Ceramic substrate, method for manufacturing ceramic substrate, wiring substrate, package, microphone device, gas sensor device

Abstract

This ceramic substrate comprises: at least one first layer having a first through-hole; and at least one second layer positioned to be superposed on the first layer. The second layer has a plurality of second through-holes each having a hole diameter smaller than the first through-hole. The second through-holes includes: a plurality of inner through-holes positioned in an inner area of the first through-hole when viewed in a plan view; and a plurality of outer through-holes positioned in an outer area of the first through-hole.

Description

Technical Field

[0001] The present disclosure relates to a ceramic substrate, a method for manufacturing a ceramic substrate, a wiring substrate, a package, a microphone device, and a gas sensor device.

Background Art

[0002] For example, sound holes are formed in a substrate used to configure a microphone device. Patent Document 1 discloses a MEMS microphone in which a lower notch is formed in the substrate, and a plurality of fine holes as sound holes are located in the notch. Patent Document 2 discloses a microphone device including a lid body in which a plurality of fine holes are located in a notch.

[0003] Further, Patent Document 3 discloses a ceramic member in which a thin ceramic plate in a window portion (large-diameter hole) has a plurality of fine through holes. It is also conceivable to use such a ceramic member as a lid body for a microphone device or a gas sensor device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0005] A ceramic substrate according to one aspect of the present disclosure includes at least one first layer having a first through hole, and at least one second layer overlapping the first layer, wherein the second layer has a plurality of second through holes having a smaller hole diameter than the first through hole, and the second through holes include a plurality of inner through holes located in an inner region of the first through hole and a plurality of outer through holes located in an outer region of the first through hole in a plan view.

[0006] A method for manufacturing a ceramic substrate according to an aspect of the present disclosure includes a step of forming a first through hole in a first sheet that is a ceramic green sheet, a step of forming a plurality of second through holes having a smaller hole diameter than the first through hole in a region having an area larger than the opening area of the first through hole in a second sheet that is a ceramic green sheet, and a step of laminating the first sheet and the second sheet such that some of the plurality of second through holes are located outside the first through hole in a plan view.

[0007] A wiring board according to an aspect of the present disclosure includes the substrate and wiring.

[0008] A method for manufacturing a wiring board according to an aspect of the present disclosure includes a step of forming a first through hole in a first sheet that is a ceramic green sheet, a step of forming a plurality of second through holes having a smaller hole diameter than the first through hole in a region having an area larger than the opening area of the first through hole in a second sheet that is a ceramic green sheet, a step of forming wiring on at least one of the first sheet and the second sheet, and a step of laminating the first sheet and the second sheet such that some of the plurality of second through holes are located outside the first through hole in a plan view.

[0009] A package according to an aspect of the present disclosure includes the substrate as a lid body and a wiring board having an element mounting region at a position overlapping the first through hole in a plan view.

[0010] A microphone device according to an aspect of the present disclosure includes the wiring board or the package and a microphone element.

[0011] A gas sensor device according to an aspect of the present disclosure includes the wiring board or the package and a gas sensor element.

[0012] An electronic device according to one aspect of the present disclosure includes the microphone device or the gas sensor device.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Embodiments for Carrying Out the Invention

[0014] In a substrate on which elements such as a microphone element are mounted, outside the region where the fine through-holes are provided, a bonding material or the like for mounting the elements is applied. There is a possibility that the bonding material or the metal material may block the fine through-holes that conduct from the outside of the substrate to the elements.

[0015] Also, for example, a microphone module in which a microphone is mounted on a mounting substrate is mounted on an electronic device such as a smartphone. When a substrate having fine through-holes is used as a lid body, a sealing material is disposed around the region where the fine through-holes of the substrate are provided between the housing of the electronic device and the substrate. In this case, there is a possibility that the sealing material may block the fine through-holes.

[0016] Furthermore, any of the above-described substrates can be realized by a ceramic substrate manufactured by laminating a layer having large-diameter holes and a layer having fine holes, but there is also a possibility that the fine through-holes may be blocked due to misalignment in the lamination process.

[0017] As described above, in the conventional substrate, there was a possibility that the number of through-holes conducting from the outside of the substrate to the elements decreased due to the spread of the bonding material or the sealing material, or due to misalignment in the lamination position in the manufacturing process of the substrate.

[0018] The ceramic substrate of the present disclosure can reduce the possibility that the number of through-holes conducting from the outside of the substrate to the elements decreases due to the spread of the bonding material or the sealing material, or due to misalignment in the lamination position in the manufacturing process of the substrate. 〔Embodiment 1〕 (Configuration of Microphone Device 200) Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the description of "parallel" only requires being parallel at a visible level and does not require being strictly parallel. Also, the description of "perpendicular" only requires being perpendicular at a visible level and does not require being strictly perpendicular.

[0019] In Embodiment 1, an example in which the ceramic substrate or wiring substrate according to the present disclosure is applied to a microphone device will be described.

[0020] The distinction between up and down in the following description is for convenience and does not limit the up and down when the package and the microphone device are actually used. In this specification, in the ceramic substrate 1 or the wiring substrate 10, the surface on which the microphone element 3 is mounted is defined as the upper surface. Also, in the drawings, the positive direction of the Z-axis is the upward direction. The X-axis direction is the major axis direction of the ceramic substrate 1 or the wiring substrate 10, and the Y-axis is an axis that intersects perpendicularly to the X-axis and the Z-axis.

[0021] FIG. 1 is a cross-sectional view when the microphone device 200 is cut along a plane perpendicular to the upper surface of the wiring substrate 10 and parallel to the X-axis direction. FIG. 1 shows the ceramic substrate 1 according to the present disclosure, the wiring substrate 10 including the ceramic substrate 1 and the wiring 2, and the microphone device 200 including the wiring substrate 10, the microphone element 3, and the semiconductor element 4. It shows a MEMS microphone device in which the microphone element 3 is a MEMS (Micro Electro Mechanical Systems) microphone.

[0022] The microphone device 200 shown in FIG. 1 shows an example including a lid 7. A configuration including the wiring substrate 10 and the lid 7 is referred to as a package 400. That is, the microphone device 200 may include the package 400 and the microphone element 3. Although the microphone device 200 includes the lid 7, the microphone device 200 may not include the lid 7.

[0023] FIG. 2 is a one-point convergence view showing the upper surface of an example of the wiring substrate 10. FIG. 3 is a one-point convergence view showing the lower surface of an example of the wiring substrate 10.

[0024] The elements constituting the microphone device 200 will be described in detail below.

[0025] (Ceramic substrate 1) As shown in FIG. 1, the ceramic substrate 1 has a first layer 101 having a first through hole 11. The ceramic substrate 1 also has a second layer 102 that overlaps the first layer 101 and has a second through hole 12 having a smaller hole diameter than the first through hole 11. The ceramic substrate 1 is, for example, rectangular or square in plan view. The first layer 101 and the second layer 102 are each an insulating layer made of an insulating material containing a ceramic material such as an aluminum oxide sintered body, a glass ceramic sintered body, a mullite sintered body, or an aluminum nitride sintered body.

[0026] The first layer 101 has a third surface 101X on the side facing the second layer 102 and a fourth surface 101Y located on the side opposite to the third surface 101X. The fourth surface 101Y of the lowermost first layer 101 constitutes a part of the outer surface (lower surface) of the ceramic substrate 1. The thickness of the first layer 101 is, for example, 0.02 mm or more and 0.20 mm or less. In the fourth surface 101Y, the first through hole 11 is, for example, circular, and its diameter is, for example, 0.1 mm or more and 1.0 mm or less.

