JP2007292510A - Ceramic electronic functional body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic electronic functional body capable of preventing gas from intruding into a communication passage through an electrode taking-out part, while using a material with base metal as a main component in one part of the communication passage, and capable of maintaining sufficient mechanical contact of the electrode taking-out part with an electrode terminal of external equipment. <P>SOLUTION: A gas sensor 100 includes an oxygen sensor element 201. The electrode terminal of the external equipment is connected to the electrode taking-out part 256 arranged exposedly in an outside to electrify the oxygen sensor element 201. The electrode taking-out part 256 includes via conductors 235, 241 and electrode pads 255, 265. The via electrodes 235, 241 comprise an oxidation-resistant material, is dense and has gas impermeability, and the electrode pads 255, 265 comprise an oxidation-resistant material, and has a texture with portions forming own outside-exposed faces 255a, 265a coarser than the via conductors 235, 241. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrical function part that performs a predetermined electrical function when energized, a conduction path that is electrically connected to the electrical function part at one end thereof, and an insulating property that covers a part of the conduction path in an airtight manner. The present invention relates to a plate-like ceramic electronic functional body having a ceramic layer.

Conventionally, ceramic electronic functional bodies such as a ceramic heater, a gas sensor element that electrically detects gas, a gas sensor element with a heater, a liquid temperature sensor element, and a liquid concentration sensor element are known. Patent Document 1 discloses an oxygen concentration detector which is an example of these ceramic electronic functional bodies. This oxygen concentration detector has a detection element in which a standard electrode and a detection electrode are formed on both surfaces of a solid electrolyte sheet, and a heater element, and these are incorporated in a frame. In this oxygen concentration detector, when the heater element is energized to raise the temperature of the detection element with a heating element, and the solid electrolyte sheet exceeds a predetermined temperature, the detection element operates as an oxygen ion conductor. In the oxygen concentration detector, oxygen ions move between the solid electrolyte sheets of the detection element based on the partial pressure difference due to oxygen between the standard electrode that is in contact with the atmosphere and the detection electrode that is in contact with the gas to be detected. The oxygen concentration in the detection gas is measured.
In this oxygen concentration detector, the heating element (electrical function part) and the lead electrode part (electrode lead part) of the heater element are formed by replacing platinum as the material with inexpensive tungsten.

Japanese Patent Publication No. 7-81982

By the way, in the energization to the electrical function part of the ceramic electronic functional body, the electrical functional part and the ceramic electronic functional body are arranged to be exposed to the outside of the ceramic electronic functional body among the conductive paths electrically conducting. There is a case where it is desired to electrically connect the electrode extraction portion and the metal electrode terminal of the external device by mechanical contact. Even in such a configuration, the conduction path (including the electrode extraction portion) may be formed of an inexpensive base metal material such as tungsten. Then, there is a possibility that gas such as air enters the ceramic electronic functional body from the electrode extraction part and comes into contact with the conduction path, and the conduction path is oxidized.
Therefore, as one of the methods for preventing oxidation of the conduction path at low cost, at least the electrode extraction part includes a noble metal such as platinum having oxidation resistance and gas impermeability or this kind of noble metal. It may be possible to prevent the gas from entering from the electrode extraction portion toward the conduction path.
However, if the entire electrode extraction part is made of an alloy containing noble metal having oxidation resistance and gas impermeability, the solid component ratio is high, so the hardness is high and the surface of the electrode extraction part becomes smooth. Even if the electrode terminal is brought into mechanical contact with the portion, there is a case where sufficient electrical continuity cannot be obtained. In particular, in the actual use of the ceramic electronic functional body when external vibration or the like is transmitted to the ceramic electronic functional body, this vibration or the like is caused between the electrode extraction portion of the ceramic electronic functional body and the electrode terminal of the external device. There is a risk of poor connection due to this.

  The present invention has been made in view of such problems, and prevents the intrusion of gas from the electrode extraction portion into the conduction path while using a material mainly composed of a base metal for a part of the conduction path. An object of the present invention is to provide a ceramic electronic functional body capable of sufficiently maintaining the mechanical contact between the electrode extraction portion and an electrode terminal of an external device.

  The solution includes an electrical function part that performs a predetermined electrical function, a conduction path that is electrically connected to the electrical function part at one end thereof, and an insulating ceramic that hermetically covers a part of the conduction path. A ceramic electronic functional body including a layer, wherein the conduction path includes an other end of the electrode, and a part of the conduction path is exposed to the outside, and is positioned closer to the one end side of the conduction path than the electrode extraction part An electrode lead portion made of a material mainly composed of a base metal and hermetically embedded in the ceramic layer, the electrode extraction portion penetrating the ceramic layer. A via conductor that is electrically connected to the electrode lead portion, and an electrode pad that is electrically connected to the via conductor and is exposed to the outside on the outer surface of the ceramic layer. Conductor is a material with oxidation resistance A ceramic electronic function comprising a dense, gas-impermeable material, the electrode pad being made of an oxidation-resistant material, and having a structure in which at least a portion forming an externally exposed surface thereof is rougher than the via conductor Is the body.

In the ceramic electronic functional body of the present invention, the via conductor of the electrode extraction portion is made of a material having oxidation resistance and is dense and gas-impermeable. The electrode pad is also made of a material having oxidation resistance.
Therefore, even when the electrode pad is exposed to an oxidizing gas such as the atmosphere, the electrode pad and the via conductor are not oxidized. In addition, since the via conductor prevents gas from entering from the electrode pad to the electrode lead portion, oxidation of the electrode lead portion can also be reliably prevented.

In addition, at least the portion of the electrode pad that forms the externally exposed surface of the electrode pad has a texture that is coarser than the via conductor. For this reason, when the portion that forms the externally exposed surface of the electrode pad is pressed, it is easily deformed by an external force such as being crushed in the thickness direction.
Therefore, when energizing the electrical function part, if the electrode terminal of the external device is pressed against the electrode pad to connect them, the portion forming the externally exposed surface of the electrode pad may be crushed by the pressing force at the time of the pressure contact. By deforming, a part of the electrode terminal of the external device bites into the electrode pad, and the mechanical contact area between the electrode pad and the electrode terminal of the external device can be increased. Furthermore, since the electrode terminal of the external device becomes difficult to slide on the electrode pad due to the deformation of the portion that forms the externally exposed surface of the electrode pad, the electrode terminal of the external device can be contacted in a more stable state.
Therefore, it is possible to suppress the occurrence of poor electrical connection between the electrode pad and the electrode terminal of the external device.

The “ceramic electronic functional body” of the present invention includes, for example, a gas sensor element that electrically detects gas, a heater element that generates heat when energized, a gas sensor element with a heater that combines this, a temperature sensor element, and a liquid concentration sensor element. A sensor element in which these and other sensor elements are combined can be used.
The “electrical function part” refers to a part that performs a predetermined function in the ceramic electronic functional body. For example, a gas sensor includes a gas detection part, a heater element includes a heat generation part, and a temperature sensor element includes a temperature sensing part. Equivalent to. Further, the shape, configuration, number, and the like of the “electrical function unit” are not particularly limited.
In addition, the “electrode lead part” is not particularly limited in form and configuration as long as it is located on one end side of the conduction path with respect to the electrode extraction part and connected to the electrode extraction part and is hermetically embedded in the ceramic layer. . For example, a conductor wiring layer disposed between the ceramic layers, a solid or hollow via conductor extending through the ceramic layer in the ceramic electronic functional body, and a combination of these may be used.

  Further, “mainly containing a base metal” means containing more than 50 wt% of a base metal, and “having oxidation resistance” specifically means that an object is exposed to the atmosphere at 400 ° C. for 100 hours. This means that the conductor resistance does not increase more than 150% with respect to its initial value.

  Furthermore, in the above-described ceramic electronic functional body, the electrode pad may be a ceramic electronic functional body made of a material containing a ceramic material forming the ceramic layer.

In the ceramic electronic functional body of the present invention, the electrode pad is formed of a material containing a ceramic material forming a ceramic layer of the ceramic electronic functional body. For this reason, the adhesion between the electrode pad and the ceramic layer is improved. Accordingly, for example, even when an external electrode terminal brought into contact with the pad slides relative to the electrode pad due to external vibration, the electrode pad is hardly peeled off from the ceramic layer.
Further, for example, compared to the case where the electrode pad is formed of a noble metal such as Pt, the use of the noble metal can be suppressed by the amount of the ceramic material used, and therefore the electrode pad can be made inexpensive. As a result, the ceramic electronic functional body can be made inexpensive.

  Other solutions include an electrical function part that performs a predetermined electrical function, a conductive path that is electrically connected to the electrical function part at one end thereof, and an insulating property that covers a part of the conductive path in an airtight manner. A ceramic electronic functional body comprising a ceramic layer, wherein the conduction path includes an other end of the electrode, and an electrode extraction portion that is partly exposed to the outside, and closer to the one end side of the conduction path than the electrode extraction portion An electrode lead portion that is located and connected to the electrode extraction portion and is made of a material mainly composed of a base metal and is hermetically embedded in the ceramic layer, and the electrode extraction portion penetrates the ceramic layer A via conductor that is electrically connected to the electrode lead portion, and an electrode pad that is electrically connected to the via conductor and is exposed to the outside on the outer surface of the ceramic layer. At least the electrode pad A conductive contact in electrical contact with the conductor, a via conductor covering portion that hermetically covers the via conductor on the outer surface of the ceramic layer, and an electrical connection with the via conductor covering portion; An externally exposed surface of the electrode pad, and an externally exposed portion that covers the via conductor covering portion. The via conductor covering portion is made of a material having oxidation resistance, and is dense and gas impermeable. The externally exposed portion is a ceramic electronic functional body made of a material having oxidation resistance and having a structure that is coarser than the via conductor covering portion.

