Imaging unit and endoscope

Abstract

The invention provides an imaging unit and an endoscope. The imaging unit includes: a semiconductor package; a planar wiring board on which a plurality of first pads and a plurality of second pads are arranged; and a three-dimensional wiring board, the second surface of which has a first region and a second region that are symmetrical with a cutout therebetween, the first region being provided with a plurality of first lands, the second region being provided with a plurality of second lands, the plurality of first lands being soldered to the plurality of first pads, the plurality of second lands being soldered to the plurality of second pads, and the plurality of second lands being soldered to the plurality of second pads. The plurality of second pads are bonded to the plurality of second pads by welding, and a first area, which is the sum of the areas of the plurality of first pads, is substantially the same as a second area, which is the sum of the areas of the plurality of second pads.

Description

Technical Field

[0001] The present invention relates to an imaging unit obtained by welding and bonding a planar wiring board and a three-dimensional wiring board, and an endoscope having the imaging unit obtained by welding and bonding a planar wiring board and a three-dimensional wiring board. Background Art

[0002] In recent years, three-dimensional circuit devices such as molded interconnect devices (MID) have been used to achieve miniaturization and high functionality of electronic devices.

[0003] Japanese Patent Application Publication No. 2017-23234 discloses an endoscope imaging unit using a special-shaped circuit substrate as a three-dimensional circuit device. The imaging unit includes an imager, a flat wiring board, and a special-shaped circuit substrate (three-dimensional wiring board) on which electronic components such as capacitors and IC chips are mounted.

[0004] It is not easy to accurately join a planar wiring board and a three-dimensional wiring board using solder. In particular, in an ultra-small image pickup unit, there is a possibility that the wiring board may move due to the interfacial tension of the molten solder. Summary of the invention

[0005] The camera unit of an embodiment of the present invention comprises: a semiconductor package including an imager; a planar wiring board having a front surface and a first surface on the opposite side of the front surface, the front surface of the planar wiring board being joined to the semiconductor package, the planar wiring board being provided with a plurality of first solder pads and a plurality of second solder pads on the first surface; and a three-dimensional wiring board having a second surface joined to the first surface, the second surface of the three-dimensional wiring board having a first area and a second area of ​​a shape symmetrical with a cut therebetween, the three-dimensional wiring board being provided with a plurality of first connection pads in the first area, the three-dimensional wiring board being provided with a plurality of second connection pads in the second area, the plurality of first connection pads being respectively welded and joined to the plurality of first solder pads, the plurality of second connection pads being respectively welded and joined to the plurality of second solder pads, the sum of the areas of the plurality of first solder pads, i.e. the first area, is substantially the same as the sum of the areas of the plurality of second solder pads, i.e. the second area.

[0006] An endoscope according to another embodiment of the present invention has a camera unit at the front end of the insertion portion, the camera unit comprising: a semiconductor package including an imager; a planar wiring board having a front surface and a first surface on the opposite side of the front surface, the front surface of the planar wiring board being joined to the semiconductor package, the planar wiring board being provided with a plurality of first solder pads and a plurality of second solder pads on the first surface; and a three-dimensional wiring board having a second surface joined to the first surface, the second surface of the three-dimensional wiring board having a first area and a second area of ​​a shape symmetrical with a cut therebetween, the three-dimensional wiring board being provided with a plurality of first connection pads in the first area, the three-dimensional wiring board being provided with a plurality of second connection pads in the second area, the plurality of first connection pads being respectively welded and joined to the plurality of first solder pads, the plurality of second connection pads being respectively welded and joined to the plurality of second solder pads, the sum of the areas of the plurality of first solder pads, i.e. the first area, is approximately the same as the sum of the areas of the plurality of second solder pads, i.e. the second area. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a perspective view of the imaging unit according to the first embodiment.

[0008] Figure 2 It is a side view of the imaging unit according to the first embodiment.

[0009] Figure 3 It is an exploded view of the imaging unit according to the first embodiment.

[0010] Figure 4 It is a top view of the planar wiring board of the image pickup unit according to the first embodiment.

[0011] Figure 5 It is a plan view of the three-dimensional wiring board of the image pickup unit according to the first embodiment.

[0012] Figure 6 It is a partial cross-sectional view of the image pickup unit according to the first embodiment.

