Substrate, package, gas sensor module, gas sensor, and method for manufacturing gas sensor

Abstract

The present invention simplifies and miniaturizes the structure of a gas sensor. This substrate comprises: a base body including a plurality of insulating layers made of a ceramic material and having a first surface and a second surface positioned on the opposite side of the first surface; a gas-sensitive body region which is positioned on the first surface and in which a gas-sensitive body is disposed; electrode wiring positioned in the gas-sensitive body region and connected to the gas-sensitive body; a heater positioned between the insulating layers and positioned so as to overlap the gas-sensitive body region in a plan perspective view; and an external electrode electrically connected to the electrode wiring or the heater.

Description

Substrate, package, gas sensor module, gas sensor, and method of manufacturing gas sensor

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

[0002] Known small gas sensors include a CAN-type gas sensor as disclosed in Patent Document 1 and a gas sensor equipped with a MEMS element as disclosed in Patent Document 2.

[0003] Japanese Patent Application Publication No. 63-275941 Japanese Patent Application Publication No. 2018-100900

[0004] A substrate according to one embodiment of the present disclosure comprises a base body including a plurality of insulating layers made of a ceramic material and having a first surface and a second surface located opposite the first surface, a gas sensing body region located on the first surface in which a gas sensing body is placed, electrode wiring located in the gas sensing body region and connected to the gas sensing body, a heater located between the insulating layers and positioned overlapping the gas sensing body region in a planar perspective view, and an external electrode electrically connected to the electrode wiring or the heater.

[0005] A package according to one aspect of the present disclosure includes the substrate and a lid.

[0006] A gas sensor according to one aspect of the present disclosure includes the package and a gas sensitive body.

[0007] A gas sensor module according to one aspect of the present disclosure includes the gas sensor and a mounting substrate, and the gas sensor is surface-mounted on the mounting substrate by soldering.

[0008] A method for manufacturing a gas sensor according to one aspect of the present disclosure includes the steps of preparing a mother substrate having a plurality of substrate regions corresponding to the substrate, forming a gas sensitive body in the gas sensitive body region, and singulating the mother substrate.

[0009] FIG. 1 is a cross-sectional view of a gas sensor according to a first embodiment of the present disclosure. FIG. 2 is a top view of a substrate according to a first embodiment of the present disclosure. FIG. 3 is a plan perspective view showing the configuration of a heater side of the substrate according to the first embodiment of the present disclosure. FIG. 4 is a bottom view of a substrate according to the first embodiment of the present disclosure. FIG. 5 is a top view of a lid according to the first embodiment of the present disclosure. FIG. 6 is a cross-sectional view of a substrate according to a second embodiment of the present disclosure. FIG. 7 is a top view of a substrate according to the second embodiment of the present disclosure. FIG. 8 is a plan perspective view showing the configuration of a heater side of the substrate according to the second embodiment of the present disclosure. FIG. 9 is a transverse cross-sectional view of a substrate according to the second embodiment of the present disclosure. FIG. 10 is a plan perspective view showing the configuration of a heater side of a cavity according to another embodiment. FIG. 11 is a plan perspective view showing the configuration of a heater side of a cavity according to another embodiment. FIG. 12 is a cross-sectional view of a cavity according to another embodiment. FIG. 13 is a cross-sectional view of a substrate according to a third embodiment of the present disclosure. FIG. 14 is a top view of a substrate according to the third embodiment of the present disclosure. FIG. 15 is a cross-sectional view of a substrate according to a fourth embodiment of the present disclosure. FIG. 16 is a top view of a substrate according to the fourth embodiment of the present disclosure. FIG. 17 is a cross-sectional view of a gas sensor according to a fifth embodiment of the present disclosure. FIG. 18 is a top view of a substrate according to the fifth embodiment of the present disclosure. FIG. 1 is a top view of a lid according to embodiment 5 of the present disclosure. FIG. 2 is a cross-sectional view of a gas sensor according to embodiment 6 of the present disclosure. FIG. 3 is a cross-sectional view of a gas sensor according to embodiment 7 of the present disclosure. FIG. 4 is a cross-sectional view of a gas sensor according to embodiment 8 of the present disclosure. FIG. 5 is a top view of a substrate according to embodiment 8 of the present disclosure. FIG. 6 is a perspective view of a gas sensor according to embodiment 8 of the present disclosure. FIG. 7 is a cross-sectional view of a gas sensor according to embodiment 9 of the present disclosure. FIG. 8 is a top view of a substrate according to embodiment 9 of the present disclosure. FIG. 9 is a cross-sectional view of a gas sensor according to embodiment 9 of the present disclosure. FIG. 10 is a cross-sectional view of another gas sensor according to embodiment 10 of the present disclosure. FIG. 11 is a cross-sectional view of another gas sensor according to embodiment 10 of the present disclosure. FIG. 12 is a cross-sectional view of another gas sensor according to embodiment 10 of the present disclosure. FIG. 13 is a cross-sectional view of another gas sensor according to embodiment 10 of the present disclosure. FIG. 14 is a cross-sectional view of another gas sensor according to embodiment 10 of the present disclosure.Fig. 20 is a schematic plan view showing a part of a mother substrate according to a twelfth embodiment of the present disclosure; Fig. 21 is a cross-sectional view of a gas sensor according to a thirteenth embodiment of the present disclosure; Fig. 22 is a top view of a gas sensor according to an eleventh embodiment of the present disclosure;

[0010] The manufacturing process for CAN-type gas sensors is complicated and it is difficult to miniaturize them. Gas sensors equipped with MEMS elements are equipped with expensive and precise MEMS chips, and during manufacturing, the MEMS chip and wiring substrate must be connected by wire bonding or the like.

[0011] One aspect of the present disclosure achieves simplified and miniaturized structure of a gas sensor.

[0012] According to one aspect of the present disclosure, the structure of the gas sensor can be simplified and made smaller.

[0013] First Embodiment Hereinafter, one embodiment of the present disclosure will be described in detail.

[0014] In the following description, the distinction between top and bottom is for convenience and does not limit the top and bottom when the substrate, package, and gas sensor are actually used. In this specification, the surface of the substrate 10 on which the gas sensor 8 is provided is defined as the top surface. In the drawings, the positive Z-axis direction is the upward direction. The X-axis direction is parallel to any side of the substrate 10, and the Y-axis is an axis perpendicular to the X-axis and Z-axis. The thickness direction of the substrate 10 is the Z-axis direction. The dimensions of the components in each figure do not necessarily faithfully represent the actual dimensions of the components and the dimensional ratios of each part. In this disclosure, a rectangular shape is not limited to a strict rectangular shape and includes a shape that can be visually recognized as a rectangle overall, even if the corners are curved.

[0015] FIG. 1 is a cross-sectional view of a gas sensor 900 according to the first embodiment, taken along the line II in a state in which a bonding material B and a lid 7 are attached to a substrate 10 shown in FIG. 2. FIG. 2 is a top view of the substrate 10. FIG. 3 is a plan perspective view showing the configuration of the heater surface of the substrate 10. The heater surface is the surface on which a heater 5, which will be described later, is located. For ease of explanation, FIG. 3 shows a virtual region of the gas-sensing region 3. FIG. 4 is a bottom view of the substrate 10. FIG. 5 is a top view of the lid 7. In this specification, a plan view viewed from the positive direction of the Z axis may be referred to as a top view, and a plan view viewed from the negative direction of the Z axis may be referred to as a bottom view.

[0016] The present disclosure relates to a substrate-type gas sensor. A gas sensor 900 according to a first embodiment includes a package 100 and a gas sensor 8. The package 100 includes a substrate 10 and a lid 7. The substrate 10 includes a base 2, a gas sensor region 3, wiring 4, and a heater 5.

[0017] (Substrate) The substrate 10 is a support substrate for the gas sensor 8 and also functions as a wiring substrate. Each member constituting the substrate 10 will be described in detail below.

[0018] The base 2 is a main body portion of the substrate 10 and includes a plurality of insulating layers 20 stacked in the thickness direction of the substrate 10. The insulating layers 20 are made of a ceramic material. The substrate 10 has a first surface 201 located in the stacking direction and a second surface 202 located on the opposite side of the first surface 201. Of the insulating layers 20 included in the base 2, the insulating layer having the first surface 201 is referred to as the first insulating layer 21. Of the insulating layers 20 included in the base 2, the insulating layer stacked on the first insulating layer 21 is referred to as the second insulating layer 22. The second insulating layer 22 is an insulating layer stacked on the side of the first insulating layer 21 opposite the first surface 201. The first insulating layer 21 may be located above the heater 5 and may be a group of insulating layers including a plurality of insulating layers 20. The second insulating layer 22 may be located on the opposite side of the heater 5 from the first insulating layer 21 and may be a group of insulating layers including a plurality of insulating layers 20.