In the ceramic electronic functional body of the present invention, the electrode pad includes a via conductor covering portion and an externally exposed portion. The via conductor covering portion of the electrode pad is made of a material having oxidation resistance and is dense and gas-impermeable. The externally exposed portion is made of a material having oxidation resistance.
Therefore, even when the electrode pad is exposed to an oxidizing gas such as the atmosphere, the electrode pad is not oxidized. In addition, the via conductor covering portion of the electrode pad can prevent gas from entering the via conductor and through the electrode lead portion, thereby reliably preventing oxidation of the electrode lead portion.

In addition, the externally exposed portion of the electrode pad has a texture that is coarser than the via conductor covering portion. For this reason, the externally exposed portion is easily deformed when an external force is applied to this portion, such as crushing in the thickness direction when pressed.
Therefore, when energizing the electrical function part, if the electrode terminal of the external device is pressed against the electrode pad to try to connect them, the external exposed portion is deformed so that the external exposed portion is crushed by the pressing force at the time of the pressure contact. A part of the electrode terminal bites into the electrode pad, and the mechanical contact area between the electrode pad and the electrode terminal of the external device can be increased. Furthermore, since the externally exposed surface of the electrode pad is deformed, the electrode terminal of the external device is less likely to slide on the electrode pad, so that the electrode terminal of the external device can be brought into contact in a more stable state.
Therefore, it is possible to suppress the occurrence of poor electrical connection between the electrode pad and the electrode terminal of the external device.

  Furthermore, in the above-described ceramic electronic functional body, the via conductor covering portion and the externally exposed portion of the electrode pad may be a ceramic electronic functional body made of a material containing a ceramic material forming the ceramic layer.

In the ceramic electronic functional body of the present invention, the via conductor covering portion and the externally exposed portion are formed of a material containing a ceramic material forming a ceramic layer of the ceramic electronic functional body. For this reason, the close contact between the via conductor covering portion and the externally exposed portion and the close contact between the via conductor covering portion and the ceramic layer are improved. Thereby, for example, even when an external electrode terminal brought into contact with the externally exposed portion slides relative to the electrode pad due to external vibration, the electrode pad is hardly peeled off from the ceramic layer. Become. Further, it is possible to reliably prevent external gas from entering the via conductor and through the electrode lead portion through the interface between the via conductor covering portion and the ceramic layer.
Further, for example, compared to the case where the electrode pad is formed of a noble metal such as Pt, the use of the noble metal can be suppressed by the amount of the ceramic material used, and therefore the electrode pad can be made inexpensive. As a result, the ceramic electronic functional body can be made inexpensive.

  Further, in the above-described ceramic electronic functional body, the via conductor covering portion may be a ceramic electronic functional body containing more of the ceramic material than the externally exposed portion.

In the ceramic electronic functional body of the present invention, the via conductor covering portion and the externally exposed portion of the electrode pad are made of a material containing a ceramic material forming the ceramic layer of the ceramic electronic functional body, and the via conductor covering portion is the externally exposed portion. Contains more ceramic material. By doing in this way, adhesiveness with a via conductor coating | coated part and a ceramic layer becomes still better.
On the other hand, in the externally exposed portion, the conductive material between the external electrode terminal and the externally exposed portion is further reduced by reducing the content of the ceramic material that is an insulating material as compared with the via conductor covering portion, thereby reducing the electrode resistance. A decrease in conductivity of the entire pad can be suppressed.

  Furthermore, it is a ceramic electronic functional body according to any one of claims 1 and 3, wherein the electrode lead-out portion is a ceramic electronic functional body made of a noble metal-base metal alloy.

In the ceramic electronic functional body of the present invention, the electrode extraction part is made of a noble metal-base metal alloy.
Thereby, since the usage-amount of a noble metal in an electrode extraction part can be suppressed by the part which uses a base metal, a ceramic electronic functional body can be made cheap.

  Furthermore, the said ceramic electronic function body is a gas sensor element, It is good to set it as the ceramic electronic function body of any one of Claims 1-6.

In the present invention, the ceramic electronic functional body is a gas sensor element. Examples of the gas sensor element include an oxygen sensor, an air-fuel ratio sensor, a NOx sensor, and a CO sensor that are mounted on an exhaust pipe of an automobile or the like and used for detecting oxygen concentration in exhaust gas flowing through the exhaust pipe. be able to.
In the gas sensor element (oxygen sensor element) of the present invention, the oxidation of itself can be prevented even if the electrode extraction portion is exposed to an oxidizing gas such as the atmosphere. Further, intrusion of oxidizing gas such as air from the electrode lead-out portion to the electrode lead portion is blocked by the via conductor or the via conductor covering portion, so that the oxidation of the electrode lead portion made of a base metal can be surely avoided.
Moreover, by making the electrode pad or the externally exposed portion of the electrode pad into a rough structure, the mechanical contact between them can be made more stable in the connection between the electrode pad and the electrode terminal of the external device. Therefore, even when vibration is transmitted to the gas sensor element due to traveling of an automobile or the like, the electrical connection between the electrode pad and the electrode terminal of the external device can be appropriately maintained.

  Furthermore, the said ceramic electronic functional body is a heater element, It is good to set it as the ceramic electronic functional body of any one of Claims 1-6.

In the present invention, the ceramic electronic functional body is a heater element. Examples of the heater element include a heater element used alone for rapid heating of cleaning water in a shower toilet, a heater element for heating and activating the heater element together with the gas sensor element described above, and the like.
Even in this heater element, even when the electrode extraction part is exposed to an oxidizing gas such as the atmosphere, the electrode extraction part itself can be prevented from being oxidized, and the oxidizing gas such as the atmosphere from the electrode extraction part to the electrode lead part can be prevented. The intrusion is also blocked by the via conductor or the via conductor covering portion, and the oxidation of the electrode lead portion made of a base metal can be surely avoided.
In addition, since the electrode pad or the externally exposed portion thereof has a rough structure, the electrical connection between the electrode terminal of the external device and the electrode pad can be appropriately maintained.

  The ceramic electronic functional body according to any one of claims 1 to 6, wherein the ceramic electronic functional body is a gas sensor element portion and a heater element portion included in a gas sensor element with a heater.

In the present invention, the ceramic electronic functional body is a gas sensor element portion and a heater element portion, respectively, of the gas sensor elements with a heater. As the gas sensor element with a heater, for example, an oxygen sensor, an air-fuel ratio sensor, a NOx sensor, a CO sensor, etc. that detect the concentration of a specific gas in the gas to be measured by heating and activating the gas sensor element with the heater element, etc. Is mentioned.
In the gas sensor element with a heater according to the present invention, the electrode extraction part in each of the gas sensor element part and the heater element part can be prevented from being oxidized even if it is exposed to an oxidizing gas such as the atmosphere. In addition, in each of the gas sensor element part and the heater element part, it is possible to prevent the invasion of oxidizing gas such as air from the electrode extraction part to the electrode lead part, and it is possible to reliably avoid the oxidation of the electrode lead part. .
In addition, in each of the gas sensor element portion and the heater element portion, the electrode pad or the externally exposed portion thereof has a rough structure, so that the electrical connection between the electrode terminal of the external device and the electrode pad can be appropriately maintained. Can do.

  Furthermore, a gas sensor using the ceramic electronic functional body according to claim 7 or 9 is preferable.

In this gas sensor, the gas sensor element to be used, or the gas sensor element part and the heater element part included in the gas sensor element with a heater have the configuration as the ceramic electronic functional body described above.
Therefore, when this gas sensor is used, even when the electrode extraction part of the gas sensor element or the gas sensor element with a heater is exposed to an oxidizing gas such as the atmosphere, the electrode extraction part itself can be prevented from being oxidized and an electrode made of a base metal The oxidation of the lead part can also be prevented. In addition, the gas sensor element (gas sensor element with a heater) can be reliably connected to the electrode terminal for conduction, so that the gas sensor can be inexpensive and highly reliable.

(Embodiment)
Embodiments of the present invention will be described below with reference to the drawings.
In the present embodiment, a gas sensor 100 using a sensor element 200 including a gas sensor element unit 201 and a heater element unit 270 will be described as an example of a ceramic electronic functional body.
FIG. 1 is a cross-sectional view showing the form and structure of a gas sensor 100 according to this embodiment. Hereinafter, in the description of the gas sensor 100 and each component of the present embodiment, the lower side in the arrangement shown in FIG. 1 is the front end side, and the upper side is the rear end side. Therefore, in FIGS. 2 and 3, the left side is the front end side and the right side is the rear end side. FIG. 2 is an exploded perspective view of a sensor element 200 (gas sensor element with a heater) incorporated in the gas sensor 100. Further, FIG. 3 is an explanatory diagram showing a state of connection between the rear end portion of the sensor element 200 and an external connection terminal.

  The gas sensor 100 according to the present embodiment is an oxygen sensor that is mounted on an exhaust pipe of an automobile or the like and is used for use, and detects an oxygen concentration in exhaust gas flowing through the exhaust pipe. The gas sensor 100 has a plate-shaped sensor element 200 held by the metal shell 102 with its tip end protruding from the tip of the metal shell 102 (see FIG. 1).

First, the sensor element 200 will be described in detail with reference to FIG.
The sensor element 200 of the present embodiment is a gas sensor element with a heater in which the oxygen sensor element 201 and the heater element 270 are combined. The oxygen sensor element 201 is a reference oxygen self-generation type oxygen sensor element. The sensor element 200 is structurally divided into a sensor substrate 210 and a lead substrate 230, which are bonded to each other via an adhesive layer 281.

  The sensor substrate 210 is formed by laminating a porous protective layer 211, a first alumina layer 213, a solid electrolyte layer 215, and a second alumina layer 217 in this order from the top in FIG. Further, in the sensor substrate 210, a detection porous electrode part 221, a solid electrolyte layer 215, and a reference porous electrode part 225 are arranged between the first alumina layer 213 and the second alumina layer 217, and oxygen detection is performed. Part 205 is formed. The porous protective layer 211 is a porous ceramic layer made of alumina, and has an outer shape of a rectangular plate having a length of about 10 mm, a width of about 4.5 mm, and a thickness of about 0.625 mm.

