Wiring board and electronic device

Abstract

The present invention reduces the planar space required for mounting a wiring board while enhancing the manufacturability and strength of the wiring board. This wiring board includes a first base body and a second base body. A part of a pair of second side surfaces of the second base body extending along a first direction orthogonal to the height direction is positioned on the same plane as the corresponding first side surface of the first base body, and at least one second side surface has a region in which an electrode is disposed to the inner side relative to the corresponding first side surface.

Description

Wiring board and electronic device

[0001] The present disclosure relates to a wiring board and an electronic device.

[0002] For example, as disclosed in Patent Document 1, an electronic device including an imaging element, which is referred to as an imaging module in Patent Document 1, is known. The electronic device according to this prior art includes a substrate, which is referred to as an imaging element mounting substrate in Patent Document 1, and the substrate includes a base, which is referred to as a substrate in Patent Document 1. The imaging element is mounted on the top surface of the base, and multiple electronic components are mounted around the imaging element on the top surface of the base.

[0003] International Publication No. 2019 / 082923

[0004] The wiring board according to the present disclosure comprises a first base having a first upper surface, a first lower surface located opposite the first upper surface, and four first side surfaces located between the first upper surface and the first lower surface; a second base having a second upper surface in contact with the first lower surface, a second lower surface located opposite the second upper surface, and four second side surfaces located between the second upper surface and the second lower surface and corresponding to the four first side surfaces; a plurality of first electrodes located on the first upper surface, a plurality of second electrodes located on the second lower surface, and a plurality of third electrodes located on the second side surfaces; and among the four second side surfaces, portions of a pair of the second side surfaces extending along a first direction perpendicular to the height direction are located on the same plane as the corresponding first side surfaces, and at least one of the second side surfaces has an area located inside a plane including the corresponding first side surface, and the third electrode is located in the area.

[0005] The electronic device according to the present disclosure comprises a wiring board according to the present disclosure, a first element connected to the first electrode, a second element connected to the second electrode, and a third element connected to the third electrode.

[0006] 1 is a schematic perspective view of a wiring board according to a first embodiment, as seen from above. FIG. 2 is a schematic perspective view of a wiring board according to a first embodiment, as seen from below. FIG. 3 is a schematic bottom view of the wiring board according to the first embodiment. FIG. 4 is a schematic view illustrating a third electrode. FIG. 5 is a schematic perspective view of an electronic device according to a first embodiment, as seen from above. FIG. 6 is a schematic perspective view of an electronic device according to a first embodiment, as seen from below. FIG. 7 is a schematic perspective view of a wiring board according to a second embodiment, as seen from above. FIG. 8 is a schematic perspective view of a wiring board according to a second embodiment, as seen from below. FIG. 9 is a schematic bottom view of a wiring board according to the second embodiment. FIG. 10 is a schematic perspective view of a wiring board according to a third embodiment, as seen from above. FIG. 11 is a schematic perspective view of a wiring board according to a third embodiment, as seen from below. FIG. 12 is a schematic side view of a wiring board according to a third embodiment. FIG. 13 is a schematic perspective view of an electronic device according to a third embodiment, as seen from the side.

[0007] In the electronic device according to the prior art, as described above, an imaging element and multiple electronic components are mounted on the upper surface of a substrate. In other words, in the substrate according to the prior art, multiple electrodes for the imaging element for mounting the imaging element are located on the upper surface of the base, and multiple electrodes for the electronic components for mounting the multiple electronic components are located around the electrodes for the imaging element on the upper surface of the base. As a result, the electronic device and the substrate tend to be larger in size in a plan view, and the planar space required for mounting the electronic device and the substrate is larger.

[0008] Hereinafter, wiring boards and electronic devices according to embodiments will be described in detail with reference to the drawings. However, for the sake of convenience, the drawings referred to below show simplified views of only the components necessary for explaining the embodiments. Therefore, wiring boards and electronic devices according to embodiments may include any components not shown in the drawings referred to. The dimensions of the components in the drawings do not necessarily faithfully represent the actual dimensions of the components and the dimensional ratios of each member.

[0009] In the specification and claims of this application, the term "first direction" refers to the width direction of the wiring board, in other words, a direction perpendicular to the height direction of the wiring board. The height direction is the up-down direction of the wiring board. Hereinafter, the first direction will be referred to as the width direction for convenience. The term "second direction" refers to a direction perpendicular to the height direction and the first direction. Hereinafter, the second direction will be referred to as the length direction for convenience. "Rectangular" is not limited to a strict rectangular shape, but includes a shape that can be visually recognized as a rectangle overall, even if, for example, the corners are curved. "Inside" refers to the side inside the outer surface of the wiring board. In the drawings, "WD" refers to the width direction, "LD" refers to the length direction, "UD" refers to the up direction, and "DD" refers to the down direction.

