JP2006337110A - Gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor capable of reducing the manufacturing cost of a gas detection element, making connectivity of a support body satisfactory and the planar shape of the support body small. <P>SOLUTION: This gas sensor 10 (gas sensor body 1) comprises first and second gas detection elements 3 and 4, and a wiring board (support body) 2 mounted therewith. The first gas detection element 3 has an outer first heater pad 34A, an outer first detection pad 33A, an inner first detection pad 33B, and an inner first heater pad 34B, these lining up in this order. The second gas detection element 4 has the same material, shape, and structure, exclusive of the material of a second gas sensitive film 42. On a pad forming side part 22P of the wiring board 2, five pads line up, the five pads comprising a board side common pad 23C, etc. connected to four pads in the detection elements 3 and 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas sensor in which two gas detection elements are mounted on a support such as a wiring board.

Conventionally, as a gas sensor for detecting the presence or absence of a plurality of gas types in a gas to be measured and a concentration change, at least two gas sensitive parts made of the same material are provided on one chip (Si element substrate). A micro gas sensor provided with a heater for individually heating is known (Patent Document 1). This Patent Document 1 also discloses a gas sensor (thick film hybrid gas sensor) having three gas sensitive parts made of different materials and one heater as a prior art.
Further, Patent Document 2 and Patent Document 3 also disclose a multi-gas identification gas detection device (gas sensor) in which a plurality of metal oxide semiconductor layers are provided on one element substrate (chip).

JP 62-15449 A JP-A-3-20658 JP-A-6-3308

By the way, when forming a gas sensitive film (metal oxide semiconductor layer) that reacts with a desired gas species, there is a case where it is desired to perform heat treatment according to the material at the time of film formation or after film formation.
However, when using a gas detection element in which a gas sensitive film (metal oxide semiconductor layer) made of a plurality of different materials is formed in one chip as in the above-described prior art, a specific gas sensitive film is used. When the heat treatment is performed at a temperature suitable for the above, there is a possibility that the characteristics of other gas sensitive films may be impaired, and there are cases where the heat treatment method and temperature may be limited, and sufficient characteristics of the gas sensitive film may not be extracted.

Therefore, it is conceivable that two gas detection elements each having a gas sensitive film that reacts with different gas types are manufactured separately and mounted on a support such as one wiring board to form a gas sensor.
In such a gas sensor, the manufacturing process of the two gas detection elements to be used is made the same (common) as much as possible, so that the devices, masks, jigs, and the like necessary for the manufacture are shared, and the gas detection elements are manufactured. Cost can be reduced. In particular, it is preferable that the two gas detection elements mounted on the support have the same configuration including materials such as detection electrodes and heaters, wiring patterns, etc., except for the gas sensitive film.
On the other hand, in order to facilitate the connection of this gas sensor, there is a demand to reduce the number of external terminals provided on the support for connection to an external circuit. Therefore, one of the pair of detection electrodes electrically connected via the gas sensitive film formed on the gas detection element and one of the pair of heater electrodes respectively connected to both ends of the heater are shared (for example, Common ground potential). Furthermore, it is preferable that one of the detection electrodes common to each gas detection element and one of the heater electrodes be further shared by the two gas detection elements.

However, if the wiring pattern is the same for the two gas detection elements in this way, depending on the wiring pattern and the arrangement of the two gas detection elements, in order to achieve such commonality, the wiring of the wiring formed on the support body is not the same. The routing becomes long or the bonding wire is complicated. In addition, there is a problem that the support side pad formed around the gas detection element needs to be enlarged, and the planar shape of the support tends to be large.
The present invention has been made in view of such problems, and in a gas sensor in which two gas detection elements are mounted on a support, the manufacturing cost of the gas detection element can be reduced and the connectivity of the support is excellent. And providing a gas sensor capable of reducing the planar shape of the support.

  The solution includes a first gas sensitive film that reacts with a first gas species, a pair of first sensing electrodes that are electrically connected via the first gas sensitive film, and a first that heats the first sensitive film. A pair of heaters, a pair of first detection connection wires connected to the first detection electrodes, a pair of first heater connection wires connected to both ends of the first heater, and a pair of connections connected to the pair of first detection connection wires, respectively. A first gas detection element having a polygonal shape in plan view, including a first detection pad and a pair of first heater pads respectively connected to the pair of first heater connection wires, and a first gas detection element that reacts to a second gas type. Two gas sensitive membranes, a pair of second sensing electrodes electrically connected via the second gas sensitive membrane, a second heater for heating the second sensitive membrane, and a pair of first sensing electrodes respectively connected to the second sensing electrodes 2 detection connection wiring, the second heater A pair of second heater connection wires connected to both ends, a pair of second detection pads connected to the pair of second detection connection wires, and a pair of second heaters connected to the pair of second heater connection wires, respectively. The first gas detection element includes a heater pad, the second gas detection element having a polygonal shape in plan view, and having the same form and material including at least the wiring pattern, and the first gas detection element and the second gas. And a pair of first detection pads and a pair of first heater pads of the first gas detection element, wherein the pair of first detection pads and the pair of first heater pads are peripheral edges of the first gas detection element. Any one of one of the first detection pads and one of the first heater pads, one of the first detection pads and one of the first heater pads, along the first take-out side. Or the other first detection pad and the other first heater pad, the other first detection pad and the other one of the other first heater pads, arranged in order, The pair of second detection pads and the pair of second heater pads of the second gas detection element are arranged along one second detection pad and one of the peripheral edges of the second gas detection element along the second extraction side. One of the second heater pads, one of the second detection pads and one of the second heater pads, one of the other second detection pads and the other second heater pad, the other second detection pad 2 and the other second heater pad are arranged in the order of the other, and the first gas detection element and the second gas detection element are the first gas in the support. Sensing element If it is translated along the first take-out side, they are arranged side by side at a position overlapping the second gas detection element, and the support is the second gas detection of the pair of first detection pads. An inner first detection pad located on the element side, an inner first heater pad located on the second gas detection element side of the pair of first heater pads, and the first gas detection on the pair of second detection pads. A support side common pad connected to the inner second detection pad located on the element side, and the inner second heater pad located on the first gas detection element side of the pair of second heater pads, and a pair of A support-side first detection pad that is connected to the remaining outer first detection pad of the first detection pads, and a support that is connected to the remaining outer first heater pad of the pair of first heater pads. A first heater pad; a support-side second detection pad connected to a remaining outer second detection pad of the pair of second detection pads; and a remaining outer second heater pad of the pair of second heater pads. A support side second heater pad to be connected, wherein the support side first detection pad and the support side first heater pad, the support side second detection pad and the support side second heater pad are the support A gas sensor arranged in a row with the common pad on the side. It is.

  In the gas sensor of the present invention, the first gas detection element and the second gas detection element have the same form and material including at least the wiring pattern. For this reason, since the first gas detection element and the second gas detection element can be manufactured using at least the processes before the formation of the first gas sensitive film and the second gas sensitive film and the subsequent processes in common. Easy and inexpensive to manufacture. In addition, since the same-shaped element is mounted, mounting on a support such as a wiring board is easy. The wiring pattern includes detection connection wiring (first detection connection wiring, second detection connection wiring), heater connection wiring (first heater connection wiring, second heater connection wiring), detection pads to be connected to these, A heater pad is also included.