  The first alumina layer 213 is a ceramic layer made of alumina, and has an outer shape of a rectangular plate having a length of about 10 mm, a width of about 4.5 mm, and a thickness of about 0.23 mm. A circular opening 214 (having a diameter of about 2.0 mm) for allowing the gas to be measured to pass to the detection porous electrode portion 221 described below is provided at a predetermined position on the tip side (left side in FIG. 2) of the first alumina layer 213. 5 mm) is formed. On the back surface (the lower surface in FIG. 2) side of the first alumina layer 213, the detection porous electrode portion 221 disposed so as to close the opening 214 and the first sensor lead electrically connected thereto. Of the portion 223, a tip portion 223p having a form extending linearly toward the rear end side (right side in FIG. 2) is formed.

The detection porous electrode part 221 is a porous electrode made of Pt, and has a circular shape with a diameter of about 2.6 mm. Since this detection porous electrode portion 221 is made of Pt, it has oxidation resistance, and even if the gas taken in through the openings 214 of the porous protective layer 211 and the first alumina layer 213 in actual use comes into contact. Conductivity can be maintained without oxidation.
The tip 223p of the first sensor lead 223 is also a porous lead made of Pt, and has a length of about 5.4 mm and a width of about 0.33 mm. Since the tip portion 223p of the first sensor lead portion 223 is also made of Pt, it has oxidation resistance, and does not oxidize even when the gas taken in through the detection porous electrode portion 221 in actual use comes into contact with the first sensor lead portion 223. Can be maintained.

  The solid electrolyte layer 215 is a layer made of alumina (Al 2 O 3) 20 wt%, zirconia (ZrO 2) 72.42 wt%, and yttria (Y 2 O 3) 7.58 wt%, and has an outer diameter of about 3.0 mm and a thickness. It has a disk shape of about 0.1 mm. The solid electrolyte layer 215 is interposed between the detection porous electrode portion 221 and a reference porous electrode portion 225 described later.

Similar to the first alumina layer 213, the second alumina layer 217 is a ceramic layer made of alumina, and its outer shape is a rectangular plate shape having a length of about 10 mm, a width of about 4.5 mm, and a thickness of about 0.23 mm. . At a predetermined position on the rear end side of the second alumina layer 217, three openings 218 (diameter of about 0.3 mm) are formed side by side in the width direction. Of these three openings 218, openings located at both ends are filled with via conductors 223s and 227s made of Pt. These via conductors 223 s and 227 s form part of the first sensor lead portion 223 and the second sensor lead portion 227.
On the surface (the upper surface in FIG. 2) side of the second alumina layer 217, a reference porous electrode portion 225 disposed so as to face the detection porous electrode portion 221 and electrically connected thereto. Of the second sensor lead portion 227, a front end portion 227p is formed which extends linearly to the rear end side (right side in FIG. 2) and then bends inward.

The reference porous electrode part 225 is a porous electrode made of Pt, like the detection porous electrode part 221, and has a circular shape with a diameter of about 2.6 mm. Since this reference porous electrode part 225 is also made of Pt, it has oxidation resistance, and in actual use, it passes through the porous protective layer 211, the opening 214 of the first alumina layer, and the detection porous electrode part 221, and further the solid electrolyte layer. Even if the gas (oxygen) pumped in 215 comes into contact, it is not oxidized and the conductivity can be maintained.
The tip 227p of the second sensor lead 227 is also a porous lead made of Pt, and has a length (length in the longitudinal direction) of about 5.4 mm and a width of about 0.33 mm. Since the tip portion 227p of the second sensor lead portion 227 is also made of Pt, it has oxidation resistance and can maintain conductivity even when gas that has entered the reference porous electrode portion 225 in actual use comes into contact.

Next, the lead substrate 230 will be described.
The lead substrate 230 is formed by laminating a third alumina layer 231, a fourth alumina layer 237, and a fifth alumina layer 239 in this order. Among these, the third alumina layer 231 is a ceramic layer made of alumina, and the outer shape thereof is a rectangular plate shape having a length of about 40 mm, a width of about 4.5 mm, and a thickness of about 0.23 mm. Near the center of the third alumina layer 231, three openings 232 (diameter of about 0.5 mm) are formed side by side in the width direction at positions corresponding to the openings 218 formed in the second alumina layer 217. Out of these openings 232, openings disposed at both ends are filled with via conductors 223t and 227t made of W, respectively. These via conductors 223t and 227t form part of the first sensor lead portion 223 and the second sensor lead portion 227.
In addition, two openings 234 (diameter of about 0.3 mm) are formed side by side in the width direction at a predetermined position on the rear end side (right side in FIG. 2) of the third alumina layer 231. These openings 234 are filled with via conductors 235 that form part of the sensor electrode extraction portion 256. The via conductor 235 has a dense structure made of Pt-18.4 wt% W, which is an alloy of noble metal and base metal, and has oxidation resistance and gas impermeability. Note that, as the dense structure, the porosity is specifically 5% or less, preferably 0%.

  On the surface (the upper surface in FIG. 2) side of the third alumina layer 231, connection pads 223u and 227u having a thickness of about 15 μm are formed so as to cover the end surfaces of the via conductors 223t and 227t. These connection pads 223u and 227u cover a tungsten layer having a thickness of about 10 μm directly covering the end surfaces of the via conductors 223t and 227t, a Ni plating layer having a thickness of about 2 μm covering the tungsten layer, and further covering the Ni plating layer. It consists of a Pt or Au plating layer with a thickness of about 3 μm. These connection pads 223u and 227u also form part of the first sensor lead portion 223 and the second sensor lead portion 227 together with the via conductors 223t and 227t.

  Further, as shown in FIG. 3, the surface 231R (the upper surface in FIG. 3) of the third alumina layer 231 has a length of about 5 mm and a width of about 1.4 mm so as to cover the end surfaces of the via conductors 235. A rectangular sensor electrode pad 255 having a thickness of about 20 μm is formed. These sensor electrode pads 255 are each made of Pt-18.4 wt% W having oxidation resistance. In addition, the sensor electrode pad 255 has a porous structure that is coarser than the via conductor 235. Specifically, the sensor electrode pad 255 has a structure with a porosity of 40% to 60%. These sensor electrode pads 255 and the via conductor 235 constitute a sensor electrode extraction portion 256. In the present embodiment, the sensor electrode extraction portion 256 corresponds to the electrode extraction portion of the present invention.

  Similar to the third ceramic layer 231, the fourth alumina layer 237 is a ceramic layer made of alumina, and has an outer shape of a rectangular plate having a length of about 40 mm, a width of about 4.5 mm, and a thickness of about 0.4 mm. . On the surface (upper surface in FIG. 2) side of the fourth alumina layer 237, via conductors 223t, which are disposed on the third ceramic layer 231 at one end of the first and second sensor lead portions 231 and 227, Rear ends 223q and 227q are formed which are electrically connected to 227t, extend linearly toward the rear end, and are electrically connected to the via conductor 235 disposed on the third ceramic layer 231 at the other end. ing. Unlike the front end portions 223p and 227p of the first and second sensor lead portions 223 and 227, the rear end portions 223q and 227q of the first and second sensor lead portions 223 and 227 are mainly made of W which is a base metal. It consists of the material.

  Further, one end of the first sensor lead portion 223 between the rear end portion 223q and the rear end portion 227q of the second sensor lead portion 227 is exposed to the central opening 232 of the fourth alumina layer 237, and the lead A gas discharge portion 261 that extends linearly to the rear end of the substrate and communicates with the outside is formed. The gas discharge part 261 is made of an insulating and porous alumina ceramic.

  The fifth alumina layer 239 is a ceramic layer made of alumina like the third ceramic layer 231 and the like, and its outer shape is a rectangular plate shape having a length of about 40 mm, a width of about 4.5 mm, and a thickness of about 0.4 mm. is there. At a predetermined position on the rear end side (right side in FIG. 2) of the fifth alumina layer 239, two openings 240 (diameter of about 0.3 mm) are formed side by side in the width direction. These openings 240 are filled with via conductors 241 that form part of the heater electrode extraction portion 266. Each of the via conductors 241 is made of an alloy of Pt-18.4 wt% W, has a dense structure, and has oxidation resistance and gas impermeability.

  As shown in FIG. 3, on the back surface 239R (the lower surface in FIGS. 2 and 3) side of the fifth alumina layer 239, a length of about 5 mm and a width so as to cover the end surface of each via conductor 241 A rectangular heater electrode pad 265 having a thickness of about 1.4 mm and a thickness of about 20 μm is formed. Each of these heater electrode pads 265 is made of an alloy of Pt-18.4 wt% W having oxidation resistance. Moreover, the heater electrode pad 265 has a porous structure that is coarser than the via conductor 241. Specifically, the heater electrode pad 265 has a structure with a porosity of 40 to 60%. In the present embodiment, the heater electrode pad 265 forms a heater electrode extraction portion 266 together with the via conductor 241. In the present embodiment, the heater electrode extraction portion 266 also corresponds to the electrode extraction portion of the present invention.

  On the other hand, between the fifth alumina layer 239 and the fourth alumina layer 237, the heat generating portion 271 located on the front end side, and both ends thereof are connected, and are wider than the heat generating portion 271 and straight toward the rear end side. A pair of heater lead portions 273 extending in a shape and electrically connected to the via conductors 241 are formed. The heat generating portion 271 is a resistor made of W and has a meandering shape with a line width of about 0.27 mm. The heater lead portion 273 is also made of W and has a line width of about 0.85 mm. The heat generating part 271 is heated to several hundred degrees Celsius (for example, 500 degrees Celsius) by energization, heats and activates the solid electrolyte layer 215, and serves as a gas sensor. The heat generating portion 271 also corresponds to the electrical function portion of the present invention. The heater lead portion 273 corresponds to the electrode lead portion of the present invention.

