KR20160126494A

KR20160126494A - Limiting current type oxygen sensor and Method of manufacturing the same

Info

Publication number: KR20160126494A
Application number: KR1020150057551A
Authority: KR
Inventors: 김양기; 전종인; 오현성; 김은숙; 박우석; 이태원; 허남정; 김의성; 김지혜
Original assignee: (주)나노아이오닉스코리아
Priority date: 2015-04-23
Filing date: 2015-04-23
Publication date: 2016-11-02
Also published as: KR101689859B1

Abstract

Disclosed are a current-limiting oxygen sensor and a manufacturing method thereof. According to the present invention, the current-limiting oxygen sensor comprises: a solid electrolyte capable of pumping oxygen ions; an anode electrode and a cathode electrode formed on an upper surface and a lower surface of the solid electrolyte, respectively; and a sensor substrate attached to a side of the cathode electrode in a surface-to-surface manner. A flat air gap area exposing at least a portion of the cathode electrode and a line-shaped pin hole opened by at least one side wall where an interface between the solid electrolyte and the sensor substrate is exposed are formed on the interface. According to the present invention, manufacturing costs of the current-limiting oxygen sensor can be reduced by reducing a weight, a size, and a thickness of the sensor and simplifying a process.

Description

TECHNICAL FIELD The present invention relates to a limiting current type oxygen sensor and a manufacturing method thereof,

TECHNICAL FIELD The present invention relates to a limiting current type oxygen sensor used for measurement of oxygen concentration and a manufacturing method thereof.

Oxygen sensors are used extensively for the purpose of measuring air pollution, improving fuel efficiency and thermal efficiency in combustion devices such as automobiles and boilers, reducing hazardous components in exhaust gases, and controlling the oxygen concentration in production facilities requiring oxygen.

The oxygen sensor is divided into a concentration cell type, an oxide semiconductor type, and a limiting current type according to the principle of the sensing.

The limit current type oxygen sensor has a merit that the oxygen concentration can be measured over a wide range as compared with the all-terrain type or oxide semiconductor type, the reference electrode is unnecessary, and it can be used at a relatively low temperature. In addition, it is possible to fabricate a sensor having a simple structure and a small element type, and is inexpensive in mass production and excellent in reproducibility, and is widely used among various types of oxygen sensors.

Conventionally, a limit current type oxygen sensor using a solid electrolyte made of Yttria Stabilized Zirconia (YSZ) containing yttria (Y ₂ O ₃ ) as an additive is known.

In a limiting current type oxygen sensor, when a cathode electrode and an anode electrode are attached to both surfaces of a solid electrolyte having conductivity with respect to oxygen ions (O ^2- ) and a voltage (hereinafter referred to as a pumping voltage) is applied to both electrodes, The surrounding oxygen is converted into oxygen ions (O ^2- ) by obtaining electrons from the cathode electrode. Further, the oxygen ions move toward the anode electrode through the solid electrolyte, and electrons are converted to oxygen molecules by giving electrons to the anode electrode. The above process is called electrochemical ion pumping, and the movement of oxygen ions through ion pumping causes a current to flow in the circuit connecting the cathode electrode and the anode electrode.

Ion pumping through the solid electrolyte reaches equilibrium in a short time, and the current magnitude thereafter is limited to a constant magnitude even as the magnitude of the pumping voltage changes. The magnitude of such a limiting current varies depending on the amount of oxygen supplied to the cathode electrode, that is, the partial pressure of oxygen and the temperature of the solid electrolyte. Therefore, if the size of the limiting current is measured under the condition that the temperature of the solid electrolyte is fixed, the oxygen concentration in the space where the cathode electrode is exposed can be accurately measured.

1 is a schematic diagram showing the structure of a limiting current type oxygen sensor widely used in the past.

1, a conventional limiting current type oxygen sensor 10 includes a solid electrolyte 11, an anode electrode 12 and a cathode electrode 13 made of a porous material for applying a pumping voltage to both sides thereof, .