[0019] As shown in Fig. 2, the shape of the base 2 in a plan view may be rectangular. The base 2 is made of 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. The shape of the base 2 in a plan view according to the first embodiment is substantially square, but may also be rectangular. As shown in Fig. 2, the base 2 may have notches at the corners. Furthermore, the shape of the base 2 in a plan view is not limited to a rectangle, and may be changed as appropriate depending on the application, etc.

[0020] The gas sensitive region 3 is located on the first surface 201 and is a region where the gas sensitive body 8 is placed. The gas sensitive region 3 may be a region on the first surface 201 that overlaps with the gas sensitive body 8 placed in the gas sensitive region 3. Alternatively, the gas sensitive region 3 may be a region located on the first surface 201 that is surrounded by virtual lines connecting alignment marks used when placing the gas sensitive body 8.

[0021] The wiring 4 includes an electrode wiring 41, an external electrode 42, and a through conductor 43. The wiring 4 may also include an interlayer conductor 44. The through conductor 43 passes through at least one insulating layer 20 in the vertical direction and connects the wirings located above and below the through conductor 43. The wiring connected via the through conductor 43 may be the electrode wiring 41, the external electrode 42, or the interlayer conductor 44. The interlayer conductor 44 is a conductor located between the insulating layers 20.

[0022] The electrode wiring 41 is a wiring having at least a portion located in the gas sensitive region 3 and connected to the gas sensitive body 8. As shown in FIG. 2 , the electrode wiring 41 may include a first portion 41P and a second portion 41L. The first portion 41P and the second portion 41L may be continuous and integral. The first portion 41P and the second portion 41L may be metallized patterns formed by printing and sintered simultaneously with the ceramic base 2. Alternatively, the first portion 41P and the second portion 41L may be metallized patterns formed by printing or vapor deposition after sintering the ceramic base 2.

[0023] The first portion 41P may be a plate-shaped conductor. The first portion 41P functions as a connection pad for connecting to the through conductor 43X and has an area larger than the diameter of the through conductor 43X in a plan view. As shown in FIG. 2 , the first portion 41P is connected to the through conductor 43X, which is positioned overlapping the first portion 41P in a planar perspective view and penetrates the base 2. The through conductor 43X is connected to the first external electrode 42X. As shown in FIG. 4 , the through conductor 43X is positioned overlapping the first external electrode 42X in a planar perspective view. The first portion 41P may have a rectangular shape with a side length larger than the diameter of a cross section of the through conductor 43 perpendicular to the Z axis. The shape of the first portion 41P is not limited to a rectangular shape and may be any shape. For example, the shape of the first portion 41P may be a circle with a diameter larger than the diameter of the cross section of the through conductor 43. In the substrate 10 shown in FIG. 2 , the two first portions 41P are positioned along diagonals of the substrate 10. The arrangement of the first portions 41P is not limited to this arrangement, and for example, two first portions 41P may be arranged along any one side of the substrate 10 having a rectangular shape.

[0024] At least a portion of the second portion 41L is located in the gas-sensitive region 3, and includes an extending portion extending from the gas-sensitive region 3 to the first portion 41P. The portion of the second portion 41L located in the gas-sensitive region 3 may have a comb-tooth shape. The shape of the portion located in the gas-sensitive region 3 is not limited to a comb-tooth shape. Alternatively, the second portion 41L may be in the shape of a single strip extending from the gas-sensitive region 3 to the first portion 41P.

[0025] In the substrate 10, the external electrodes 42 are located on the second surface 202 of the base 2 and are electrically connected to the electrode wiring 41 or the heater 5. Positioning the external electrodes 42 on the second surface 202 enables surface mounting. For example, as shown in FIG. 4 , the external electrodes 42 may include two first external electrodes 42X electrically connected to the two electrode wirings 41, respectively, and two second external electrodes 42Y electrically connected to the two terminals of the heater 5, respectively. The first external electrodes 42X are electrically connected to the electrode wiring 41 via through conductors 43X. The second external electrode 42Y is electrically connected to the heater 5 via through conductors 43Y. In the substrate 10, the two first external electrodes 42X are located along a diagonal line of the substrate 10. In other words, the two first external electrodes 42X are located at opposite corners of the base 2. The arrangement of the first external electrodes 42X is not limited to this arrangement. For example, two first external electrodes 42X may be arranged along any one side of the rectangular substrate 10.

[0026] When the gas sensor 900 is mounted on a mounting board such as a printed circuit board (PCB), the external electrode 42 is connected to a circuit board (external electric circuit) of the device via a solder material. In the substrate 10, the external electrode 42 may be provided from the second surface 202 to a side surface of the base 2. When the substrate 10 has a notch at a corner as shown in FIGS. 1 and 2 , the external electrode 42 located on the side surface may be located in the notch.

[0027] The electrode wiring 41, external electrodes 42, through conductors 43, and interlayer conductors 44 primarily contain, as a conductive material, a metal such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, platinum, nickel, or cobalt, or an alloy containing these metals. The electrode wiring 41 and external electrodes 42 are formed on the surface of the base 2 as a metal layer, such as a metallized layer or plated layer, of a conductive material. The metal layer may be a single layer or multiple layers. The interlayer conductor 44 is formed inside the base 2 by metallizing a conductive material.

[0028] For example, when the electrode wiring 41 and the external electrode 42 are tungsten metallized layers, they can be formed by applying a metal paste prepared by mixing tungsten powder with an organic solvent and an organic binder by a method such as screen printing to predetermined positions on the insulating layer 20. Furthermore, the through conductors 43 may be formed by providing through holes at predetermined positions on the ceramic green sheet prior to printing the metal paste, and filling the through holes with the same metal paste as above.

[0029] Furthermore, the exposed surface of the metallized layer after firing may be further coated with a plating layer of nickel, gold, or the like using electrolytic plating or electroless plating.

[0030] The heater 5 is located between the first insulating layer 21 and the second insulating layer 22. The gas sensor 8 detects gas while being heated to approximately 200 to 500°C, although this varies depending on the gas to be detected. The heater 5 is used to heat the gas sensor 8. The heater 5 may have a heater circuit pattern as shown in FIG. 3. The heater 5 is connected to a heater terminal 44Y located on the same interlayer as the heater 5. As shown in FIG. 3, the heater 5 and the heater terminal 44Y may be integrally formed. The heater terminal 44Y is an example of an interlayer conductor 44. The heater terminal 44Y is connected to a through conductor 43Y that overlaps the heater terminal 44Y in a planar perspective view and penetrates the second insulating layer 22. The heater terminal 44Y functions as a connection pad for connecting to the through conductor 43Y and has an area larger than the diameter of the through conductor 43Y in a planar view. The heater terminal 44Y may have a circular planar shape as shown in Fig. 3, or may have another shape such as a rectangular shape. The through conductor 43Y is positioned to overlap the second external electrode 42Y in a planar perspective view, and is connected to the second external electrode 42Y.

[0031] In order to improve the heating efficiency of the gas sensitive body 8 by the heater 5, the first insulating layer 21 may be thinner than the second insulating layer 22. In other words, the distance between the heater 5 and the first surface 201 may be shorter than the distance between the heater 5 and the second surface 202. When the first insulating layer 21 is thinner than the second insulating layer 22, heat from the heater 5 is more easily transferred to the first surface side where the gas sensitive body 8 is located than to the second surface side connected to the outside.

[0032] The distance between the heater 5 and the first surface 201 may be 10 μm or more and 100 μm or less. In other words, the thickness of the first insulating layer 21 may be 10 μm or more and 100 μm or less. When the thickness of the first insulating layer 21 is 100 μm or less, heat from the heater 5 is easily transferred to the gas sensitive body 8. Furthermore, when the thickness of the first insulating layer 21 is 10 μm or more, the risk of the heater being exposed to the first surface 201 can be reduced. Furthermore, when the thickness of the first insulating layer 21 is 10 μm or more, electrical insulation between the heater 5 and the electrode wiring 41 can be ensured.

[0033] Meanwhile, the external electrode 42 located on the second surface 202 is bonded to the circuit electrode of the mounting board via solder or a conductive adhesive made of resin. Because heat from the heater 5 is more easily transferred to the first surface side where the gas sensitive element 8 is located than to the second surface side, by positioning the external electrode 42 on the second surface 202, the thermal influence on the conductive adhesive can be reduced. Therefore, for example, the distance between the heater 5 and the second surface 202 may be 100 μm or more. In other words, the thickness of the second insulating layer 22 may be 100 μm or more. By having the thickness of the second insulating layer 22 be 100 μm or more, the thermal influence of the heater 5 on the conductive adhesive can be reduced.

