board body 10 and a second board body 20, but a reinforcing member 270 is cored on the second board body 20. The second embodiment is different from the first embodiment in that a multilayer substrate 27 is embedded.

  The reinforcing member 270 is composed of a rectangular plate material having a through hole 270a for forming the interlayer connection portion 223 and a cavity 270b, and is housed in the housing portion 213 of the first end portion 11a, as in the first embodiment. . Although the cavity 270 b is filled with the first insulating material 241, electronic components may be accommodated in the cavity 270. The type of electronic component is not particularly limited, and typically chip-type components such as capacitors, inductors, and resistors are used. Of course, other semiconductor chips such as ICs and various sensor components can be used. .

  Both surfaces of the reinforcing member 270 are covered with a first insulating material 241, and are electrically connected to the circuit portion 22 (first and second wiring layers 221 and 222) on the first insulating material 241. A third wiring layer 224 is provided. The third wiring layer 224 is made of a metal film such as copper patterned in a predetermined shape, and constitutes an interlayer connection portion that connects each surface through the through hole of the reinforcing member 270.

  Also in the circuit board 200 of the present embodiment, the reinforcing member 270 and the first end portion 11a of the flexible wiring substrate 11 are closer to the first mounting surface S21 than the second mounting surface S22 of the reinforcing portion 12. Arranged.

  According to the circuit board 200 of the present embodiment configured as described above, the same operational effects as those of the first embodiment described above can be obtained. In particular, according to the present embodiment, since the multilayer substrate 27 is embedded in the second substrate body 20, it is possible to achieve high functionality and high density mounting of the second substrate body 20.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, a various change can be added.

  For example, in the above embodiment, the planar shapes of the second substrate body 20 and the reinforcing member 23 are both formed in a rectangular shape, but the present invention is not limited to this, and may be a polygon other than a rectangle, a circle, or other geometric shapes. It may be formed.

  The reinforcing member 23 constituting the reinforcing portion 12 is not limited to a metal plate-like member, and may be constituted by a metal frame-like member. In this case, an element-embedded substrate in which electronic components are accommodated in the hollow portion (cavity) of the reinforcing member can be configured as the circuit substrate.

  Further, in the above embodiment, both the first end portion 11a of the flexible wiring substrate 11 and the reinforcing member 23 are disposed close to the lower surface S21 (first mounting surface) of the reinforcing portion 12. Without being limited thereto, only the first end portion 11a of the flexible wiring substrate 11 may be disposed close to the lower surface S21 (first mounting surface) of the reinforcing portion 12.

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate main body 11 ... Flexible wiring base material 12 ... Reinforcement part 20 ... 2nd board | substrate body 22 ... Circuit part 23 ... Reinforcement member 41 ... Imaging element 30 ... Control board 100,200 ... Circuit board 211 ... 1st resin layer 212 ... 2nd resin layer 213 ... accommodating part 233 ... 3rd resin layer S11 ... 1st main surface S12 ... 2nd main surface S21 ... 1st mounting surface S22 ... 2nd mounting surface

Claims (6)

A flexible wiring board having a first end portion having a first main surface and a second main surface orthogonal to the thickness direction, and a second end portion opposite to the first end portion Material,
A first resin layer that selectively covers the first main surface of the first end, and a second resin layer that selectively covers the second main surface of the first end. A first mounting surface having a first wiring layer provided on the first resin layer and electrically connected to the flexible wiring substrate; A second mounting surface having a second wiring layer electrically connected to the flexible wiring substrate; and a metal plate-like or frame-like reinforcing member embedded in the first end portion. A reinforcing part having
The first end portion is disposed closer to the first mounting surface than the second mounting surface. The circuit board according to claim 1,
The first end has a bottomed or bottomless recess,
The reinforcing member is disposed in the recess. The circuit board according to claim 1 or 2,
The reinforcing member is a circuit board that is electrically connected to the circuit portion. The circuit board according to any one of claims 1 to 3,
The reinforcing portion further includes a third resin layer provided between the second main surface and the second resin layer and made of a resin material having a smaller coefficient of thermal expansion than the second resin layer. Have a circuit board. The circuit board according to any one of claims 1 to 4,
A circuit board further comprising an imaging device mounted on the first mounting surface and electrically connected to the circuit unit. A circuit board according to any one of claims 1 to 5,
The reinforcing member is disposed closer to the first mounting surface than the second mounting surface.

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