In order to measure the limiting current in the limiting current type oxygen sensor 10, in order to control the amount of oxygen supplied to the cathode electrode 13 to be dependent on the oxygen concentration, a diffusion barrier barrier.

The limiting current type oxygen sensor 10 illustrated in FIG. 1 includes a cap structure 16 on the cathode electrode 13 side as an example of a diffusion barrier. The cap structure 16 is formed with a predetermined diffusion space A under the cathode electrode 13 and a gas diffusion hole 14 through which a gas to be measured for oxygen concentration is introduced into the diffusion space A .

The cap structure 16 includes a side wall portion 17 extending downward from a position spaced a predetermined distance from the edge of the cathode electrode 13 and a lower portion of the side wall portion 17 toward a center portion of the oxygen sensor 10 And a bottom portion 18 that is vertically bent and extends to the gas diffusion bore 14.

The gas diffusion bore 14 has a diameter and a length capable of ensuring Knudsen-type gas diffusion. Here, the nucin-type gas diffusion occurs when the pore size is smaller or smaller than the mean free path of the gas. In the case of gas diffusion, the partial pressure of oxygen increases linearly with the magnitude of the limiting current.

On the other hand, the solid electrolyte 11 of the limiting current type oxygen sensor 10 needs to be heated to a temperature capable of causing ion pumping (hereinafter referred to as reaction temperature), for example, several hundreds degrees.

To this end, a thin film heater 17 is provided below the bottom portion 18 of the cap structure 16. The thin film heater 17 receives electric power from a separate DC power source 19 through a lead wire 18 and generates resistance heat to a temperature of several hundreds degrees. Then, heat is conducted to the side of the solid electrolyte 11, and the temperature of the solid electrolyte 11 rises to a temperature at which ion pumping can occur.

The conventional limiting current type oxygen sensor 10 including the cap structure 16 as a diffusion barrier has a complicated process for forming the cap structure 6 and thus has a high manufacturing cost and a limitation in miniaturization of the sensor.

For example, in order to form the diffusion space A and the gas diffusion bore 14 by using the cap structure 6 inside the sensor, a groove is formed in the sheet base material constituting the cap structure 16, And then forming the bottom portion 18 and then punching the gas diffusion bore 14 in the central portion of the bottom portion 18.

Alternatively, a bottom portion 18 in which a gas diffusion hole 14 is formed in the central portion and a spacer-shaped side wall portion 17 to be attached in the vicinity of the cathode electrode 13 are independently fabricated, It is necessary to carry out a process of vertically stacking the layers.

In order to overcome the above problems of the cap structure 16, a technique of replacing the diffusion barrier with a porous insulating film has been commercialized. For example, a technique of coating a porous film in which alumina (Al ₂ O ₃ ) and YSZ are mixed on a particle basis is coated on the surface of the cathode electrode 13.

However, when the porous film is coated, the resolution of the sensor is deteriorated in a specific range of oxygen concentration, and the reproducibility of the sensor is deteriorated due to minute changes in porosity. Further, in order to form a porous film, a process of synthesizing a raw material powder in paste form and coating, drying, and firing must be performed. Therefore, there is a limit in reducing the manufacturing cost of the sensor by simplifying the process.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a limiting current type oxygen sensor including a diffusion barrier structure capable of spreading in a wide range of oxygen concentration, There is a purpose.

According to an aspect of the present invention, there is provided a limiting current type oxygen sensor comprising: a solid electrolyte capable of pumping oxygen ions; An anode electrode and a cathode electrode respectively formed on the upper and lower surfaces of the solid electrolyte; And a sensor substrate attached on the surface of the cathode electrode facing the cathode electrode, wherein a flat air gap region for exposing at least a part of the cathode electrode is formed on an interface between the solid electrolyte and the sensor substrate, And a line-shaped pinhole that is opened through one exposed sidewall is formed.

According to an aspect of the present invention, a spacer defining the flat void region may be interposed at the interface between the solid electrolyte and the sensor substrate.

According to another aspect, the apparatus may further include a cathode lead pad interposed between the solid electrolyte and the sensor substrate so as to overlap the cathode electrode, and at least a part of the cathode lead pad exposed to the outside along the upper surface of the sensor substrate.