Such a lead substrate 230 and the sensor substrate 210 described above are bonded via a bonding layer 281. The bonding layer 281 is made of crystallized glass, and has an outer shape of a rectangular plate having a length of about 10 mm, a width of about 4.5 mm, and a thickness of about 5 μm. At a predetermined position on the rear end side (right side in FIG. 2) of the bonding layer 281, three openings 282 (diameter of about 0.7 mm) are formed side by side in the width direction. These openings 282 are formed at positions corresponding to the three openings 218 formed in the second alumina layer 217 of the sensor substrate 210 and the three openings 232 formed in the third ceramic layer 231 of the lead substrate 230. ing. Of the three openings 282, openings 282 located at both ends are filled with a brazing material (dense) made of Ag-5 wt% Pd to form connection portions 223r and 227r. These connecting portions 223r and 227r form part of the first and second sensor lead portions 223 and 227, respectively, and electrically connect the front end portions 223p and 227p and the rear end portions 223q and 227q. Yes.
Thus, the first sensor lead portion 223 electrically connects the detection porous electrode portion 221 and the sensor electrode extraction portion 256, and the second sensor lead portion 227 electrically connects the reference porous electrode portion 225 and the sensor electrode extraction portion 256. Is made conductive.
As described above, the sensor element 200 includes the rear end portions 223q and 227q of the first and second sensor lead portions 223 and 227 and the oxygen sensor element portion 240 stacked from the gas discharge portion 261 to the porous protective layer 211. 4 is a heater-attached gas sensor element combined with the heater element 270 laminated from the 4 alumina layer 237 to the heater electrode pad 265, and can obtain the functions of both.

  By the way, in actual use of the gas sensor 100 (sensor element 200), the heat generating portion 271 is heated to several hundred degrees by energization, and the solid electrolyte layer 215 is heated and activated. For this reason, not only the fixed electrolyte layer 215 but also the entire sensor element 200 is heated, and the rear end portions 223q and 227q of the first and second sensor leads 223 and 227 and the heater lead portion 273 also have a high temperature exceeding 330 ° C., for example. It may become. Since the rear end portions 223q and 227q and the heater lead portion 273 of the first and second sensor lead portions 223 and 227 are made of a material mainly composed of base metal W, as described above, at such a high temperature. When oxygen is present, these are oxidized, and when it is severe, there is a possibility that conduction is not possible.

However, in the present embodiment, the via conductor 235 of the sensor electrode extraction portion 256 is made of a dense material (Pt-W) having oxidation resistance and gas impermeability. Therefore, the via conductor 235 prevents gas (atmosphere) from entering the rear end portions 223q and 227q from the sensor electrode pad 255 to the first and second sensor lead portions 223 and 227, and the first and second sensors. Oxidation of the rear end portions 223q and 227q of the lead portions 223 and 227 is prevented.
Similarly, in the present embodiment, the via conductor 241 of the heater electrode extraction portion 266 is made of a dense material (Pt-W) having oxidation resistance and gas impermeability. As described above, since the via conductor 241 prevents the gas (atmosphere) from entering the heater lead portion 273 from the heater electrode pad 265, the heater lead portion 273 is also prevented from being oxidized.

  As described above, of the first and second sensor lead portions 223 and 227, the via conductors 223r and 227r are made of a brazing material (dense) of Ag-5 wt% Pd. For this reason, oxygen that has entered through the front end portions 223p and 227p of the first and second sensor lead portions from the detection porous electrode portion 221 and the reference porous electrode portion 225 becomes the via conductors 223t and 227t and the rear end portion 223q, The via conductors 223r and 227r prevent the 227q from entering and oxidizing them.

Such a sensor element 200 is manufactured as follows.
First, first to fifth unfired alumina sheets that become the first to fifth alumina layers 213, 217, 231, 237, and 239 after firing are prepared. Specifically, 97 parts by mass of alumina powder, 3 parts by mass of yttria 5.4 mol% co-precipitated zirconia, 14 parts by mass of butyral resin, and 7 parts by mass of dibutyl phthalate are mixed, and a mixed solvent composed of toluene and methyl ethyl ketone. To make a slurry. And this is made into a sheet form by a doctor blade method, and toluene and ethyl methyl ketone are volatilized to produce first to fifth unfired alumina sheets. In addition, the first unfired alumina sheet is perforated with openings 214, the second unfired alumina sheet is perforated with openings 218, the third unfired alumina sheet is perforated with openings 232 and 234, and the fifth unfired alumina sheet. Openings 240 are drilled in the alumina sheet.

  On the other hand, an unfired solid electrolyte sheet that becomes the solid electrolyte layer 215 after firing is produced. Specifically, alumina powder 20 wt%, zirconia 72.42 wt%, yttria 7.58 wt%, butyral resin 12 wt%, and dibutyl phthalate 6 wt% are mixed, and a mixed solvent composed of toluene and methyl ethyl ketone is further mixed. To make a slurry. Then, this is formed into a sheet by a doctor blade method, and toluene and methyl ethyl ketone are volatilized to produce an unfired solid electrolyte sheet.

  Further, an unfired protective sheet that becomes the porous protective layer 211 after firing is prepared. Specifically, 100 parts by mass of alumina powder, 22 parts by mass of carbon powder (true spherical particles, average particle size 5 μm), 14 parts by mass of butyral resin, and 7 parts by mass of dibutyl phthalate are blended, and further toluene and methyl ethyl ketone. A mixed solvent consisting of And this is made into a sheet form by a doctor blade method, and toluene and methyl ethyl ketone are volatilized to produce an unfired protective sheet.

Next, the first sensor pattern that becomes the detection porous electrode part 221 and the tip part 223p of the first sensor lead part 223 after firing, and the reference porous electrode part 225 and the tip part 227p of the second sensor lead part 227 after firing, The second sensor pattern and the unsintered via conductors 223s and 227s after firing are formed on the second unsintered alumina sheet. Specifically, 20 parts by mass of yttria 5.4 mol% co-precipitated zirconia powder, 100 parts by mass of Pt powder, and 7 parts by mass of etose binder are mixed, and further mixed with butyl carbitol as a solvent, Get a sex paste. Then, the conductive paste is filled and printed in two openings 218 at both ends of the three openings 218 formed in the second unfired alumina sheet, and dried to form unfired via conductors. Then, the second sensor pattern is printed with a thickness of 20 ± 10 μm using this conductive paste on one surface (surface to be a surface) of the unfired second alumina sheet and dried. Subsequently, a bonding paste obtained by diluting an unfired solid electrolyte sheet with butyl carbitol in advance with a thickness of 20 μm is printed on one surface of the second unfired alumina sheet on which the second sensor pattern is formed. An unfired solid electrolyte sheet to be the solid electrolyte layer 215 is bonded onto the laminated paste, and vacuum bonded under conditions of 35 ± 5 kg / cm ² at 50 ° C. for 90 seconds. Then, the first sensor pattern is printed with a thickness of 20 ± 10 μm on the one surface of the unfired second alumina sheet on which the unfired solid electrolyte sheet is laminated, and dried.

Further, a sensor laminate that becomes the sensor substrate 210 after firing is produced. Specifically, the first non-fired alumina sheet in a state where the above-described green solid electrolyte sheet is laminated is used for the first non-fired alumina sheet using a bonding paste obtained by diluting the green sheet for alumina layer with butyl carbitol. The fired alumina sheet and the unfired protective sheet are bonded together and integrated by vacuum pressing under conditions of 35 ± 5 kg / cm ² at 50 ° C. for 90 seconds to produce a sensor laminate.

  Next, the sensor laminate is fired to produce the sensor substrate 210. Specifically, the sensor laminate is heated and degreased at 400 ° C. for 6 hours in an air atmosphere. Then, this is baked at 1520 ° C. for 2 hours in an air atmosphere. Thus, the sensor substrate 210 is formed.

Next, a method for manufacturing the lead substrate 230 will be described.
First, unfired via conductors that become via conductors 223t and 227t and via conductors 235 after firing are formed on the third unfired alumina sheet. In addition, a connection pad pattern that becomes a part of the connection pads 223u and 227u after firing and a sensor electrode pad pattern that becomes the sensor electrode pad 255 after firing are formed on the sheet.
Specifically, W45 vol%, alumina 8 vol%, polyvinyl butyral resin 20 vol%, and solvent 27 vol% are mixed to obtain a high-density tungsten conductive ink. Then, this high density tungsten conductive ink is filled and printed in two openings at both ends among the three openings 232 formed at a predetermined position on the tip side from the center of the third unfired alumina sheet, and the unfired via conductor is printed. Form.
In addition, 3 parts by mass of alumina powder and 100 parts by mass of tungsten powder were added, 6 parts by mass of etose binder was added, and further a third paste was prepared using a conductive paste prepared by mixing butyl carbitol as a solvent. A connection pad pattern is formed on one surface (surface to be a surface) of the fired alumina sheet by printing it in a disk shape covering the unfired via conductor and drying it.

  On the other hand, Pt 40 vol%, W 10 vol%, alumina 3 vol%, polyvinyl butyral resin 20 vol%, and solvent 27 vol% are mixed to obtain a high-density Pt-W conductive ink. Then, this high density Pt-W conductive ink is filled and printed in the two openings 234 of the third unfired alumina sheet to form unfired via conductors. 100 parts by mass of 81.6 vol% of Pt powder and 18.4 vol% of tungsten powder, 3 parts by mass of alumina powder and 6 parts by mass of etose binder are added, and butyl carbitol is further mixed as a solvent. Using the prepared conductive paste, on one surface (surface to be the surface) of the third unfired alumina sheet, a rectangular shape covering the unfired via conductor is printed and dried to form a sensor electrode pad pattern. Form.

  Next, a first sensor lead pattern that becomes the rear end portion 223q of the first sensor lead portion 223 after firing, and a second sensor lead pattern that becomes the rear end portion 227q of the second sensor lead portion 227 after firing, Form on an unfired alumina sheet. Specifically, 3 parts by mass of alumina powder, 100 parts by mass of tungsten powder, and 6 parts by mass of etose binder are blended, and butyl carbitol is further mixed as a solvent to prepare a conductive paste. And this is printed on one side (surface used as the surface) of the 4th non-baking alumina sheet, it is made to dry, and the 1st sensor lead pattern and the 2nd sensor lead pattern are formed.