[0034] (Gas Sensitive Body) The gas sensitive body 8 contains a metal oxide semiconductor material according to the type of the gas sensor 900. An example of the metal oxide semiconductor material is tin oxide (SnO ２ etc.), indium oxide (In ２ O ３ etc.), zinc oxide (ZnO etc.), tungsten oxide (WO ３ etc.) and iron oxide (Fe ２ O ３The gas sensor may include one or more selected from the group consisting of a metal oxide semiconductor, a fluorine-containing gas ...

[0035] (Cover) In the gas sensor 900, the gas sensor 8 is protected by the cover 7. In the example shown in FIG. 1 , the gas sensor 900 includes a cap-shaped cover 7 that collectively covers the electrode wiring 41 and the gas sensor 8 located on the first surface 201 of the substrate 10. As shown in FIGS. 1 and 5 , the cover 7 may have a through hole 71 for ventilation. The cover 7 may have multiple through holes 71. Providing multiple through holes can improve ventilation. Furthermore, the through hole 71 may be located at a position that does not overlap with the gas sensor 8 in a planar perspective view. Not overlapping with the gas sensor 8 in a planar perspective view can reduce the possibility of dust or the like that enters through the through hole 71 adhering to the gas sensor 8.

[0036] The lid body 7 may be made of, for example, ceramic or metal. FIG. 1 shows an example in which the lid body 7 is made of metal. By using a metal lid body 7, a cap-shaped lid body can be easily manufactured by bending. Furthermore, compared to when the lid body 7 is made of a ceramic material, the lid body 7 can be formed thinner, allowing the package 100 and the gas sensor 900 to be made smaller.

[0037] The metal lid 7 and the substrate 10 can be bonded together using, for example, a resin. That is, the bonding material B may be a resin. Alternatively, the lid 7 and the substrate 10 may be bonded together by soldering or brazing. These bonding methods are performed by heating the entire surface using a batch furnace, a tunnel furnace, or the like. In the case of soldering or brazing, a frame-shaped metal film may be positioned on the first surface 201, and the lid 7 may be bonded onto the frame-shaped metal film. The frame-shaped metal film may be formed on the first surface 201 by metallizing.

[0038] When joining the metal lid 7 and the frame-shaped metal film, direct seam welding, laser welding, or electron beam welding may be used. These welding methods involve localized heating of the joint, allowing sealing at lower temperatures than joining by heating the entire surface. When the lid 7 is made of metal, an iron-nickel (Fe—Ni) alloy or an iron-nickel-cobalt (Fe—Ni—Co) alloy may be used as the material for the lid 7. These alloys have a small thermal expansion difference with ceramics, making them suitable for the lid 7 of the substrate 10.

[0039] As described above, the substrate 10 includes a base body 2 that includes a plurality of insulating layers 20 made of a ceramic material and has a first surface 201 and a second surface 202 located on the opposite side to the first surface 201. The substrate 10 includes a gas sensor region 3 located on the first surface 201, where a gas sensor 8 is disposed. The substrate 10 includes electrode wiring 41 located on the gas sensor region 3 and connected to the gas sensor 8. The substrate 10 includes a heater 5 located between the first insulating layer 21 and the second insulating layer 22, overlapping the gas sensor region 3 in a plan view. The substrate 10 also includes an external electrode 42 that is electrically connected to the electrode wiring 41 or the heater 5.

[0040] The substrate 10 is configured so that a gas sensitive body can be directly disposed on the wiring substrate, thereby simplifying the structure and miniaturizing the gas sensor manufactured using the substrate 10. Furthermore, the simplified structure also simplifies the manufacturing process, contributing to reduced manufacturing costs. Furthermore, the substrate 10 does not require an additional MEMS (microelectromechanical system) with a built-in heater or an alumina substrate with a printed heater circuit, and the heater is built into the wiring substrate itself, so that the wiring substrate can become a gas sensor device by applying a gas sensitive body to it.

[0041] The package 100 includes the substrate 10 and the lid 7, and can therefore protect the gas sensitive element 8. Furthermore, the package 100 can simplify the structure of a gas sensor manufactured using the package 100 and reduce its size.

[0042] The gas sensor 900 can be made smaller than conventional gas sensors by including the package 100 and the gas sensitive element 8. The gas sensor 900 also has a configuration that allows it to be modularized by surface mounting. FIG. 6 is a cross-sectional view of a gas sensor module 90 including the gas sensor 900. The gas sensor module 90 includes a mounting substrate 50 and the gas sensor 900. In the example shown in FIG. 6, the mounting substrate 50 is mounted with the gas sensor 900, a semiconductor IC 60, and a capacitor 70. The semiconductor IC 60 may be, for example, an ASIC (application specific integrated circuit). The gas sensor 900, the semiconductor IC 60, and the capacitor 70 are each surface-mounted on the mounting substrate 50 with solder S. As shown in FIG. 6, the gas sensor 900 can be directly soldered onto the mounting substrate together with electronic components such as the semiconductor IC and the capacitor to form the gas sensor module 90.

[0043] [Embodiment 2] Another embodiment of the present disclosure will be described below. For convenience of explanation, components having the same functions as those described in the above embodiment will be denoted by the same reference numerals, and their description will not be repeated. In Embodiment 2, a substrate 10A, which is another embodiment, will first be described using Figures 7 to 10.

[0044] Fig. 7 is a cross-sectional view of the substrate 10A according to the second embodiment, taken along the line VII-VII in Fig. 8. Fig. 8 is a top view of the substrate 10A. Fig. 9 is a planar perspective view showing the configuration of the heater surface of the substrate 10A. Fig. 10 is a cross-sectional view of the substrate 10A, taken along the line X-X in Fig. 7. In Figs. 8, 9, and 10, the shapes of the components and cavities in planar perspective are appropriately indicated by dashed lines to make the positional relationships easier to understand.

[0045] The substrate 10A differs from the substrate 10 of embodiment 1 in that it has a cavity 6 therein. The substrate 10A includes a base 2A. The base 2A has the cavity 6 between the heater 5 and the second surface 202. More specifically, the base 2A has a hollow structure with the cavity 6 inside the second insulating layer 22. The cavity 6 is located overlapping the heater 5 in a top perspective view. Furthermore, the outer edge of the cavity 6 may be larger than the heater 5 in a plan perspective view. Because the cavity 6 is located between the heater 5 and the external electrode 42, heat conduction to the bonding material or solder and the external terminal is reduced. As shown in FIG. 7 , the second insulating layer 22 is an insulating layer group including multiple insulating layers 20. The intermediate insulating layer 20 of the multiple insulating layers 20 may have a through-hole. The through-hole and the insulating layers 20 located above and below it may form the cavity 6. The shape of the cavity 6 may be rectangular in plan view as shown in Figures 7 to 10. The shape of the cavity 6 is not limited to a rectangle.

[0046] 8, the second portion 41L of the electrode wiring 41 may be in the shape of a single strip extending from the gas sensitive region 3 to the first portion 41P. The thickness of the second portion 41L may be designed appropriately taking into consideration the resistance, design tolerance, etc. Also, as shown in FIG. 8, the two first portions 41P located on the first surface 201 may be arranged to be approximately symmetrical with respect to a center line connecting the centers of the opposing sides in a plan view.

[0047] As shown in FIGS. 7 and 8 , the first portion 41P of the electrode wiring is connected to a through conductor 43X1 that overlaps the first portion 41P in a planar perspective and penetrates the first insulating layer 21. As shown in FIG. 9 , the through conductor 43X1 is connected to a through conductor 43X2 via an interlayer conductor 44X. The through conductors 43X1 and 43X2 are located inside the interlayer conductor 44X in a planar perspective. To improve connection reliability, the area of ​​the interlayer conductor 44X at the joint surface between the interlayer conductor 44X and the through conductor 43X1 or 43X2 may be larger than the area of ​​the through conductor 43X1 or 43X2. As shown in FIG. 10 , the through conductor 43X2 is a conductor that overlaps the first external electrode 42X in a planar perspective and penetrates the second insulating layer 22. The through conductor 43X2 is connected to the first external electrode 42X.

[0048] By providing the cavity 6 between the heater 5 and the second surface 202, as in the substrate 10A, it is possible to reduce the conduction of heat from the heater to the second surface 202, and to reduce the possibility of remelting of the solder joined to the mounting substrate during secondary mounting. Furthermore, since the heat from the heater 5 is more easily conducted to the gas sensor 8 side than through the cavity 6, which has a low thermal conductivity, the heat from the heater 5 can be conducted efficiently to the gas sensor 8.