According to another aspect, the line-shaped pinhole may remain as a trace while the combustible wire is burned. In this case, the grain boundaries of the crystals constituting the solid electrolyte and the sensor substrate may be exposed through the inner wall of the line-shaped pinhole. In addition, a combustion by-product of the combustible wire may be present in a trace amount on the inner wall of the line-shaped pin hole.

According to another aspect, the flat void region may be left as a trace while the combustible sheet segment is burned. In this case, the combustion by-products of the combustible sheet slice may be present in a trace amount on the inner wall of the flat void region.

Preferably, the solid electrolyte and the sensor substrate may be made of yttria stabilized zirconia (YSZ).

The limiting current type oxygen sensor according to the present invention may further include a cathode lead wire and an anode lead wire electrically connected to the cathode electrode and the anode electrode.

Further, the limiting current type oxygen sensor according to the present invention may further include a heater substrate attached to the lower side of the sensor substrate, and a thin film line heater formed on the lower surface of the heater substrate.

According to an aspect of the present invention, there is provided a method of manufacturing a limiting current type oxygen sensor, comprising: (a) forming an anode electrode and a cathode electrode on an upper surface and a lower surface of a green sheet for a solid electrolyte; (b) preparing a green sheet for a sensor substrate; (c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for sensor substrate, the method comprising the steps of: (a) Inserting a combustible wire in the form of a line in contact with the other end exposed to the outside air between green sheets to prepare a laminated structure; And (d) co-firing the laminated structure to simultaneously sinter the green sheet for a solid electrolyte and the green sheet for a sensor substrate to burn the combustible sheet segment and the combustible wire, To form a line-shaped pinhole which is opened to the outside.

Preferably, the combustible wire may be a synthetic resin yarn, a paper yarn, an animal fiber yarn, or a carbon fiber. The flammable sheet slice may be made of synthetic resin, paper or carbon.

Preferably, the present invention may further comprise a step of pressing the laminated structure using a hot isostatic press.

Preferably, the green sheet for a solid electrolyte and the green sheet for a sensor substrate may include stabilized zirconia particles to which yttria is added.

The present invention is a method for manufacturing a sensor substrate, comprising the steps of: (a) forming a cathode lead line pad, one end of which is overlapped with the cathode electrode and the other end thereof is exposed to the outside along the surface of the green sheet for sensor substrate, On the upper surface of the green sheet for the sensor substrate. In this case, the present invention may further include connecting the cathode lead wire and the anode lead wire to the exposed portion of the cathode lead wire pad and the anode electrode, respectively.

According to an aspect of the present invention, in the step (a), the cathode electrode may be formed such that a part of the cathode electrode is exposed to the outside along a lower surface of the green sheet for solid electrolyte. In this case, the method may further include connecting the cathode lead wire and the anode lead wire to the exposed portion of the cathode electrode and the anode electrode, respectively.

According to another aspect, the present invention provides a method of manufacturing a semiconductor device, comprising: preparing a heater substrate having a thin film line heater formed on a lower surface thereof; And fixing the laminated structure having the flat void region and the line-shaped pinhole to the heater substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a limiting current type oxygen sensor, comprising: (a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte; (b) preparing a green sheet for a sensor substrate; (c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for a sensor substrate, wherein a spacer having a through hole formed in the inside thereof so as to expose a central portion of the cathode electrode Inserting a line-shaped combustible wire having one end into contact with the through-hole and the other end exposed to the outside air between the green sheets to prepare a laminated structure; And (d) co-firing the laminated structure to simultaneously sinter the green sheet for a solid electrolyte and the green sheet for a sensor substrate to burn the combustible sheet segment and the combustible wire, To form a line-shaped pinhole which is opened to the outside.