  The gas sensor according to the present invention includes a support-side common pad on the support, and connects the inner first detection pad, the inner first heater pad, the inner second detection pad, and the inner second heater pad. Yes. For this reason, although it has two gas detection elements, it is sufficient if five support side pads are formed on the support. Accordingly, the number of terminals formed on the support for connection with an external circuit is only a small number of five, and the connectivity is good. In addition, since the support side common pad is connected to the inner first detection pad, the inner first heater pad, the inner second detection pad, and the inner second heater pad that are located close to each other, bonding for connection is performed. The wires are short and can be connected with low resistance.

  Moreover, in the first gas detection element, the pair of first detection pads and the pair of first heater pads are arranged along the first extraction side in a predetermined order, and in the second gas detection element, the pair of second detection pads and A pair of second heater pads are arranged along the second extraction side in a predetermined order. Correspondingly, the support side first detection pad and the support side first heater pad, and the support side second detection pad and the support side second heater pad are arranged in a row with the support side common pad interposed therebetween. It becomes. For this reason, compared with what forms a support side pad in the outer side of each edge of the gas detection element among the supports, the area of the support can be reduced and the size can be reduced. In addition, it is possible to reduce the dimension in the direction in which the two gas detection elements are arranged or in the direction perpendicular thereto. In addition, the routing of the internal wiring or the bonding wire in the support body can be easily and shortened.

In the gas sensor of the present invention, examples of the first gas detection element and the second gas detection element include a gas sensitive film, a detection electrode, a heater and the like formed on an appropriate element substrate. As the element substrate, for example, an insulating ceramic substrate made of alumina or the like, a single crystal semiconductor substrate made of Ge, Si, particularly a Si element substrate can be used. More preferably, a gas detection element in which a part of the Si element substrate is thinned by using anisotropic etching to form a diaphragm part, and a gas sensitive film, a detection electrode, a heater, etc. are formed in this part can be mentioned. .
In the gas sensor of the present invention, each of the first gas detection element and the second gas detection element has a gas sensitive film and a pair of detection electrodes that are electrically connected to each other. This type of gas detection element functions in the same manner even when the detection electrode is electrically used in reverse (with the positive electrode being a negative electrode and the negative electrode being a positive electrode). Similarly, the heater functions similarly (can be heated) even if the heater electrode is used in reverse. Therefore, the first gas detection element and the second gas detection element function in the same manner although the electrical roles of the respective pads are reversed. Therefore, according to the nature of the gas sensitive film, the first gas type and the second gas detection element. Gas detection is possible for each gas type.

In the gas sensor of the present invention, the first gas sensitive film and the second gas sensitive film may have the same form and material, or at least one of the form and the material may be different.
Any gas-sensitive film can be used as long as its electrical characteristics change in response to a specific gas species, and examples thereof include an oxide semiconductor film. Examples of the oxide semiconductor used for the gas sensitive film include ZnO, SnO ₂ , WO ₃ , In ₂ O ₃ , TiO ₂ , V ₂ O _{5 and the} like. Depending on the type of gas to be detected, the composition of the main oxide semiconductor may be selected as appropriate. In addition, the composition that is the main component of the oxide semiconductor may be made common, and the type of catalyst added thereto may be appropriately changed according to the type of gas to be detected. Specifically, there is a gas sensor in which the first gas sensitive film is composed of an oxide semiconductor mainly composed of WO ₃ while the second gas sensitive film is composed of an oxide semiconductor mainly composed of SnO ₂ .
Further, the first gas sensitive film has a structure in which Au is added as a catalyst to the surface of the oxide semiconductor mainly composed of SnO ₂ , while the second gas sensitive film is composed of the surface of the oxide semiconductor mainly composed of SnO _2. In addition, a gas sensor having a configuration in which Pd or Pt is added as a catalyst to the above can be mentioned.

  In addition, any heater may be used as long as it generates heat when energized. For example, the material forming the conductive path has a high volume resistivity, or the line width and cross-sectional area of the conductive path are reduced. Examples include linear heaters that generate heat by increasing the resistance. In this linear heater, the conductive path can be in the form of a zigzag or double spiral in addition to a linear shape. Moreover, the heater etc. which arrange | position a resistor in planar shape and generate | occur | produce the whole surface are also mentioned.

  Furthermore, as the support, the first gas detection element and the second gas detection element are mounted, and support side pads such as a support side first detection pad for supporting these and taking out each of these pads to the outside. As long as it is provided. For example, there may be mentioned a form in which terminal pins are fixed to a base metal plate such as a metal can package while being insulated with a glass seal or the like, or a wiring board such as a ceramic package or a resin package. Among these, as the wiring board, a flat board having a required wiring formed can be used, and a wiring board having a cavity (cavity) for accommodating the first and second gas detection elements can also be used. Can be used. The wiring board is suitably made of ceramic such as alumina, mullite, silicon nitride, aluminum nitride, glass, resin such as epoxy resin or BT resin, or composite material of ceramic powder and resin. The material can be used. In particular, when used at a high temperature or for a gas sensor that raises the heater temperature, it is preferable to use a ceramic wiring board.

Furthermore, the connection between the support body such as the wiring board and the first gas detection element and the second gas detection element is performed by a detection pad formed on the surface of the gas detection element, a heater pad, and a support side pad formed on the support body. Side first detection pad, support side first heater pad, support side common pad, etc.) may be connected by a bonding wire using a wire bonding technique, or a TAB lead may be used.
In addition, the support side first detection pad and the support side first heater pad, and the support side second detection pad and the support side second heater pad may be arranged in a line with the support side common pad interposed therebetween. Well, depending on the shape of the support, for example, in addition to arranging them in a straight line, a form in which they are arranged in an arc is also included.

  The gas sensor may be a gas sensor in which the first gas type is an oxidizing gas and the second gas type is a reducing gas.

  The gas sensor according to the present invention can detect both the oxidizing gas such as NOx and the reducing gas such as CO and HC contained in the exhaust gas, thereby reliably detecting the concentration change of the exhaust gas. it can. Therefore, this gas sensor can be easily applied to a flap opening / closing control system for controlling ventilation in a vehicle interior of an automobile.

  Furthermore, the gas sensor according to any of the above, wherein the first detection pad, the first heater pad, the second detection pad, and the second heater pad, the support side first detection pad, and the support side first heater. The pad, the support side common pad, the support side second detection pad, and the support side second heater pad are each connected by a bonding wire, and these may be gas sensors that are covered with an insulating material.

Due to the nature of the gas sensor, the first gas sensitive film and the second gas sensitive film of the first gas detecting element and the second gas detecting element need to be exposed to the gas to be measured (for example, outside air or exhaust gas). . Therefore, the entire first gas detection element and second gas detection element cannot be covered in an airtight manner as in the case where the IC chip is mounted on the wiring board.
On the other hand, pads (first detection pad, first heater pad) formed on the first gas detection element, pads (second detection pad, second heater pad) formed on the second gas detection element, wiring board, and the like Support side pads (support side first detection pad, support side first heater pad, support side common pad, support side second detection pad, support side second heater pad) formed on the support body and bonding for connecting them When the wires are exposed to the outside, there is a possibility that a short circuit may occur due to adhesion of water droplets or other foreign matters or collision of foreign matters.
On the other hand, in the gas sensor of the present invention, since each pad and bonding wire are covered with an insulating material, a short circuit is unlikely to occur due to adhesion or collision of foreign matter, and the gas sensor is more reliable.

  The gas sensor according to claim 3, wherein the first detection pad, the first heater pad, the second detection pad, the second heater pad, the support side first detection pad, the support side first heater pad, and the support side. The common pad, the support-side second detection pad, the support-side second heater pad, and the bonding wire connecting them may be gas sensors that are sealed with an insulating sealing resin material.