[0049] Furthermore, since the substrate 10A has a hollow structure, the area of ​​the second surface 202 can be ensured even if a cavity 6 is provided below the heater 5. This increases the degree of freedom in arranging the external electrodes 42 located on the second surface 202. Furthermore, since the area of ​​the external electrodes 42 can be increased, mounting reliability is improved.

[0050] (Another embodiment 1 of cavity 6) Figures 11 to 14 are views showing another embodiment of cavity 6. Figures 11 to 13 are planar perspective views showing the configuration of the heater surface. Figure 14 is a cross-sectional view taken along the same cross section as Figure 7. In Figures 11 to 13, in order to make the positional relationship easier to understand, the shapes of each member and cavity when viewed from above are appropriately indicated by dashed lines.

[0051] As shown in Fig. 11 , the substrate 10A may have multiple cavities 6 at positions overlapping the heaters 5 in a planar perspective view. In the example shown in Fig. 11 , the second insulating layer 22 is an insulating layer group including multiple insulating layers 20, and an intermediate insulating layer 20 among the multiple insulating layers 20 may have multiple through holes. The multiple through holes may be located in different insulating layers 20. As shown in Fig. 11 , the shape of the cavity 6 may be circular in a planar view. The entire multiple through holes may be larger than the heaters 5. In other words, the multiple through holes may be arranged over an area wider than the heaters 5 in a planar perspective view.

[0052] By having a plurality of cavities 6 in the substrate 10A, parts of the insulating layer 20 are located between the cavities 6, which can reduce a decrease in the strength and rigidity of the substrate due to the cavities 6. Furthermore, it can reduce the risk of deformation occurring during the manufacture of the substrate 10A, which includes the insulating layer 20 made of a ceramic material.

[0053] 12, the substrate 10A may have a large number of minute cavities 6 at positions overlapping with the heaters 5 in a planar perspective view. In the example shown in Fig. 12, the second insulating layer 22 is an insulating layer group including a plurality of insulating layers 20, and an intermediate insulating layer 20 among the plurality of insulating layers 20 may have a plurality of through holes. The plurality of through holes may be located in different insulating layers 20.

[0054] By having a large number of minute cavities 6 in the substrate 10A, it is possible to further reduce the reduction in the strength and rigidity of the substrate due to the cavities 6. It is also possible to further reduce the possibility of deformation occurring during the manufacturing of the substrate 10A including the insulating layer 20 made of a ceramic material.

[0055] 13 , the substrate 10A may have multiple cavities 6 of different sizes in plan view at positions overlapping the heater 5 in plan view. The multiple cavities 6 include a large-diameter cavity 6 that is approximately the same size as the gas-sensitive region 3 and overlaps the gas-sensitive region 3, and small-diameter cavities 6 surrounding it. The large-diameter cavity 6 located on the opposite side of the heater 5 from the gas-sensitive region 3 efficiently conducts heat to the gas-sensitive region 3, while the distributed arrangement of the multiple cavities 6 reduces a decrease in substrate strength and rigidity due to the cavities 6. Furthermore, among the small-diameter cavities 6, the cavity 6 located between the heater 5 and the external electrode 42 is larger than the others, thereby more effectively reducing heat conduction to the external electrode 42.

[0056] Even when the sizes of the plurality of cavities 6 are different, it is possible to reduce the reduction in the strength and rigidity of the substrate due to the cavities 6. It is also possible to reduce the possibility of deformation occurring during the manufacture of the substrate 10A including the insulating layer 20 made of a ceramic material.

[0057] Alternatively, as shown in FIG. 14 , the substrate 10A may have a large number of microvoids arranged three-dimensionally within the base body 2A. The microvoids are an example of the cavity 6. While the cavity 6 described above is a through-hole that penetrates the insulating layer 20, each of the numerous microvoids does not penetrate the insulating layer 20. In other words, the height of the microvoid is significantly smaller than the thickness of the insulating layer 20. Multiple microvoids exist in the thickness direction of one insulating layer 20. The region where the numerous microvoids are arranged may be located in a position that overlaps with the heater 5 in a planar perspective view. The numerous microvoids arranged three-dimensionally can be formed, for example, by filling the through-holes for forming the cavity 6 shown in FIG. 7 with a ceramic green sheet, ceramic paste, or the like containing a large amount of binder, and then firing the resulting material.

[0058] The presence of a large number of microvoids in the substrate 10A can reduce the reduction in the strength and rigidity of the substrate due to the cavities 6. Furthermore, the possibility of deformation occurring during the manufacturing of the substrate 10A including the insulating layer 20 made of a ceramic material can be reduced.

[0059] Alternatively, a layer made of a ceramic material having a lower thermal conductivity than other layers may be provided between the heater 5 and the external electrode 42. This makes it difficult for heat to be transferred to the solder or bonding material joined to the external electrode 42 and to the external terminal, reducing the possibility of the solder remelting.

[0060] Third Embodiment In a third embodiment, a substrate 10B according to another embodiment will be described with reference to FIGS.

[0061] Fig. 15 is a cross-sectional view of the substrate 10B according to the third embodiment, taken along the line XV-XV in Fig. 16. Fig. 16 is a top view of the substrate 10B.

[0062] The substrate 10B differs from the substrate 10A of the second embodiment in that it includes a through-hole 61 extending from the cavity 6 to the first surface 201. The substrate 10B also differs from the substrate 10A in the arrangement of the electrode wiring 41 on the first surface 201. As shown in Fig. 16 , the two first portions 41P located on the first surface 201 may be arranged along any one side of the substrate 10A.

[0063] Furthermore, the substrate 10B differs from the substrate 10A of embodiment 2 in the shape of the second portion 41L of the electrode wiring 41. As shown in Fig. 16, the shape of the portion of the second portion 41L located in the gas sensitive region 3 may have a pad shape.

[0064] The substrate 10B includes a base body 2B. The base body 2B has four through holes 61. As shown in Fig. 16, the through holes 61 are positioned so as not to overlap the gas sensitive region 3 in a planar perspective view, but to overlap the cavity 6. The number of through holes 61 is not limited to four. Furthermore, the number, position, size, shape, etc. of the through holes 61 are not particularly limited and can be changed as appropriate, as long as they do not overlap the gas sensitive region 3 and penetrate from the cavity 6 to the surface of the substrate 10B.

[0065] By providing the through holes 61 as in the substrate 10B, the thermal insulation is improved compared to the substrate 10A of the second embodiment, and the conduction of heat from the heater 5 to the second surface 202 can be further reduced. Furthermore, the gas in the cavity 6 heated by the heater 5 is more easily vented to the outside, which can reduce the temperature rise of the second surface 202. Furthermore, by providing the through holes 61, the through holes 61 act as gas vent holes in the firing process of the substrate 10 including the insulating layer 20 made of a ceramic material, thereby reducing the possibility of deformation occurring during the manufacturing process.

[0066] Fourth Embodiment In a fourth embodiment, a substrate 10C according to another embodiment will be described with reference to FIGS.

[0067] Fig. 17 is a cross-sectional view of a substrate 10C according to embodiment 4, and is a cross-sectional view taken along line XVII-XVII in Fig. 18. Fig. 18 is a top view of the substrate 10C. In Fig. 18, the shapes of the components in a planar perspective view are appropriately indicated by dashed lines to make the positional relationships easier to understand.

[0068] The substrate 10C differs from the substrate 10A of embodiment 2 in that the cavity is a recess 6A opening to the second surface 202. The substrate 10C has the recess 6A opening to the second surface 202 at a position overlapping the heater 5 in a planar perspective view. More specifically, the second insulating layer of the substrate 10C has the recess 6A opening to the second surface 202. As shown in FIG. 17 , the second insulating layer 22 is an insulating layer group including a plurality of insulating layers 20, and among the plurality of insulating layers 20, an insulating layer 20 other than the insulating layer where the heater 5 is located may have a through-hole forming the recess 6A. The shape of the recess 6A may be rectangular in plan view, as shown in FIG. 18 . The shape of the recess 6A is not limited to a rectangle and may be designed as appropriate.

[0069] When the cavity is recessed, as in the substrate 10C, it is possible to make the cavity larger than in the hollow structure of the substrate 10A of the second embodiment. Furthermore, since the cavity is an open recess 6A, heat is dissipated from the inner surface of the recess 6A to the outside. This further improves the thermal insulation. Furthermore, recessed structures are easier to manufacture than hollow structures.

[0070] 17, the outer edge of the bottom surface of the recess 6A may be located further outward than the outer edge of the heater 5. This configuration can improve thermal insulation. In addition, in the cross section shown in FIG. 17, the angle θ formed by a line extending from the outer edge of the heater 5 in the Z-axis direction and a line connecting the outer edge and the outer edge of the bottom surface of the recess 6A may be 45° or more. By locating the recess 6A in a range where most of the heat from the heater 5 is conducted, thermal insulation can be improved.