[0027] The second layer 102 has a second surface 102X on the side facing the first layer 101 and a first surface 102Y located on the side opposite to the second surface 102X. The first surface 102Y of the uppermost second layer 102 constitutes a part of the outer surface (upper surface) of the ceramic substrate 1. In other words, the ceramic substrate 1 has a first surface 102Y and a fourth surface 101Y that constitute a part of the outer surface.

[0028] The ceramic substrate 1 has a plurality of fine second through-holes 12 that are smaller than the first through-holes 11, thereby realizing a substrate that allows gas to pass through but is difficult for water to pass through. The thickness of the second layer 102 is, for example, 0.02 mm or more and 0.20 mm or less. The second through-holes 12 are substantially circular, and their diameter is, for example, 0.010 mm or more and 0.050 mm or less. By the thickness of the second layer 102 and the diameter of the second through-holes 12 being within the above ranges, the ceramic substrate 1 can have excellent waterproof performance. Also, by the thickness of the second layer 102 being 0.20 mm or less, it can have excellent air permeability. Thereby, when the ceramic substrate 1 is applied to a microphone device, excellent acoustic characteristics can be obtained.

[0029] Also, the second through-holes 12 are arranged in the second layer 102 at a constant array pitch (hole pitch). The hole pitch of the second through-holes 12 can be appropriately set in consideration of the characteristics, strength, etc. required for the microphone device or gas sensor device using the ceramic substrate 1, according to the thickness of the second layer 102, the size of the second through-holes 12, and the size of the first through-holes 11. The hole pitch of the second through-holes 12 is, for example, 0.05 mm or more and 0.30 mm or less. The hole pitch referred to here is the distance between the centers of the second through-holes 12, as shown by DP in FIGS. 4 and 5. The arrangement of the second through-holes 12 in FIG. 5 is a lattice arrangement (square lattice arrangement), and the center-to-center distance in the X direction and the Y direction, that is, the shortest center-to-center distance, is defined as the hole pitch DP. Since the arrangement of the second through-holes 12 in FIG. 4 is a 60° staggered arrangement (also called a regular triangular lattice arrangement), the hole pitch DP is the same in any direction.

[0030] As shown in FIGS. 1 and 2, the first surface 102Y of the second layer 102 has an element mounting region R. Although the element mounting region R is also described in FIG. 3, the element mounting region R in FIG. 3 is a projection of the element mounting region R on the first surface 102Y onto the fourth surface 101Y (lower surface) for understanding the positional relationship between the first through-hole 11 and the element mounting region R. In the present embodiment, the element mounting region R is a region where the microphone element 3 is mounted. The element mounting region R may be a region overlapping the microphone element 3 mounted in the element mounting region R on the first surface 102Y. Alternatively, the element mounting region R may be a region surrounded by a virtual line connecting alignment marks, which is located on the first surface 102Y and is used when mounting the microphone element 3 mounted in the element mounting region R.

[0031] FIG. 4 is a schematic plan view when the element mounting region R of the wiring board 10 is viewed in plan from the upper surface of the wiring board 10 (from the positive Z-axis direction). As shown in FIG. 4, since the element mounting region R is positioned so as to surround the first through-hole 11 in the plan view, the acoustic characteristics of the microphone device 200 can be improved.

[0032] The second through-hole 12 includes a plurality of inner through-holes 121 located in the inner region of the first through-hole 11 and a plurality of outer through-holes 122 located in the outer region of the first through-hole 11 in the plan view of the ceramic substrate 1. The inner region of the first through-hole 11 means a region inside the outer edge of the first through-hole 11 in the plan view of the ceramic substrate 1. The outer region of the first through-hole 11 means a region outside the outer edge of the first through-hole 11 in the plan view of the ceramic substrate 1. The second through-hole 12 is positioned at the same hole pitch from the inner region to the outer region of the first through-hole 11. The second through-hole 12 located across the inner region and the outer region of the first through-hole 11 is defined as the inner through-hole 121.

[0033] In the ceramic substrate 1, a second through-hole 12 is located from the inner region to the outer region of the first through-hole 11. In other words, the first through-hole 11 is located within the arrangement region of the second through-hole 12. Therefore, even if the centers of the arrangement region of the second through-hole 12 and the first through-hole 11 do not coincide, the ceramic substrate 1 is such that the second through-hole 12 is not blocked by the first layer 101 within the first through-hole 11.

[0034] As shown in FIG. 1, when the microphone device 200 is configured using the ceramic substrate 1, the microphone element 3 is joined to the ceramic substrate 1 by a joining material 19. In this case, the inner through-hole 121 is an effective through-hole that conducts from the outside of the substrate to the element and effectively acts as a sound hole for taking in sound from the outside. Since the ceramic substrate 1 has the outer through-hole 122, even when the joining material 19 spreads during the joining process of joining the microphone element 3, the spread of the joining material 19 to the first through-hole 11 side (inner through-hole 121 side) is suppressed by the outer through-hole 122. Therefore, the possibility that the inner through-hole 121 is blocked by the joining material 19 can be reduced. That is, the possibility that the number of effective through-holes decreases due to the spread of the joining material 19 can be reduced, and the possibility that the acoustic effect of the microphone device 200 deteriorates can be reduced. Also, when the joining material 19 slightly enters the outer through-hole 122, the joining strength is improved by the anchor effect.

[0035] The outer through-hole 122 may be in the outer region of the first through-hole 11 and located inside the element mounting region R. Thereby, the possibility that the joining material 19 spreads to the first through-hole 11 side can be reduced.

[0036] Also, the outer through-hole 122 may be located at a position overlapping the element joining region (the region where the joining material is located) in the element mounting region R. Since the joining material 19 also spreads outside the element mounting region R, a part of the joining region may be located outside the element mounting region R. By positioning the outer through-hole 122 at a position overlapping the element joining region, the joining material 19 can slightly enter the outer through-hole 122, and the joining strength can be improved.

[0037] On the other hand, even if the outer through-hole 122 is located outside the element mounting region R or the bonding region, the above-described effects cannot be obtained. Further, the second through-hole 12 is a fine through-hole, and the cost of manufacturing the ceramic substrate 1 increases as the number of the second through-holes 12 increases. By limiting the region where the outer through-hole 122 exists, it is possible to achieve both the effect of reducing the possibility that the effective through-hole is blocked by the above-described bonding material 19 or the like and the effect of suppressing an excessive increase in the manufacturing cost of the ceramic substrate 1. In addition, it is possible to reduce the possibility that the number of the second through-holes 12 becomes excessive and the strength of the ceramic substrate 1 decreases.

[0038] Therefore, as shown in FIG. 4, in the plan view, the outer through-hole 122 is a region outside the first through-hole 11 and is defined by a distance L (L = 2DP) that is two hole pitches DP of the second through-hole 12 away from the outer edge of the first through-hole 11. within the domain It may be located in the region.

[0039] The arrangement shape of the plurality of second through-holes 12 in the second layer 102 is not particularly limited. However, as shown in FIG. 4, in the second layer 102, the second through-holes 12 may have a staggered arrangement. More specifically, the second through-holes 12 may have a 60° staggered arrangement. FIG. 5 is a schematic plan view of the element mounting region R of the ceramic substrate 1 when viewed in plan from the upper surface of the ceramic substrate 1 (from the positive Z-axis direction), showing an example of another arrangement shape of the second through-holes 12. In FIG. 5, the second through-holes 12 have a grid arrangement.