[0013] Fig. 7A It is a top view of the planar wiring board of the image pickup unit according to the first embodiment.

[0014] Figure 7B It is a plan view of the three-dimensional wiring board of the image pickup unit according to the first embodiment.

[0015] Figure 8 It is a perspective view of an endoscope according to a second embodiment. DETAILED DESCRIPTION

[0016] <First Embodiment>

[0017] Hereinafter, the imaging unit 1 according to the first embodiment of the present invention will be described using the accompanying drawings. In addition, the accompanying drawings based on the embodiments are schematic. The relationship between the thickness and width of each part of the accompanying drawings, the ratio of the thickness of each part, etc. are different from the actual. The drawings also include parts with different size relationships and ratios. The illustration of some components and the marking of the reference numerals are omitted.

[0018] like Figure 1-Figure 5 As shown, the image pickup unit 1 includes a semiconductor package 40 , a planar wiring board 10 , a three-dimensional wiring board 20 , an electronic component 30 , and a cable 50 .

[0019] Sometimes, a three-axis orthogonal coordinate system is used for the description, in which the direction of the optical axis O of the imaging unit 1 is the X-axis. Figure 1 , left direction) is called "front" or "front end side". The direction in which the X-axis value decreases ( Figure 1 , right direction) is called "back" or "base end side". The direction in which the Y-axis value increases is called "up", and the direction in which the Y-axis value decreases is called "down". The direction approaching the optical axis O is called "inside", and the direction away from the optical axis O is called "outside".

[0020] The semiconductor package 40 has an imager 41 and a glass cover 42 bonded to the light receiving surface of the imager 41. The imager 41 is a CCD, CMOS, etc. that converts the subject image into a camera signal. The semiconductor package 40 is a CSP (Chip Size Package) produced by bonding a glass wafer to a semiconductor wafer having a plurality of imagers 41 and then cutting the wafer. The size of the semiconductor package 40 is, for example, 1 mm square to 3 mm square. The semiconductor package 40 may also be bonded to a semiconductor chip that processes the camera signal on the back of the imager 41.

[0021] The planar wiring board 10 has a front surface 10SA and a first surface 10SB on the opposite side of the front surface 10SA. The planar wiring board 10 is, for example, a multilayer wiring board in which wiring is formed in a plurality of wiring layers. A plurality of front surface pads (not shown) of the front surface 10SA are respectively bonded to a plurality of external terminals (not shown) of the rear surface 40SB of the semiconductor package 40 (imager 41) using solder 61.

[0022] A plurality of first pads 11 (11A to 11C) and a plurality of second pads 12 (12A to 12D) are disposed on the first surface 10SB. A plurality of third pads 13 (13A to 13F) are disposed between the plurality of first pads 11 and the plurality of second pads 12.

[0023] In addition, in this specification, "pad" and "connection land" are both "electrodes" composed of a conductive pattern for soldering and joining. That is, "pad", "connection land" and "electrode" are structures with the same function, but different names are used for the convenience of explanation. In addition, the shape of the electrode can also be a quadrilateral with chamfered corners, a polygon, a circle, an ellipse, etc.

[0024] The electronic component 30 (30A-30C) is bonded to the third pad 13 using solder 63. Since the electronic component 30 is housed in the cutout C20 of the three-dimensional wiring board 20, the length (dimension in the optical axis direction) of the camera unit 1 is short. In addition, in the camera unit 1 in which the electronic component 30 is mounted on the planar wiring board 10 bonded to the imager 41, the distance between the imager 41 and the electronic component 30 is short. Since the wiring impedance between the imager 41 and the electronic component 30 is small, the camera unit 1 can obtain a high-quality image.

[0025] In the image pickup unit 1, the electronic components 30 are three chip capacitors. The electronic components 30 may be inductors, coils, driver ICs, etc. The number of the electronic components 30 is not limited to three.

[0026] The three-dimensional wiring board 20 is a molded circuit device (MID: Molded Interconnect Device) manufactured by injection molding and having wiring etc. on the surface. The base material of the MID is epoxy resin, liquid crystal polymer, polyimide, polycarbonate, etc. The three-dimensional wiring board 20 as the MID can be easily manufactured in a complex shape.