  Next, a gas release pattern that forms the gas release path 261 after firing is formed. Specifically, 13 parts by mass of polyvinyl butyral is blended with 100 parts by mass of a mixture of 60 vol% carbon and 40 vol% alumina, and butyl carbitol is mixed as a solvent to obtain a paste. And this is printed between the 1st sensor lead pattern and the 2nd sensor lead pattern among the 4th non-baking alumina sheets, it is made to dry, and a gas discharge pattern is formed.

Next, an unfired via conductor that becomes the via conductor 241 after firing is formed on the fifth unfired alumina seed. Also, a heater electrode pad pattern that becomes a part of the heater electrode pad 265 after firing is formed on the sheet. Specifically, Pt 40 vol%, W 10 vol%, alumina 3 vol%, polyvinyl butyral resin 20 vol%, and solvent 27 vol% are mixed to prepare a high-density Pt-W conductive ink. Then, this high density Pt-W conductive ink is filled and printed in the two openings 240 formed in the vicinity of the rear end of the fifth unfired alumina sheet to form unfired via conductors.
Further, 100 parts by mass of 81.6 vol% of Pt powder and 18.4 vol% of tungsten powder was added, 3 parts by mass of alumina powder and 6 parts by mass of etose binder were added, and butyl carbitol was further used as a solvent. Using the conductive paste prepared by mixing, printing on a predetermined shape so as to cover the unfired via conductor on one surface of the fifth unfired alumina sheet (the surface to be the back surface 239R), dried, A heater electrode pad pattern (a pattern of the heater electrode pad layer) is formed.

  Next, a heat generation pattern that becomes the heat generating portion 271 after baking and a heater lead pattern that becomes the heater lead portion 273 after baking are formed on the fifth unfired alumina sheet. Specifically, 12 parts by mass of alumina powder, 100 parts by mass of tungsten powder, and 8 parts by mass of etose binder are blended, and butyl carbitol is further mixed as a solvent to obtain a conductive paste. And this electrically conductive paste is printed on one side (surface used as the surface) of a 5th unbaking alumina sheet, and it is made to dry, and a heat generating pattern is formed. Further, 3 parts by mass of alumina powder, 100 parts by mass of tungsten powder, and 6 parts by mass of etose binder are blended, and butyl carbitol is further mixed as a solvent to obtain a conductive paste. Then, this conductive paste is printed on the surface of the fifth unfired alumina sheet and dried to form a heater lead pattern.

Next, a lead laminate that becomes the lead substrate 230 after firing is fabricated. Specifically, the unfired alumina layer sheet is butyl on one surface (the back surface) of the third unfired alumina sheet and the one surface (the back surface) of the fourth unfired alumina sheet. The pasting paste diluted with carbitol is printed with a thickness of 20 μm. Thereafter, the third unfired alumina sheet, the fourth unfired alumina sheet, and the fifth unfired alumina sheet were bonded together and integrated by vacuum pressing at 35 ± 5 kg / cm ² at 50 ° C. for 90 seconds. Make it.

  Next, this lead laminate is fired to produce a lead substrate 230. Specifically, the lead laminate is degreased by heating at 250 ° C. for 6 hours in an air atmosphere. Then, this is baked at 1540 ° C. for 4 hours in a hydrogen wetting atmosphere.

Next, a Pd colloid is nucleated on each of the patterns of the lead substrate 230 that are mainly W and form part of the connection pads 223u and 227u. Thereafter, Ni plating is applied to form a Ni plating layer on the W pattern. Further, this is baked (H ₂ furnace 800 ° C. sinter). Next, Pt plating or Au plating is performed, and a Pt plating layer or Au plating layer is formed on the Ni plating layer. Further, this is baked (H ₂ furnace 800 ° C. sinter). In this way, connection pads 223u and 227u made of a tungsten layer, a Ni plating layer, and a Pt or Au plating layer are formed. Thus, the lead substrate 230 is completed.

Next, the sensor substrate 210 and the lead substrate 230 are bonded. Specifically, a polyvinyl butyral resin is blended with SiO2-ZnO-based glass powder, and butyl carbitol is further mixed as a solvent to obtain a glass paste. Then, this is printed on the back surface of the sensor substrate 210 with a thickness of 20 μm while forming the three openings 282 so as to avoid the openings 218 and the via conductors 223 s and 227 s.
Next, a brazing material made of Ag-5 wt% Pd is printed in two openings located at both ends of the three openings 282. Thereafter, the heater substrate 210 and the sensor substrate 230 are bonded together and dried. Next, it is degreased by heating at 400 ° C. for 4 hours in an atmosphere of N 2 —O 2 (250 ppm or less) at 250 ° C. for 4 hours in an air atmosphere. Furthermore, the substrate is baked at 1050 ° C. for 2 hours in a nitrogen atmosphere to completely bond both substrates. This also connects the via conductors 223s, 227s and the connection pads 223u, 227u both mechanically and electrically via the connection parts 223r, 227r made of brazing material. Thus, the sensor element 200 is completed.

Next, returning to FIG. 1, another part of the gas sensor 100 will be described.
The flange portion 125 assembled integrally with the sensor element 200 includes an alumina ceramic ring 121, a talc ring 122 filled and compressed with talc powder, and a cylindrical shape that can accommodate the ceramic ring 121 and the talc ring 122 therein. It comprises the metal holder 120 which makes | forms. The flange portion 125 is assembled to the sensor element 200 as follows.
First, a ring-shaped talc molded body having an opening cross-sectional area large enough to allow the sensor element 200 to be inserted is prepared, and a metal holder 120, a ceramic ring 121, and a talc molded body are sequentially arranged at predetermined positions of the sensor element 200. . Then, the talc molded body is crushed and compressed and deformed to form the talc ring 121, and the metal holder 120 and the ceramic ring 121 are integrally assembled to the sensor element 200 together with the talc ring 122. Thereby, the flange part 125 for engaging with the step part 109 of the metal shell 102 is provided in a state of being fixed to the sensor element 200.

  On the distal end side (lower side in FIG. 1) of the metal shell 102, a step portion 109 whose inner diameter is reduced is provided. Further, the outer diameter of the flange portion 125 is configured to be substantially the same as the inner diameter of the metal shell 102 at the rear end side portion (upward in the drawing) of the step portion 109. In the metal shell 102 with which the metal holder 120 is engaged, a talc ring 123 is further filled and compressed in the layer on the rear end side (the upper layer in FIG. 1) with respect to the metal holder 120. As a result, the flange portion 125 is held airtight in the metal shell 102 and the sensor element 200 is also positioned and fixed with respect to the metal shell 102. The compression of the talc ring 123 is performed by being pressed by the sleeve 130 when a sleeve 130 described later is incorporated into the metal shell 102.

  Further, on the tip side of the stepped portion 109 of the metal shell 102, the tip side portion of the sensor element 200 is exposed to the air. A bottomed substantially cylindrical inner protector 103 that covers and protects the distal end side portion and an outer protector 104 that covers the inner protector 103 are fixed to the metal shell 102 by laser welding. A plurality of outside air communication holes 105 and 106 are opened in the inner protector 103 and the outer protector 104 so that the tip side portion of the sensor element 200 is exposed to the atmosphere around the gas sensor 100.

  On the other hand, on the rear end side of the talc ring 123, a multistage cylindrical alumina sleeve 130 is disposed. The sleeve 130 is accommodated in the metal shell 102 together with the flange portion 125 while pressing the talc ring 123. The sleeve 130 has a shaft hole 131 penetrating in the axial direction, and the sensor element 200 is inserted through the shaft hole 131. In a state where the sleeve 130 is accommodated in the metal shell 102, the electrode pads 255 and 265 (see FIG. 2) of the sensor element 200 are exposed to the rear end side from the crimped portion 107 of the metal shell 102. Note that a pair of element guides (not shown) projecting from the rear end surface of the sleeve 130 along the axial direction of the sleeve 130 in the rear end direction. Each element guide is for guiding both ends of the sensor element 200 in the short direction.

  When the crimping portion 107 of the metal shell 102 is bent inward and crimped, the sleeve 130 is pressed toward the distal end side of the metal shell 102 via the stainless steel ring member 108 interposed inside. Then, since the talc ring 123 is compressed and deformed to fill the surrounding gap, the sensor element 200 having the sleeve 130 and the flange portion 125 is hermetically held and fixed in the metal shell 102.

  The rear end portion of the sensor element 200 that protrudes from the metal shell 102 to the rear end side and has the electrode pads 255 and 265 of the sensor element 200 is formed in the thickness direction of the sensor element 200 by the pair of electrode holders 140. It is sandwiched. The electrode holder 140 has an end on the tip side engaged with the element guide of the sleeve 130, an inner wall surface 142 facing the sensor element 200 guided by the element guide, and an axial cross section configured together with the element guide. And an outer wall surface 144 that forms a curved outer peripheral surface that is circular. A flange 147 is provided on the outer wall surface 144 on the distal end side of the electrode holder 140.

  Further, two openings 146 penetrating the inner wall surface 142 and the outer wall surface 144 are provided at substantially the center of the electrode holder 140. A protrusion 163 of an electrode fitting 160 described later is engaged with the opening 146, and the electrode fitting 160 is positioned. Two electrode fittings 160 are engaged with each electrode holder 140 in order to make electrical connection with each electrode pad 255, 265 of the sensor element 200. Then, in order to maintain the engagement of the electrode holder 140 while the electrode holder 140 is engaged with the element guide while holding the electrode fitting 160, a cylindrical holding fitting is provided on the outer wall surface 144 of the pair of electrode holders 140. 148 is engaged. In a state where the holding metal fitting 148 is engaged with the electrode holder 140, the electrode metal fitting 160 sandwiched between the inner wall surface 142 of the electrode holder 140 and the sensor element 200 is bent. Due to the urging force, the electrode fitting 160 presses the electrode holder 140 against the inner periphery of the holding fitting 148, so that the holding fitting 148 is prevented from coming off.