According to another aspect of the present invention, there is provided a method of manufacturing a limiting current type oxygen sensor, comprising: (a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte; (b) preparing a green sheet for a sensor substrate; (c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for sensor substrate, the method comprising the steps of: (a) Inserting a combustible wire in the form of a line in contact with the other end exposed to the outside air between green sheets to prepare a laminated structure; (d) fixing the laminated structure on a green sheet for a heater substrate on which a thin film line heater is formed; And (e) simultaneously firing the green sheet for a heater substrate to which the laminated structure is fixed, simultaneously sintering the green sheet for a solid electrolyte, the green sheet for a sensor substrate and the green sheet for a heater substrate, And burning the combustible wire to form a line-shaped pinhole with a flat void area in place.

According to another aspect of the present invention, there is provided a method of manufacturing a limiting current type oxygen sensor, comprising: (a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte; (b) preparing a green sheet for a sensor substrate; (c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for a sensor substrate, wherein a spacer having a through hole formed in the inside thereof so as to expose a central portion of the cathode electrode Inserting a line-shaped combustible wire having one end into contact with the through-hole and the other end exposed to the outside air between the green sheets to prepare a laminated structure; (d) fixing the laminated structure on a green sheet for a heater substrate on which a thin film line heater is formed; And (e) simultaneously firing the green sheet for a heater substrate to which the laminated structure is fixed, simultaneously sintering the green sheet for a solid electrolyte, the green sheet for a sensor substrate and the green sheet for a heater substrate, burning the combustible wire And forming a line-shaped pinhole communicating with the flat through-hole and opening to the outside air side.

According to the present invention, a step of forming a cathode lead line pad may be formed between the step (b) and the step (c), wherein the cathode lead line pad overlaps with a part of the cathode electrode on the upper surface of the green sheet for sensor substrate .

According to an aspect of the present invention, a diffusion barrier structure of a limit current type oxygen sensor including a line-shaped pinhole and a planar void region communicating with each other can be formed by a simple process. Also, since the space occupied by the diffusion barrier structure is minimized, it is possible to reduce the thickness of the oxygen sensor. In addition, the manufacturing cost of the oxygen sensor can be reduced by simplifying the process. In addition, it is possible to manufacture a limiting current type oxygen sensor in which the oxygen concentration exhibits a linear dependence on the magnitude of the limiting current over a wide range of oxygen concentration.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given above, serve to further the understanding of the technical idea of the invention, And should not be construed as interpretation.
1 is a schematic diagram showing the structure of a limiting current type oxygen sensor widely used in the past.
2 is a cross-sectional view illustrating the structure of a limiting current type oxygen sensor according to an embodiment of the present invention.
FIG. 3 is a top plan view of the limiting current type oxygen sensor of FIG. 1, showing the major components inside.
4 is a cross-sectional view illustrating a structure of a limiting current type oxygen sensor according to another embodiment of the present invention.
FIG. 5 is a top plan view of the limiting current type oxygen sensor disclosed in FIG.
6 is a cross-sectional view illustrating a structure of a limiting current type oxygen sensor according to another embodiment of the present invention.
FIG. 7 is a top plan view of the limiting current type oxygen sensor disclosed in FIG. 6, showing the major components inside.
FIG. 8 is a process flow chart sequentially showing a manufacturing method of the limiting current type oxygen sensor disclosed in FIG. 2. FIG.
FIG. 9 is a process flow chart sequentially showing the manufacturing method of the limiting current type oxygen sensor disclosed in FIG.
FIG. 10 is a process conceptual diagram showing a process of forming a laminated structure in the process shown in FIG. 8 in three dimensions.
FIG. 11 is a process conceptual diagram showing a process of forming a laminated structure in the process shown in FIG. 9 in a stereoscopic manner.
12 is a process conceptual diagram showing a modification of the process of forming a laminated structure in the processes shown in FIG.
13 is a process conceptual diagram showing a modification of the process of forming a laminated structure in the processes shown in FIG.
14 is a graph showing the measurement of the operating characteristics of the limiting current type oxygen sensor manufactured in the experimental example.
FIGS. 15 and 16 are photographs taken at a magnification of 1000 times and 2000 times of the line-shaped pinhole structure of the limiting current type oxygen sensor manufactured as an experimental example.
17 is a photograph of a section of a flat pore structure of the limiting current type oxygen sensor manufactured as an experimental example by an electron microscope.