[0027] The three-dimensional wiring board 20 has a second surface 20SA disposed opposite to the first surface 10SB of the planar wiring board 10. The second surface 20SA has a cutout C20 that reaches both side surfaces. In other words, the three-dimensional wiring board 20 has two arm portions 29 (29A, 29B) protruding forward. As described later, in the ultra-small camera unit 1, the thickness T3 of the arm portion 29 is, for example, only 0.3 mm.

[0028] There is a cutout C20 between the two arms 29A and 29B. Figure 3 As shown, the wall surface C20SS (C20SSA, C20SSB) of the cutout C20 is orthogonal to the first surface 10SB.

[0029] The second surface 20SA is divided into a first region 20SA1 and a second region 20SA2 that are line-symmetrical about the center line of the cutout C20. Figure 5 , Figure 6As shown, there is a chamfered area C20C (C20CA) between the first area 20SA1 of a substantially rectangular shape and the first wall surface C20SSA of the cutout C20. There is a chamfered area C20CC between the first area 20SA1 and the upper side surface of the three-dimensional wiring board 20. In the second area 20SA2 of a shape symmetrical to the first area 20SA1, there is also a second chamfered area C20CB between it and the second wall surface C20SSB. There is a chamfered area C20CD between the second area 20SA2 and the lower side surface of the three-dimensional wiring board 20. The chamfered area C20C may be a curved surface or a flat surface.

[0030] A plurality of first lands 21 ( 21A to 21C) are disposed in the first region 20SA1 . A plurality of second lands 22 ( 22A to 22D) are disposed in the second region 20SA2 . The first lands 21 are smaller than the first pads 11 , and the second lands 22 are smaller than the second pads 12 .

[0031] The first land 21 is bonded to the first pad 11 using the first solder 62A. The second land 22 is bonded to the second pad 12 using the second solder 62B. As described later, the first solder 62A and the second solder 62B are, for example, solders 62 of the same thickness formed by solidifying solder pastes of the same composition.

[0032] The first connection pad 21 of the three-dimensional wiring board 20 is extended to the base end side to form the wiring 21W. The cable 50 is joined to the end of the wiring 21W at the base end 28 of the three-dimensional wiring board 20 using solder 64. The second connection pad 22 is connected to the wiring 22W, and the cable 50 is joined to the end of the wiring 22W using solder 64. A plurality of cables 50 are bundled at the base end side to form a composite cable covered by an outer sheath shield and an outer sheath. In addition, the base end 28 may be inclined relative to the second surface 20SA in a direction in which the wirings 21W and 22W approach each other.

[0033] When manufacturing the imaging unit 1 , for example, the electronic component 30 is bonded to the planar wiring board 10 , the semiconductor package 40 is bonded to the planar wiring board 10 , the planar wiring board 10 is bonded to the three-dimensional wiring board 20 , and the cable 50 is bonded to the three-dimensional wiring board 20 .

[0034] like Figure 1 As shown, the planar wiring board 10 and the three-dimensional wiring board 20 are accommodated in a virtual space 40S obtained by extending the imager 41 in the optical axis direction. Therefore, the dimension of the imaging unit 1 perpendicular to the optical axis O is small.

[0035] In addition, the peripheries of each of the plurality of welded joints are sealed with a sealing resin (not shown).

[0036] It is not easy to accurately join the planar wiring board 10 and the three-dimensional wiring board 20 using the solder 62. In particular, in the ultra-small camera unit 1, movement caused by the interfacial tension of the molten solder 62 may occur. If the relative position of the planar wiring board 10 and the three-dimensional wiring board 20 deviates from the specified position, when stress is applied from the outside, the stress is concentrated on the joint, so the joint reliability is reduced. The molten solder 62 may short-circuit with the solder 63 that joins the mounted electronic component 30. When the second surface 20SA is not parallel to the first surface 10SB but is curved, the external dimensions of the camera unit 1 increase.

[0037] <Size and Configuration>

[0038] In order to not only prevent the movement caused by the interfacial tension of the molten solder 62 but also accurately join the planar wiring board 10 and the three-dimensional wiring board 20 using the solder 62 by the self-alignment effect, the size and arrangement of each of the plurality of electrodes (pads and connection lands) are important.