  In the gas sensor of the present invention, since each pad and bonding wire are sealed with a sealing resin material, it is difficult to cause a short circuit due to adhesion or collision of water droplets or other foreign matters, and it is difficult to deform and effectively prevent disconnection. Therefore, it becomes a more reliable gas sensor.

  Furthermore, in the gas sensor according to claim 4, the sealing resin material may be a gas sensor that is disposed apart from the first gas sensitive film and the second gas sensitive film.

  In the gas sensor of the present invention, since the sealing resin material is disposed apart from the first gas sensitive film and the second gas sensitive film, the detection sensitivity and heat caused by the sealing resin material adhering to the gas sensitive part are detected. It is possible to appropriately prevent deterioration of characteristics such as characteristics.

  The gas sensor according to claim 5, wherein the gas sensor is disposed on at least surfaces of the first gas detection element and the second gas detection element, and the first gas sensitive film, the first detection pad, and the first Partitioning between the second gas sensitive film and the second detection pad and the second heater pad between the heater pad and the sealing resin material to the first gas sensitive film and the second gas sensitive film; A gas sensor including a dam member that prevents intrusion may be used.

  In the gas sensor of the present invention, a dam member is formed to prevent the sealing resin material from entering the first gas sensitive film or the second gas sensitive film. It is possible to reliably prevent deterioration in characteristics such as detection sensitivity and thermal characteristics due to adhesion.

  Still further, the dam member is formed between the first gas sensitive film and the first detection pad and the first heater pad, and between the second gas sensitive film, the second detection pad and the second heater pad. Preferably, the gas sensor is configured to extend in parallel with the first extraction side and the second extraction side.

  In this gas sensor, the dam member is disposed between the first gas sensitive film and the first detection pad and the first heater pad, and between the second gas sensitive film and the second detection pad and the second heater pad. The form extends in parallel. Therefore, for example, among the rectangular first and second gas detection elements, terminal pads are distributed and arranged on each of the four sides, so that they are widely distributed on the periphery of the first and second gas detection elements. Compared with the case, the site | part which provides a dam member can be decreased, and a 1st, 2nd gas detection element can be reduced in size. In addition, the support side terminal pads (support side first detection pad, support side first heater pad, support side common pad, support side second detection pad, support side second heater pad) of the support are also the first and second gas. Since it can arrange | position along the 1st, 2nd extraction edge of a detection element, the magnitude | size of a support body can also be made small.

  In addition, a flat plate-shaped gas-sensitive part that reacts to a predetermined gas type, a plurality of gas-sensitive parts that extend from the gas-sensitive part and transmit power, signals, etc. that are input to or output from the gas-sensitive part A gas detection element including element wiring and a plurality of terminal pads connected to the element wiring located on the surface of the element wiring, and the gas detection element mounted with the surface facing outward, the terminal pad And a support body including a plurality of support-side terminal pads that are electrically connected to each other via a conduction member, wherein the plurality of terminal pads, the plurality of support-side terminal pads, and the conduction member are sealed. An insulating sealing resin material, and at least disposed on the surface of the gas detection element, partitioning between the gas sensitive part and the plurality of terminal pads, and sealing resin to the gas sensitive part Intrusion of material A dam member made to prevent, preferably a gas sensor comprising a.

Due to the nature of the gas sensor, it is necessary to expose the gas sensitive film portion of the gas detection element to a gas to be measured (for example, outside air or exhaust gas). Therefore, the entire gas detection element cannot be covered airtightly as in the case where the IC chip is mounted on the wiring board.
On the other hand, if conductive pads such as pads formed on the gas detection element, support-side pads formed on the support, and bonding wires connecting them are exposed to the outside, water droplets or other foreign substances may adhere or There is a possibility that they may be short-circuited or disconnected due to collisions.

  In contrast, in the gas sensor described above, a plurality of terminal pads, a plurality of support-side terminal pads, and a conductive member are sealed with a sealing resin material, thereby causing problems such as a short circuit or disconnection due to adhesion or collision of water droplets or foreign matter. Can be prevented. In addition, since the dam member is formed, the sealing resin material does not enter the gas sensitive part, and the detection sensitivity, thermal characteristics, etc. due to the sealing resin material adhering to the gas sensitive part. It is possible to reliably prevent characteristic deterioration.

  Further, in the gas sensor described above, each of the plurality of terminal pads is arranged along a predetermined extraction side of the periphery of the gas detection element, and the dam member includes the gas sensitive portion and the plurality of the plurality of terminal pads. It is preferable that the gas sensor has a configuration extending in parallel with the extraction side between the terminal pads.

  In this gas sensor, the terminal pad is arranged along the take-out side, and the dam member is configured to extend in parallel with the take-out side between the gas sensitive portion and the plurality of terminal pads. For this reason, for example, a dam member is provided compared to a case in which terminal pads are dispersed and arranged on each of the four sides of a rectangular gas detection element, as compared with a case where the gas detection element is widely dispersed on the periphery. The number of parts can be reduced, and the gas detection element can be reduced in size. In addition, since the support-side terminal pad of the support can be arranged along the take-out side of the gas detection element, the size of the support can also be reduced.

  Embodiments of the present invention will be described based on examples and modifications.

  First, the gas sensor 10 which concerns on the Example of this invention is demonstrated with reference to FIGS. As shown in FIG. 1, the gas sensor 10 of the present embodiment includes a gas sensor main body 1 composed of a wiring board (support) 2 on which two gas detection elements 3 and 4 are mounted, and the gas sensor main body 1 (wiring board 2). It consists of a protected surface 2S and a protective cover 9 that covers the cavity 21 (concave portion) surrounded by the protected surface 2S.

  As shown in FIGS. 1 and 2, the wiring board 2 has a substantially rectangular parallelepiped shape, is surrounded by a substantially rectangular frame-shaped protected surface 2S, and has two gas detection elements 3 and 4 mounted therein. A cavity 21 forming a space is recessed. Among the side surfaces of the wiring board 2, of the opposing short side portions, the protected surface 2 </ b> S side constitutes guide recesses 2 </ b> A and 2 </ b> B that are recessed inward. Engagement recesses 2C and 2D which are further recessed inward one step are formed on the opposite side (back surface 2E side) of the protected surface 2S from the guide recesses 2A and 2B (see FIG. 3).

  On the other hand, the protective cover 9 is a substantially flat plate-shaped protective plate portion 91 that covers the protected surface 2S of the wiring board 2 and the cavity 21, and an engagement that is bent at right angles from both end portions of the protective plate portion 91 and extends. And has a substantially U shape when viewed from the side. Among these, the protective plate 91 is provided with vent holes 91A at a plurality of predetermined positions, and the gas to be measured is guided to the two gas detection elements 3 and 4 through the vent holes 91A. Further, a direction indicating notch 91B indicating the mounting direction of the protective cover 9 is formed on the peripheral edge of the protective plate 91, and it is erroneously attached to the gas sensor main body 1 (wiring board 2) in a state rotated by 180 degrees. Is preventing. Further, the engaging portions 92 and 93 are respectively formed with locking claws 92A and the like (the engaging portion 93 side is not shown) near the tips thereof.

  Since the protective cover 9 has the above-described form, the engaging portions 92 and 93 are arranged along the guide recesses 2A and 2B of the wiring board 2, and the protective plate portion 91 is connected to the protected surface 2S and the cavity of the wiring board 2. Approaches 21. The protective cover 9 is locked to the gas sensor body 1 (wiring board 2) by engaging the locking claws 92A and the like of the protective cover 9 with the engaging recesses 2C and 2D of the wiring board 2.