[0010] A wiring board 1 and an electronic device 100 according to the first embodiment will be described with reference to FIGS. 1 to 6. FIG. 1 is a schematic perspective view of the wiring board 1 according to the first embodiment, as seen from above. FIG. 2 is a schematic perspective view of the wiring board 1 according to the first embodiment, as seen from below. FIG. 3 is a schematic bottom view of the wiring board 1 according to the first embodiment. IVA in FIG. 4 is a schematic view showing a third electrode 6 spanning three insulating layers 31, and is a schematic view showing an enlarged view of the insulating layers 31 and the third electrode 6 in a recess 32, which will be described later. IVB in FIG. 4 is a cross-sectional view taken along line A-A in IVA in FIG. 4. FIG. 5 is a schematic perspective view of the electronic device 100 according to the first embodiment, as seen from above. FIG. 6 is a schematic perspective view of the electronic device 100 according to the first embodiment, as seen from below.

[0011] As shown in the example of FIGS. 1 and 2 , the wiring board 1 according to the first embodiment may include a first base 2 that is rectangular in plan view. The first base 2 may include a plurality of insulating layers stacked in the height direction. Specifically, as shown in FIGS. 1 and 2 , the first base 2 may be composed of two insulating layers 21. The first base 2 may be composed of a plurality of insulating layers 21 other than two, or a single insulating layer 21. The insulating layer 21 may be made of insulating ceramics such as an aluminum oxide sintered body (alumina ceramics), an aluminum nitride sintered body, a mullite sintered body, or a glass ceramic sintered body.

[0012] In the present disclosure, the "height direction" and the "up-down direction" may be directions along the stacking direction of the wiring board 1, as in the wiring board 1 of the first embodiment. The "width direction" may be a direction along one direction in which the insulating layer 21 of the wiring board 1 extends, and may be, for example, a left-right direction when facing the front of the wiring board 1. The "length direction" may be a direction along one direction in which the insulating layer 21 of the wiring board 1 extends and may be a direction intersecting the "width direction", and may be, for example, a direction connecting the front side and the back side of the wiring board 1.

[0013] The first substrate 2 may have a first upper surface 2u, a first lower surface 2d located opposite the first upper surface 2u, and four first side surfaces 2s located between the first upper surface 2u and the first lower surface 2d. The first upper surface 2u and the first lower surface 2d of the first substrate 2 may be parallel, and the first side surfaces 2s of the first substrate 2 may be perpendicular to the first upper surface 2u and the first lower surface 2d. Two of the first side surfaces 2s of the first substrate 2 may be parallel to the width direction WD, and the remaining two first side surfaces 2s of the first substrate 2 may be parallel to the length direction LD. In the present disclosure, "parallel" may include a state in which the two directions are strictly parallel, as well as a state in which the two directions are generally parallel. For example, "generally parallel" may include a state in which the angle between the two directions is 5 degrees or less, a state in which the angle between the two directions is 10 degrees or less, or a state in which the angle between the two directions is 15 degrees or less. Also, in the present disclosure, even when two surfaces are curved, the two surfaces may be considered to be parallel if the tangent direction of either of the two surfaces is "substantially parallel."

[0014] The wiring board 1 may include a second base 3 that is H-shaped in bottom view and located below the first base 2. The second base 3 may include a plurality of insulating layers 31, 10 or more layers stacked in the height direction. The second base 3 may also include a plurality of insulating layers 31, 9 or less layers. The insulating layers 31 may include the same insulating ceramic as the insulating layers 21.

[0015] The second substrate 3 may have a second upper surface 3u in contact with the first lower surface 2d of the first substrate 2, a second lower surface 3d located on the opposite side of the second upper surface 3u, and four second side surfaces 3s located between the second upper surface 3u and the second lower surface 3d and corresponding to the four first side surfaces 2s, respectively. The corresponding first side surfaces 2s and second side surfaces 3s refer to first side surfaces 2s and second side surfaces 3s facing in the same direction. The second upper surface 3u and second lower surface 3d of the second substrate 3 may be parallel, and the second side surfaces 3s of the second substrate 3 may be perpendicular to the second upper surface 3u and second lower surface 3d. Two second side surfaces 3s of the second substrate 3 may be parallel to the width direction WD, and the remaining two second side surfaces 3s of the second substrate 3 may be parallel to the length direction LD.

[0016] As shown in Figures 1 to 3, a pair of second side surfaces 3s extending along the width direction WD may have a portion of each second side surface 3s located on the same plane as the corresponding first side surface 2s. Furthermore, at least one second side surface 3s may have a region F located inside a plane including the corresponding first side surface 2s. The outer edge of the second base 3 may overlap with or be located inside the outer edge of the first base 2 in a bottom view. In the present disclosure, a bottom view may refer to a planar view or a see-through view of an object from one of the up and down directions.

[0017] 1 to 3, the second side surface 3s extending along the length direction LD may have a region F located entirely inside a plane including the corresponding first side surface 2s. In other words, the entire second side surface 3s extending along the length direction LD may be located entirely inside a plane including the corresponding first side surface 2s. "Inside the plane" means being closer to the inside of the wiring board than the plane.

[0018] 1 to 3 , at least one of the second side surfaces 3s may have a recess 32 recessed inward from a plane including the corresponding first side surface 2s. Furthermore, in the second side surface 3s having the recess 32, a region F located inward from a plane including the corresponding first side surface 2s may be an inner surface of the recess 32. For example, a pair of second side surfaces 3s parallel to the width direction WD of the second base 3 may have the recess 32 recessed inward from a plane including the corresponding first side surface 2s.