[0039] In the camera unit 1, the size of the first pad 11 is, for example, 0.16 mm × 0.25 mm. The size of the second pad 12 is, for example, 0.11 mm × 0.25 mm. The number N1 of the first pads 11 is "3", and the number N2 of the second pads 12 is "4". That is, the number N1 of the first pads is different from the number N2 of the second pads. However, the sum of the areas of the first pads 11 (the first area S11 = 0.12 mm 2 ) and the sum of the areas of the plurality of second pads 12 (second area S12 = 0.11 mm 2 ) are roughly the same.

[0040] The plurality of first pads 11 and the plurality of second pads 12 of the planar wiring board 10 of the camera unit 1 are arranged in symmetrical regions across the cutout C20. The interfacial tension of the molten solder 62 is approximately proportional to the bonding area. The interfacial tension of the molten first solder 62A is approximately the same as the interfacial tension of the molten second solder 62B.

[0041] It should be noted that, in the present specification, “the A value is substantially the same as the B value” means that the A value exceeds 85% of the B value and is less than 115% (including 100%) of the B value.

[0042] As long as the first area S11 and the second area S12 are substantially the same, at least one of the plurality of first pads 11 and the plurality of second pads 12 may include a plurality of pads having different areas.

[0043] Furthermore, in the camera unit 1, the size of the first connection pad 21 is, for example, 0.16 mm×0.16 mm. The size of the second connection pad 22 is, for example, 0.11 mm×0.16 mm. That is, the first connection pad 21 and the second connection pad 22 are smaller than the first solder pad 11 and the second solder pad 12. The number of first connection pads of the first connection pad 21 is the same as the number of first solder pads N1. The number of second connection pads of the second connection pad 22 is the same as the number of second solder pads N2.

[0044] The number N1 of the plurality of first connection pads 21 is different from the number N2 of the plurality of second connection pads 22. However, the total area of ​​the plurality of first connection pads 21 (third area S21 = 0.0768 mm 2 ) and the sum of the areas of the plurality of second connection pads 22 (the fourth area S22 = 0.0704 mm 2 ) are roughly the same.

[0045] Even if there is an influence of the solder 62 spread to the first pad 11 and the second pad 12, the interfacial tension of the molten solder 62 acts symmetrically across the cutout C20 during bonding. Therefore, the planar wiring board 10 and the three-dimensional wiring board 20 are accurately bonded using the solder 62.

[0046] The first interval between the first pad 11 and the first connection pad 21 is substantially the same as the second interval between the second pad 12 and the second connection pad 22. In other words, the thickness T62A of the first solder 62A joining the first pad 11 and the first connection pad 21 and the thickness T62B of the second solder 62B joining the second pad 12 and the second connection pad 22 are the same thickness T2 (refer to Figure 6 ). The thickness T2 of the solder 62 is, for example, 20 μm to 30 μm. In addition, the thickness T1 of the electrode (pad, connection land) (see Figure 6 ) is, for example, 5 μm-10 μm.

[0047] Therefore, the sum of the volumes of the plurality of first solders 62A, i.e., the first volume V62A (third area S21×T62), is substantially the same as the sum of the volumes of the plurality of second solders 62B, i.e., the second volume V62B (fourth area S22×T62). The plurality of first solders 62A join the plurality of first pads 11 to the plurality of first connection pads 21, respectively, and the plurality of second solders 62B join the plurality of second pads 12 to the plurality of second connection pads 22, respectively.

[0048] In addition, the number N1 of the first pads and the number N2 of the second pads of the second pads may of course be the same.

[0049] The interfacial tension of the molten solder 62 during bonding is preferably in a direction perpendicular to the cutout C20 (in Figure 2It is preferred that the optical axis O be viewed from a direction perpendicular to the optical axis O, that is, in the YZ plane ( Figure 4 as well as Figure 5 ), the interfacial tension of the molten solder 62 acts symmetrically about the central axes 10X, 20X in the left-right direction of each of the first surface 10SB and the second surface 20SA.

[0050] For this purpose, the central axis 10X of the planar wiring board 10 and the central axis 20X of the three-dimensional wiring board 20 are further arranged on the same plane. Furthermore, it is preferred that the outer end surfaces of the plurality of electrodes respectively connected to the outer sides of the plurality of first pads 11, the plurality of second pads 12, the plurality of first bumps 21, and the plurality of second bumps 22 are respectively arranged on the same plane.