[0071] 17 and 18 show an example in which the substrate 2C has one large rectangular recess in plan view, but the number, shape, and size of the recess are not limited to this example. The recess may be circular in plan view, or multiple recesses may be provided, as shown in FIGS. 11, 12, and 13. Having multiple recesses improves the strength of the substrate 10C compared to a single large recess 1. The substrate 10C may also have through-holes extending from the bottom surface of the recess 6A to the first surface 201. The through-holes further improve insulation and reduce heat conduction from the heater 5 to the second surface 202. Furthermore, the gas in the recess 6A heated by the heater 5 can be more easily vented to the outside, reducing the temperature rise of the second surface 202. Furthermore, the through-holes function as gas vents during the firing process of the substrate 10C including the insulating layer 20 made of a ceramic material, thereby reducing the possibility of deformation during the manufacturing process.

[0072] 19 to 21 , a gas sensor 900D, a package 100D, and a substrate 10D, which are another embodiment of the first embodiment, will be described. The gas sensor 900D according to the fifth embodiment includes a package 100D and a gas sensor 8. The package 100D includes a substrate 10D and a lid 7D. The substrate 10D includes a base 2, an insulating frame 23, a gas sensor region 3, wiring 4, and a heater 5.

[0073] Fig. 19 is a cross-sectional view of the gas sensor 900D, and Fig. 20 is a cross-sectional view taken along line XVIX-XVIIX, showing the state in which the bonding material B and the lid 7D are attached. Fig. 20 is a top view of the substrate 10D. In Fig. 20, the shape of the through conductor 43X when viewed from above is indicated by a dashed line to make the positional relationship easier to understand. Fig. 21 is a top view of the lid 7D.

[0074] The fifth embodiment differs from the first embodiment in that the gas sensor 900D includes a flat lid 7D and the substrate 10D includes an insulating frame 23. Unless otherwise specified below, the fifth embodiment has the same configuration as the first embodiment.

[0075] In the fifth embodiment, the substrate 10D includes an insulating frame 23 positioned on the first surface 201 of the base 2 so as to surround the gas sensor region 3. The length of the insulating frame 23 in the Z-axis direction is greater than the height of the gas sensor 8. The insulating frame 23 may be an insulating layer made of the same ceramic material as the base 2. By including the insulating frame 23 in the substrate 10D, a space capable of accommodating the gas sensor 8 can be formed, thereby simplifying the shape of the lid. Furthermore, during the manufacturing process of the gas sensor 900D, the gas sensor 8 can be protected when the gas sensor 8 is applied to the substrate 10D before the lid 7D is fixed.

[0076] The gas sensor 900D may include a flat lid 7D that covers the housing recess defined by the base 2 and the insulating frame 23. Making the lid 7D flat facilitates manufacturing. The lid 7D may have a plurality of through holes 71, as shown in FIG. 21 . Providing a plurality of through holes 71 can improve breathability. The through holes 71 may also be located at a position that does not overlap with the gas sensor 8 in a planar perspective view. Not overlapping with the gas sensor 8 in a planar perspective view can reduce the possibility of dust or the like that enters through the through holes 71 adhering to the gas sensor 8.

[0077] The lid 7D may be made of a ceramic material. By using a ceramic lid 7D, a difference in thermal expansion between the lid 7D and the substrate 10D does not occur, reducing the possibility that the gas sensor 900D will be deformed by thermal stress due to this difference in thermal expansion. This results in a gas sensor 900D with high connection reliability between the gas sensitive element 8 and the electrode wiring 41, and between the external electrode 42X and the mounting substrate.

[0078] The lid 7D made of a ceramic material and the insulating frame 23 may be bonded using a bonding material B such as glass frit or resin. Alternatively, a frame-shaped metal film may be provided on the upper surface of the insulating frame 23 and bonded using brazing material or solder. When the frame-shaped metal film and the lid 7D are bonded using brazing material, a metal film having the same configuration as the frame-shaped metal film may also be provided on the underside of the lid 7D. A nickel film may be formed by plating on the surfaces of the frame-shaped metal film and the lid 7D to improve the bondability of the brazing material.

[0079] 22 , a gas sensor 900E, a package 100E, and a substrate 10E according to another embodiment will be described. The gas sensor 900E according to the sixth embodiment includes a package 100E and a gas sensor 8. The package 100E includes a substrate 10E and a lid 7D. The substrate 10E includes a base 2E, an insulating frame 23, a gas sensor region 3, wiring 4, and a heater 5.

[0080] 22 is a cross-sectional view of a gas sensor 900E, showing a cross section at the same position as in FIG. 19. In the sixth embodiment, the substrate 10E has a recess 6A that opens to the second surface 202 at a position that overlaps with the heater 5 in a planar perspective view. More specifically, the second insulating layer of the substrate 10C has the recess 6A that opens to the second surface 202.

[0081] By providing the recess 6A, the conduction of heat from the heater 5 to the second surface 202 can be reduced.

[0082] [Embodiment 7] In embodiment 7, a gas sensor 900F, a package 100F, and a substrate 10F, which are another embodiment of embodiment 6 shown in Fig. 22, will be described with reference to Fig. 23. The gas sensor 900F according to embodiment 7 includes a package 100F and a gas sensor 8. The package 100F includes a substrate 10F and a lid 7D. The substrate 10F includes a base 2F, an insulating frame 23, a gas sensor region 3, wiring 4, and a heater 5.

[0083] 23 is a cross-sectional view of a gas sensor 900F. In the seventh embodiment, the substrate 10F has a hollow cavity 6 instead of the recess 6A of the substrate 10E of the sixth embodiment. Even with this configuration, it is possible to reduce the conduction of heat from the heater 5 to the second surface 202.

[0084] 24 to 26 , a gas sensor 900G, a package 100G, and a substrate 10G according to another embodiment will be described. The gas sensor 900G according to the eighth embodiment includes a package 100G and a gas sensor 8. The package 100G includes a substrate 10G and a lid 7D. The substrate 10G includes a base 2, an insulating frame 23G, a gas sensor region 3, wiring 4, and a heater 5.

[0085] Fig. 24 is a cross-sectional view of the gas sensor 900G, taken along the arrows XXIV-XXIV, showing the state in which the bonding material B and the lid 7D are attached to the substrate 10G of Fig. 25. Fig. 25 is a top view of the substrate 10G. Fig. 26 is a perspective view of the gas sensor 900G. In Fig. 25, to make the positional relationship easier to understand, the shapes of the through conductor 43X and the through hole 25 when viewed from above are indicated by dashed lines.

[0086] In the eighth embodiment, the substrate 10G has a through hole that penetrates from the inner surface of the insulating frame 23G to the outer surface of the substrate 10G. More specifically, the insulating frame 23G of the substrate 10G has a through hole 25 that penetrates from the outer surface to the inner surface of the insulating frame 23G. In the example shown in Fig. 25, one through hole 25 is located in the center of one side of the insulating frame 23G, but the position, number, and shape of the through hole 25 are not limited to this.

[0087] Gas heated by the heater 5 disposed below the gas sensor 8 is discharged to the outside through the through-hole 71 in the lid 7D by the rising air current. This causes the internal pressure of the package 100G to drop, and external gas flows into the package 100G through the through-hole 25 in the insulating frame 23G. In other words, a series of gas flows is formed. This improves the gas permeability in the package 100G, and improves the accuracy of gas detection by the gas sensor 8.

[0088] 27 to 29 , a gas sensor 900H, a package 100H, and a substrate 10H according to another embodiment will be described. The gas sensor 900H according to the ninth embodiment includes a package 100H and a gas sensor 8. The package 100H includes a substrate 10H and a lid 7D. The substrate 10H includes a base 2H, an insulating frame 23, a gas sensor region 3, wiring 4, and a heater 5.

[0089] Fig. 27 is a cross-sectional view of the gas sensor 900H, taken along the line XXVII-XXVII, showing a state in which the bonding material B and the lid body 7D are attached to the substrate 10H of Fig. 28. Fig. 28 is a top view of the substrate 10H. Fig. 29 is a cross-sectional view of the gas sensor 900H, taken along the line XXIX-XXVIIX, showing a state in which the bonding material B and the lid body 7D are attached to the substrate 10H of Fig. 28. In Fig. 28, to make the positional relationship easier to understand, the shapes of the through conductors 43X and part of the through holes when viewed from above are shown with dashed lines.

[0090] In the ninth embodiment, the substrate 10H has a through-hole that penetrates from the first surface 201 to the outer surface of the substrate 10H. In other words, the through-hole of the substrate 10H penetrates from the outer surface of the substrate 10H to the accommodation space for the gas sensor 8 in the package 100H. The through-hole opens to the side surface of the substrate 10H and the first surface 201. For example, the first insulating layer 21 of the substrate 10H may have a recess 26, and the recess may form the through-hole in the substrate 10H.