[0040] In FIGS. 4 and 5, the distance (hole pitch DP) between the second through holes 12 is the same for both the staggered arrangement and the grid arrangement. Also, the hole diameters of the second through holes 12 are the same. On the other hand, when comparing the staggered arrangement and the grid arrangement, since the interval in the Y-axis direction is smaller in the staggered arrangement, the number of inner through holes 121 is larger in the staggered arrangement. That is, the staggered arrangement can arrange more second through holes 12 with the same diameter per unit area when compared with the grid arrangement having the same hole pitch DP. Furthermore, among the staggered arrangements, the 60° staggered arrangement in which an equilateral triangle is formed when the centers of adjacent holes are connected by a straight line can arrange the most second through holes 12 per unit area.

[0041] In the microphone device 200, in order to obtain good acoustic characteristics, it is better that the ratio of the total area of the hole portions of the inner through holes 121, which are effective through holes, to the area of the hole portion of the first through hole 11 is higher. That is, it is better that the number of inner through holes 121 is larger. From the above, considering the acoustic characteristics, the arrangement of the second through holes 12 may be a staggered arrangement. By arranging the plurality of second through holes 12 in a staggered arrangement, the acoustic characteristics of the microphone device 200 can be improved.

[0042] Also, in the grid arrangement and the 60° staggered arrangement, the hole pitch DP of the second through holes 12 is the same. Even when the number of second through holes 12 increases by adopting the 60° staggered arrangement, it is considered that the possibility of reducing the strength of the ceramic substrate 1 is low. Also, when compared with other staggered arrangements, in the 60° staggered arrangement, all the hole intervals are the same, and there is no portion where the hole interval is small and the strength is small, so it is difficult to be a starting point of fracture and the strength is high. From the above, by having the second through holes 12 in a 60° staggered arrangement, the strength and acoustic characteristics of the microphone device 200 can be improved.

[0043] Since the ceramic substrate 1 has a laminated structure of ceramic insulating layers, a three-dimensional wiring structure can be configured. Also, since layers with different thicknesses can be laminated, the fine second through-hole 12 is formed in the thin second layer 102 that is easy to form, and laminated with the first layer 101 or a plurality of first layers having a sufficient thickness to ensure strength, thereby ensuring the strength of the entire substrate. Further, the ceramic substrate 1 can reduce corrosion and deterioration against water or gas compared to a substrate made of metal or organic material. Furthermore, the ceramic substrate 1 can have high strength compared to a substrate made of silicon. Therefore, the ceramic substrate 1 can be thinned. Further, since it has high strength, the number of through-holes can be increased, and the total area of the openings of the effective through-holes can be increased.

[0044] FIG. 6 is a schematic plan view when the element mounting region R of the ceramic substrate 1 showing another example of the shape of the first through-hole 11 is viewed in plan from the upper surface of the ceramic substrate 1 (from the positive Z-axis direction).

[0045] The cross-sectional shape of the first through-hole 11 in the plane (X-Y plane) parallel to the ceramic substrate 1 is not limited to a circular shape, and may be a polygonal shape such as a quadrangle.

[0046] For example, the figure indicated by reference numeral 6001 in FIG. 6 shows an example in which the first layer 101 has a first through-hole 11A having a quadrangular cross-sectional shape. The dimensions of the first through-hole 11 at this time are such that, for example, the length of the side of the quadrangle (the distance between opposite sides) corresponds to the above diameter. Also, when the first through-hole 11 is polygonal, each corner may have a rounded shape like the first through-hole 11A. By having a quadrangular cross-sectional shape like the first through-hole 11A, the effective through-holes can be increased. When the cavity shape of the microphone element 3 is quadrangular in plan view, the quadrangular first through-hole 11 may be adopted.

[0047] Further, the diagram indicated by reference numeral 6002 in FIG. 6 shows an example in which the first layer 101 has a first through-hole 11B with a hexagonal cross-sectional shape. When the cross-sectional shape of the first through-hole 11 is a regular hexagonal shape like the first through-hole 11B, the arrangement shape of the second through-holes 12 may be a 60° staggered arrangement. With this configuration, the number of effective through-holes can be increased.

[0048] In FIG. 1, an example is shown in which the ceramic substrate 1 has a three-layer structure in which two first layers 101 and one second layer 102 are laminated. However, the ceramic substrate 1 only needs to include at least one first layer 101 and at least one second layer 102.

[0049] FIG. 7 shows a cross-sectional view of a ceramic substrate 1A as a modified example of the ceramic substrate 1. As in the ceramic substrate 1A shown in FIG. 7, the second layer 102 may be sandwiched between two first layers 101. That is, the openings of the first through-holes 11 are on both sides of the ceramic substrate 1A with the second through-holes 12 interposed therebetween. With the above configuration, the possibility of the second through-holes 12 being damaged due to contact with external articles can be reduced. Also, even with this configuration, the possibility that the number of through-holes conducting from the outside of the substrate to the elements is reduced due to misalignment of the lamination positions in the manufacturing process of the substrate is reduced.

[0050] (Manufacturing Method of Ceramic Substrate 1) The ceramic substrate 1 can be manufactured, for example, by the following manufacturing method including the following first to fifth steps. The second step and the third step may be performed either first or in parallel.

[0051] The first step is a step of producing a first sheet, which is a ceramic green sheet that becomes the first layer 101, and a second sheet, which is a ceramic green sheet that becomes the second layer 102, by firing. In the first step, raw material powders such as aluminum oxide and silicon oxide are formed into a sheet shape together with a suitable organic binder and organic solvent to produce the first sheet or the second sheet.

[0052] The second step is a step of forming a first through hole 11 in the first sheet. The first through hole 11 is formed, for example, by punching the first sheet using a mold or the like. The hole diameter at the time of punching is a size such that the hole diameter after firing is 0.1 mm or more and 1.0 mm or less.

[0053] The third step is a step of forming a plurality of second through holes 12 in the second sheet. More specifically, in the third step, a plurality of second through holes 12 having a hole diameter smaller than that of the first through hole 11 are formed in a region of the second sheet having an area larger than the opening area of the first through hole 11. At this time, the position of the region where the plurality of second through holes 12 are formed is a position overlapping the first through hole 11 when the first sheet and the second sheet are laminated in a later fourth step. That is, the region where the plurality of second through holes 12 are formed includes the first through hole 11 and is a region larger than the opening of the first through hole 11 in a plan view when the first sheet and the second sheet are laminated in a later fourth step. For example, the region where the second through holes 12 are formed may be a region defined by a distance L (L = 2DP) that is two hole pitches DP outside the outer edge of the first through hole 11 in the plan view at the time of lamination. With this configuration, even when a lamination shift of about two hole pitches DP occurs during lamination, the possibility of the inner through hole 121 decreasing can be reduced. Specifically, when the hole pitch is 0.30 mm, a lamination shift of about 0.60 mm can be tolerated.

[0054] The second through hole 12 is formed, for example, by punching the second sheet using a mold or the like. The hole diameter at the time of punching is a size such that the hole diameter after firing is 0.010 mm or more and 0.050 mm or less. The first through hole 11 and the second through hole 12 may be formed using a laser.

[0055] The fourth step is a step of laminating the first sheet and the second sheet in a plan view such that some of the plurality of second through holes 12 are located outside the first through hole 11.

[0056] The fifth step is a step of firing the laminate laminated in the fourth step at a temperature of 1300 to 1600 °C.