  Next, the gas sensor main body 1 will be described in more detail. The gas sensor main body 1 is configured by mounting two gas detection elements 3 and 4 on a wiring board 2. Among them, the wiring board 2 is an electronic component formed by laminating ceramic insulating layers, specifically, four layers of alumina ceramic insulating layers 24, 25, 26, and 27, as shown in FIGS. It is a package. A plurality of so-called castellations recessed in a substantially semi-cylindrical shape or a quarter-cylindrical shape are formed on the side surface portion of the wiring board 2, and the internal wiring of the wiring board 2 is drawn out to the castellation portion. Further, through this castellation, it is routed to the lower surface of the wiring board 2 (not shown) and can be soldered to a printed board or the like.

  In this wiring board 2, a ceramic insulating layer 25 constituting a back surface ventilation groove 25 </ b> A is laminated on a substantially rectangular flat plate-shaped ceramic insulating layer 24 positioned at the lowermost layer, and further, a ceramic insulating layer 26 having a substantially rectangular frame shape. Are stacked. Further, a ceramic insulating layer 27 that is narrower than the ceramic insulating layer 26 and has a substantially rectangular frame shape is laminated thereon. Thereby, the ceramic insulating layer 25 constitutes the bottom portion 21 </ b> B of the cavity 21, and the ceramic insulating layer 26 constitutes the step portion 22 in the cavity 21.

Among these, the five substrate-side pads 23 are arranged in a row on the pad forming side portion 22P corresponding to one side of the step portion 22 that is one step higher than the bottom portion 21B and surrounds the bottom portion 21B in a square shape. Is formed. Specifically, in FIG. 2, from the left, the substrate side first heater pad 23A, the substrate side first detection pad 23B, the substrate side common pad 23C, the substrate side second detection pad 23D, and the substrate side second heater pad 23E are displayed. The pad forming side portions 22P are collected and arranged in a line in this order.
These board-side pads 23 can be connected to the outside by a known structure. Specifically, the board-side pads 23 are each led to a castellation formed on the side surface of the wiring board 2 through an internal wiring (not shown), and a connection pad on the back surface 2E through a conductive layer formed on the castellation. (Not shown). Thereby, this gas sensor 1 can be mounted on a support substrate such as a printed board.

  As described above, the first gas detection element 3 and the second gas detection element 4 are accommodated and mounted in the cavity 21 of the wiring board 2. Each of the first gas detection element 3 and the second gas detection element 4 has a rectangular shape in a plan view, and has a gas sensitive part having a diaphragm structure.

Specifically, as shown in FIG. 5, the first gas detection element 3 is formed of a rectangular flat plate-like silicon chip, and the first gas sensitive part 31 is slightly closer to the center in FIG. Have The first gas sensitive part 31 is formed using a known semiconductor manufacturing technique so that comb teeth mesh with each other on the double spiral heater 38 (see FIG. 7B) shown in FIG. A pair of first detection electrodes 36 </ b> A and 36 </ b> B (see FIG. 7A) arranged with a space therebetween are formed to overlap each other while being electrically insulated from each other. Further thereon, a rectangular first gas sensitive film 32 made of a metal oxide semiconductor (specifically SnO ₂ ) is deposited so as to cover them, and is applied to the pair of first detection electrodes 36A, 36B. Electrically connected. In the present embodiment, the first gas sensitive film 32 is made of Au as a catalyst dispersed and adhered to the surface of SnO ₂ . Since the first gas detection element 3 is configured as described above, when the heater 38 is energized, the first gas sensitive film 32 is heated and activated, and becomes an oxidizing gas (first gas type) such as NOx. In response, the resistance value changes. Therefore, the concentration change of the oxidizing gas can be detected by measuring the resistance value of the first gas sensitive film 32 between the pair of first detection electrodes 36A and 36B.

  As shown in the cross-sectional views of FIGS. 3 and 4, the first gas detection element 3 has a concave diaphragm structure in which the thickness of the silicon chip is reduced toward the surface 3B side in the first gas sensitive portion 31. It is part 3A. In the present embodiment, the first gas sensitive film 32 having the same size as this is deposited on the rectangular diaphragm portion 3AD in which the thickness of the silicon chip is reduced to a flat plate shape in the diaphragm structure portion 3A. Has been. As a result, the temperature of the diaphragm portion 3AD easily rises due to energization of the heater 38, so that the response of the first gas detection element 3 is improved.

The ends of the pair of first detection electrodes 36A and 36B formed on the first gas sensitive part 31 are drawn out of the first gas sensitive part 31 and are respectively connected to the first detection connection wirings 35A and 35B. Electrically connected.
The first detection connection wires 35A and 35B have a line width sufficiently thicker than the line width of the first detection electrodes 36A and 36B. This is because the resistance generated in the first detection connection wirings 35A and 35B is as low as possible.

  By the way, of the first detection connection wirings 35A and 35B, the connection portions with the first detection electrodes 36A and 36B are tapered so that the line width gradually decreases, specifically, the first detection connection wirings 35A and 35B. Of these, taper portions 35AT and 35BT having a so-called one-taper shape in which the outer side in the line width direction gradually approaches the inner side. If the line width is suddenly changed, the portion may be easily broken, and this is to prevent this.

  On the other hand, of the first heater connection wirings 37A and 37B, the connection portion with the heater 38 is also tapered in a gradually narrowing line width, specifically, a beak shape, and the lines of the first heater connection wirings 37A and 37B. The taper portions 37AT and 37BT have a so-called double taper shape whose width gradually approaches the center. If the line width is suddenly changed, the portion may be easily broken, and this is to prevent this. Further, this is because heat generation is selectively performed by the thin diaphragm portion 3AD, and heat generation outside the diaphragm portion 3AD and heat escape to the outside are reduced. Furthermore, since there is a difference in thickness between the diaphragm portion 3AD and the outside thereof, there is a possibility that cracks may occur in the wiring passing therearound in the vicinity of the boundary portion between them (the peripheral edge 3ADP of the diaphragm portion 3AD). Therefore, instead of the heater 38 having a narrow line width, the first heater connection wires 37A and 37B having a large line width are positioned at the boundary portion (periphery 3ADP). Further, among the first heater connection wirings 37A and 38B, taper portions 37AT and 37BT are arranged at the boundary portion (periphery 3ADP) to further avoid stress concentration and prevent disconnection and the like.

  However, in the present embodiment, both end portions of the heater 38 are connected to the first heater connection wires 37 </ b> A and 37 </ b> B in the first gas sensitive portion 31. Therefore, of the first heater connection wirings 37A and 37B, the tapered portions 37AT and 37BT are arranged so as to straddle the peripheral edge 32P of the first gas sensitive film 32 and the peripheral edge 3ADP of the diaphragm portion 3AD of the diaphragm structure portion 3A. Has been. Since the thin diaphragm portion 3AD and the peripheral edge portion thicker than this have different behaviors against heat, the wiring of the heater 38 having a relatively narrow line width straddles the peripheral edge 3ADP of the diaphragm portion 3AD. The first heater connection wires 37A and 37B that are relatively thicker than the heater 38 and the first heater connection wires 37A and 37B are connected to each other at the periphery 3ADP of the diaphragm portion 3AD. It is because it is hard to produce malfunctions, such as a disconnection, if it was made to straddle.