[0091] In the example shown in FIGS. 27 and 28, one through-hole is located in the center of one side of the substrate 10H, but the position, number and shape of the through-hole are not limited to this.

[0092] Even with the configuration of the gas sensor 900H of embodiment 9, as with the gas sensor 900G of embodiment 8, it is possible to improve the gas permeability in the package 100G, and to improve the gas detection accuracy of the gas sensor 8.

[0093] Tenth Embodiment In the tenth embodiment, a gas sensor 900I, a package 100I, and a substrate 10I according to another embodiment will be described first with reference to FIG. 30 . FIG. 30 is a cross-sectional view of the gas sensor 900I according to the tenth embodiment. The gas sensor 900I according to the tenth embodiment includes a package 100I and a gas sensor 8. The package 100I includes a substrate 10I and a lid 7I. The substrate 10I includes a base 2H, an insulating frame 23I, a gas sensor region 3, wiring 4, and a heater 5.

[0094] The insulating frame 23I includes a first frame 231 positioned on the first surface 201 of the base 2H to surround the gas-sensing region 3, a second frame 232 positioned on the upper surface of the first frame 231, and a third frame 233 positioned on the upper surface of the second frame 232. In a planar perspective view, the inner edge of the second frame 232 is positioned outward from the inner edge of the third frame 233. Also, in a planar perspective view, the inner edge of the third frame 233 may overlap or be positioned outward from the inner edge of the first frame 231. The portion of the third frame 233 that protrudes inward from the substrate 10I beyond the second frame 232 functions as a limiting portion that limits movement of the lid 7I in a direction away from the substrate 10I. In other words, the insulating frame 23I of the substrate 10I has a limiting portion 233L that limits movement of the lid 7I in a direction away from the substrate 10I.

[0095] The lid 7I is an elastic metal lid, and may have a through-hole 71. In the package 100I, the edge of the lid 7I is located inside the insulating frame 23I. In addition, the edge of the lid 7I is located below the limiting portion 233L.

[0096] With this configuration, the lid body 7I is held to the substrate 10I by the elastic force of the lid body 7I and the limiting portion 233L that limits the movement of the lid body 7I. This allows the lid body 7I to be held by the substrate 10I without being bonded to the substrate 10I using a bonding material such as resin.

[0097] Next, a lid body 7J, which is another embodiment, will be described with reference to FIG. 31 . FIG. 31 is a cross-sectional view of a gas sensor 900J showing another embodiment. The gas sensor 900J shown in FIG. 31 has the same configuration as the gas sensor 900I shown in FIG. 30 except for the shape of the lid body 7J. The lid body 7J is also a lid body made of elastic metal. The lid body 7J has a curved or bent portion formed by bending outward at its end. The curved or bent portion of the lid body 7J makes it easier to insert the lid body 7J into the insulating frame 23I.

[0098] Next, an insulating frame 23K and a lid 7K according to another embodiment will be described with reference to FIG. 32 . FIG. 31 is a cross-sectional view of a gas sensor 900K according to another embodiment. The insulating frame 23K shown in FIG. 32 includes a first frame 231 positioned on the first surface 201 of the base 2H so as to surround the gas-sensing region 3, and a second frame 232 positioned on the upper surface of the first frame 231. On the substrate 10K, the inner edge of the second frame 232, which is positioned in the uppermost layer, is positioned outside the inner edge of the third frame 233. This configuration facilitates insertion of the lid 7K into the insulating frame 23K.

[0099] The lid 7K is made of an elastic metal. The elastic force of the lid 7K allows the lid 7K to be held to the substrate 10K without using resin or the like. The lid 7K has a cap shape and has a curved or bent portion formed by bending the end portion outward. The curved or bent portion of the lid 7K makes it easier to insert the lid 7K into the insulating frame 23K.

[0100] Next, an insulating frame 23L and a lid 7L according to another embodiment will be described with reference to Fig. 33. Fig. 33 is a cross-sectional view of a gas sensor 900L according to another embodiment. The insulating frame 23L shown in Fig. 33 is positioned on the first surface 201 of the base 2H so as to surround the gas-sensing region 3. In a planar perspective view, the outer edge of the insulating frame 23L is positioned outside the outer edge of the base 2H.

[0101] The lid 7L is made of an elastic metal and has a cap shape that can accommodate the insulating frame 23L, and has a bent portion formed by bending the end portion inward.

[0102] The bent portion of the lid body 7L can be engaged with a protruding portion 23LX of the insulating frame 23L that protrudes outward beyond the base body 2H. In other words, the protruding portion 23LX of the insulating frame 23L that protrudes outward beyond the base body 2H functions as a limiting portion that limits movement of the lid body 7I in a direction away from the substrate 10I.

[0103] With this configuration, the lid 7L can be held to the substrate 10L without using a bonding material such as resin. By not using a bonding material that may be deteriorated by external environments such as gas or humidity, long-term reliability is improved.

[0104] Next, a substrate 10N and a lid 7N according to another embodiment will be described with reference to FIGS. 34 and 35. FIG. 34 is a cross-sectional view of a gas sensor 900N according to another embodiment. FIG. 34 shows a cross-sectional view taken along the arrows XXXIV-XXXIV in FIG. 35. FIG. 35 is a top view of the gas sensor 900N. The substrate 10N shown in FIGS. 34 and 35 has a base 2N with a recess 6A. The base 2N also has a through-hole 61N that penetrates from the bottom of the recess 6A to the first surface 201 of the base 2N.

[0105] The lid 7N is an elastic metal lid. The lid 7N has a cap-shaped main body that covers the gas sensor 8 and claws extending from the main body. The claws are inserted into the through-holes 61N and engage with the bottom surface of the recess 6A. The lid 7N may have a through-hole 71. The lid 7N may have, for example, a notch 72 in the main body to prevent short-circuiting with the electrode wiring 41 and to improve ventilation.

[0106] With this configuration, the lid body 7N can be held to the substrate 10N without using a bonding material such as resin. By not using a bonding material that may be deteriorated by external environments such as gas or humidity, long-term reliability is improved.

[0107] In the examples shown in the above-described first to tenth embodiments, the gas sensors 900, 900D, 900E, 900F, 900G, 900H, 900I, 900J, 900K, 900L, and 900N each include a lid. However, the lid is not an essential component of the gas sensor. In other words, it should be understood that aspects of these gas sensors that do not include a lid are also within the scope of the present disclosure.

[0108] [Embodiment 11] In embodiment 11, a gas sensor 900M and a substrate 10M, which are another embodiment of embodiment 5, will be described with reference to Figures 36 and 37. Figure 36 is a cross-sectional view of the gas sensor 900M, taken along line XXXVI-XXXVI in Figure 37. Figure 37 is a top view of the substrate 10M. The gas sensor 900M according to embodiment 11 includes a substrate 10M and a gas sensor 8. The substrate 10M includes a base body 2M, an insulating frame 23M, a gas sensor region 3, wiring 4, and a heater 5.

[0109] The substrate 10M has a first external electrode 42X and a second external electrode 42Y on an insulating frame 23M. That is, the gas sensitive region 3 differs from the other embodiments described above in that it is located between the surface on which the first external electrode 42X and the second external electrode 42Y are located and the surface on which the heater 5 is located. The first external electrode 42X is electrically connected to the electrode wiring 41 via a through conductor 43X. The second external electrode 42Y is electrically connected to the heater 5 via a through conductor 43Y.

[0110] Positioning the first external electrode 42X and the second external electrode 42Y on the insulating frame 23M allows surface mounting on the upper surface of the insulating frame 23M. Positioning the first external electrode 42X and the second external electrode 42Y on the insulating frame 23M also increases the distance from the heater 5 to the two external electrodes. This reduces the thermal effects on the conductive bonding material when mounting the gas sensor 900M. In this case, the substrate 10M can also serve as a lid, eliminating the need for a separate lid. This provides the following advantages: simplification of the manufacturing process, reduction in manufacturing costs, and realization of a low-profile gas sensor.

[0111] Furthermore, the base 2M of the substrate 10M has through holes 27 for ventilation. Specifically, the base 2M has through holes that penetrate from the first surface 201 to the outer surface of the substrate 10M. More specifically, the base 2M has through holes 27 that penetrate from the first surface 201 to the second surface 202. The base 2M may have a plurality of through holes 27. By having a plurality of through holes 27, the breathability can be improved.