[0057] Since the ceramic green sheet shrinks by about 10% to 20% due to firing, the holes formed in the green sheet can have a hole diameter that is about 10% to 20% larger than the diameters of the first through hole 11 and the second through hole 12 after firing. Also, since the ceramic green sheet before firing is a soft material, it is easy to perform the above-described fine hole processing. Therefore, the ceramic substrate 1 can easily form fine through holes such as those with a diameter of 100 μm or less, which are considered difficult for metal substrates or organic substrates. In addition, the method of forming fine through holes in the ceramic green sheet using a mold or the like has higher productivity compared to the method of forming through holes by etching on a substrate made of silicon or the like. That is, the ceramic substrate 1 can improve productivity compared to substrates composed of other materials.

[0058] Also, the thinner the ceramic green sheet, the easier it is to form fine through holes. By using a thin green sheet as the ceramic green sheet constituting the second layer 102, fine second through holes 12 can be easily formed. Also, the ceramic green sheet constituting the first layer 101 can have a thickness and number of layers corresponding to the strength required for the ceramic substrate 1. That is, in the fourth step, a plurality of first layers 101 may be laminated. Since the ceramic substrate 1 is a laminate in which the second layer 102 having fine second through holes 12 and the other first layer 101 are laminated, it becomes easy to ensure a required substrate thickness while having fine through holes.

[0059] The manufacturing method of the ceramic substrate according to the present disclosure includes a step of forming a first through-hole 11 in a first sheet which is a ceramic green sheet. The manufacturing method of the ceramic substrate according to the present disclosure includes a step of forming a plurality of second through-holes 12 having a smaller hole diameter than the first through-hole 11 in a region of a second sheet which is a ceramic green sheet and having an area larger than the opening area of the first through-hole 11. The manufacturing method of the ceramic substrate according to the present disclosure includes a step of laminating the first sheet and the second sheet in a plan view such that some of the plurality of second through-holes 12 are located outside the first through-hole 11.

[0060] By the manufacturing method, a ceramic substrate 1 including a plurality of inner through-holes 121 located in the inner region of the first through-hole 11 and a plurality of outer through-holes 122 located in the outer region of the first through-hole 11 in a planar perspective can be manufactured. That is, a substrate in which the possibility of a bonding material or a sealing material blocking an effective through-hole can be reduced can be manufactured.

[0061] Further, the second sheet after the third step has a plurality of second through-holes 12 having a smaller hole diameter than the first through-hole 11 in a region having an area larger than the opening area of the first through-hole 11. Therefore, even when a misalignment occurs in the lamination of the first sheet and the second sheet in the fourth step, the possibility of reducing the number of effective through-holes can be reduced.

[0062] (Wiring substrate 10) As shown in FIG. 1, the wiring substrate 10 includes a ceramic substrate 1 and wiring 2.

[0063] For example, in the example shown in FIG. 1, the wiring board 10 includes, as wiring 2, connection pads 2A, terminal electrodes 2D, through conductors 2B, and internal wiring layers 2C. On the upper surface of the wiring board 10, connection pads 2A for connecting to the microphone element 3 and a bonding metal layer 6 are provided. Also, on the lower surface of the wiring board 10, terminal electrodes 2D for connecting to an external electric circuit are provided. These connection pads 2A and terminal electrodes 2D are electrically connected by through conductors 2B and internal wiring layers 2C provided inside the wiring board 10. The through conductors 2B penetrate the insulating layers (the first layer 101 and the second layer 102), and the internal wiring layers 2C are disposed between the insulating layers. The terminal electrodes 2D may be provided not on the lower surface of the wiring board 10 but from the lower surface to the side surface or on the side surface. Also, on the lower surface of the wiring board 10, a sealing metal layer 8 surrounding the opening of the first through hole 11 is provided.

[0064] The wiring 2, the bonding metal layer 6, and the sealing metal layer 8 mainly include, for example, metals such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, platinum, nickel, or cobalt, or alloys containing these metals as conductor materials. The wiring 2, the bonding metal layer 6, and the sealing metal layer 8 are formed on the surface of the wiring board 10 as metal layers such as metallized layers or plated layers of conductor materials. The above metal layer may be a single layer or multiple layers. Also, the wiring 2 is formed inside the wiring board 10 by metallization of the conductor material.

[0065] In the method for manufacturing a wiring board according to the present disclosure, a step of forming the wiring 2 may be added to at least one of the first sheet and the second sheet before the fourth step in the method for manufacturing the ceramic board described above. The other steps are the same as those in the method for manufacturing the ceramic board.

[0066] The connection pad 2A, the internal wiring layer 2C, the terminal electrode 2D of the wiring 2, the bonding metal layer 6, and the sealing metal layer 8 can be formed as follows. For example, when the wiring 2 is a tungsten metallization layer, a metal paste prepared by mixing tungsten powder with an organic solvent and an organic binder is printed by a method such as a screen printing method at a predetermined position on the first sheet and the second sheet, whereby it can be formed. Further, the through-conductor 2B may be formed by providing a through-hole at a predetermined position of a ceramic green sheet prior to the printing of the above metal paste and filling the through-hole with the same metal paste as described above.

[0067] Further, a plating layer such as nickel or gold may be further deposited on the exposed surface of the metallization layer after firing by using an electrolytic plating method or an electroless plating method or the like.

[0068] That is, the method for manufacturing a wiring board according to the present disclosure includes the following steps. A step of forming a first through-hole 11 in a first sheet which is a ceramic green sheet. A step of forming a plurality of second through-holes 12 having a smaller hole diameter than the first through-hole 11 in a region of a second sheet which is a ceramic green sheet and having an area larger than the opening area of the first through-hole 11. A step of forming a wiring on at least one of the first sheet and the second sheet. A step of laminating the first sheet and the second sheet in a plan view such that some of the plurality of second through-holes 12 are located outside the first through-hole 11.

[0069] By the manufacturing method, it is possible to manufacture a wiring board that can reduce the possibility that a bonding material or a sealing material blocks an effective through-hole. Further, even when a misalignment occurs in the lamination of the first sheet and the second sheet, it is possible to reduce the possibility that the number of effective through-holes is reduced.

[0070] The wiring board 10 includes a ceramic substrate 1 and wirings 2. Thus, similar to the ceramic substrate 1, even if the center of the arrangement region of the second through-hole 12 and the center of the first through-hole 11 do not coincide, the wiring board 10 is a substrate in which the second through-hole 12 is not blocked by the first layer 101 in the first through-hole 11. Also, it is possible to reduce the possibility that the number of through-holes for conducting from the outside of the substrate to the elements is reduced due to misalignment of the stacking positions in the manufacturing process of the wiring board 10. Furthermore, a wiring board 10 can be realized that can reduce the possibility that the number of effective through-holes is reduced even when the bonding material 19 spreads in the bonding process of bonding the microphone element 3.

[0071] (Microphone element 3) The microphone element 3 is a MEMS microphone semiconductor element having a diaphragm structure or a beam structure, such as a sensor device having a vibrating electrode, and is fixed to the element mounting region R on the wiring board 10. The microphone element 3 is, for example, fixed by bonding the lower surface of the microphone element 3 to the element mounting region R of the wiring board 10 with the bonding material 19. An electrode (not shown) disposed on the upper surface of the microphone element 3 and the wiring board 10 or the semiconductor element 4 are electrically connected to each other by a connecting member 5.

[0072] In the microphone device 200, the terminal electrode 2D provided on the lower surface or the like of the wiring board 10 among the wirings 2 is electrically connected to an external electric circuit, whereby the microphone element 3 mounted on the wiring board 10 and the external electric circuit are electrically connected. That is, the microphone element 3 and the external electric circuit are electrically connected to each other via a connecting member 5 such as a bonding wire and the wiring 2. The external electric circuit is, for example, an electric circuit of a mounting substrate (circuit board) mounted on an electronic device such as a smartphone.