[0051] That is, the outer end surface 11AF of the first pad 11A, the outer end surface 12AF of the second pad 12A, the outer end surface 21AF of the first connection pad 21A, and the outer end surface 22AF of the second connection pad 22A are located on the plane F1. In addition, the outer end surface 11CF of the first pad 11C, the outer end surface 12CF of the second pad 12D, the outer end surface 21CF of the second connection pad 21C, and the outer end surface 22DF of the second connection pad 22D are located on the plane F2.

[0052] In addition, the center of gravity points G11, G12, G21, G22 of the electrode groups of the first pads 11, the second pads 12, the first connection pads 21, and the second connection pads 22 are preferably located on the same plane FG. The plane FG includes the central axis 10X and the central axis 20X.

[0053] The camera unit 1 can prevent the three-dimensional wiring board 20 from being accidentally moved due to the interfacial tension of the molten solder 62. Furthermore, even if the plane wiring board 10 and the three-dimensional wiring board 20 are not arranged at the correct position before joining, the three-dimensional wiring board 20 can be moved to the correct position and joined by the self-alignment effect caused by the interfacial tension of the molten solder 62.

[0054] <Position of the inner end of the connection plate>

[0055] As described above, the thickness T3 of the arm portion 29 of the three-dimensional wiring board 20 is 0.3 mm. The lower limit of the thickness T3 is, for example, 0.2 mm. When the lower limit of the thickness T3 is less than the above lower limit, not only the mechanical strength cannot be ensured, but also injection molding is difficult. For miniaturization, the upper limit of the thickness T3 is, for example, less than 1 mm. In addition, the thickness T3 of the arm portion 29 is the difference between a first distance L1 and a second distance L2, wherein the first distance L1 is the distance from the outer side surface 20SS of the three-dimensional wiring board 20 to the optical axis O, and the second distance L2 is the distance from the wall surface C20SSA of the cutout C20 close to the plurality of first pads 11 and the wall surface C20SSB close to the plurality of second pads 12 to the optical axis ( Figure 6 ). That is, in the imaging unit 1, the difference between the first distance L1 and the second distance L2 is greater than 0.2 mm and less than 1 mm.

[0056] For bonding reliability, the land inner end 21T of the first land 21 preferably extends to the wall surface C20SS (C20SSA) of the cutout C20. However, in the ultra-small imaging unit 1, if the land inner end 21T of the first land 21 extends, the solder 62 and the solder 63 may short-circuit.

[0057] If the thickness T3 of the arm portion 29 is reduced, even if the first connection pad 21 is extended to the first chamfered area C20CA or the first wall surface C20SSA of the cutout C20, the solder 62 will not short-circuit with the solder 63. However, if the thickness T3 is reduced, not only the mechanical strength cannot be ensured, but also injection molding becomes difficult. In the image pickup unit 1 where the thickness T3 cannot be reduced to less than a specified value, the size of the first connection pad 21 and the size of the second connection pad 22 are limited.

[0058] For example, Figure 6 As shown, the inner end 21T of the first connection pad 21 does not extend to the wall C20SS (first wall C20SSA) of the cutout C20. The first wall C20SSA is the wall C20SS close to the first pad 11. It is more preferred that the inner end 21T of the first connection pad 21 does not extend to the chamfered area C20C (first chamfered area C20CA) like the camera unit 1. Similarly, although not shown, the second connection pad 22 does not extend to the wall C20SS (second wall C20SSB) of the cutout C20. The second wall C20SSB is the wall C20SS close to the second pad 12. The second connection pad 22 is more preferably not extended to the chamfered area C20C (second chamfered area C20CB).

[0059] <Positional Relationship of Joining Parts>

[0060] In the ultra-small imaging unit 1, it is necessary to ensure mechanical strength while preventing the molten solder 62 from short-circuiting the joints (third pads 13, solder 63) of the mounted electronic component 30. Therefore, the positional relationship of the plurality of joints of the planar wiring board 10, the three-dimensional wiring board 20, and the electronic component 30 is important.