[0019] As shown in the examples of FIGS. 1 to 3 , each second side surface 3 s of the second substrate 3 may have a region F. The surface roughness of the region F of the second substrate 3 may be greater than the surface roughness of the second side surface 3 s located on the same plane as the first side surface 2 s. The surface roughness, particularly the arithmetic mean roughness (Ra), of the region F of the second substrate 3 may be, for example, 1.5 μm or more and 7.0 μm or less, or even 1.7 μm or more and 6.0 μm or less. The surface roughness of the second side surface 3 s of the second substrate 3 located on the same plane as the first side surface 2 s of the first substrate 2 may be, for example, 0.1 μm or more and 1.5 μm or less, or even 0.6 μm or more and 1.0 μm or less. In FIGS. 1 , 2 , IV A of FIG. 4 , 5 , and 6 , the region F is indicated by dotted hatching.

[0020] As in the examples shown in FIGS. 1 and 2 , a plurality of first electrodes 4 may be located on the first upper surface 2u of the first substrate 2 for electrically connecting to the imaging element 110 serving as the first element, as shown in FIGS. 5 and 6 . The plurality of first electrodes 4 may be printed on the first upper surface 2u of the first substrate 2 and formed by firing. The plurality of first electrodes 4 may be arranged at intervals in the width direction WD and the length direction LD, and the arrangement pattern of the plurality of first electrodes 4 may be changed as appropriate. Each of the first electrodes 4 may be made of a metal powder metallization containing, for example, tungsten (W), molybdenum (Mo), manganese (Mn), silver (Ag), or copper (Cu) as a component.

[0021] 1 to 3 , a plurality of second electrodes 5 for electrically connecting to a capacitor 120 as a second element, as shown in FIG. 6 , may be located on the second lower surface 3 d of the second base 3. The plurality of second electrodes 5 may be printed on the second lower surface 3 d of the second base 3 and formed by firing. The plurality of second electrodes 5 may be arranged at intervals in the width direction WD and the length direction LD, and the arrangement pattern of the plurality of second electrodes 5 may be changed as appropriate. The same metal powder metallization as that of the first electrode 4 may be used for each second electrode 5.

[0022] As shown in the examples IVA and IVB in FIGS. 1 , 2 , and 4A and 4B, a plurality of third electrodes 6 for electrically connecting to a cable 130 or a capacitor 140 serving as a third element, as shown in FIGS. 5 and 6 , may be located in the region F of the second side surface 3 s of the second base 3. In the region F of the second side surface 3 s having the recess 32, the plurality of third electrodes 6 may be located on a surface extending in the stacking direction of the insulating layer 31. Alternatively, the plurality of third electrodes 6 may be located on the bottom surface of the recess 32, in other words, on a surface parallel to the corresponding first side surface 2 s. In each region F, the plurality of third electrodes 6 may include third electrodes 6 located at different heights. In other words, in each region F, one third electrode 6 may be located at a different height from another third electrode 6.

[0023] Furthermore, any of the third electrodes 6 may span three or more insulating layers 31, as shown in IVA in FIG. 4 . The side of any of the third electrodes 6 may include a side edge 6s extending in the height direction, and the side edge 6s may be distorted with respect to the height direction. In other words, the side edge 6s of the third electrode 6 extending in the stacking direction may not be straight and may have a step. As shown in FIG. 4 , the multiple third electrodes 6 may include via conductors that extend through at least one insulating layer 31 and protrude from the second side surface 3s, which is the surface of the second base 3. As shown in FIG. 4 , the via conductor included in the third electrode 6 extends across multiple layers in the stacking direction. The via conductor included in the third electrode 6 may be split in half. The same metal powder metallization as that of the first electrode 4 may be used for each of the third electrodes 6.

[0024] 1 , 2 , 5 , and 6 , a plurality of third electrodes 6 for electrical connection to the cable 130 may be electrically connected to the corresponding first electrodes 4 or second electrodes 5 by internal wiring. Any of the third electrodes 6 for electrical connection to the cable 130 may be electrically connected to the third electrode 6 for electrical connection to the capacitor 140 by internal wiring. This allows signals to be input to and output from the imaging element 110, and power to be supplied to the imaging element 110.

[0025] As shown in the example of FIGS. 1 and 2, when the first substrate 2 and the second substrate 3 are made of, for example, an aluminum oxide sintered body, the first substrate 2 and the second substrate 3 are manufactured as follows.

[0026] A slurry is produced by adding an appropriate organic binder and solvent to raw material powders such as aluminum oxide and silicon oxide. This slurry is formed into sheets using a doctor blade method, a calendar roll method, or the like to produce ceramic green sheets for the insulating layer 21 and the insulating layer 31. Subsequently, as needed, multiple ceramic green sheets for the insulating layer 21 are stacked to produce a laminate for the first substrate 2. Multiple ceramic green sheets for the insulating layer 31 are stacked to produce a laminate for the second substrate 3. Region F of the second substrate 3 is formed by punching with a die at the location of the ceramic green sheets for the insulating layer 31. The laminate for the first substrate 2 or the laminate of the ceramic green sheets for the insulating layer 31 and the laminate for the second substrate 3 is then fired at a high temperature, e.g., approximately 1300 to 1600°C, to form a sintered body. The sintered body is then sliced ​​along the outer edge of the first substrate 2 to produce the first substrate 2 and the second substrate 3. As a method for cutting the sintered body, dicing may be used instead of slicing.