[0073] The microphone element 3 includes, for example, a diaphragm and a back plate. The diaphragm and the back plate act like a parallel-plate capacitor. When the diaphragm vibrates due to sound pressure, the gap length with the back plate changes, causing a change in capacitance. The microphone element 3 transmits this change to the semiconductor element 4 as an electrical signal.

[0074] The semiconductor element 4 is, for example, an integrated circuit such as an ASIC (Application Specific Integrated Circuit). The semiconductor element 4 has a function of amplifying, for example, the electrical signal received from the microphone element 3. The semiconductor element 4 is electrically connected to the microphone element 3 and the wiring board 10 by a connection member 5, for example. Passive components (not shown) such as capacitors may be mounted on the wiring board 10 in addition to the semiconductor element 4. The passive components are connected to the connection pads 2A by soldering, for example.

[0075] (Cover) In the example shown in FIG. 1, the microphone element 3 is sealed and protected by the cover 7 on the upper surface side of the wiring board 10. In the example shown in FIG. 1, the microphone device 200 includes a box-shaped (cap-shaped) cover 7 that collectively covers the connection pads 2A on the upper surface of the wiring board 10, the microphone element 3, and the connection member 5.

[0076] The lid 7 is made of materials such as metal, resin, and ceramics, and is joined to the wiring board 10. The lid 7 may be joined via a sealing bonding material. Examples of the sealing bonding material include resin adhesives, glass, brazing materials containing solder, etc. When joining the lid 7 and the wiring board 10 with a brazing material, a bonding metal layer 6 may be provided on the upper surface of the wiring board 10 so as to surround the region R on the upper surface of the wiring board 10 and the connection pads 2A arranged outside thereof. Also, when the lid 7 is made of metal, the lid 7 may be joined to the bonding metal layer 6 on the wiring board 10 by welding such as seam welding or laser welding. In the case of joining using a brazing material or the like, it is overall heating by reflow heating, whereas in the case of joining by seam welding or laser welding, it can be local heating only at the joint part. Therefore, the influence of heat on the microphone element 3 and the semiconductor element 4 can be reduced. The bonding metal layer 6 may be formed of a metal film such as a plating film or a metallized layer, for example. When the lid 7 is made of a material with low wettability (bondability) of a brazing material, such as resin or ceramics, a bonding metal layer may also be formed on the lid 7.

[0077] When the lid 7 is made of a conductive material such as metal, it can function as a shielding member against noise invading from the outside. Also, as shown in FIG. 1, the bonding metal layer 6 and the sealing metal layer 8 may be connected by the wiring 2 (through-conductor 2B and internal wiring layer 2C). Since the sealing metal layer 8 is connected to the ground potential of the external circuit, the lid 7 is connected to the ground potential of the external circuit via the wiring 2 and the sealing metal layer 8. With this configuration, the shielding performance can be further enhanced by connecting to the ground potential via the bonding metal layer 6. Thereby, acoustic noise is reduced and the operation reliability is improved.

[0078] (Summary) The microphone device 200 includes a wiring board 10 and a microphone element 3. With this configuration, it has excellent waterproof characteristics. Also, it is possible to realize the microphone device 200 that can reduce the possibility of deterioration of the acoustic effect of the microphone device 200 due to the decrease in the number of effective through-holes caused by the spread of the bonding material 19.

[0079] In the microphone device 200, the second layer 102 of the wiring board 10 has a second surface 102X facing the first layer 101 and a first surface 102Y located on the opposite side of the second surface. The first surface 102Y has an element mounting region R, and the element mounting region R is positioned so as to surround the first through-hole 11 in a plan view.

[0080] With this configuration, in the bonding process of bonding the microphone element 3, even when the bonding material 19 spreads, it is possible to realize a wiring board that can reduce the possibility of a decrease in the number of effective through-holes. Also, the possibility that water that has entered through the opening formed in the mounting board reaches the microphone element 3 is reduced by the second layer 102. Even if water enters from the first through-hole 11, since the outer through-hole 122 exists, it becomes difficult for the water to reach the microphone element 3.

[0081] Also, when the wiring board 10 is used as a board for mounting the microphone element 3, by mounting the microphone element 3 on the first surface 102Y, the acoustic characteristics can be improved. Since a recess 13 defined by the first through-hole 11 of the first layer 101 and the lower surface of the second layer 102 is formed on the lower surface of the wiring board 10, the possibility of damage to the second layer 102 due to contact with external articles can be reduced. By the recess 13 acting as an air pocket, the possibility of external water reaching the second layer 102 can be reduced. Since there is no recess 13 on the upper surface of the wiring board 10, the element mounting region R is likely to be flat, and the possibility of tilting when mounting the microphone element 3 is reduced.

[0082] (Modification Example 1 of Microphone Device) FIG. 8 is a cross-sectional view of a microphone device 201 which is a modified example of the microphone device 200. The microphone device 201 includes a package 400A, a microphone element 3, and a semiconductor element 4. The package 400A has a wiring board 10, a frame-shaped portion 14, and a lid body 7A.

[0083] The frame-shaped portion 14 forms an accommodation recess for accommodating the microphone element 3, connection pads 2A, and a connection member 5. The frame-shaped portion 14 may be made of the same insulating material as the ceramic substrate 1. The frame-shaped portion 14 may be integrally formed with the wiring board 10. The lid body 7A is flat and is a member that closes the opening of the accommodation recess.

[0084] Regarding other configurations of the microphone device 201, they are the same as those of the microphone device 200 in Embodiment 1 shown in FIG. 1. When the frame-shaped portion 14 is integrally formed with the insulating layers (the first layer 101 and the second layer 102), the wiring board 10 has a cavity for accommodating the microphone element 3 and the like on its upper surface. As a result, it becomes integral up to the frame-shaped portion 14, and since the thickness of the wiring board 10 increases, the strength is improved. Also, since the joint portion of the lid body 7A is separated from the mounting positions of the microphone element 3 and the semiconductor element 4, the influence of heat when welding the lid body 7A is reduced. Furthermore, since the lid body 7A is flat, it is easy to manufacture and the cost can be suppressed.

[0085] In addition to the above configuration, a through-conductor penetrating the frame-shaped portion 14 and connected to the bonding metal layer 6 may be provided, and the through-conductor may be connected to a ground potential via a wiring 2. With this configuration, together with the metal lid body 7A bonded to the bonding metal layer 6, it can function as a shield against external electromagnetic waves. Thereby, a microphone device 201 with less noise can be realized.

[0086] (Modified Example 2 of Microphone Device) FIG. 9 is a cross-sectional view of the microphone device 202 and the mounting substrate 50 as a modified example. The microphone device 202 includes a package 400, a microphone element 3, and a semiconductor element 4. In the microphone device 202, the microphone element 3 and the wiring substrate 10 are flip-chip connected. That is, the microphone element 3 is connected to the connection pad 2A via the terminal 16. In this case, the microphone element 3 is connected to the semiconductor element 4 via the wiring 2 in the wiring substrate 10. FIG. 9 shows an example in which the microphone device 202 has a box-shaped lid 7, but the configuration for protecting the microphone element 3, the semiconductor element 4, the connection member 5, and the connection pad 2A is not limited to this example.