  Further, in this embodiment, the heater 38 is a heater of a type that generates heat by the resistance of the wiring when energized, as shown in FIG. 7B, and the wiring has a double spiral shape. Yes. Moreover, the line width is increased toward the center. This is so that the portions of the first detection electrodes 36A and 36B and the first gas sensitive film 32, which are located between the first detection electrodes 36A and 36B and whose resistance is measured, are heated evenly. Therefore, in the heater 38, the amount of heat generation is increased in the peripheral portion where heat easily escapes, and the amount of heat generation is decreased in the inner portion where heat is difficult to escape.

  The first detection connection wirings 35A and 35B and the first heater connection wirings 37A and 37B formed on the first gas detection element 3 are the first extraction side 3P (see FIG. 5) among the rectangular peripheral edges of the first gas detection element 3. They extend in parallel to each other and are concentrated in this vicinity along the first extraction side 3P. Each of the end portions is a pad capable of wire bonding. Specifically, the first gas detection element 3 includes an outer first heater pad 34A, an outer first detection pad 33A, an inner first detection pad 33B, and an inner first heater pad 34B from the left side in FIGS. However, they are lined up in this order.

In the present embodiment, the second gas detection element 4 (see FIGS. 5 and 7) is made of a material of the second gas sensitive film 42 (more specifically, a material of the catalyst) applied to the second gas sensitive part 41. ), Including the wiring pattern, it has the same material, shape and configuration as the first gas detection element 3 described above. The material of the second gas sensitive film 42 is formed by dispersing and adhering Pd as a catalyst on the same SnO ₂ surface as that of the first gas sensitive film 32. Therefore, unlike the first gas detection element 3, the second gas detection element 4 heats and activates the second gas sensitive film 42 to reduce a reducing gas (second gas) such as CO and HC. The resistance value changes in response to the species. Therefore, by measuring the resistance value of the second gas sensitive film 42 between the pair of second detection electrodes 46A and 46B, the concentration or concentration change of the reducing gas can be detected.
Further, the second detection connection wires 45A and 45B and the second heater connection wires 47A and 47B formed on the second gas detection element 4 are also the second extraction side 4P (FIG. 2) of the rectangular peripheral edge of the second gas detection element 4. , See FIG. 5) and extend in parallel to each other, and are concentrated in the vicinity along the second extraction side 4P. Each of the end portions is a pad capable of wire bonding. 2 and 5, the second gas detection element 4 includes an inner second heater pad 44A, an inner second detection pad 43A, an outer second detection pad 43B, and an outer second heater pad 44B in this order from the left side. Are lined up.
As described above, the second gas detection element 4 is made of the same material as the first gas detection element 3 including the wiring pattern except for the material of the second gas sensitive film 42 (specifically, the material of the catalyst). Since it has a shape and configuration, detailed description thereof is omitted.

Now, each of the first gas detection element 3 and the second gas detection element 4 having such a material, shape, and configuration is configured on the upper surface of the ceramic insulating layer 25 in the wiring board 2 as shown in FIG. Are fixed to the bottom 21B of the cavity 21 to be aligned. Specifically, as can be easily understood from FIG. 2, the first gas detection element 3 and the second gas detection element 4 are parallel to each other along the first extraction side 3P of the first gas detection element 3 itself. If it is moved, they are arranged side by side at a position just overlapping the second gas detection element 4.
For fixing, the back side portion of the first gas detection element 3 on the back side of the outer first heater pad 34A, the outer first detection pad 33A, the inner first detection pad 33B, and the inner first heater pad 34B is ceramic. The insulating layer 25 is fixed using an adhesive layer 6 made of resin. Thus, the first gas detection element 3 is held in a cantilever manner in the cavity 21 of the wiring board 2. The adhesive layer 6 has dimensions that do not reach the diaphragm structure 3A.
Although not shown, the second gas detection element 4 also has a back surface portion of the back surface 4C, such as the outer second heater pad 44A, fixed to the ceramic insulating layer 25 using an adhesive layer 6 made of a resin, The second gas detection element 4 is held in a cantilever manner in the cavity 21 of the substrate 2.

Thus, the pads such as the outer first heater pad 34A of the first gas detection element 3 and the pads such as the inner second heater pad 44A of the second gas detection element 4 and the pad forming side portion of the step portion 22 of the wiring board 2 are used. The substrate side pads such as the substrate side first heater pads 23A arranged in 22P are arranged substantially in parallel.
As shown in FIG. 2, the outer first heater pad 34A of the first gas detection element 3 is the substrate-side first heater pad 23A of the wiring board 2, and the outer first detection pad 33A is the substrate-side first detection pad 23B. The inner first detection pad 33B and the inner first heater pad 34B are connected to the substrate-side common pad 23C via bonding wires 51A, 51B, 51C, and 51D, respectively.
Similarly, the inner second heater pad 44A and the inner second detection pad 43A of the second gas detection element 4 are disposed on the substrate side common pad 23C, and the outer second detection pad 43B is disposed on the substrate side second detection pad 23D. The heater pad 44B is connected to the substrate-side second heater pad 23E via bonding wires 52A, 52B, 52C, and 52D, respectively.

Thus, if the substrate-side common pad 23C is set to a common potential (ground potential), between the outer first heater pad 34A and the inner first heater pad 34B having the ground potential in the first gas detection element 3. By flowing an electric current, the first gas sensitive film 32 can be heated by energizing the heater 38. Further, the resistance value of the first gas sensitive film 32 between the first detection electrodes 36A and 36B can be measured between the outer first detection pad 33A and the inner first detection pad 33B having the ground potential. Thus, the first gas detection element 3 can detect a change in the concentration of an oxidizing gas such as NOx.
Similarly, in the second gas detection element 4, a current is passed between the inner second heater pad 44 </ b> A and the outer second heater pad 44 </ b> B set to the ground potential, thereby energizing the heater 48 and the second gas sensitive film. 42 can be heated. In addition, the resistance value of the second gas sensitive film 42 between the second detection electrodes 46A and 46B can be measured between the inner second detection pad 43A and the outer second detection pad 43B set to the ground potential. Thus, the second gas detection element 4 can detect a change in the concentration of reducing gas such as CO and HC.
In the present embodiment, the current flowing through the heater 38 of the first gas detection element 3 and the current flowing through the heater 48 of the second gas detection element 4 can be controlled separately. In consideration of the characteristics of the gas sensitive films 32 and 42, the temperature of the heaters 38 and 48 can be controlled so as to be suitable for the element (sensitive film or the like).

  As described above, in the gas sensor 10 (gas sensor main body 1) of the present embodiment, the first and second gas sensitive films 32 and 42 are identical to each other including the wiring pattern except for the material (specifically, the material of the catalyst). The 1st, 2nd gas detection elements 3 and 4 which have a material, a shape, and a structure are used. For this reason, as will be described later, the first gas detection element and the second gas detection element share at least the processes before the formation of the first and second gas sensitive films 32 and 42 and the subsequent processes. Since it can be manufactured, it can be manufactured easily and inexpensively. In addition, since the gas detection elements 3 and 4 having the same shape are mounted on the wiring board 2, mounting on the wiring board 2 is easy.

  In addition, the gas sensor 10 (gas sensor main body 1) includes a substrate-side common pad 23C on the wiring board 2, which includes the first inner detection pad 33B and the first inner heater pad 34B of the first gas detection element 3, and the first first heater pad 34B. The two gas detection elements 4 are connected to the inner second detection pad 43A and the inner second heater pad 44A. Therefore, the gas sensor 10 (the gas sensor main body 1) includes the two gas detection elements 3 and 4, but the connection to these is sufficient with the five substrate-side pads 23 including the substrate-side common pad 23C. Further, the number of terminals for connection to the external circuit formed on the back surface 2E on the wiring board 2 is only five, which facilitates connection. Moreover, since the substrate-side common pad 23C is connected to the inner first detection pad 33B, the inner first heater pad 34B, the inner second detection pad 43A, and the inner second heater pad 44A that are located close to each other. Bonding wires 51C, 51D, 52A, and 52B for connection are also short, and both can be connected with low resistance.