Hereinafter, a limiting current type oxygen sensor according to the present invention will be described in detail with reference to the accompanying drawings. The following drawings are provided by way of example so that the idea of the present invention can be sufficiently transmitted. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms. Also, like reference numerals designate like elements throughout the specification.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the following description and the accompanying drawings, descriptions of well-known functions and constructions that may unnecessarily obscure the gist of the present invention will be omitted.

FIG. 2 is a cross-sectional view showing the structure of a limiting current type oxygen sensor according to an embodiment of the present invention, and FIG. 3 is a top plan view showing a major internal structure of a limiting current type oxygen sensor. In Fig. 3, the lower and right side views of the upper perspective view are cross-sectional views taken along lines I-I 'and II-II', respectively.

2 and 3, the limiting current type oxygen sensor 20 according to an embodiment of the present invention includes a solid electrolyte 21 capable of transporting oxygen ions through ion pumping, An anode lead 22a and a cathode lead 23a connected to the respective electrodes 22 and 23 and an anode lead 22a and a cathode lead 23a connected to the electrodes 22 and 23, A sensor substrate 24 attached to the side of the cathode electrode 23 in a face-to-face manner, and a substantially rectangular air gap region (not shown) for exposing a part of the surface of the cathode electrode 23 and a surface of the sensor substrate 24 B ₁ ), and a line-shaped pinhole (B ₂ ), one side of which communicates with the flat void region (B ₁ ) and the other side of which is open to the outside air side through the side wall of the limiting current type oxygen sensor (20).

Preferably, other void regions do not exist separately at the interface between the solid electrolyte 21 and the sensor substrate 24 except for the void region B ₁ and the line-shaped pinhole B ₂ .

Since the line-shaped pinhole B ₂ is in communication with the gap region B ₁ , an external gas to be measured for oxygen concentration flows through the line-shaped pinhole B ₂ to the gap region B ₁ It can spread.

The number of the line-shaped pinholes (B ₂ ) is not limited to one, and can be increased to two or more if necessary in consideration of the specification of the limit current type oxygen sensor (20).

In the present invention, the solid electrolyte 21 is not particularly limited as long as it is a material capable of pumping oxygen ions. Preferably, the solid electrolyte 21 may be made of YSZ material which is widely used as a solid electrolyte of an oxygen sensor.

The thickness of the solid electrolyte 21 is determined by the dimension of the sensor, and may be appropriately selected in the range of 50-300 .mu.m, for example.

The anode electrode 22 and the cathode electrode 23 are not particularly limited as far as they are porous conductive materials. The anode electrode 22 and the cathode electrode 23 may be made of a porous thin film made of a noble metal such as platinum (Pt) or gold (Au)

Alternatively, the anode electrode 22 and the cathode electrode 23 may be made of a composite material in which at least one of glass particles and YSZ particles is mixed using a noble metal as a matrix.

The thickness of the anode electrode 22 and the cathode electrode 23 is determined by the dimension of the sensor. For example, the thickness of the anode electrode 22 and the cathode electrode 23 may be appropriately selected in the range of 5-40um.

Although not essential, a portion 23 'of the cathode electrode 23 is exposed to the outside through a cut-out portion (see D in FIG. 8) formed on one side of the sensor substrate 24, 23 'may be connected to the cathode lead wire 23a. Further, the surface of the exposed portion 23 'may be completely covered with an insulating material such as glass.

The anode lead wire 22a and the cathode lead wire 23a may be made of a noble metal wire such as platinum (Pt) or gold (Au), as long as the anode lead wire 22a and the cathode lead wire 23a are made of a metal having low resistance and electrical conductivity.

The sensor substrate 24 may be made of the same material as the solid electrolyte 21, for example, a YSZ material, as long as the sensor substrate 24 is insulating and has the same or similar thermal expansion coefficient as the solid electrolyte 21.