[0087] Also, the microphone device 202 is mounted on the mounting substrate 50 such that the side of the wiring substrate 10 having the recess 13 faces the mounting substrate 50. The microphone device 202 is mounted on the mounting substrate 50 by connecting the terminal electrode 2D and the sealing metal layer 8 of the microphone device 202 and the wiring 52 of the mounting substrate 50 via the conductive bonding material 9. Thereby, the microphone device 202 is electrically connected to the mounting substrate 50.

[0088] The sealing metal layer 8 is provided so as to surround the opening of the recess 13. By joining the sealing metal layer 8 to the mounting substrate 50 via a conductive bonding material 9 such as solder, the possibility that water entering from the opening 51 of the mounting substrate 50 spreads through the space between the microphone device 202 and the mounting substrate 50 can be reduced. The conductive bonding material 9 functions as a sealing material.

[0089] For example, when a resin adhesive (including a conductive adhesive) is used instead of solder as the conductive bonding material 9, or when a non-adhesive sealing material such as an O-ring is inserted between the microphone device 202 and the mounting substrate 50, the sealing metal layer 8 may not be provided. The same applies to other embodiments of the mounting method.

[0090] (Modified Example 3 of Microphone Device) FIG. 10 is a cross-sectional view of the microphone device 203 and the mounting substrate 50, showing a modified example of the mounting form in which the lower surface of the microphone device 203 (the lower surface of the wiring substrate 10) is mounted facing away from the side facing the mounting substrate 50. In this mounting example, the microphone device 203 has a configuration having a first through-hole 11 (recess 13) and a second through-hole 12 as sound holes on the side opposite to the mounting substrate 50, and is also referred to as an upper sound hole type.

[0091] The microphone device 203 includes a package 400B, a microphone element 3, and a semiconductor element 4. The package 400B has an intermediate substrate 15 (connection substrate) for electrical connection between the wiring substrate 10 and the mounting substrate 50. The wiring 2 of the wiring substrate 10 is drawn out to the upper surface of the wiring substrate 10. The intermediate substrate 15 has a frame-shaped portion 15A and a flat plate portion 15B that closes the opening of the frame-shaped portion 15A. The intermediate substrate 15 constitutes a cap-shaped insulator having a recess by the frame-shaped portion 15A and the flat plate portion 15B. The intermediate substrate 15 has a wiring 20. The wiring 20 includes a terminal electrode 20D and a through-conductor 20B. On the upper surface of the frame-shaped portion 15A, a terminal electrode 20D connected to the connection pad 2A of the wiring substrate 10 is provided. Also, on the lower surface of the flat plate portion 15B, a terminal electrode 20D for connection to an external electric circuit is provided. These two terminal electrodes 20D are electrically connected by a through-conductor 20B provided inside the intermediate substrate 15. The through-conductor 20B is disposed so as to penetrate the frame-shaped portion 15A and the flat plate portion 15B. By the wiring 20, the wiring 2 of the wiring substrate 10 and the wiring 52 of the mounting substrate 50 are electrically connected. The intermediate substrate 15 also serves as a lid and seals the microphone element 3 etc. mounted on the wiring substrate 10.

[0092] In the example of FIG. 10, the conductive bonding material 9 that joins the wiring board 10 and the relay board 15 has both the function as an electrical connection material and the function as a sealing material. In the example of FIG. 10, the conductive bonding material 9 may be arranged in a frame shape along the outer periphery of the relay board 15 using an anisotropic conductive resin or the like. Thereby, short - circuiting between the plurality of terminal electrodes 20D (between the terminal electrodes 2D) can be prevented and sealing can be achieved. The conductive bonding material 9 may be used to connect the plurality of terminal electrodes 2D and the wiring 20 (terminal electrode 20D) of the relay board 15 respectively, and a sealing material may be arranged outside thereof. When the sealing material is a brazing material, solder, or the like, a frame - shaped sealing metal layer for the sealing material can be provided.

[0093] Also, when the microphone device 203 is mounted on an electronic device, the sealing metal layer 8 is joined to the housing of the electronic device via a conductive bonding material 9 such as solder. Alternatively, the microphone device 203 may be joined to the housing by a resin sealing material. When using a resin sealing material, the outermost layer 101 of the wiring board 10 may have through - holes having a hole diameter similar to that of the second through - hole 12 around the first through - hole. Thereby, the possibility that the bonding material or the sealing material spreads toward the first through - hole 11 can be reduced.

[0094] (Modification Example 4 of Microphone Device) FIG. 11 is a cross - sectional view of a microphone device 204 as a modification example. As shown in FIG. 11, the microphone device 204 includes a package 400C, a microphone element 3, and a semiconductor element 4. The package 400C includes a ceramic substrate 1B, a frame portion 14, and a wiring board 100. The wiring board 100 has three insulating layers, and wiring 2 is provided through the inside of the wiring board 100 so as to conduct electricity from the upper surface to the lower surface, but is not limited thereto. The wiring board 100 only needs to be provided with an element mounting region R for mounting the wiring 2 and the microphone element 3, and other structures are not particularly limited. As the wiring board 100, a known wiring board may be used.

[0095] The package 400C has a housing recess 21 (recess) formed by a wiring board 100 and a frame portion 14 provided on the upper surface of the wiring board 100, and members such as a microphone element 3, a semiconductor element 4, and a connection member 5 can be housed in the housing recess 21. The frame portion 14 may be provided on the wiring board 100. That is, the wiring board 100 may have a housing recess 21 and an element mounting region R on the bottom surface of the housing recess 21. A ceramic substrate 1B is disposed so as to cover the housing recess 21. The ceramic substrate 1B and the frame portion 14 may be joined by a brazing material via a bonding metal layer 6 provided on the ceramic substrate 1B, for example. The means for joining the ceramic substrate 1B and the frame portion 14 is not particularly limited.

[0096] The ceramic substrate 1B is different from the above-described ceramic substrate 1 in that the first layer 101 is one layer. That is, the ceramic substrate 1B has one first layer 101 and one second layer 102. Other points are the same as those of the ceramic substrate 1.

[0097] When the microphone device 204 is viewed in a plan view, the ceramic substrate 1B has a first through hole 11 (recess 13) at a position corresponding to the element mounting region R of the microphone element 3 in the package 400C.

[0098] The ceramic substrate 1B has waterproofness that can significantly reduce the possibility of water entering the housing recess, and also has other performances (strength, etc.) required as a lid. The ceramic substrate 1B is a lid in which the effective through holes are not reduced due to lamination misalignment. When the microphone device 204 is mounted on an electronic device, the microphone device 204 is joined to the housing of the electronic device by, for example, a resin sealing material. When the resin sealing material is provided so as to surround the region where the second through hole 12 is located, the presence of the outer through hole 122 can reduce the possibility of the sealing material spreading toward the effective through hole, and thus the possibility of reduction of the effective through hole can be reduced.

[0099] 〔Embodiment 2〕 Other embodiments of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated. In Embodiment 2, an example in which the ceramic substrate or the wiring substrate according to the present disclosure is applied to a gas sensor device will be described.

[0100] (Configuration of Gas Sensor Device 300) FIG. 12 is a cross-sectional view of the gas sensor device 300. FIG. 12 shows a cross-section of the gas sensor device 300 mounted on the mounting substrate 50. The gas sensor device 300 includes a wiring substrate 10A and a gas sensor element 3G.

[0101] The wiring substrate 10A has a ceramic substrate 1C and wiring 2 and The ceramic substrate 1C has a first layer 101 having a first through-hole 11, a second layer 102 having a second through-hole 12, and a frame portion 103. The frame portion 103 is located on the surface of the first layer 101 so as to surround the first through-hole 11.