  Moreover, the first detection pad 33 and the first heater pad 34 of the first gas detection element 3 are arranged along the first extraction side 3P, and the second detection pad 41 and the second heater pad 44 of the second gas detection element are arranged. It arrange | positions along the 2nd extraction edge 4P. The substrate side first heater pad 23A, the substrate side first detection pad 23B, the substrate side common pad 23C, the substrate side second detection pad 23D, and the substrate side second heater pad 23E are arranged in a line. For this reason, it is possible to reduce the area (installation area) of the wiring board 2 and reduce the size as compared with the wiring board in which the pads on the board side are formed outside the peripheral edges of the gas detection element. it can. In addition, it is possible to reduce the dimension in the direction in which the two gas detection elements 3 and 4 are arranged (the left-right direction in FIG. 2) or the direction perpendicular thereto (the vertical direction in FIG. 2). In addition, the wiring of the internal wiring in the wiring board 2 can be shortened.

  Further, as described above, the back surface ventilation groove 25 </ b> A is formed in the wiring board 2. As shown in FIGS. 2 and 4, the back surface ventilation groove 25 </ b> A is disposed so as to cross the diaphragm structures 3 </ b> A and 4 </ b> A of the first and second gas detection elements 3 and 4. Therefore, the ventilation slits 26A and 26C formed by the gap between the ceramic insulating layer 26 of the wiring board 2 and the first and second gas detection elements 3 and 4 and the first and second gas detection elements 3 and 4 Through the ventilation slit 26B formed by the gap and the back surface ventilation groove 25A, the diaphragm structures 3A and 4A and the outside can be ventilated. Thus, even when the heaters 38 and 48 are energized and heated, or when the energization is interrupted and cooled, the pressure on the back surfaces 3C and 4C side of the first and second gas detection elements 3 and 4 becomes too high, Or it becomes too low and can prevent malfunctions, such as diaphragm part 3AD and 4AD being damaged.

Next, manufacture of the gas sensor 10 according to the present embodiment will be described.
First, the wiring board 2 used for the gas sensor main body 1 will be described. The wiring board 2 is manufactured by a known method. Specifically, a green sheet using ceramic powder mainly composed of alumina is punched into a predetermined form, and a tungsten paste is printed on a pattern serving as an internal wiring or a substrate side pad on the front surface or the back surface. Tungsten paste is also applied to the side surface of the through hole that will later become a castellation. Thereafter, the punched green sheets are laminated (four layers in this embodiment) and pressed to form a sheet laminate. Next, a break groove is formed in the sheet laminate so that it can be easily divided into individual pieces after firing. Furthermore, it cut | disconnects to the size for baking which several pieces collected, and bakes after a degreasing process. Next, nickel plating and gold plating are performed on the exposed portion of the tungsten metallized layer, and after passing through inspection of predetermined electrical characteristics (characteristics such as energization and insulation), appearance inspection, etc., it is divided into individual wiring boards 2.

On the other hand, the first and second gas detection elements 3 and 4 are manufactured as follows. First, a single crystal silicon wafer for semiconductor is prepared and cleaned. On this silicon wafer, performs SiO2 film formation, and Si ₃ N ₄ film formation. Next, heaters 38 and 48 (see FIG. 7B) and first and second heater connection wirings 37 and 47 are formed. Specifically, for example, a Ta layer is deposited by sputtering, and then a Pt layer is formed. Subsequently, patterning and etching by photolithography are performed to form heaters 38 and 48 and first and second heater connection wirings 37 and 47. Thereafter, an insulating Si ₃ N ₄ film is deposited so as to cover the heaters 38 and 48. Next, contact portions for forming the first and second heater pads 34 and 44 are formed at the end portions of the first and second heater connection wirings 37 and 47. Specifically, for example, the Si ₃ N ₄ film deposited on the first and second heater connection wirings 37 and 47 is removed by etching to form a contact portion.

Next, a pair of first and second detection electrodes 36 and 46 (see FIG. 7A) and a pair of first and second detection connection wirings 35 and 45 are formed on the deposited Si ₃ N ₄ film. To do. As an example, a Ti layer is deposited by sputtering, and a Pt layer is further formed. Subsequently, patterning and etching by photolithography are performed to form the first and second detection electrodes 36 and 46 and the first and second detection connection wirings 35 and 45. Thereafter, the above-described contact portions and the end portions of the first and second detection connection wirings 35 and 45 are used as pads capable of wire bonding. As an example, a Cr layer and an Au layer are formed by sputtering, patterning and etching processes are performed by photolithography, and the end portions of the contact portion and the first and second detection connection wirings 35 and 45 are connected to the first and first portions. 2 detection pads 33 and 43 and first and second heater pads 34 and 44.
Next, diaphragm structures 3A and 4A are formed at predetermined positions from the back surface of the silicon wafer by anisotropic etching. Up to this point, the manufacturing process is common to the first and second gas detection elements 3 and 4.

Next, with respect to the above-described silicon wafer for obtaining the first gas detection element 3, a silicon mask cut out in the shape (square shape) of the first gas sensitive portion 31 is placed, and then the silicon wafer is heated to a predetermined temperature. Then, a gas-sensitive film of a metal oxide semiconductor made of SnO ₂ is deposited by sputtering. Thereafter, Au serving as a catalyst is deposited on the gas sensitive film by sputtering to form a square first gas sensitive film 32 on the first gas sensitive part 31. Next, the silicon wafer having the first gas sensitive film 32 is subjected to heat treatment (thermal annealing) with a predetermined heat treatment pattern (maximum temperature, holding time, temperature increase rate, temperature decrease rate, etc.). Thereafter, after confirming characteristics and the like, the silicon wafer is cut to obtain individual first gas detection elements 3.

On the other hand, with respect to the above-described silicon wafer for obtaining the second gas detection element 4, after placing a silicon mask cut out in the shape (square shape) of the second gas sensitive portion 41, the silicon wafer is heated to a predetermined temperature. Then, a gas-sensitive film of a metal oxide semiconductor made of SnO ₂ is deposited by sputtering. Up to this point, it is the same as the first gas sensitive film. Thereafter, Pd serving as a catalyst is deposited on the gas sensitive film by sputtering, and the second gas sensitive film 42 having a square shape is formed on the second gas sensitive part 41. Next, the silicon wafer having the second gas sensitive film 42 is subjected to heat treatment (thermal annealing) with a heat treatment pattern (maximum temperature, holding time, temperature increase rate, temperature decrease rate, etc.) different from the case of obtaining the first gas detection element 3. . Thereafter, after confirming the characteristics and the like, the silicon wafer is cut to obtain individual second gas detection elements 4.

As described above, in this embodiment, most of the first gas detection element 3 and the second gas detection element 4 are common processes. A common photomask is used. For this reason, the 1st, 2nd gas detection elements 3 and 4 can be manufactured cheaply, therefore the gas sensor 10 can be manufactured inexpensively. Thus, the first gas detection element 3 and the second gas detection element 4 have the same material, shape and configuration except for the materials of the first and second gas sensitive films 32 and 42.
In particular, in the gas sensor 10 of the present embodiment, SnO ₂ is used as the oxide semiconductor of the first and second gas sensitive films, and only the catalyst (Au and Pd) is different. For this reason, a process can be made common until formation of an oxide semiconductor, and the 1st, 2nd gas detection elements 3 and 4 and gas sensor 10 can be manufactured cheaply.
On the other hand, when the heat treatment is performed during or after the formation of the first and second gas sensitive films 32 and 42, the wafer (gas sensitive film) can be heat treated at an appropriate temperature or heat treatment pattern regardless of the other. The first and second gas sensitive films 32 and 42 can have appropriate characteristics.