[0061] Regarding the positional relationship of the plurality of bonding portions, the portion including the first region 20SA1 and the portion including the second region 20SA2 are symmetrical across the optical axis O. Therefore, in the following, Figure 6 The upper portion including the first area 20SA1 is shown as an example for explanation. Figure 6 It is a partial cross-sectional view of a cross section parallel to the optical axis O of the imaging unit 1 and perpendicular to the wall surface C20SS of the cutout C20.

[0062] like Figure 6 As shown, the third distance L3 is preferably between the second distance L2 and the fourth distance L4. The third distance L3 is the distance between the pad inner end 11T of the first pad 11 and the optical axis O. The second distance L2 is the distance between the first wall surface C20SSA close to the first pad 11 and the optical axis O. The fourth distance L4 is the distance between the pad inner end 21T of the first pad 21 and the optical axis O.

[0063] That is, if the third distance L3 is greater than the second distance L2, there is a possibility of short circuit between the solder 62 and the solder 63. If the fourth distance L4 is smaller than the third distance L3, the area of ​​the joint portion is reduced, so the joint reliability is reduced.

[0064] Similarly, the distance between the inner end of the second soldering pad 12 and the optical axis O (the same as the third distance L3) is preferably between the distance between the wall C20SS close to the second soldering pad 12, i.e., the second wall C20SSB, and the optical axis O (the same as the second distance L2) and the distance between the inner end of the connecting pad of the second connecting pad 22 (not shown) and the optical axis O (the same as the fourth distance L4).

[0065] Furthermore, it is preferable that a fifth distance L5 between the pad outer end 13T of the third pad 13 and the optical axis O is shorter than the second distance L2. According to the above configuration, a short circuit between the solder 62 and the solder 63 can be prevented.

[0066] use Fig. 7A and Figure 7B The top view shown in FIG. further illustrates the above structure. Fig. 7A As shown, the inner edge of the edge lines formed by the plurality of first pads 11 is set as edge line A1, and the inner edge of the edge lines formed by the plurality of second pads 12 is set as edge line A2. The edge line closest to the first pad 11 among the edges formed by the plurality of third pads 13 is set as edge line B1, and the edge line closest to the second pad 12 is set as edge line B2.

[0067] like Figure 7B As shown, the inner ridgeline among the ridgelines formed by the plurality of first lands 21 is set as ridgeline C1, and the inner ridgeline among the ridgelines formed by the plurality of second lands 22 is set as ridgeline C2. The ridgeline of the wall surface C20SS close to the first land 21, i.e., the first wall surface C20SSA, is set as ridgeline D1, and the ridgeline of the wall surface C20SS close to the second land 22, i.e., the second wall surface C20SSB, is set as ridgeline D2.

[0068] It is preferred that the ridgeline A1 is located between the ridgeline C1 and the ridgeline D1, and the ridgeline A2 is located between the ridgeline C2 and the ridgeline D2.

[0069] It is preferable that the ridgeline B1 is located inside the ridgeline D1 (on the optical axis side), and the ridgeline B2 is located inside the ridgeline D2 (on the optical axis side).

[0070] In addition, it is preferred that the sixth distance L6 of the outermost surface 30SA of the plurality of electronic components 30 from the optical axis O is shorter than the second distance L2. According to the structure, the electronic component 30 can be easily accommodated in the cutout C20. In addition, the plurality of first pads 11 (11A-11C) and the plurality of second pads 12 (12A-12D) on the planar wiring board 10 can be prevented from contacting the plurality of third pads 13 (13A-13F). The solder applied to each pad can be prevented from contacting each other.

[0071] In addition, if a fillet is formed at the joint, the joint reliability is improved. Therefore, the seventh distance L7 between the outer ends of the pads of the plurality of first pads 11 and the plurality of second pads 12 and the optical axis O is preferably longer than the first distance L1 between the outer side surface 20SS of the three-dimensional wiring board 20 and the optical axis O. In addition, the fifth distance L5 between the outer ends 13T of the pads of the plurality of third pads 13 and the optical axis O is preferably longer than the sixth distance L6 between the outermost surfaces 30SA of the plurality of electronic components 30 and the optical axis O.

[0072] <Types of pads and lands>

[0073] Preferably, the fifth area S5, which is the sum of the areas of the grounded pads among the first pads 11, the second pads 12 and the third pads 13, is greater than the area of ​​the largest non-ground pad among the ungrounded non-ground pads.