[0112] The through holes 27 may be located at the corners of a rectangular region inside the insulating frame 23M in a plan view. By arranging the through holes 27 at corners with a large area, it is possible to reduce a decrease in strength of the base 2M. The through holes 27 may have an L-shape extending from each corner along the inner surface of the insulating frame 23M. By making the through holes 27 L-shaped, it is possible to increase the area of ​​the through holes 27 while ensuring the area of ​​the region in which the gas sensitive region 3 and the electrode wiring 41 are disposed.

[0113] The larger the through-hole 27, the less heat conduction from the heater 5 to the external electrode 42 and the more the gas to be detected is permeable, thereby improving the sensing accuracy of the gas sensor. Also, by enlarging the through-hole 27, the area where the heater 5 is connected to the outer periphery of the substrate 10M becomes smaller. This makes it easier for heat from the heater 5 to be transferred to the gas sensitive body 8, improving the heating efficiency of the gas sensitive body 8.

[0114] In the substrate 10M of the eleventh embodiment, the distance between the heater 5 and the first surface 201 may also be smaller than the distance between the heater 5 and the second surface 202. Because the first insulating layer 21 is thinner than the second insulating layer 22, heat from the heater 5 is more easily transferred to the first surface 201 side where the gas sensitive body 8 is located than to the second surface 202 side connected to the outside.

[0115] The distance between the heater 5 and the first surface 201 may be 10 μm or more and 100 μm or less. This configuration can reduce the risk of the heater 5 being exposed to the first surface 201. Furthermore, the distance between the heater 5 and the second surface 202 may be 100 μm or more. This configuration can reduce the temperature rise of the second surface 202.

[0116] Furthermore, the insulating frame 23M may have a through-hole that penetrates from the inner surface to the outer surface of the substrate 10M. The outer surface of the substrate 10M includes the outer surface of the substrate 10M and the second surface 202. In other words, the substrate 10M may further have a through-hole that penetrates from the inner surface to the outer surface of the insulating frame 23M. This configuration can improve gas permeability in the package 100G and increase the accuracy of gas detection by the gas sensor 8.

[0117] 27, the substrate 10M may further have a through-hole penetrating from the first surface 201 to the outer surface of the substrate 10M (the side surface of the base 2M). This configuration can improve the gas permeability in the package 100G, and can improve the gas detection accuracy of the gas sensor 8.

[0118] Fig. 38 is a cross-sectional view of a gas sensor module 90A including a gas sensor 900M. Fig. 38 shows a state in which the gas sensor module 90A is attached to a housing 80 of an electronic device or the like.

[0119] The gas sensor module 90A includes a mounting substrate 50 and a gas sensor 900M. In the example shown in FIG. 38 , the mounting substrate 50 is mounted with the gas sensor 900M, a semiconductor IC 60, and a capacitor 70. The gas sensor 900, the semiconductor IC 60, and the capacitor 70 are each surface-mounted on the mounting substrate 50 with solder S. The mounting substrate 50 has a through-hole 52 at a position corresponding to the gas sensor 8. The housing 80 may also have a through-hole 82 at a position corresponding to the gas sensor 8 or the through-hole 52. As shown in FIG. 38 , the gas sensor 900M can be directly soldered onto the mounting substrate 50 together with electronic components such as the semiconductor IC 60 and the capacitor 70 to form the gas sensor module 90A.

[0120] 38 , the gas sensor 900M and other components are mounted on the surface of the mounting substrate 50 opposite the housing 80. If the through-hole 82 of the housing 80 and the through-hole 52 of the mounting substrate 50 are large and have sufficient ventilation, the substrate of the gas sensor 900M does not need to have a through-hole.

[0121] Alternatively, the gas sensor 900M and the electronic components may be mounted on the surface of the mounting substrate 50 facing the housing 80. In this case, the mounting substrate 50 does not need to have the through-hole 52.

[0122] [Embodiment 12] In embodiment 12, a method for manufacturing the gas sensor 900 according to embodiment 1 will be described with reference to Fig. 39. Fig. 39 is a schematic plan view showing a part of a mother substrate MB according to an illustrative embodiment.

[0123] First, a mother substrate is prepared, which has a plurality of substrate regions 10X corresponding to the substrate 10. As shown in Fig. 39, the mother substrate MB has a plurality of substrate regions 10X corresponding to the substrate 10 of the first embodiment.

[0124] When the base 2 of the substrate 10 is made of an aluminum oxide sintered body, the mother substrate MB is fabricated as follows. A slurry is produced by adding an appropriate organic binder and solvent to raw material powders such as aluminum oxide and silicon oxide and mixing them. This slurry is formed into a sheet using a doctor blade method, a calendar roll method, or the like to produce a ceramic green sheet for the insulating layer 20 of the substrate 2. The ceramic green sheet for the insulating layer 20 is then punched appropriately to form through holes for the via conductors 43, and filled with a metal paste to form the via conductors 43. Metal paste for the electrode wiring 41, external electrodes 42, interlayer conductors 44, frame-shaped metal film M, and heater 5 is then applied by a method such as screen printing. Multiple ceramic green sheets for the insulating layers are then stacked to produce a laminate. The laminate is then fired at a high temperature (approximately 1300 to 1600°C) to produce the mother substrate MB.

[0125] After the mother substrate MB is prepared, the gas sensor 8 is formed. The gas sensor 8 is obtained by forming a semiconductor material to become the gas sensor 8 in the form of a thin or thick film in the gas sensor region 3 of each substrate region 10X of the mother substrate MB, and then sintering the semiconductor material at a high temperature of about 500°C to 800°C.

[0126] After the gas sensor 8 is formed, the cover 7 is fixed to each substrate region 10X by, for example, resin bonding.

[0127] Thereafter, the mother substrate MB is divided into individual pieces by a method such as snap breaking or dicing, thereby obtaining a plurality of gas sensors 900 .

[0128] The above-described method enables highly efficient mass production of the substrate 10. Furthermore, since the gas sensor 900 has a simple structure in which the gas sensitive body 8 is directly disposed on the substrate 10, the gas sensor 900 can be manufactured through a simple process.

[0129] Embodiment 13 In embodiment 13, a package and a gas sensor are described that include a substrate on which a first external electrode 42X and a second external electrode 42Y are located on an insulating frame 23P, and a lid. Figures 40 and 41 illustrate a gas sensor 900P that is an example of such an embodiment. Figure 40 is a cross-sectional view of the gas sensor 900P, taken along the XXXX-XXXX line in Figure 41. Figure 41 is a top view of the gas sensor 900P.

[0130] The substrate 10P has a similar configuration to the substrate 10M shown in Fig. 36 except that it has a step that can lock the lid body 7P. The step for locking the lid body 7P may be formed on the inner surface of the through hole 27 as shown in Fig. 40.

[0131] The lid 7P may be made of metal. The lid 7P has a cap-shaped main body that covers the gas sensitive element 8 and claws that extend from the main body. The claws are inserted into the through-holes 27 and are engaged with the bottom surface of the first insulating layer. The lid 7P may have a through-hole on its top surface.

[0132] The examples shown in Figures 40 and 41 are merely examples and are not limited to the above-mentioned examples. For example, the package and gas sensor may be the examples shown in Figures 30, 31, or 32 in which the first external electrode 42X and the second external electrode 42Y are located on the insulating frame. Alternatively, the package and gas sensor may be the package and gas sensor having the substrate 10M shown in Figures 36 and 37 and a flat lid that is bonded to the insulating frame 23M other than the first external electrode 42X and the second external electrode 42Y located at the corners. The lid may be ceramic.

[0133] Even when the first external electrode 42X and the second external electrode 42Y are located on the insulating frame 23P, the gas sensing element 8 can be protected by providing the lid.

[0134] [Summary] (1) The substrate in the first aspect of the present disclosure comprises a base body including a plurality of insulating layers made of a ceramic material and having a first surface and a second surface located opposite the first surface, a gas sensor region located on the first surface where a gas sensor is placed, electrode wiring located on the gas sensor region and connected to the gas sensor, a heater located between the insulating layers and overlapping the gas sensor region in a planar perspective view, and an external electrode located on the second surface and electrically connected to the electrode wiring or the heater.

[0135] (2) A substrate according to a second aspect of the present disclosure is the substrate according to the first aspect, wherein the distance between the heater and the first surface is smaller than the distance between the heater and the second surface.

[0136] (3) A substrate according to a third aspect of the present disclosure is the substrate according to the first or second aspect, wherein the distance between the heater and the first surface is 10 μm or more and 100 μm or less.

[0137] (4) A fourth aspect of the present disclosure provides a substrate according to any one of the first to third aspects, wherein the distance between the heater and the second surface is 100 μm or more.

[0138] (5) A substrate according to a fifth aspect of the present disclosure is the substrate according to any one of the first to fourth aspects, wherein the base body has a cavity between the heater and the second surface.