Next, the first gas detection element 3 and the second gas detection element 4 are joined to the upper surface of the ceramic insulating layer 25 of the wiring board 2 via an adhesive, and fixed and mounted in a cantilever manner. Next, the first and second detection pads 33 and 43 and the first and second heater pads 34 and 44 of the first and second gas detection elements 3 and 4 and the substrate-side pad 23 of the wiring board 2 are bonded to each other. The gas sensor main body 1 is completed by wire bonding using the wire 51A or the like and electrically connecting them.
Further, the protective cover 9 formed by punching and bending a metal plate is engaged with the protective plate portion 91 so that the protected surface 2S of the gas sensor body 1 (wiring board 2) and the cavity 21 are covered. The gas sensor 10 is completed.

(Modification)
Next, a gas sensor 110 according to a modification of the above-described embodiment will be described with reference to FIGS.
The gas sensor 110 according to the present modification is the same as the gas sensor 10 according to the above-described embodiment, but further includes the first detection pad 33 and the first heater pad 34 of the first gas detection element 3 and the second detection pad of the second gas detection element 4. 43 and the second heater pad 44, the board-side pad 23 of the wiring board 2, and the bonding wires 51A connecting them are different only in that they are resin-sealed.
Therefore, in the gas sensor 110 according to the modification, the protective cover 9 (see FIG. 1), the wiring board 2, and the first and second gas detection elements 3 and 4 are the same as those in the embodiment, and thus the description thereof is omitted.

Among the gas sensors 110 according to this modification, in the gas sensor main body 101, two sides extending in the vertical direction in FIG. 8 among the square-shaped step portions 22 of the wiring board 2 can be easily understood with reference to FIG. A dam member 107 made of an epoxy resin or the like is provided so as to bridge between the two. As shown in FIG. 9, the dam member 107 includes, on the surface 3 </ b> B of the first gas detection element 3, the first detection pad 33 and the first heater pad 34 side (first extraction side) from the first gas sensing portion 31. On the 3P side, on the lower side of the first gas sensitive portion 31 in FIG. 8, it is formed in a form extending in parallel to the first extraction side 3P. Similarly, the second gas detection element 4 has a surface 4B on the second detection pad 43 and second heater pad 44 side (second extraction side 4P side, in FIG. (Lower side than the two-gas sensitive portion 41) is formed in a form extending in parallel with the second extraction side 4P.
Thus, the dam member 107 partitions the first gas sensitive film 32 from the first detection pad 33 and the first heater pad 34 on the surface 3B of the first gas detection element 3. Similarly, on the surface 4 </ b> B of the second gas detection element 4, the second gas sensitive film 42, the second detection pad 43, and the second heater pad 44 are partitioned.

  Further, as shown in FIG. 9, the surface 3B of the first gas detection element 3 and the second gas detection element 4 positioned below the dam member 107 in FIG. The front surface 4B and the step portion 22 (pad forming side portion 22P) of the wiring board 2 are covered with a sealing resin material 108 made of an insulating epoxy resin or the like. Accordingly, the pair of first detection pads 33 and the pair of first heater pads 34 of the first gas detection element 3, the pair of second detection pads 43 and the pair of second heater pads 44 of the second gas detection element 4, and wiring The five substrate-side pads 23 of the substrate 2 and the eight bonding wires 51A connecting these are resin-sealed. On the other hand, the sealing resin material 108 is separated from the first gas-sensitive film 32 and the second gas-sensitive film 42 by the dam member 107 and is prevented from entering these.

In the gas sensor 10 according to the above-described embodiment, the first and second gas sensing films 32 and 42 of the first and second gas detection elements 3 and 4 are used as gas to be measured (for example, outside air or exhaust gas). Need to be exposed.
Meanwhile, the first detection pad 33 and the first heater pad 34 formed on the first gas detection element 3, the second detection pad 43 and the second heater pad 44 formed on the second gas detection element, and the wiring board 2 are formed. The five substrate-side pads 23 and the bonding wires 51A that connect them are exposed to the outside even though the protective cover 9 is covered. For this reason, there is a possibility that they may be short-circuited or disconnected from each other due to adhesion of water droplets or other foreign matters or collision of foreign matters.

  On the other hand, in the gas sensor 110 (gas sensor main body 101) of this modification, the pads 33, 34, 43, and 44 of the first and second gas detection elements 3 and 4, the bonding wire 51A and the like are insulating sealing resin. Sealed with a material 108. For this reason, even if water droplets or other foreign matters adhere or foreign matters collide, short-circuiting between pads or bonding wires is unlikely to occur. In addition, the bonding wires 51A and the like are not easily deformed, and the disconnection can be effectively prevented. Thus, a more reliable gas sensor (gas sensor body) is obtained.

  In particular, in the gas sensor 110 (gas sensor main body 101) of this modification, the dam member 107 is formed to prevent the sealing resin material 108 from entering the first gas sensitive film or the second gas sensitive film. Therefore, it is possible to reliably prevent deterioration in characteristics such as gas detection sensitivity and thermal characteristics due to the sealing resin material 108 adhering to the first and second gas sensitive portions 31 and 41.

  In the gas sensor 110 according to this modification, the dam member 107 and the sealing resin material 108 are manufactured as follows. First, after the gas sensor main body 1 according to the above-described embodiment is manufactured, an insulating epoxy resin having high thixotropic property and low fluidity is used by using a dispenser, of the square-shaped step portion 22 of the wiring board 2. In FIG. 8, it is applied in a straight line between two sides extending in the vertical direction, and then cured. Thereby, the dam member 107 that rises on the step portion 22 and on the surfaces 3B and 4B of the first and second gas detection elements 3 and 4 is formed. Next, insulation with high fluidity is provided on the step portion 22 (pad forming side 22P) and the surfaces 3B and 4B of the first and second gas detection elements 3 and 4 which are located below the dam member 107 in FIG. An epoxy resin is poured and cured to form the sealing resin material 108. As a result, the pads 33, 34, 43, 44 of the first and second gas detection elements 3, 4 and the bonding wire 51A are sealed with the insulating sealing resin material 108.

In the above, the present invention has been described with reference to the embodiments and the modified examples. However, the present invention is not limited to the above-described embodiments and the like, and it can be applied as appropriate without departing from the gist thereof. Not too long.
For example, in the embodiments and the like, the heaters 38 and 48 exemplify heaters in which the heater wiring itself generates heat due to resistance, but heaters that generate heat in a planar shape can also be used.