[0074] For example, the first pad 11A and the second pad 12D are ground pads. The first pads 11B and 11C are non-ground pads connected to a power source. The second pads 12A, 12B, and 12C are non-ground pads for signal flow. The sum of the areas of the plurality of ground pads is the fifth area S5 (0.0675 mm 2 ) is larger than the area of ​​the first pad 11B (0.04 mm2 )big.

[0075] According to the above configuration, it is possible to prevent the degradation of the electrical characteristics of the image pickup unit 1 due to the increase in impedance.

[0076] In addition, it is preferred that the connection pad interval between the second pad 12 (second connection pad) and the third pad 13 (third connection pad) directly connected on the inner layer of the planar wiring board 10 among the multiple second pads 12 and the multiple third pads 13 is shorter than the interval between the second pad 12 (second non-connection pad) and the third pad 13 (third non-connection pad) not directly connected on the inner layer of the wiring board.

[0077] For example, the second pad 12A and the third pad 13B are the second connection pad and the third connection pad that are directly connected. The second pad 12A and the third pad 13A are the second non-connection pad and the third non-connection pad that are not directly connected. The connection pad interval D10 between the second pad 12A and the third pad 13B is shorter than the non-connection pad interval D11 between the second pad 12A and the third pad 13A.

[0078] According to the above configuration, since the wiring in the planar wiring board 10 is short, the image pickup unit 1 can obtain good electrical characteristics.

[0079] <Second Embodiment>

[0080] like Figure 8 As shown in FIG. 1 , the endoscope 9 of this embodiment includes: a front end portion 9A, which is provided with an imaging unit 1; a bendable bending portion 9B, which is connected to the base end of the front end portion 9A; and an elongated soft portion 9C, which is connected to the base end of the bending portion 9B. The bending portion 9B is bent by the user operating an operating portion 9D. The front end portion 9A, the bending portion 9B, and the soft portion 9C are insertion portions inserted into the body. A universal cable 9E extending from the operating portion 9D is connected to a processor, etc., not shown.

[0081] The endoscope 9 includes the imaging unit 1 and is therefore highly reliable, compact, and high-performance.

[0082] The endoscope 9 is a flexible endoscope for medical use, but the endoscopes of other embodiments may be industrial endoscopes or rigid endoscopes having a rigid straight tube instead of the flexible portion 9C. Furthermore, the imaging unit 1 may be used for a direct-view endoscope in which the object direction is the tip direction.

[0083] The three-dimensional wiring board 20 is not limited to a molded circuit device (MID). For example, the three-dimensional wiring board 20 can also be made by processing with a 3D printer or cutting. The material of the three-dimensional wiring board 20 is not limited to resin, and ceramic or epoxy glass can also be used.

[0084] The present invention is not limited to the above-described embodiments and the like, and various changes and modifications can be made without departing from the spirit and scope of the present invention.

Claims

1. A camera unit, wherein: The camera unit comprises: A semiconductor package including an imager; a planar wiring board having a front surface and a first surface opposite to the front surface, the front surface of the planar wiring board being bonded to the semiconductor package, and the planar wiring board being provided with a plurality of first pads and a plurality of second pads on the first surface; as well as A three-dimensional wiring board having a second surface joined to the first surface, the second surface of the three-dimensional wiring board having a first area and a second area symmetrically shaped with a cutout therebetween, the three-dimensional wiring board being provided with a plurality of first connection pads in the first area, and the three-dimensional wiring board being provided with a plurality of second connection pads in the second area, The plurality of first connection pads are respectively welded and joined with the plurality of first solder pads, and the plurality of second connection pads are respectively welded and joined with the plurality of second solder pads. A first area which is a sum of areas of the plurality of first pads is substantially the same as a second area which is a sum of areas of the plurality of second pads.

2. The imaging unit according to claim 1, wherein: The number of first pads of the plurality of first pads is different from the number of second pads of the plurality of second pads.

3. The imaging unit according to claim 1, wherein: The planar wiring board is provided with a plurality of third pads between the plurality of first pads and the plurality of second pads. The camera unit includes a plurality of electronic components soldered to the plurality of third pads. The plurality of electronic components are housed in the cutouts of the three-dimensional wiring board.