  Further, on the rear end side of the electrode holder 140, an alumina separator 150 for guiding four lead wires 168 for electrically connecting the sensor element 200 and an external circuit to the electrode fitting 160. Is disposed and is in contact with the electrode holder 140. The separator 150 has a substantially cylindrical shape, and a disk-shaped small protrusion 151 is provided in the vicinity of the center of the rear end side surface. And around this small protrusion 151, the four guide holes 152 penetrated in the axial direction are provided. The guide hole 152 includes a small-diameter portion 153 having a relatively small diameter located on the rear end side (upper side in FIG. 1) where the small protrusion 151 is provided. The diameter of the small diameter portion 153 is substantially equal to the thickness of the lead wire 168.

  Inside the guide hole 152, the base 162 of the electrode fitting 160 is accommodated. The base portion 162 is a portion where the lead wire 168 is caulked and integrated with the electrode fitting 160. The base portion 162 includes a caulking portion 165 for caulking the outer periphery of the insulating film covering the conducting wire in the lead wire 168 and preventing the disconnection, and caulking for electrically connecting the caulking wire in the lead wire 168. Part 164. The caulking portion 165 for caulking the outer periphery of the lead wire 168 is formed larger in diameter than the caulking portion 164 for caulking the conducting wire. For this reason, the crimping portion 165 is larger in diameter than the lead wire 168 in a state where the lead wire 168 is crimped, and is larger than the inner diameter of the small diameter portion 153 of the guide hole 152 of the separator 150. 153 cannot pass.

Further, the tip 161 of the electrode fitting 160 joined to the base 162 is a portion that makes electrical connection by contacting the electrode pads 255 and 265 of the sensor element 200, and is formed in a U-shaped spring shape. . The tip portions 161 of these electrode fittings 160 are in contact with the sensor electrode pad 255 of the sensor electrode extraction portion 256 and the heater electrode pad 265 of the heater electrode extraction portion 266, respectively, so as to be electrically connected to the lead substrate 230 (FIG. 3).
Further, a projecting piece 163 for engaging with the opening 146 of the electrode holder 140 and positioning the electrode holder 140 and the electrode fitting 160 is provided at a substantially central position in the axial direction of the tip portion 161.

  A substantially cylindrical stainless steel protective cover 170 that covers and protects the electrode holder 140 and the separator 150 is fixed to the outer periphery of the crimping portion 107 of the metal shell 102. A plug member 171 made of fluoro rubber is fitted into the rear end portion of the protective cover 170, and only the lead wire 168 is inserted. The stopper member 171 is fixed inside the protective cover 170 in an elastically deformed state by caulking the protective cover 170 positioned around the radial direction of the stopper member 171 inward. Further, a tubular holding metal fitting 148 is fitted so as to surround the circumference of the electrode holder 140 in the radial direction, and a protruding portion 149 provided on the holding metal fitting 148 is in contact with the inner wall of the protective cover 170. The projecting portion 149 is provided so as to protrude in four directions, whereby the holding metal fitting 148 and the electrode holder 140 are held in the protective cover 170.

Next, assembly of the sensor element 200 to the gas sensor 100 configured as described above will be described.
The sensor element 200 in which the flange portion 125 is integrally assembled is inserted into the metal shell 102 with the detection unit side as the distal end side of the metal shell 102. Then, the sensor element 200 is positioned with respect to the metallic shell 102 at a position where the end portion on the distal end side of the flange portion 125 contacts the stepped portion 109 on the distal end side of the metallic shell 102.

Next, the talc ring 123 is passed through the center hole from the rear end side of the sensor element 200, and then the rear end portion of the sensor element 200 is passed through the shaft hole 131 of the sleeve 130, near the rear end of the sensor element 200. Is exposed from the shaft hole 131.
In this state, the ring member 108 is placed on the sleeve 130 and caulking is performed by bending the caulking portion 107 of the metal shell 102 inward. The sleeve 130 receives a pressing force by caulking in the distal direction of the metal shell 102 via the ring member 108 and compresses the talc ring 123. As a result, the talc ring 123 is deformed to fill the surrounding gap, and the sensor element 200 and the flange portion 125 are fixed in the metal shell 102.

  On the other hand, the protruding piece 163 of the electrode fitting 160 integrated with the lead wire 168 by the crimping at the crimping portions 164 and 165 is engaged with the opening 146 of the electrode holder 140. Then, the electrode fitting 160 is positioned and held with respect to the electrode holder 140. In this state, the electrode holder 140 is engaged with the element guide so as to be sandwiched from both sides of the sensor element 200 in the thickness direction. The tip 161 of the electrode fitting 160 sandwiched between the inner wall surface 142 of the electrode holder 140 and the plate surface of the sensor element 200 abuts on the electrode pads 255 and 265 of the sensor element 200, respectively. At this time, the sensor element 200 is positioned with respect to the element guide of the sleeve 130, and the electrode holder 140 is also positioned with respect to the engaging element guide.

  Then, the separator 150 is brought into contact with the electrode holder 140, and in this state, the protective cover 170 is put on the electrode holder 140 and the separator 150. The protective cover 170 is press-fitted into the metal shell 102 and then fixed by laser welding all around. The protruding portion 149 of the holding metal fitting 148 comes into contact with the inner wall. As a result, the holding metal 148 is held in the protective cover 170, and the electrode holder 140 held by the holding metal 148 is also positioned in the protective cover 170.

  As described above, in the gas sensor 100 according to the present embodiment, since the tip portion 161 of the electrode fitting 160 is formed in a U-shaped spring shape, when sandwiched by the electrode holder 140, the plate surface of the sensor element 200 and the electrode The inner wall surface 142 of the holder 140 is urged in a direction away from both. In this state, in order to hold down the outer periphery of the electrode holder 140 and maintain the engagement therebetween, a holding metal fitting 148 is put on the outer periphery of the electrode holder 140. By doing in this way, the front-end | tip part 161 of the electrode metal fitting 160 is maintained in the state press-contacted with each electrode pad 255,265 of the sensor element 200, and the electrical connection between both is stabilized.

By the way, in this embodiment, the sensor electrode pad 255 and the heater electrode pad 265 are made of a material having oxidation resistance (Pt—W), like the via conductors 235 and 241. However, unlike the via conductors 235 and 241 having a dense structure, the sensor electrode pad 255 and the heater electrode pad 265 have a coarser structure, more specifically, a porous structure.
As described above, the entire sensor electrode pad 255 and heater electrode pad 265 including the portion forming the externally exposed surfaces 255a and 265a have a coarser structure than the via conductors 235 and 241. For this reason, when an external force is applied to the sensor electrode pad 255 and the heater electrode pad 265 in the connection between the distal end portion 161 of the electrode fitting 160 and the sensor electrode extraction portion 256 or the connection between the distal end portion 161 and the heater electrode extraction portion 266. It is easy to deform.
Thereby, when energizing the detection porous electrode part 221, the reference porous electrode part 225, and the heat generation part 271, the tip part 161 of the electrode fitting 160 is brought into pressure contact with the electrode pads 255 and 265, and these are connected to each other. Then, due to the pressing force at the time of the pressure contact, the electrode pads 255 and 265 are crushed and deformed, and a part of the tip portion 161 bites into the electrode pads 255 and 265. Thereby, the mechanical contact area of the electrode pads 255 and 265 and the electrode fitting 160 can be increased.
Furthermore, since the electrode pads 255 and 265 are deformed, the tip portion 161 of the electrode terminal 160 is less likely to slide on the electrode pads 255 and 265, so that the electrode fitting 160 can be brought into contact in a more stable state.
Therefore, in the sensor element 200 and the gas sensor 100 of the present embodiment, the occurrence of poor electrical connection between the electrode pads 255 and 265 and the tip portion 161 of the electrode fitting 160 can be suppressed.

In the gas sensor 100 of the present embodiment, the via conductors 235 and 241 are the first and second sensor leads in the sensor electrode extraction portion 256 and the heater electrode extraction portion 266 that are in contact with an oxidizing gas such as the atmosphere. 223, 227 rear end portions 223q, 227q and a material that is less susceptible to oxidation than tungsten forming the heater lead portion 273, specifically, Pt-18.4 wt% W having oxidation resistance and gas impermeability. Has been.
Therefore, even if the sensor electrode extraction unit 256 and the heater electrode extraction unit 266 are exposed to gas such as the atmosphere, the via conductors 235 and 241 are connected to the first and second sensors from the sensor electrode extraction unit 256 and the heater electrode extraction unit 266, respectively. Gas intrusion to the rear end portions 223q and 227q of the lead portions 223 and 227 and the heater lead portion 273 is prevented. Therefore, even if the rear end portions 223q and 227q of the first and second sensor lead portions 223 and 227 and the heater lead portion 273 are made of a base metal such as tungsten, the oxidation can be appropriately prevented in actual use.
Further, since the via conductors 235 and 241 formed of Pt-18.4 wt% W which is a noble metal-base metal alloy have oxidation resistance and gas impermeability, the via conductors 235 and 241 are all formed of noble metal. In contrast, the use of noble metal can be suppressed by the amount of base metal used. Thereby, the via conductors 235 and 241 and the gas sensor 100 can be made inexpensive.

(Embodiment 2)
Next, a second embodiment will be described with reference to FIG.
The gas sensor 101 according to the present embodiment (see FIG. 1) and the sensor element 300 used therefor differ from the gas sensor 100 according to the first embodiment described above and the sensor element 200 used therefor only in the configuration of the electrode extraction portion, and otherwise. The part of is the same. Therefore, description of the same part as Embodiment 1 is omitted or simplified, and it demonstrates centering on a different part.

  The sensor element 300 according to the second embodiment includes a sensor substrate 210 and a lead substrate 330 including a heater element portion 370. Of the sensor element 300, the sensor electrode extraction portion 356 is the same as the sensor electrode extraction portion 256 of the first embodiment in that it includes a via conductor 335 and a sensor electrode pad 355. The heater electrode extraction portion 366 is the same as the heater electrode extraction portion 266 of the first embodiment in that it includes a via conductor 341 and a heater electrode pad 365. The same is true in that the via conductors 335 and 341 are each made of a Pt-18.4 wt% W alloy which is a dense and gas-impermeable noble metal-base metal alloy.