[0102] As the gas sensor element 3G, for example, a substrate-type semiconductor gas sensor is used. The substrate-type semiconductor gas sensor is obtained by forming a semiconductor material serving as a gas-sensitive portion 31G in a thin film or thick film form on the surface of a support substrate 32G and then firing it. A platinum comb-shaped electrode (not shown) is provided on the surface of the support substrate 32G, and a platinum wire wired between the electrodes is used as a signal line to extract a sensor output. Heating of the gas-sensitive portion 31G is performed by a platinum heater (not shown) on the back side of the support substrate 32G. The gas sensor element 3G may be a MEMS-type semiconductor gas sensor using a MEMS substrate having a diaphragm structure incorporating a heater as a support substrate.

[0103] The gas sensing part 31G detects gas generally in a state heated to about 200 to 500°C by a heater, although there are differences depending on the gas to be detected. Therefore, the material of the package housing the gas sensor element 3G should be a material with a low possibility of gas generation or corrosion even when exposed to high temperatures. Ceramics are less likely to corrode due to various gases or moisture. Also, even when exposed to high temperatures, the gas generation from the ceramic itself is very small. From this perspective, ceramics may be the material of the substrate of the gas sensor device 300.

[0104] The gas sensor element 3G is flip-chip connected to the ceramic substrate 1C. That is, the gas sensor element 3G is connected to the ceramic substrate 1C by joining an electrode (not shown) provided on the surface of the support substrate 32G and the connection pad 2A with a conductive bonding material 9 such as a gold bump and a solder bump. A sealing member 17 that reduces the volume of the space communicating with the outside is provided between the ceramic substrate 1C and the gas sensor element 3G.

[0105] The sealing member 17 may be an underfill material for reinforcing the bonding strength of the gas sensor element 3G to the ceramic substrate 1C by the conductive bonding material 9. The underfill material may be arranged not only around the conductive bonding material 9 such as a gold bump or a solder bump but also over the entire circumference of the gas sensor element 3G (support substrate 32G). And by filling the gap between the gas sensor element 3G and the ceramic substrate 1C, the sealing member 17 that reduces the volume of the space communicating with the first through hole 11 can be obtained.

[0106] In the example of FIG. 12, the gas sensor element 3G is flip-chip connected to the ceramic substrate 1C. For this reason, there is no need for the height to accommodate the pad for the bonding wire and the loop of the bonding, and as a result, the gas sensor device 300 can be made smaller and thinner.

[0107] The gas sensor device 300 includes a wiring board 10A and a gas sensor element 3G. With this configuration, a gas sensor device having air permeability and waterproofness can be realized. The wiring board 10A is a board in which the effective through-holes have not decreased due to lamination misalignment. Therefore, the gas sensor device 300 has excellent air permeability and good sensitivity. Also, when the gas sensor device 300 is mounted on an electronic device, the gas sensor device 300 may be arranged so that the position of the opening of the housing of the electronic device coincides with the position of the first through-hole 11 and is mounted on the housing of the electronic device. In this case, a sealing member or the like is provided along the outer edge of the region where the second through-hole 12 is formed.

[0108] When the gas sensor device 300 is mounted on an electronic device, the gas sensor device 300 is joined to the housing of the electronic device by, for example, a resin sealing material. When the resin sealing material is provided so as to surround the region where the second through-hole 12 is located, the presence of the outer through-hole 122 can reduce the possibility that the sealing material spreads toward the effective through-holes, and thus the possibility of a decrease in the effective through-holes can be reduced. Thereby, the possibility of deterioration of the sensitivity of the gas sensor device 300 can be reduced.

[0109] In the gas sensor device 300, the first layer 101 of the wiring board 10A has a third surface 101X facing the second layer 102 and a fourth surface 101Y located on the opposite side of the third surface. The fourth surface 101Y has an element mounting region R, and the element mounting region R is positioned so as to surround the first through-hole 11 in a plan view.

[0110] With this configuration, the wiring board 10A can mount elements on the side of the first layer 101 having the first through-hole 11. For example, when the wiring board 10A is used as a board for mounting the gas sensor element 3G, by mounting the gas sensor element 3G on the fourth surface 101Y, the gas sensing portion 31G can be accommodated inside the first through-hole 11. In the example of FIG. 12, the gas sensing portion 31G is located outside the first through-hole 11, but by adjusting the thickness of the conductive bonding material 9, the gas sensing portion 31G may be accommodated inside the first through-hole 11. With this configuration, the gas sensor device 300 can be made smaller. Also, the gas sensing portion 31G can be disposed at a position close to the outer surface of the package 400D. Further, since the air heated and risen by the gas sensing portion 31G tends to gather in the second through-hole (the recess of the board), the discharge of the heated air is promoted. Also, along with this, more air outside the package can be taken in. Thereby, the gas sensing sensitivity is improved.

[0111] (Modification example of gas sensor device) FIG. 13 is a cross-sectional view of a gas sensor device 301 as a modification example. The gas sensor device 301 includes a package 400D and a gas sensor element 3G. The package 400D includes a ceramic substrate 1B and a wiring board 100A having a housing recess 21 for housing the sensor element and wiring 2. The wiring board 100A has an element mounting region R on the bottom surface of the housing recess 21. The ceramic substrate 1B constitutes the lid of the package 400D. The gas sensor device 301 can be, for example, a rectangular shape such as a rectangular shape or a square shape in plan view.

[0112] The ceramic substrate 1B is as described in Embodiment 1. In the gas sensor device 301 of FIG. 13, the first surface 102Y of the ceramic substrate 1B constitutes a part of the outer surface of the package 400D, and the fourth surface 101Y is disposed so as to face the gas sensor element 3G.

[0113] The wiring board 100A is a board on which the gas sensor element 3G is mounted. The wiring board 100A has functions such as ensuring mechanical strength as a board for mounting the gas sensor element 3G and ensuring insulation between a plurality of wirings 2. The size of the housing recess 21 of the wiring board 100A only needs to be able to house the gas sensor element 3G and can be of any shape and any size. Also, the shape of the inner surface of the housing recess 21 is not particularly limited. As shown in FIG. 13, the inner surface of the housing recess 21 may be a stepped shape. Also, it may be an inclined surface having an inclination with respect to the bottom surface of the wiring board 100A. The wiring board 100A has wirings 2 inside and on the surface.

[0114] With the above configuration, a gas sensor device having air permeability and waterproofness can be realized. Also, the gas that has passed through the second through-hole 12 can more easily pass through the first through-hole 11 and proceed toward the gas-sensitive part 31G of the gas sensor element 3G. Therefore, the sensor sensitivity can be improved.

[0115] Also, the ceramic substrate 1B has waterproofness that can significantly reduce the possibility of water entering the housing recess, and has other performances (such as strength) required as a lid body. The ceramic substrate 1B is a lid body in which the effective through-holes have not decreased due to lamination misalignment. Further, when the gas sensor device 301 is mounted on an electronic device, the gas sensor device 301 is joined to the housing of the electronic device by, for example, a resin sealing material. When the resin sealing material is provided so as to surround the region where the second through-hole 12 is located, the presence of the outer through-hole 122 can reduce the possibility of the sealing material spreading toward the effective through-hole, and thus the possibility of the effective through-hole decreasing can be reduced. Thereby, the possibility of the sensitivity of the gas sensor device 301 deteriorating can be reduced.