The sensor substrate 24 is preferably thicker than the solid electrolyte 21 because it functions to mechanically support the upper structure. As an example, the thickness of the sensor substrate 24 may be suitably selected in the range of 200-800um.

The limiting current type oxygen sensor 20 includes a heater substrate 27 attached to the lower surface of the sensor substrate 24 and a thin film type line heater 28 attached to the lower surface of the heater substrate 27. [ As shown in FIG.

The thin film type line heater 28 is connected to the DC power source DC1 through the heater lead line 29 to generate resistance heat and the generated heat is transmitted to the solid electrolyte 21 side. Then, the temperature of the solid electrolyte 21 rises to a temperature at which oxygen ions can be pumped (hereinafter referred to as a reaction temperature). Here, the reaction temperature varies depending on the kind of the solid electrolyte, for example, about 400-700 degrees Celsius.

The specifications of the DC power source DC1 and the material, thickness, length, etc. of the thin film type line heater 28 can be appropriately selected so that the solid electrolyte 21 can be heated to a temperature of 400-700 degrees.

For example, the DC power source DC1 may have an operating voltage of about 3-7V. The thin film type line heater 28 may be made of platinum (Pt).

The line heater 28 is formed on the lower surface of the heater substrate 27 but may be formed at the interface between the heater substrate 27 and the sensor substrate 24. [

The anode lead line 22a and the cathode lead line 23a may be connected to a DC power source DC2 that applies a pumping voltage of several volts to pump the oxygen ions through the solid electrolyte 21. [ Here, the pumping voltage varies depending on the type of the solid electrolyte 21 and the reaction temperature at which ion pumping occurs. For example, the pumping voltage may be appropriately selected in the range of 1-5 V.

When the solid electrolyte 21 is heated to the reaction temperature and an appropriate level of pumping voltage is applied to the anode electrode 22 and the cathode electrode 23, an electrochemical reaction condition is established in which ion pumping occurs. In this case, the oxygen diffused into the void region B ₁ through the line-shaped pinhole B ₂ is reduced at the surface of the cathode electrode 23 exposed in the void region B ₁ to be converted into oxygen ions, And is pumped to the anode electrode 22 side through the anode 21. The oxygen ions reaching the anode electrode 22 lose electrons by the oxidation reaction and are again converted into oxygen gas and released to the outside air.

When such oxygen ions are pumped, a current flows through the closed loop circuit in which the anode lead wire 22a and the cathode lead wire 23a are connected. When the ion pumping reaches a parallel state within a short time, the magnitude of the current is also constantly limited. When the magnitude of the limiting current is measured through the shunt resistor (R), the oxygen concentration of the outside air can be accurately measured.

The gap area B ₁ and the line type pinhole B ₂ are sandwiched between the solid electrolyte 21 and the sensor substrate 24 during the manufacturing process of the limiting current type oxygen sensor 20, The flammable sheet segment and the combustible wire may be traces created by burning in a co-firing process.

In this case, the void region B ₁ has a spatial structure corresponding to the flammable sheet segment, and the line-shaped pinhole B ₂ has a cylindrical inner wall structure corresponding to the shape of the combustible wire.

The boundaries of the ceramic crystal grains constituting the solid electrolyte 21 and the sensor substrate 24 may be exposed on the inner wall of the gap region B ₁ and the line-shaped pinhole B ₂ .

In addition, a trace amount of carbon component which can not be visually recognized can exist in the void region (B ₁ ) and the inner wall of the line-shaped pinhole (B ₂ ). The trace amount of carbon component may be derived from the combustion of the combustible sheet segment and the combustible wire.

Preferably, the flammable sheet piece is formed of a thin film having a shape of a rectangular plate, a circular plate or the like. Further, the material of the flammable sheet slice is not particularly limited as long as it can be burned in the co-firing process. As an example, the flammable sheet slice may be made of paper or a synthetic resin such as polyethylene (PE), polypropylene (PP), or carbon.