4. The imaging unit according to claim 1, wherein: The third area which is the sum of the areas of the plurality of first connection pads is substantially the same as the fourth area which is the sum of the areas of the plurality of second connection pads.

5. The imaging unit according to claim 1, wherein: The first volume is substantially the same as the second volume, wherein the first volume is the sum of the volumes of the plurality of first solders respectively joining the plurality of first solder pads to the plurality of first connection pads, and the second volume is the sum of the volumes of the plurality of second solders respectively joining the plurality of second solder pads to the plurality of second connection pads.

6. The imaging unit according to claim 1, wherein: A first interval between the plurality of first pads and the plurality of first connection pads and a second interval between the plurality of second pads and the plurality of second connection pads are substantially the same.

7. The imaging unit according to claim 1, wherein: The outer side end surfaces of the plurality of electrodes located on the same outer side of the plurality of first pads, the plurality of second pads, the plurality of first connection pads, and the plurality of second connection pads are located on the same plane.

8. The imaging unit according to claim 6, wherein: The center of gravity of each of the plurality of first pads, the plurality of second pads, the plurality of first connection pads, and the plurality of second connection pads is located on the same plane.

9. The imaging unit according to claim 1, wherein: The difference between the first distance and the second distance is greater than 0.2 mm and less than 1 mm, the first distance is the distance from the outer side surface of the three-dimensional wiring board to the optical axis, and the second distance is the distance from the wall surface of the incision close to the multiple first pads and the multiple second pads to the optical axis.

10. The imaging unit according to claim 9, wherein: The plurality of first connection pads do not extend to the first chamfered area between the first area and the first wall surface of the cutout, The plurality of second connection pads do not extend to a second chamfered area between the second area and a second wall surface of the cutout.

11. The imaging unit according to claim 3, wherein: In a cross section parallel to the optical axis and orthogonal to the wall of the incision, a third distance between the inner end of each of the multiple first solder pads and the multiple second solder pads and the optical axis is between the second distance and the fourth distance, the second distance being the distance from the wall of the incision respectively close to the multiple first solder pads and the multiple second solder pads to the optical axis, and the fourth distance being the distance between the inner end of each of the multiple first connecting pads and the multiple second connecting pads and the optical axis.

12. The imaging unit according to claim 11, wherein: A fifth distance between an outer side end of each of the plurality of third pads and the optical axis is shorter than the second distance.

13. The imaging unit according to claim 12, wherein: A sixth distance between the outermost surfaces of the plurality of electronic components and the optical axis is shorter than the second distance.

14. The imaging unit according to claim 3, wherein: A fifth area, which is a sum of areas of grounded pads among the first, second and third pads, is larger than an area of ​​a largest non-ground pad among ungrounded non-ground pads.

15. The imaging unit according to claim 1, wherein: A connection pad interval between second connection pads and third connection pads directly connected on an inner layer of the planar wiring board among the plurality of second pads and the plurality of third pads is shorter than a non-connection pad interval between second non-connection pads and third non-connection pads not directly connected.

16. The camera unit according to claim 1, wherein: The planar wiring board and the three-dimensional wiring board are accommodated in a virtual space obtained by extending the imager in the optical axis direction.

17. The camera unit according to claim 1, wherein: The three-dimensional wiring board is a molded circuit device.

18. An endoscope having an imaging unit at a front end portion of an insertion portion, wherein: The camera unit comprises: A semiconductor package including an imager; a planar wiring board having a front surface and a first surface opposite to the front surface, the front surface of the planar wiring board being bonded to the semiconductor package, and the planar wiring board being provided with a plurality of first pads and a plurality of second pads on the first surface; as well as A three-dimensional wiring board having a second surface joined to the first surface, the second surface of the three-dimensional wiring board having a first area and a second area symmetrically shaped with a cutout therebetween, the three-dimensional wiring board being provided with a plurality of first connection pads in the first area, and the three-dimensional wiring board being provided with a plurality of second connection pads in the second area, The plurality of first connection pads are respectively welded and joined with the plurality of first solder pads, and the plurality of second connection pads are respectively welded and joined with the plurality of second solder pads. A first area which is a sum of areas of the plurality of first pads is substantially the same as a second area which is a sum of areas of the plurality of second pads.

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