However, the sensor electrode pad 355 according to the second embodiment is disposed on the third alumina layer inside and covers the via conductor covering portion 355A disposed so as to cover the via conductor 355, and covers the sensor electrode pad 355. The externally exposed portion 355B forming the externally exposed surface 355S has a double structure. Among these, the via conductor covering portion 355A is made of a material containing 8 wt% alumina in Pt-18.4 wt% W which is a noble metal-base metal, has a dense structure, and has oxidation resistance and gas impermeability. Have. The via conductor covering portion 355A hermetically covers the via conductor 335 on the outer surface 231R of the third alumina layer 231, and is in electrical contact with the via conductor 335.
On the other hand, the externally exposed portion 355B is made of a material containing 3 wt% of alumina in Pt-18.4 wt% W and has an oxidation resistance, but has a coarser structure than the via conductor covering portion 355A, specifically, a porous material. It consists of an organization. More specifically, the porosity of the externally exposed portion 355B is in the range of 40 to 60%.

In addition, the heater electrode pad 365 of the second embodiment also includes a via conductor covering portion 365A that is located on the fifth alumina layer and is disposed so as to cover the via conductor 341, and covers the via conductor covering portion 365A. The externally exposed portion 365B forming the externally exposed surface 365S has a double structure. Among these, the via conductor covering portion 365A is made of a material containing 8 wt% alumina in Pt-18.4 wt% W which is a noble metal-base metal, has a dense structure, and has oxidation resistance and gas impermeability. Have. The via conductor covering portion 365A hermetically covers the via conductor 341 on the outer surface 239R of the fifth alumina layer 239, and is in electrical contact with the via conductor 341.
On the other hand, the externally exposed portion 365B is also made of a material containing 3 wt% of alumina in Pt-18.4 wt% W and has an oxidation resistance, but is coarser than the via conductor covering portion 365A, specifically, porous. Consists of quality organization. Specifically, the porosity of the externally exposed portion 365B is in the range of 40 to 60%.

As described above, in the second embodiment, of the sensor electrode pad 355 and the heater electrode pad 365, the externally exposed portions 355B and 365B have a coarser structure than the via conductor covering portions 335A and 365A. For this reason, when an external force is applied to the externally exposed portions 355B and 365B in the connection between the distal end portion 161 of the electrode fitting 160 and the sensor electrode extraction portion 356 and the connection between the distal end portion 161 and the heater electrode extraction portion 366, This part is easily deformed.
Accordingly, when energizing the detection porous electrode part 221, the reference porous electrode part 225, and the heat generation part 271, the tip part 161 of the electrode fitting 160 is pressed against the electrode pads 355 and 365, and these are connected to each other. Then, the externally exposed portions 355B and 365B of the electrode pads 355 and 365 are crushed and deformed by the pressing force at the time of the pressure contact, and a part of the distal end portion 161 bites into the externally exposed portions 355B and 365B. Thereby, the mechanical contact area of each electrode pad 355, 365 and the electrode metal fitting 160 can be taken large.
Furthermore, since the externally exposed portions 355B and 365B of the electrode pads 355 and 365 are deformed, the tip portion 161 of the electrode terminal 160 is difficult to slide on the electrode pads 355 and 365, so that the electrode fitting 160 can be contacted in a more stable state. Can be made.
Therefore, also in the sensor element 300 and the gas sensor 101 of the second embodiment, it is possible to suppress the occurrence of poor electrical connection between the electrode pads 355 and 365 and the tip portion 161 of the electrode fitting 160.

Further, in the second embodiment, among the sensor electrode pad 355 and the heater electrode pad 365, the via conductor covering portions 355A and 365A have the third alumina layer 231 or the fifth alumina as compared to the externally exposed portions 355B and 365B. The same alumina as the layer 239 was included (8 wt%). As a result, the close contact with the third and fifth alumina layers 231 and 239 is improved, and the gas such as the atmosphere enters the inside through the interface between the via conductor coating portions 355A and 365A and the third and fifth alumina layers 231 and 239. It is possible to reliably prevent the progress.
On the other hand, by reducing the alumina contained in the external exposed portions 355B and 365B from that of the via conductor covering portions 355A and 365A, the conduction resistance in the external exposed portions 355B and 365B is further suppressed, and the electrode pads 355 and 365 Prevents a decrease in conductivity.

As described above, in the second embodiment, in addition to the via conductors 335 and 341, the sensor electrode pad 355 and the via conductor covering portions 355A and 365A of the heater electrode pad 365 also have oxidation resistance and gas impermeability. is doing. For this reason, even if the sensor electrode extraction part 356 is exposed to an oxidizing gas such as the atmosphere, the via conductor covering part 355A and the via conductor 335 go to the rear end parts 223q and 227q of the first and second sensor lead parts 223 and 227. Prevent gas intrusion. Similarly, even if the heater electrode extraction portion 366 is exposed to an oxidizing gas such as the atmosphere, the via conductor covering portion 365A and the via conductor 341 prevent gas from entering the heater lead portion 273. Therefore, it is possible to prevent oxidation of the rear end portions 223q and 227q and the heater lead portion 273 of the first and second sensor lead portions 223 and 227 mainly composed of a base metal.
Further, since the via conductor covering portions 355A and 365A are formed of Pt-18.4 wt% W, which is a noble metal-base metal alloy, compared to the case where these are made of noble metal, the amount of noble metal used is less than that of the noble metal. Use can be suppressed and the gas sensor 101 can be made inexpensive.

(Embodiment 3)
Next, a third embodiment will be described with reference to FIGS.
In the first and second embodiments described above, gas sensor 100 and 101 including sensor elements 200 and 300 in which oxygen sensor element parts 201 and 301 are combined with heater element parts 270 and 370 are illustrated as ceramic electronic functional bodies, respectively. explained.
On the other hand, as can be easily understood by comparing FIG. 2 and FIG. 5, the third embodiment has a configuration in which the sensor element 200 in the gas sensors 100 and 101 is replaced and the heater element portion 270 is removed therefrom. The gas sensor 102 incorporating the sensor element 400 will be described. That is, the sensor element 400 incorporated in the gas sensor 102 according to the third embodiment is the same as the oxygen sensor element portion 201 in the sensor element 200 according to the first embodiment.
Therefore, the description of the same parts as those in the first embodiment will be omitted or simplified, and different parts will be mainly described. FIG. 5 is an exploded perspective view of the sensor element 400 incorporated in the gas sensor 102.

In the sensor element 400 of the third embodiment, the sensor electrode extraction portion 456 includes a via conductor 435 and a sensor electrode pad 455. The via conductor 435 is also made of a Pt-18.4 wt% W alloy as a noble metal-base metal alloy, has a dense structure, and has oxidation resistance and gas impermeability.
On the other hand, the sensor electrode pad 455 is made of Pt-18.4 wt% W, which is a noble metal-base metal like the via conductor 435, and has a structure rougher than the via conductor 435 although it has oxidation resistance. Specifically, it consists of a porous structure, and its porosity is in the range of 40 to 60%. The sensor electrode pad 455 is disposed so as to cover the via conductor 435 and is in conduction therewith.

The gas sensor 102 according to the third embodiment can be used, for example, as an oxygen sensor that is mounted on an exhaust pipe of an automobile or the like and detects an oxygen concentration in exhaust gas flowing through the exhaust pipe.
When this gas sensor 102 is used in the exhaust pipe of such an automobile, the via conductor 435 has oxidation resistance and gas impermeability even if the sensor electrode extraction portion 456 is exposed to gas such as the atmosphere. For this reason, invasion of gas from the sensor electrode extraction portion 456 to the rear end portions 223q and 227q of the first and second sensor lead portions 223 and 227 is prevented. Therefore, oxidation of the rear end portions 223q and 227q of the first and second sensor lead portions 223 and 227 mainly composed of base metal can be prevented.

Furthermore, also in the third embodiment, the sensor electrode pad 455 is made of a material (Pt—W) having oxidation resistance, like the via conductor 435. However, unlike the via conductor 435 having a dense structure, the sensor electrode pad 455 has a coarser structure, specifically, a porous structure. In other words, the entire sensor electrode pad 455 including the portion forming the external exposed surface 455a has a rougher structure than the via conductor 435. For this reason, in the connection between the distal end portion 161 of the electrode fitting 160 and the sensor electrode extraction portion 46, it is easily deformed when an external force is applied to the sensor electrode pad 255.
Accordingly, when energizing the detection porous electrode part 221, the reference porous electrode part 225, and the heat generation part 271, the tip part 161 of the electrode fitting 160 is brought into pressure contact with the sensor electrode pad 455 so that they are connected to each other. The sensor electrode pad 455 is crushed and deformed by the pressing force at the time of this pressure contact, and a part of the tip portion 161 bites into the sensor electrode pad 455. Thereby, a large mechanical contact area between the sensor electrode pad 455 and the electrode fitting 160 can be secured.
Furthermore, since the sensor electrode pad 455 is deformed, the tip 161 of the electrode terminal 160 is less likely to slide on the sensor electrode pad 455, so that the electrode fitting 160 can be contacted in a more stable state.
Therefore, also in the sensor element 400 and the gas sensor 102 according to the third embodiment, it is possible to suppress the occurrence of poor electrical connection between the electrode pad 455 and the tip portion 161 of the electrode fitting 160.

(Embodiment 4)
Next, a fourth embodiment will be described with reference to FIGS.
In the first and second embodiments, the gas sensors 100 and 101 including the sensor elements 200 and 300 in which the oxygen sensor element parts 201 and 301 are combined with the heater element parts 270 and 370 are described as ceramic electronic functional bodies, respectively.
On the other hand, in the fourth embodiment, a heater element 570 will be described as a ceramic electronic functional body. In addition, the heater element 570 according to the fourth embodiment differs from the heater element portion 270 in the sensor element 200 according to the first embodiment described above in the configuration of the heater electrode lead-out portion. It is the same thing. The heater electrode extraction portion 566 is the same as the heater element portion 370 in the sensor element 300 according to the second embodiment.
Therefore, the description of the same parts as those in the first to third embodiments will be omitted or simplified, and different parts will be mainly described. FIG. 7 is an exploded perspective view of the heater element 570.