[0139] (6) A substrate according to a sixth aspect of the present disclosure is the substrate according to the fifth aspect, wherein the cavity is a recess that opens to the second surface.

[0140] (7) A seventh aspect of the present disclosure provides a substrate according to the fifth or sixth aspect, wherein the base body further includes a through-hole extending from the cavity to the first surface.

[0141] (8) In an eighth aspect of the present disclosure, the substrate is the substrate of any one of the first to seventh aspects, further comprising an insulating frame on the first surface, the insulating frame being positioned to surround the gas-sensing region.

[0142] (9) A ninth aspect of the present disclosure provides a substrate according to the eighth aspect, wherein the base body is positioned so as to overlap the heater in a plan view perspective and has a recess that opens to the second surface.

[0143] (10) In a tenth aspect of the present disclosure, the substrate of the eighth aspect has a through hole that penetrates from the inner surface of the insulating frame to the outer surface of the substrate.

[0144] (11) In an eleventh aspect of the present disclosure, the substrate is the substrate of any one of the first to tenth aspects, further comprising a through hole that penetrates from the first surface to the outer surface of the substrate.

[0145] (12) In the twelfth aspect of the present disclosure, the substrate includes a base body having a first surface, including a plurality of insulating layers made of a ceramic material, a gas sensing region located on the first surface where a gas sensing body is placed, an insulating frame body located on the first surface so as to surround the gas sensing region, electrode wiring located in the gas sensing region and connected to the gas sensing body, a heater located between the insulating layers and positioned overlapping the gas sensing body region in a planar perspective view, and an external electrode located on the insulating frame body and electrically connected to the electrode wiring or the heater.

[0146] (13) A substrate according to a thirteenth aspect of the present disclosure is the substrate according to the twelfth aspect, further comprising a through-hole that penetrates from the first surface to the outer surface of the base.

[0147] (14) A fourteenth aspect of the present disclosure is a substrate in the substrate of aspect 12 or 13, wherein the base includes a second surface located opposite the first surface, and the distance between the heater and the first surface is smaller than the distance between the heater and the second surface.

[0148] (15) A fifteenth aspect of the present disclosure provides a substrate according to the fourteenth aspect, wherein the distance between the heater and the first surface is 10 μm or more and 100 μm or less.

[0149] (16) A substrate according to a sixteenth aspect of the present disclosure is the substrate according to the fourteenth or fifteenth aspect, wherein the distance between the heater and the second surface is 100 μm or more.

[0150] (17) In a seventeenth aspect of the present disclosure, the substrate is the substrate of any one of the twelfth to sixteenth aspects, further comprising a through hole that penetrates from the inner surface of the insulating frame to the outer surface of the substrate.

[0151] (18) In an eighteenth aspect of the present disclosure, the substrate is the substrate of any one of aspects 12 to 16, further comprising a through hole that penetrates from the first surface to the outer surface of the substrate.

[0152] (19) A package according to a nineteenth aspect of the present disclosure includes the substrate according to any one of aspects 1 to 11 above and a lid.

[0153] (20) A package according to a twentieth aspect of the present disclosure is the package according to the nineteenth aspect, wherein the lid is made of metal.

[0154] (21) A package according to a twenty-first aspect of the present disclosure is the package according to the nineteenth aspect, wherein the lid is made of a ceramic material.

[0155] (22) A package in a 22nd aspect of the present disclosure comprises the substrate of aspect 8 above and a lid body, the lid body being made of an elastic metal, and the edge of the lid body being located inside the insulating frame body.

[0156] (23) A package according to a 23rd aspect of the present disclosure is the package according to the 22nd aspect, wherein the insulating frame has a limiting portion that limits movement of the lid in a direction away from the substrate.

[0157] (24) A gas sensor according to a twenty-fourth aspect of the present disclosure includes the package according to any one of the nineteenth to twenty-third aspects and a gas sensor.

[0158] (25) A gas sensor according to a twenty-fifth aspect of the present disclosure includes the substrate according to any one of the twelfth to eighteenth aspects and a gas sensor.

[0159] (26) A gas sensor module according to a twenty-sixth aspect of the present disclosure includes the gas sensor according to the twenty-fourth aspect and a mounting substrate, and the gas sensor is surface-mounted on the mounting substrate via a conductive adhesive material.

[0160] (27) A gas sensor module according to a twenty-seventh aspect of the present disclosure includes the gas sensor according to the twenty-fifth aspect and a mounting substrate, and the gas sensor is surface-mounted on the mounting substrate via a conductive adhesive material.

[0161] (28) A gas sensor module in a 28th aspect of the present disclosure is the gas sensor module of the 27th aspect, wherein the mounting substrate has a through hole at a position opposite the gas sensor that allows gas to flow in from the outside.

[0162] (29) A method for manufacturing a gas sensor in a 29th aspect of the present disclosure includes the steps of preparing a mother substrate having a plurality of substrate regions corresponding to any one of the substrates in aspects 1 to 18 above, forming a gas sensor in the gas sensor region, and singulating the mother substrate.

[0163] 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. 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 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 a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure.

[0164] DESCRIPTION OF SYMBOLS 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, 10K, 10L, 10M, 10N... Substrate 2, 2A, 2B, 2C, 2E, 2H, 2M... Base body 20... Insulating layer 21... First insulating layer 22... Second insulating layer 23, 23G, 23I, 23K, 23L, 23M... Insulating frame body 233L... Restriction portion 25, 27... Through hole 3... Gas sensitive region 4... Wiring 41... Electrode wiring 42... External electrode 43, 43X, 43X1, 43X2, 43Y... Through conductor 44, 44X... Interlayer conductor 44Y... Heater terminal (interlayer conductor) 5... Heater 6... Cavity 61... Through hole 7, 7D, 7I, 7J, 7K, 7L, 7N, 7P... Lid body 71... Through hole 8... Gas sensor B... Bonding material 100, 100D, 100E, 100F, 100G, 100H, 100I... Package MB... Mother substrate 10X... Substrate area 900, 900D, 900E, 900F, 900G, 900H, 900I, 900J, 900K, 900L, 900M, 900N, 900P... Gas sensor 90, 90A... Gas sensor module

Claims

1. a substrate including a plurality of insulating layers made of a ceramic material, the substrate having a first surface and a second surface opposite the first surface; a gas sensor region located on the first surface, the gas sensor region being a region in which a gas sensor is disposed; an electrode wiring located in the gas sensor region and connected to the gas sensor; a heater positioned between the insulating layers and overlapping the gas sensing region in a plan view perspective; A substrate comprising an external electrode electrically connected to the electrode wiring or the heater.

2. The substrate of claim 1 , wherein the distance between the heater and the first surface is less than the distance between the heater and the second surface.

3. The substrate according to claim 1 , wherein the base has a cavity between the heater and the second surface, the cavity being positioned so as to overlap the heater when viewed from above.

4. The substrate according to claim 3 , wherein the cavity is a recess that opens to the second surface.

5. The substrate of claim 3 , wherein the base further comprises a through-hole extending from the cavity to the first surface.

6. The substrate of claim 1 having a through hole extending from the first surface to an outer surface of the substrate.

7. The substrate according to claim 1 , further comprising an insulating frame on the first surface, the insulating frame being positioned to surround the gas sensitive region.

8. The substrate according to claim 7 , further comprising a through-hole extending from the inner surface of the insulating frame to the outer surface of the substrate.

9. The substrate of claim 1 , wherein the external electrode is located on the second surface.

10. The substrate of claim 7 , wherein the external electrodes are located on the insulating frame.

11. A package comprising the substrate according to claim 1 and a lid.

12. A device comprising the substrate according to claim 7 or 8 and a lid, the lid is an elastic metal lid, The package, wherein an edge of the lid is located inside the insulating frame.

13. The package according to claim 12 , wherein the insulating frame has a limiting portion that limits movement of the lid in a direction away from the substrate.

14. A gas sensor comprising the package according to claim 11 and a gas sensitive body.

15. A gas sensor comprising the substrate according to claim 1 and a gas sensitive body.

16. A gas sensor comprising: the gas sensor according to claim 14; and a mounting substrate; The gas sensor module is configured such that the gas sensor is surface-mounted on the mounting substrate via a conductive adhesive material.

17. A gas sensor including the substrate and the gas sensitive body according to claim 10, and a mounting substrate, the gas sensor is surface-mounted on the mounting substrate via a conductive bonding material; The mounting substrate has a through-hole at a position facing the gas sensitive body to allow gas to flow in from the outside.

18. Providing a mother substrate having a plurality of substrate areas corresponding to the substrate of any one of claims 1 to 10; forming a gas sensitizer in the gas sensitizer region; and dividing the mother substrate into individual pieces.