[0027] The first side surface 2s of the first substrate 2 and the second side surface 3s of the second substrate located on the same plane are formed by slicing a sintered body, etc. As a result, the surface roughness of the first side surface 2s and the second side surface 3s located on the same plane as the first side surface 2s is smaller than the surface roughness of a region F of the second side surface 3s located inside the plane including the first side surface 2s and formed by punching.

[0028] As in the example shown in FIGS. 1 and 2, when the first electrode 4, the second electrode 5, and the third electrode 6 are metallized layers containing, for example, tungsten, they can be formed as follows.

[0029] The first electrode 4 is formed by printing a metal paste, prepared by mixing tungsten powder with an organic solvent and an organic binder, onto a ceramic green sheet for the insulating layer 21 by a method such as screen printing, and then firing the laminate for the wiring board 1. The second electrode 5 is formed by printing a metal paste onto a ceramic green sheet for the insulating layer 31 by a method such as screen printing, and then firing the laminate for the wiring board 1. The third electrode 6 is formed by providing a hole for the third electrode 6 in the ceramic green sheet for the insulating layer 31, filling the hole for the third electrode 6 with a metal paste, and then firing the laminate for the wiring board 1.

[0030] 1 and 2 , the surfaces of the first electrode 4, the second electrode 5, and the third electrode 6 that are exposed to the outside may be coated with a nickel plating layer / gold plating layer as a metal plating layer by a plating method such as electrolytic plating or electroless plating. This can effectively reduce corrosion of the first electrode 4, etc. The metal plating layer is not limited to a nickel plating layer / gold plating layer, and may be other metal plating layers including a nickel plating layer / palladium plating layer / gold plating layer, etc.

[0031] 5 and 6 , the electronic device 100 may include a wiring substrate 1 and an imaging element 110 as a first element mounted on the first upper surface 2u side of the first base 2. Each electrode of the imaging element 110 is electrically connected to a corresponding first electrode 4 by solder or a conductive adhesive. The imaging element 110 is one of electronic components, such as a CMOS (Complementary Metal Oxide Semiconductor) or a CCD (Charge Coupled Device), and converts an optical image formed on an imaging surface into an electrical signal and outputs the electrical signal.

[0032] 6 , the electronic device 100 may include a plurality of capacitors 120 as second elements mounted on the second lower surface 3 d of the second base 3, where the capacitors 120 are one type of electronic component. The electrodes of each of the plurality of capacitors 120 may be electrically connected to the corresponding second electrode 5 by solder or conductive adhesive. Instead of any of the plurality of capacitors 120, another electronic component such as a resistor may be mounted on the second lower surface 3 d of the second base 3. The electronic device 100 may include a ground terminal electrically connected to a central second electrode 5 of the plurality of second electrodes 5. The electronic device 100 may include a heat sink thermally connected to the central second electrode 5 of the plurality of second electrodes 5.

[0033] 5 and 6 , the electronic device 100 may include a plurality of cables 130 as a plurality of third elements mounted in the region F of the second base 3. Each cable 130 may be electrically connected to a corresponding third electrode 6 of the wiring board 1 by solder or a conductive adhesive. The electronic device 100 may include a plurality of capacitors 140 as a plurality of third elements mounted in the region F of the second base 3. An electrode of each of the plurality of capacitors 140 may be electrically connected to a corresponding third electrode 6 of the wiring board 1 by solder or a conductive adhesive. Instead of any of the plurality of capacitors 140, another electronic component such as a resistor may be mounted in the region F of the second base 3.

[0034] When the cable 130 and the capacitor 140 are mounted in the same region F of the second base 3, by positioning the cable 130 on the second lower surface 3d side of the second base 3, the cable 130 does not need to detour around the capacitor 140, and the wiring structure of the cable 130 is simplified.

[0035] As shown in the example in FIG. 3 , in the configuration of the wiring board 1 according to the first embodiment, at least one second side surface 3 s has a region F located inside a plane including the corresponding first side surface 2 s, and multiple third electrodes are located in the region F. This allows for miniaturization of the electronic device when a third element is disposed on the second side surface 3 s of the wiring board 1 to form an electronic device. Furthermore, even if the number of electrodes including the third electrode 6 is increased, the wiring board 1 can be miniaturized in a planar view. In other words, even if the number of elements including the third element mounted on the wiring board 1 is increased, the wiring board 1 and the electronic device 100 can be miniaturized in a planar view. This allows for space saving in the planar space required for mounting the wiring board 1 and the electronic device 100.

[0036] 3 , when the second side surface 3s extending along the length direction LD intersecting with the width direction WD has the region F over the entirety, it is possible to increase the number of third electrodes 6 that can be arranged on the second side surface 3s. Furthermore, even if the number of electrodes including the third electrodes 6 is increased, it is possible to reduce the size of the wiring substrate 1 in a plan view.

[0037] 1 to 3 , at least one second side surface 3 s may have a recess 32 recessed inward from a plane including the corresponding first side surface 2 s, and region F may be the inner surface of recess 32. In this case, the strength of wiring board 1 is increased, and even if the number of electrodes including third electrode 6 is increased, wiring board 1 can be made smaller in size in a plan view.