[0116] (Example of mounting on an electronic device) FIG. 14 is a partial cross-sectional view of an electronic device 501 including a microphone device 201. Specific examples of the electronic device in which the microphone device according to one aspect of the present disclosure is mounted are not particularly limited, but for example, a communication information terminal such as a smartphone, a game machine, and earphones. The electronic device 501 includes a microphone device 201, a mounting substrate 50, and a housing 60.

[0117] An opening 61 serving as a sound hole is formed in the housing 60 of the electronic device 501. In the electronic device 501, the microphone element 3, the opening 51 of the mounting substrate 50, and the opening 61 of the housing 60 are arranged in alignment so as to communicate with each other. A ring-shaped sealing material 62 is arranged along the outer edges of the opening 61 and the opening 51 between the housing 60 and the mounting substrate 50. The sealing material 62 may be a solder material or a gasket. Examples of the material of the sealing material 62 include a rubbery resin sealing material and a metal such as solder. The sealing material 62 may be sandwiched between the housing 60 and the mounting substrate 50, or the housing 60 and the mounting substrate 50 may be adhered (joined) by the sealing material 62.

[0118] With the above configuration, since the effective through holes do not decrease, it is possible to realize an electronic device 501 having excellent waterproof and dustproof properties while improving the acoustic characteristics.

[0119] FIG. 15 is a partial cross-sectional view of an electronic device 502 including a microphone device 204. The electronic device 501 includes a microphone device 204, a mounting substrate 50, and a housing 60. In the electronic device 502, a microphone element 3 and an opening 61 of the housing 60 are arranged in alignment so as to communicate with each other. A sealing material 62 may be arranged along the outer edge of a region where the opening 61 and the second through-hole 12 are located between the housing 60 and the mounting substrate 50. Alternatively, the sealing material 62 may be arranged at a position overlapping a part of the outer through-hole 122 in a plan view. When the sealing material 62 is a resin sealing material, the presence of the outer through-hole 122 can reduce the possibility that the sealing material spreads toward the effective through-hole, and thus the possibility of a decrease in the effective through-hole can be reduced. As a result, since the effective through-hole does not decrease, it is possible to realize an electronic device 501 having excellent waterproof and dustproof properties while maintaining good acoustic characteristics.

[0120] FIG. 16 is a cross-sectional view of an electronic device 503 including a gas sensor device 300. Specific examples of an electronic device in which a gas sensor device according to an aspect of the present disclosure is mounted are not particularly limited, and examples include a gas detector such as a gas leak alarm, an alcohol checker, an air conditioner, or an air purifier. The electronic device 503 includes a gas sensor device 300, a mounting substrate 50, and a housing 60.

[0121] The electronic device 503 is arranged such that the position of the first through-hole 11 coincides with the position of the opening 61 of the housing 60. In other words, the electronic device 503 is arranged such that the second through-hole 12, the first through-hole 11, and the opening 61 communicate with each other, and the gas sensor device 300 is mounted on the housing 60. A sealing material 62 may be arranged along the outer edge of the region where the opening 61 and the second through-hole 12 are located between the gas sensor device 300 and the housing 60. Alternatively, the sealing material 62 may be arranged at a position overlapping a part of the outer through-hole 122 in a plan view. When the sealing material 62 is a resin sealing material, the presence of the outer through-hole 122 can reduce the possibility that the sealing material spreads toward the effective through-hole, and thus the possibility of a decrease in the effective through-hole can be reduced. As a result, since the effective through-hole does not decrease, an electronic device 503 having excellent air permeability and high sensitivity can be realized.

[0122] FIG. 17 is a cross-sectional view of an electronic device 504 including a gas sensor device 301. The electronic device 504 includes a gas sensor device 301, a mounting substrate 50, and a housing 60.

[0123] Regarding this configuration as well, similar to the electronic device 503, when the sealing material 62 is a resin sealing material, the presence of the outer through-hole 122 can reduce the possibility that the sealing material spreads toward the effective through-hole, and thus the possibility of a decrease in the effective through-hole can be reduced. As a result, since the effective through-hole does not decrease, an electronic device 504 having excellent air permeability and high sensitivity can be realized.

[0124] As described above, the invention according to the present disclosure has been described based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. That is, the invention according to the present disclosure can be variously modified within the scope shown in the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Also, note that these deformations or modifications are included in the scope of the present disclosure.

Description of Symbols

[0125] 1, 1A, 1B, 1C ··· Ceramic substrates 2, 20, 22, 52 ··· Wiring 3 ··· Microphone element 3G ··· Gas sensor element 10, 10A ··· Wiring boards 100, 100A ··· Wiring boards 11, 11A, 11B ··· First through-holes 12 ··· Second through-hole 121 ··· Inner through-hole 122 ··· Outer through-hole 21 ··· Accommodating recess (recess) 200, 201, 202, 203, 204 ··· Microphone devices 300, 301 ··· Gas sensor devices 400, 400A, 400B, 400C, 400D ··· Packages 501, 502, 503, 504 ··· Electronic devices

Claims

1. At least one first layer having a first through hole, At least one second layer positioned overlapping the first layer, and comprising: The second layer has a plurality of second through holes having a smaller hole diameter than the first through hole, The second through holes include a plurality of inner through holes located in the inner region of the first through hole and a plurality of outer through holes located in the outer region of the first through hole in a plan view, a ceramic substrate.

2. In the second layer, the second through holes have a staggered arrangement, the ceramic substrate according to claim 1.

3. The outer through holes are located in a region defined by a distance two hole pitches of the second through holes away from the outer edge of the first through hole in a plan view, the ceramic substrate according to claim 1.

4. Forming a first through hole in a first sheet which is a ceramic green sheet; Forming a plurality of second through holes having a smaller hole diameter than the first through hole in a region having an area larger than the opening area of the first through hole in a second sheet which is a ceramic green sheet; Laminating the first sheet and the second sheet such that some of the plurality of second through holes are located outside the first through hole in a plan view, a method for manufacturing a ceramic substrate.

5. A wiring board comprising the ceramic substrate according to claim 1 and wiring.

6. The second layer has a second surface facing the first layer and a first surface located on the opposite side of the second surface, The first surface has an element mounting region, The element mounting region is located so as to surround the first through hole in a plan view, the wiring board according to claim 5.

7. The first layer has a third surface facing the second layer and a fourth surface located on the opposite side of the third surface, The fourth surface has an element mounting region, The element mounting region is located so as to surround the first through hole in a plan view, the wiring board according to claim 5.

8. Forming a first through hole in a first sheet which is a ceramic green sheet; Forming a plurality of second through holes having a smaller hole diameter than the first through hole in a region having an area larger than the opening area of the first through hole in a second sheet which is a ceramic green sheet; A step of forming wiring on at least one of the first sheet and the second sheet; A method of manufacturing a wiring board, including: laminating the first sheet and the second sheet in a plan view such that some of the plurality of second through holes are located outside the first through hole.

9. A ceramic substrate according to claim 1 as a lid, A package including a wiring board having an element mounting region at a position overlapping the first through hole in a plan view.

10. The package according to claim 9, wherein the wiring board includes a recess, and the element mounting region is provided on a bottom surface of the recess.

11. A microphone device including the wiring board according to claim 5 and a microphone element.

12. A gas sensor device including the wiring board according to claim 5 and a gas sensor element.

13. A microphone device including the package according to claim 9 and a microphone element.

14. A gas sensor device including the package according to claim 9 and a gas sensor element.

15. An electronic device including the microphone device according to claim 11 or 13.

16. An electronic device including the gas sensor device according to claim 12 or 14.

Images