In the heater element 570 of the fourth embodiment, the heater electrode extraction portion 566 includes a via conductor 541 and a heater electrode pad 565 as shown in FIG. Among these, the via conductor 541 is made of Pt-18.4 wt% W, like the via conductor 241 of Embodiment 1, has a dense structure, and has oxidation resistance and gas impermeability.
On the other hand, the heater electrode pad 565 is composed of two layers of an inner via conductor covering portion 565A and an externally exposed portion 565B covering the via conductor covering portion 565A. Of these, the via conductor covering portion 565A is made of a material containing 8 wt% of the same alumina as the alumina forming the fifth alumina layer 239 as a common substrate in Pt-18.4 wt% W which is a noble metal-base metal. And gas-impermeable. The via conductor covering portion 565A hermetically covers the via conductor 541 on the outer surface 239R of the fifth alumina layer 239 and is in electrical contact with the via conductor 541.
However, the externally exposed portion 565B forming the externally exposed surface 565S of the heater electrode pad 565 is slightly different from the via conductor covering portion 565A and contains alumina in Pt-18.4 wt% W. It is 3 wt%, which is less than the covering portion 565A. Further, the externally exposed portion 565B is made of a texture that is coarser than the via conductor covering portion 565A. Specifically, it has a porous structure, and its porosity is 40 to 60%.

  By configuring the heater electrode extraction portion 566 in this way, even when the heater element 570 is exposed to an atmosphere such as air, for example, the via conductor 541 and the via conductor covering portion 541 are not connected to the heater electrode extraction portion 566. Thus, it is possible to prevent gas such as air from entering the heater lead portion 273 and to reliably prevent oxidation of the heater lead portion 273 mainly composed of base metal (tungsten).

Moreover, in the fourth embodiment, in the heater electrode pad 565, the externally exposed portion 565B has a coarser structure than the via conductor covering portion 565A. For this reason, when an external force is applied to the externally exposed portion 565B in the connection between the tip portion 161 of the electrode fitting 160 and the heater electrode extraction portion 566, this portion is easily deformed.
As a result, when energizing the heat generating portion 271, the tip 161 of the electrode fitting 160 is brought into pressure contact with the heater electrode pad 565 so that they are connected to each other. The external exposed portion 565B is crushed and deformed, and a part of the tip portion 161 bites into the external exposed portion 565B. Thereby, a large mechanical contact area between the heater electrode pad 565 and the electrode fitting 160 can be secured.
Furthermore, since the externally exposed portion 565B of the heater electrode pad 565 is deformed, the tip portion 161 of the electrode terminal 160 is less likely to slide on the heater electrode pad 565, so that the electrode fitting 160 can be contacted in a more stable state. .
Therefore, even in the heater element 570 of the fifth embodiment, it is possible to suppress the occurrence of poor electrical connection between the heater electrode pad 565 and the tip portion 161 of the electrode fitting 160.

Further, also in the fourth embodiment, in the heater electrode pad 565, the via conductor covering portion 565A contains more (8 wt%) of the same alumina as the fifth alumina layer 239 than the externally exposed portion 565B. Thereby, the close contact with the fifth alumina layer 239 is improved, and it is possible to surely prevent the gas such as the air from proceeding to the inside through the interface between the via conductor covering portion 565A and the fifth alumina layer 239.
On the other hand, the alumina contained in the external exposed portion 565B is less than that of the via conductor covering portion 565A, so that the conduction resistance in the external exposed portion 565B is suppressed to a lower level, and the decrease in the conductivity at the heater electrode pad 565 is prevented. Yes.

In the above, the present invention has been described with reference to the first to fourth embodiments. However, the present invention is not limited to these embodiments, and can be appropriately modified and applied without departing from the scope of the present invention. Needless to say.
For example, in the first, second, third, and fourth embodiments, Pt-18.4 wt% W has been described as an example of the noble metal-base metal alloy. However, noble metal-base metal alloys having other compositions having oxidation resistance are used. It can also be used. It is also clear that noble metals such as Pt can be used without mixing base metals.

It is a longitudinal cross-sectional view of gas sensor 100,101,102 which concerns on Embodiment 1-3. It is an exploded perspective view of sensor elements 200 and 300 used for gas sensors 100 and 101 concerning Embodiments 1-3. It is explanatory drawing which shows the mode of a connection with the rear-end part of the sensor element 200 used for the gas sensor 100 which concerns on Embodiment 1, and an external connection terminal. It is explanatory drawing which shows the mode of a connection with the rear-end part of the sensor element 300 used for the gas sensor 101 which concerns on Embodiment 2, and an external connection terminal. It is a disassembled perspective view of the sensor element 400 used for the gas sensor 102 which concerns on Embodiment 3. FIG. It is explanatory drawing which shows the mode of the connection of the rear-end part of the sensor element 400 used for the gas sensor 102 which concerns on Embodiment 3, and an external connection terminal. 6 is an exploded perspective view of a heater element 570 according to Embodiment 4. FIG. It is explanatory drawing which shows the mode of the connection of the rear-end part of the heater element 570 which concerns on Embodiment 4, and an external connection terminal.

Explanation of symbols

200,300 Sensor element (gas sensor element with heater)
400 Gas sensor element (ceramic electronic functional body)
201, 301 Oxygen sensor element (gas sensor element, ceramic electronic functional body)
205 Oxygen detection unit (electrical function unit)
223 1st sensor lead part 223q Rear end part (electrode lead part)
227 Second sensor lead portion 227q Rear end portion (electrode lead portion)
270, 370 Heater element (ceramic electronic functional body)
570 Heater element (ceramic electronic functional body)
239R Outer surface 271 Heat generating part (electrical function part)
273 Heater lead (electrode lead)
266,366 Heater electrode extraction part (electrode extraction part)
241 Via conductor 231R Outer surface 256, 356, 456 Sensor electrode extraction part (electrode extraction part)
235, 335, 435 Via conductor 255, 355, 455 Sensor electrode pad (electrode pad)
355A Via conductor covering portion 355B External exposed portions 255a, 355S, 456a External exposed surfaces 266, 366, 566 Heater electrode extraction portion (electrode extraction portion)
241, 341, 541 Via conductors 265, 365, 565 Heater electrode pads (electrode pads)
365A, 565A Via conductor covering portion 365B, 565B External exposed portion 265a, 365S, 565S External exposed surface

Claims (10)

Ceramic electronic device comprising: an electrical functional part that performs a predetermined electrical function; a conductive path that is electrically connected to the electrical functional part at one end thereof; and an insulating ceramic layer that hermetically covers a part of the conductive path A functional body,
The conduction path is
An electrode extraction part including the other end of itself and a part of which is exposed to the outside;
An electrode lead portion, which is located on the one end side of the conduction path from the electrode extraction portion and connected to the electrode extraction portion, is made of a material mainly composed of a base metal, and is hermetically embedded in the ceramic layer. Have
The electrode extraction part is
A via conductor penetrating the ceramic layer and electrically connected to the electrode lead portion;
An electrode pad electrically connected to the via conductor and exposed to the outside on the outer surface of the ceramic layer, and
The via conductor is
Made of oxidation-resistant material, dense and gas-impermeable,
The electrode pad is
A ceramic electronic functional body made of a material having oxidation resistance and having a structure in which at least a portion forming an externally exposed surface is rougher than the via conductor. The ceramic electronic functional body according to claim 1,
The electrode pad is
A ceramic electronic functional body made of a material containing a ceramic material forming the ceramic layer. Ceramic electronic device comprising: an electrical functional part that performs a predetermined electrical function; a conductive path that is electrically connected to the electrical functional part at one end thereof; and an insulating ceramic layer that hermetically covers a part of the conductive path A functional body,
The conduction path is
An electrode extraction part including the other end of itself and a part of which is exposed to the outside;
An electrode lead portion, which is located on the one end side of the conduction path from the electrode extraction portion and connected to the electrode extraction portion, is made of a material mainly composed of a base metal, and is hermetically embedded in the ceramic layer. Have
The electrode extraction part is
A via conductor penetrating the ceramic layer and electrically connected to the electrode lead portion;
An electrode pad electrically connected to the via conductor and exposed to the outside on the outer surface of the ceramic layer, and
The electrode pad is
A via conductor covering portion that is in electrical contact with at least the via conductor, and airtightly covers the via conductor on the outer surface of the ceramic layer;
An electrical connection with the via conductor covering portion, forming an externally exposed surface of the electrode pad, and an externally exposed portion covering the via conductor covering portion,
The via conductor covering portion is
Made of oxidation-resistant material, dense and gas-impermeable,
The externally exposed part is
A ceramic electronic functional body made of a material having oxidation resistance and having a structure rougher than the via conductor covering portion. The ceramic electronic functional body according to claim 3,
The via conductor covering portion and the externally exposed portion of the electrode pad are
A ceramic electronic functional body made of a material containing a ceramic material forming the ceramic layer. The ceramic electronic functional body according to claim 4,
The via conductor covering portion is
The ceramic material,
A ceramic electronic functional body containing more than the externally exposed portion. A ceramic electronic functional body according to any one of claims 1 and 3,
The electrode extraction part is
Ceramic electronic functional body made of precious metal-base metal alloy. The ceramic electronic functional body according to any one of claims 1 to 6, wherein the ceramic electronic functional body is a gas sensor element. The ceramic electronic functional body according to any one of claims 1 to 6, wherein the ceramic electronic functional body is a heater element. The ceramic electronic functional body according to any one of claims 1 to 6, wherein the ceramic electronic functional body is a gas sensor element portion and a heater element portion included in a gas sensor element with a heater. A gas sensor using the ceramic electronic functional body according to claim 7 or 9.

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