[0038] 1 and 2 , when each second side surface 3 s of the second base 3 has a region F, it is possible to further increase the number of electrodes including the third electrode 6. Furthermore, when one region F includes third electrodes 6 located at different heights, it is also possible to further increase the number of electrodes including the third electrode 6.

[0039] 3 , in the configuration of the wiring board 1 according to the first embodiment, among the four second side surfaces 3 s, a pair of second side surfaces 3 s extending along a width direction WD perpendicular to the height direction are partially located on the same plane as the corresponding first side surfaces 2 s. This simplifies the alignment of the laminate for the first base 2 or the ceramic green sheet for the insulating layer 31 with the laminate for the second base 3, thereby improving the manufacturability of the wiring board 1 and the electronic device 100. Furthermore, the strength of the wiring board 1 can be increased compared to when all four second side surfaces 3 s of the second base 3 are located inside the plane including the first side surfaces 2 s of the first base 2.

[0040] According to the configuration of the wiring board 1 according to the first embodiment, the surface roughness of the region F of the second base 3 is greater than the surface roughness of the second side surface 3s of the second base 3, which is located on the same plane as the first side surface 2s of the first base 2. Therefore, when a capacitor 140 or the like serving as a third element is solder-mounted in the region F of the second base 3, the solder is less likely to flow in the region F of the second base 3, thereby preventing short circuits between adjacent third electrodes 6. When a capacitor 140 or the like serving as a third element is mounted in the region F of the second base 3 using a conductive adhesive, the surface area of ​​the region F of the second base 3 is increased, thereby increasing the mounting strength, for example, the adhesion strength, of the capacitor 140 or the like relative to the region F of the second base 3.

[0041] As shown in the example IVB of Fig. 4, the third electrode 6 may protrude from the second side surface 3s of the second base 3. In this case, when a capacitor 140 or the like is solder-mounted as a third element in the region F of the second base 3, the lifting of the capacitor 140 or the like relative to the second base 3 can be reduced. This allows the electronic device 100 to be made smaller in plan view. If the third electrode 6 did not protrude from the surface of the second base 3, the amount of solder would increase and the lifting of the capacitor 140 or the like relative to the second base 3 would increase when the capacitor 140 or the like is solder-mounted in the region F of the second base 3.

[0042] As shown in the example IVA in Figure 4, at least one third electrode 6 may include a side edge 6s extending in the height direction, and the side edge 6s may be distorted relative to the height direction. In other words, the side edge 6s of any third electrode 6 may not be straight, but may be offset in the width direction WD or the length direction LD. In this case, when a capacitor 140 or the like serving as a third element is solder-mounted in the region F of the second base 3, the self-alignment function of the solder makes it easy to align the solder mounting. This allows the capacitor 140 or the like to be easily mounted in the correct position on the wiring board 1, further improving the manufacturability of the electronic device 100.

[0043] A wiring board 1A according to a second embodiment of the present disclosure will be described with reference to Fig. 7 to Fig. 9. Fig. 7 is a schematic perspective view of the wiring board 1A according to the second embodiment as seen from above. Fig. 8 is a schematic perspective view of the wiring board 1A according to the second embodiment as seen from below. Fig. 9 is a schematic bottom view of the wiring board 1A according to the second embodiment.

[0044] 7 and 8, the wiring board 1A according to the second embodiment of the present disclosure has the same configuration as the wiring board 1 according to the first embodiment, except for some components. The following describes the configuration of the wiring board 1A that differs from the wiring board 1 according to the first embodiment. For ease of explanation, the same reference numerals are used to designate components that have the same functions as the components described in the first embodiment.

[0045] 9 , a portion of a pair of second side surfaces 3s parallel to the width direction WD of the second base 3 may be located on the same plane as the corresponding first side surfaces 2s of the first base 2. Furthermore, at least a portion of the pair of second side surfaces 3s parallel to the length direction LD of the second base 3 may be located on the same plane as the first side surfaces 2s of the first base 2. The outer edge of the second base 3 may overlap the outer edge of the first base 2 or may be located inside the outer edge of the first base 2 in a bottom view.

[0046] As shown in the examples shown in Figures 7 to 9, each second side surface 3s of the second substrate 3 may have a recess 32 recessed inward from a plane including the corresponding first side surface 2s in a bottom view. In this case, a region F of the second side surface 3s located inside the plane including the corresponding first side surface 2s is the inner surface of the recess 32. The surface roughness of region F of the second substrate 3 may be greater than the surface roughness of the second side surface 3s of the second substrate 3 located in the same plane as the first side surface 2s of the first substrate 2. The surface roughness of region F of the second substrate 3, particularly the arithmetic mean roughness (Ra), may be, for example, 1.5 μm or more and 7.0 μm or less, or even 1.7 μm or more and 6.0 μm or less. The surface roughness of the second side surface 3s of the second substrate 3 located in the same plane as the first side surface 2s of the first substrate 2 may be, for example, 0.1 μm or more and 1.5 μm or less, or even 0.6 μm or more and 1.0 μm or less. In FIGS. 7 and 8, the area F is hatched with dots.