In the embodiment, etc., in the first gas detection element 3, the pads are arranged from the left side in FIGS. 2 and 5 from the left side first heater pad 34A, the outside first detection pad 33A, the inside first detection pad 33B, The inner first heater pads 34B are illustrated in a line in this order. Similarly, in the second gas detection element 4, each pad has an inner second heater pad 44A, an inner second detection pad 43A, an outer second detection pad 43B, and an outer second heater pad 44B arranged in a line in this order. Exemplified what is.
However, in the first gas detection element 3, the order of the inner first detection pad 33B and the inner first heater pad 34B is changed, and the outer first heater pad 34A, the outer first detection pad 33A, the inner first heater pad 34B, It is assumed that the inner first detection pads 33B are arranged in a line in the order. In the second gas detection element 4, the order of the outer second detection pad 43B and the outer second heater pad 44B is changed, and the inner second heater pad 44A, the inner second detection pad 43A, the outer second heater pad 44B, It can also be arranged in a line in the order of the outer second detection pads 43B. Even when using the first and second gas detection elements as described above, the two gas detection elements are driven using the five substrate-side pads of the wiring board 2 and the resistance of each gas sensitive film is measured. Gas concentration and concentration change can be measured.

It is a disassembled perspective view of the gas sensor concerning an Example. It is a top view of the gas sensor main body which removed the protective cap among the gas sensors concerning an Example. It is A-A 'arrow sectional drawing of the gas sensor main body which removed the protective cap among the gas sensors concerning an Example. It is B-B 'arrow sectional drawing of the gas sensor main body which removed the protective cap among the gas sensor main bodies concerning an Example. It is a top view which shows the wiring form of a 1st gas detection element and a 2nd gas detection element. It is a principal part enlarged view which shows the form of the detection electrode and heater electrode in a 1st, 2nd gas detection part. (A) is explanatory drawing which extracts and shows the form of the detection electrode in a 1st, 2nd gas detection part, (b) is the form of a heater electrode. It is a top view of the gas sensor main body which removed the protective cover among the gas sensors concerning a modification. It is C-C 'arrow sectional drawing of the gas sensor main body which removed the protective cover among the gas sensors concerning a modification.

Explanation of symbols

10,110 Gas sensor 1,101 Gas sensor body 2 Wiring board (support)
2S Protected surface 21 Cavity 23 Substrate side pad (support side terminal pad)
23A Substrate side first heater pad (support side first heater pad)
23B Substrate side first detection pad (support side first detection pad)
23C Board side common pad (Support side common pad)
23D substrate side second detection pad (support side second detection pad)
23E Substrate side second heater pad (support side second heater pad)
3 1st gas detection element 3P 1st taking-out edge 31 1st gas sensitive part 32 1st gas sensitive film 32P peripheral edge 33 (of 1st gas sensitive film) 1st detection pad (terminal pad)
33A Outside first detection pad 33B Inside first detection pad 34 First heater pad (terminal pad)
34A Outside first heater pad 34B Inside first heater pads 35, 35A, 35B First detection connection wiring (element wiring)
35AT, 35BT Taper portions 36, 36A, 36B First detection electrodes 37, 37A, 37B First heater connection wiring (element wiring)
38 1st heater 4 2nd gas detection element 4P 2nd extraction edge 41 2nd gas sensitive part 42 2nd gas sensitive film 42P Perimeter 43 (of 2nd gas sensitive film) 43 2nd detection pad (terminal pad)
43A Inner second detection pad 43B Outer second detection pad 44 Second heater pad (terminal pad)
44A Inner second heater pad 44B Outer second heater pad 45, 45A, 45B Second detection connection wiring (element wiring)
45AT, 45BT Tapered portions 46, 46A, 46B Second detection electrodes 47, 47A, 47B Second heater connection wiring (element wiring)
48 2nd heater 51A, 51B, 51C, 51D, 52A, 52B, 52C, 52D Bonding wire (conduction member)
107 Dam member 108 Sealing resin material

Claims (6)

A first gas sensitive membrane that reacts with a first gas species;
A pair of first sensing electrodes electrically connected via the first gas sensitive membrane;
A first heater for heating the first sensitive film;
A pair of first detection connection wires respectively connected to the first detection electrodes;
A pair of first heater connection wires respectively connected to both ends of the first heater;
A pair of first detection pads respectively connected to the pair of first detection connection wires; and
A first gas detection element having a polygonal shape in plan view, including a pair of first heater pads respectively connected to the pair of first heater connection wires;
A second gas sensitive membrane that reacts to a second gas species;
A pair of second sensing electrodes electrically connected via the second gas sensitive membrane;
A second heater for heating the second sensitive film;
A pair of second detection connection wires respectively connected to the second detection electrodes;
A pair of second heater connection wires respectively connected to both ends of the second heater;
A pair of second detection pads respectively connected to the pair of second detection connection wires; and
A pair of second heater pads respectively connected to the pair of second heater connection wires,
The first gas detection element is the same in form and material including at least a wiring pattern.
A second gas detection element having a polygonal shape in plan view;
A gas sensor comprising: a support body on which the first gas detection element and the second gas detection element are mounted;
The pair of first detection pads and the pair of first heater pads of the first gas detection element are:
Along the first take-out side of the periphery of the first gas detection element,
One of one first detection pad and one first heater pad, one of the first detection pad and one first heater pad, the other first detection pad and the other first heater pad Any one of the pads, the other first detection pad and the other one of the other first heater pads are arranged in order,
The pair of second detection pads and the pair of second heater pads of the second gas detection element,
Along the second extraction side of the peripheral edge of the second gas detection element,
Either one of the second detection pads and one of the second heater pads, the other of the one second detection pad and one of the second heater pads, the other second detection pad, and the other second heater Any one of the pads, the other second detection pad and the other one of the other second heater pads are arranged in order,
The first gas detection element and the second gas detection element are positions where the first gas detection element and the second gas detection element overlap the second gas detection element when the first gas detection element is translated along the first extraction side in the support. Arranged side by side,
The support is
An inner first detection pad positioned on the second gas detection element side of the pair of first detection pads; an inner first heater pad positioned on the second gas detection element side of the pair of first heater pads; An inner second detection pad located on the first gas detection element side of the pair of second detection pads, and an inner second heater located on the first gas detection element side of the pair of second heater pads. A support side common pad to be connected to the pad,
A support-side first detection pad connected to the remaining outer first detection pad of the pair of first detection pads;
A support side first heater pad connected to the remaining outer first heater pad of the pair of first heater pads;
A support-side second detection pad connected to the remaining outer second detection pad of the pair of second detection pads;
A support-side second heater pad connected to the remaining outer second heater pad of the pair of second heater pads,
The support side first detection pad and the support side first heater pad, and the support side second detection pad and the support side second heater pad are arranged in a row with the support side common pad interposed therebetween. Gas sensor. The gas sensor according to claim 1,
The first gas species is an oxidizing gas;
The gas sensor, wherein the second gas type is a reducing gas. The gas sensor according to claim 1 or 2, wherein
The first detection pad, the first heater pad, the second detection pad, and the second heater pad; the support side first detection pad; the support side first heater pad; the support side common pad; the support side second detection pad; And the support side second heater pad are each connected by a bonding wire,
These are gas sensors that are covered with an insulating material. The gas sensor according to claim 3,
The first detection pad, the first heater pad, the second detection pad, the second heater pad, the support side first detection pad, the support side first heater pad, the support side common pad, the support side second detection pad, the support side first 2 A gas sensor in which the heater pad and the bonding wire connecting them are sealed with an insulating sealing resin material as the insulating material. The gas sensor according to claim 4,
A gas sensor in which the sealing resin material is disposed apart from the first gas sensitive film and the second gas sensitive film. The gas sensor according to claim 5,
At least disposed on the surfaces of the first gas detection element and the second gas detection element, between the first gas sensitive film and the first detection pad and the first heater pad, and the second gas sensitive film, A gas sensor comprising a dam member that partitions between the second detection pad and the second heater pad and prevents the sealing resin material from entering the first gas sensitive film and the second gas sensitive film.

Images