[0047] 7 to 9 , in the configuration of the wiring board 1A according to the second embodiment, all second side surfaces 3s have a region F located inside a plane including the corresponding first side surface 2s. Furthermore, multiple third electrodes 6 are located in the region F of all second side surfaces 3s. Therefore, even if the number of electrodes including the third electrodes 6 is increased, the wiring board 1A can be made smaller in plan view. This allows for space saving in the planar space on which the wiring board 1A is mounted.

[0048] 9 , in the configuration of the wiring board 1A according to the second embodiment, a portion of all of the second side surfaces 3s is located on the same plane as the corresponding first side surfaces 2s of the first base 2. This simplifies the alignment of the laminate for the first base 2 or the ceramic green sheet for the insulating layer 31 with the laminate for the second base 3, thereby improving the manufacturability of the wiring board 1A. Furthermore, the strength of the wiring board 1 can be increased compared to when all four second side surfaces 3s of the second base 3 are located inside a plane including the first side surfaces 2s of the first base 2.

[0049] 7 and 8 , in the configuration of the wiring board 1A according to the second embodiment, the surface roughness of the region F of the second base 3 is greater than the surface roughness of the second side surface 3s of the second base 3, which is located on the same plane as the first side surface 2s of the first base 2. Therefore, when a capacitor 140 or the like serving as a third element is solder-mounted in the region F of the second base 3, the solder is less likely to flow in the region F of the second base 3, thereby preventing short circuits between adjacent third electrodes 6. When a capacitor 140 or the like serving as a third element is mounted in the region F of the second base 3 using a conductive adhesive, the surface area of ​​the region F of the second base 3 is increased, thereby increasing the mounting strength, e.g., adhesion strength, of the capacitor 140 or the like relative to the region F of the second base 3.

[0050] Additionally, the wiring board 1A according to the second embodiment has the same effects as the wiring board 1 according to the first embodiment described above.

[0051] A wiring board 1B and an electronic device 100B according to a third embodiment of the present disclosure will be described with reference to FIGS. 10 to 13. FIG. 10 is a schematic perspective view of the wiring board 1B according to the third embodiment, as viewed from above. FIG. 11 is a schematic perspective view of the wiring board 1B according to the third embodiment, as viewed from below. FIG. 12 is a schematic side view of the wiring board 1B according to the third embodiment. FIG. 13 is a schematic perspective view of the electronic device 100B according to the third embodiment, as viewed from the side.

[0052] 10 and 11 , the wiring board 1B according to the third embodiment of the present disclosure has the same configuration as the wiring board 1 according to the first embodiment, except for some components. The following describes the configuration of the wiring board 1B that differs from the wiring board 1 according to the first embodiment. For ease of explanation, the same reference numerals are used to designate components that have the same functions as the components described in the first embodiment.

[0053] 10 and 11 , the wiring board 1B according to the third embodiment may include a first base 2 that is rectangular in plan view. The wiring board 1B may also include a second base 3 located below the first base 2. The first base 2 and the second base 3 may each include a plurality of insulating layers stacked in the width direction WD.

[0054] In the present disclosure, the "height direction" and "up-down direction" may be directions intersecting or perpendicular to the stacking direction of the wiring board 1, as in the wiring board 1B of the third embodiment. The "width direction" may be the stacking direction of the insulating layers of the wiring board 1B, and may be, for example, the left-right direction when facing the front of the wiring board 1. The "length direction" is a direction along one direction in which the insulating layers 21 of the wiring board 1 extend, and may also be a direction intersecting the "width direction," and may be, for example, a direction connecting the front side and the back side of the wiring board 1.

[0055] 12 , a portion of a pair of second side surfaces 3s parallel to the width direction WD of the second base 3 may be located on the same plane as the corresponding first side surfaces 2s. At least a portion of a pair of second side surfaces 3s parallel to the length direction LD of the second base 3 may be located on the same plane as the corresponding first side surfaces 2s of the first base 2. Furthermore, at least one second side surface 3s may have a region F located inside a plane including the corresponding first side surface 2s.

[0056] More specifically, as shown in the examples shown in FIGS. 10 to 12 , at least one of a pair of second side surfaces 3s parallel to the length direction LD of the second substrate 3 may have a region F located inside a plane including the corresponding first side surface 2s. Furthermore, at least one of a pair of second side surfaces 3s parallel to the width direction WD of the second substrate 3 may have a region F located inside a plane including the corresponding first side surface 2s. Furthermore, a lower region of at least one of the second side surfaces 3s parallel to the length direction LD may have a region F located inside a plane including the corresponding first side surface 2s over the entire length direction LD. In other words, at least one of the second side surfaces 3s parallel to the length direction LD may have a region located on the same plane as the plane including the corresponding first side surface 2s, and a region F located inside a plane including the corresponding first side surface 2s over the entire length direction LD. Furthermore, the second substrate 3 may have a second side surface 3s whose entire surface is located on the same plane as the corresponding first side surface 2s.

[0057] The surface roughness of region F of the second substrate 3 may be greater than the surface roughness of the second side surface 3s of the second substrate 3 located on the same plane as the first side surface 2s of the first substrate 2. The surface roughness of region F of the second substrate 3, particularly the arithmetic mean roughness (Ra), may be, for example, 1.5 μm or more and 7.0 μm or less, or even 1.7 μm or more and 6.0 μm or less. The surface roughness of the second side surface 3s of the second substrate 3 located on the same plane as the first side surface 2s of the first substrate 2 may be, for example, 0.1 μm or more and 1.5 μm or less, or even 0.6 μm or more and 1.0 μm or less. In Figures 10, 11, and 13, region F is indicated by dotted hatching.

[0058] As in the example shown in Fig. 10, a plurality of first electrodes 4 may be located on the first upper surface 2u of the first base 2 for electrical connection with an image sensor 150 serving as a first element, as shown in Fig. 13. A plurality of second electrodes 5 may be located on the second lower surface 3d of the second base 3 for electrical connection with a connector 160 serving as a second element, as shown in Fig. 13.

[0059] 10 and 11 , a region F of one second side surface 3 s parallel to the longitudinal direction LD may be provided with a plurality of third electrodes 6 for electrical connection to a connector 170 serving as a third element, as shown in Fig. 13 . Furthermore, a region F of the second side surface 3 s parallel to the width direction WD may be provided with a plurality of third electrodes 6 for electrical connection to a capacitor 175 serving as a third element. The region F where the third electrodes 6 connected to the capacitor 175 are located may be an inner surface of a recess 32 recessed inward from a plane including the corresponding first side surface 2 s.

[0060] 10 , 11 , and 13 , a flexible circuit board 180 may be connected to the connector 160. A flexible circuit board 190 may be connected to the connector 170. The multiple first electrodes 4 may be electrically connected to the corresponding second electrodes 5 or third electrodes 6 by internal wiring. This allows signals to be input to and output from the image sensor 150, and power to be supplied to the image sensor 150.

[0061] 13 , the electronic device 100B may include a wiring board 1B, an imaging element 150 as a first element mounted on the first upper surface 2u of the first base 2, and a connector 160 as a second element mounted on the second lower surface 3d. Furthermore, the electronic device 100B may include a connector 170 and / or a capacitor 175 as a third element mounted on the second side surface 3s.

[0062] The first base 2 and the second base 3 may include a plurality of insulating layers stacked in the width direction WD, or the first base 2 and the second base 3 may be integrally formed by a plurality of insulating layers. In addition, the first electrode 4, the second electrode 5, and the third electrode 6 may be formed as described above in the first embodiment.

[0063] 13 , the electronic device 100B may include an image sensor 150 mounted on the first upper surface 2u. Each electrode of the image sensor 150 is electrically connected to a corresponding first electrode 4 by solder or a conductive adhesive. The image sensor 150 is an electronic component such as a CMOS or CCD, and converts an optical image formed on the imaging surface into an electrical signal for output.

[0064] 13 , the electronic device 100B may include a connector 160 mounted on the first upper surface 2u. The connector 160 is one of the electronic components, and each electrode of the connector 160 is electrically connected to a corresponding second electrode 5 by solder or a conductive adhesive.

[0065] The electronic device 100B may include a connector 170 and / or a capacitor 175 as a third element in the region F of the second side surface 3s. The connector 170 is one of the electronic components, and each electrode of the connector 170 is electrically connected to a corresponding third electrode 6 by solder or a conductive adhesive. The capacitor 175 is one of the electronic components, and each electrode of the capacitor 175 is electrically connected to a corresponding third electrode 6 by solder or a conductive adhesive.

[0066] 10 to 12 , in the configuration of the wiring board 1B according to the third embodiment, at least one second side surface 3s has a region F located inside a plane including the corresponding first side surface 2s, and the third electrode 6 is located in the region F. Therefore, even if the number of electrodes including the third electrode 6 is increased, the wiring board 1B can be made smaller in plan view. In other words, even if the number of elements including the third element mounted on the wiring board 1B is increased, the wiring board 1B and the electronic device 100B can be made smaller in plan view. This allows for space saving in the planar space required for mounting the wiring board 1B and the electronic device 100B.

[0067] According to the configuration of the wiring board 1B of the third embodiment, a portion of each pair of second side surfaces 3s extending along the width direction WD is located on the same plane as the corresponding first side surfaces 2s. This simplifies the alignment of the laminate for the first base 2 or the ceramic green sheets for the insulating layer 31 with the laminate for the second base 3, thereby improving the manufacturability of the wiring board 1B and the electronic device 100B. Furthermore, the strength of the wiring board 1B can be increased compared to when the four second side surfaces 3s of the second base 3 are located closer to the center in both the width direction WD and the length direction LD with respect to the first side surfaces 2s of the first base 2.

[0068] According to the configuration of the wiring board 1B according to the third embodiment, the surface roughness of the region F of the second base 3 is greater than the surface roughness of the second side surface 3s of the second base 3, which is located on the same plane as the first side surface 2s of the first base 2. Therefore, when a capacitor 140 or the like serving as a third element is solder-mounted in the region F of the second base 3, the solder is less likely to flow in the region F of the second base 3, thereby preventing short circuits between adjacent third electrodes 6. When a capacitor 140 or the like serving as a third element is mounted in the region F of the second base 3 using a conductive adhesive, the surface area of ​​the region F of the second base 3 is increased, thereby increasing the mounting strength, for example, the adhesion strength, of the capacitor 140 or the like relative to the region F of the second base 3.

[0069] Additionally, the wiring board 1B according to the third embodiment has the same effects as the wiring board 1 according to the first embodiment described above.

[0070] In one embodiment, (1) a wiring substrate includes a first base having a first upper surface, a first lower surface opposite the first upper surface, and four first side surfaces between the first upper surface and the first lower surface, a second base having a second upper surface in contact with the first lower surface, a second lower surface opposite the second upper surface, and four second side surfaces between the second upper surface and the second lower surface and corresponding to the four first side surfaces, a plurality of first electrodes located on the first upper surface, a plurality of second electrodes located on the second lower surface, and a plurality of third electrodes located on the second side surfaces, wherein a pair of the second side surfaces, each extending along a first direction perpendicular to a height direction, are partially located on the same plane as the corresponding first side surface, and at least one of the second side surfaces has a region located inside a plane including the corresponding first side surface, and the third electrode is located in the region.

[0071] (2) In the wiring board of (1), the second side surface extending along a second direction intersecting the first direction has the region over the entire surface.

[0072] (3) In the wiring board of (1) or (2), at least one of the second side surfaces has a recess recessed inward from a plane including the corresponding first side surface, and the region is the inner surface of the recess.

[0073] (4) In the wiring board according to any one of (1) to (3), each of the second side surfaces may have the region.

[0074] (5) In the wiring substrate according to any one of (1) to (4), the plurality of third electrodes include third electrodes positioned at different heights in one of the regions.

[0075] (6) In the wiring board according to any one of (1) to (5), the first base and the second base include a plurality of insulating layers stacked in the height direction.

[0076] (7) In the wiring board according to any one of (1) to (5), the first base and the second base include a plurality of insulating layers stacked in the first direction.

[0077] (8) In the wiring board of (6) or (7), the third electrode includes a via conductor that extends through at least one of the insulating layers and protrudes from the surface of the second side surface.

[0078] (9) In the wiring substrate according to any one of (1) to (8), at least one of the third electrodes includes a side edge extending in a height direction, and the side edge is distorted with respect to the height direction.

[0079] (10) An electronic device includes a wiring substrate according to any one of (1) to (9), a first element connected to the first electrode, a second element connected to the second electrode, and a third element connected to the third electrode.

[0080] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments and their modifications. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in the embodiments and their modifications are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art could easily make various modifications or alterations based on the present disclosure. It should also be noted that these modifications or alterations are included in the scope of the present disclosure.

[0081] REFERENCE SIGNS LIST 1 Wiring board (wiring board according to the first embodiment) 2 First base 2u First upper surface 2d First lower surface 2s First side surface 21 Insulating layer 3 Second base 3u Second upper surface 3d Second lower surface 3s Second side surface 31 Insulating layer 32 Recessed portion F Region 4 First electrode 5 Second electrode 6 Third electrode 100 Electronic device (electronic device according to the first embodiment) 110 Imaging element (first element) 120 Capacitor (second element) 130 Cable (third element) 140 Capacitor (third element) 1A Wiring board (wiring board according to the second embodiment) 1B Wiring board (wiring board according to the third embodiment) 4 First electrode 5 Second electrode 100B Electronic device (electronic device according to the third embodiment) 150 Imaging element (first element) 160 Connector (second element) 170 Connector (third element) 175 Capacitor (third element) 180 Flexible circuit board 190 Flexible circuit board

Claims

1. A wiring board comprising: a first base having a first upper surface, a first lower surface located opposite the first upper surface, and four first side surfaces located between the first upper surface and the first lower surface; a second base having a second upper surface in contact with the first lower surface, a second lower surface located opposite the second upper surface, and four second side surfaces located between the second upper surface and the second lower surface and corresponding to the four first side surfaces; a plurality of first electrodes located on the first upper surface; a plurality of second electrodes located on the second lower surface; and a plurality of third electrodes located on the second side surfaces; wherein of the four second side surfaces, portions of a pair of the second side surfaces extending along a first direction perpendicular to the height direction are located on the same plane as the corresponding first side surfaces; and at least one of the second side surfaces has an area located inside a plane including the corresponding first side surface, and the third electrode is located in said area.

2. The wiring board according to claim 1, wherein the second side surface extending along a second direction intersecting the first direction has the region over the entirety thereof.

3. A wiring board according to claim 1 or 2, wherein at least one of the second side surfaces has a recess recessed inward from a plane including the corresponding first side surface, and the region is the inner surface of the recess.

4. The wiring board according to any one of claims 1 to 3, wherein each of said second side surfaces has said region.

5. The wiring board according to any one of claims 1 to 4, wherein the plurality of third electrodes include third electrodes located at different heights in one of the regions.

6. The wiring board according to any one of claims 1 to 5, wherein the first base and the second base include a plurality of insulating layers stacked in the height direction.

7. The wiring board according to any one of claims 1 to 5, wherein the first base and the second base include a plurality of insulating layers stacked in the first direction.

8. A wiring board according to claim 6 or 7, wherein the third electrode includes a via conductor extending through at least one of the insulating layers and protruding from the surface of the second side surface.

9. The wiring board according to any one of claims 1 to 8, wherein at least one of the third electrodes includes a side edge extending in the height direction, and the side edge is distorted with respect to the height direction.

10. An electronic device comprising: a wiring board according to any one of claims 1 to 9; a first element connected to the first electrode; a second element connected to the second electrode; and a third element connected to the third electrode.

Images