Preferably, the combustible wire extends in a straight line and takes the form of a wire having a circular cross section. The material constituting the combustible wire is not particularly limited as long as it can be burned in the co-firing process. For example, a synthetic resin such as polyethylene (PE) or polypropylene (PP) Yarn or animal fiber yarn, or carbon fiber.

In another embodiment, the void region B ₁ may be formed by a spacer S sandwiched between the solid electrolyte 21 and the sensor substrate 24 during the fabrication of the limiting current type oxygen sensor 20 (See FIG. 12). The spacer S may be made of an insulating material having the same or similar thermal expansion coefficient as the solid electrolyte 21 and the sensor substrate 24, for example, YSZ, including through holes corresponding to the gap region B ₁ at the central portion thereof. have. When the air gap area (B ₁₎ is formed by a spacer (S), the limiting current type oxygen sensor 20 according to the present invention may include a spacer (S) along the periphery of the gap area (B ₁₎ .

On the other hand, even when the void region B ₁ is formed by the spacer S, the line-shaped pinhole B ₂ can be easily removed from the solid electrolyte 21 and the sensor substrate 24 May be traces formed by burning in the co-firing process.

The combustible wire may be sandwiched between the solid electrolyte 21 and the sensor substrate 24 so that one end of the combustible wire overlaps with the through hole through one edge of the spacer S as shown in FIG.

Preferably, the diameter and the length of the line-shaped pin holes (B ₂₎ is that the line-shaped pin holes (B ₂₎ may be determined to perform the diffusion barrier of the press senhyeong. As an example, the line-shaped pinhole (B ₂ ) has a diameter ranging from several to several tens of μm.

Preferably, the area of the void region (B ₁ ) may be determined in consideration of the specification of the limiting current type oxygen sensor (20) such as resolution. As an example, the area of the void region (B ₁ ) can be appropriately selected in the range of 30 to 80% based on the area of the cathode electrode (23).

The limiting current type oxygen sensor 20 shown in Figs. 2 and 3 is constructed in such a manner that a diffusion barrier is formed by a line-shaped pinhole B ₂ and a space region B ₁ for providing a space where oxygen reduction reaction takes place Since the height of the line-shaped pinhole (B ₂ ) is larger than that of the line-shaped pinhole (B ₂ ), the thickness of the conventional oxygen sensor is considerably thinner. Therefore, it is possible to reduce the thickness of the limit current type oxygen sensor. Since the gap region B ₁ and the line-shaped pinhole B ₂ are formed by the burning of the combustible wire pieces and the combustible sheet pieces sandwiched between the solid electrolyte 21 and the sensor substrate 24, simple. Therefore, the structure of the limiting current type oxygen sensor is advantageous in reducing the manufacturing cost.

FIG. 4 is a cross-sectional view showing the structure of a limiting current type oxygen sensor 20 'according to another embodiment of the present invention, and FIG. 5 is a top plan view showing a major internal structure of a limiting current type oxygen sensor 20' . In Fig. 5, the lower and right side views of the upper perspective view are cross-sectional views taken along lines I-I 'and II-II', respectively.

The limiting current type oxygen sensor 20 'disclosed in FIGS. 4 and 5 is constructed such that the cathode lead wire pad 30 is sandwiched between the sensor substrate 24 and the solid electrolyte 21 to cover at least a part of the area of the cathode electrode 23 And the remaining configuration is the same as the above-described embodiment.

The cathode lead wire pad 30 is an intermediate connecting member used for electrically connecting the cathode lead wire 23a to the cathode electrode 23 hidden inside the limiting current type oxygen sensor 20 '. At least a portion 30 'of the cathode lead wire 30 is exposed to the outside through a cutout portion (see D in FIGS. 9 and 11) formed on one side of the solid electrolyte 21, ') Is connected to the cathode lead wire 23a. At this time, it is preferable that the exposed portion is covered with an insulating material such as glass.

If the cathode lead wire 30 is a material having a good electrical conductivity, there is no particular limitation on the type and thickness of the material, and preferably the same material and thickness as the cathode electrode 23. As an example, the cathode lead wire pad 30 may be formed of a porous thin film made of platinum (Pt).

2, the cathode lead wire 23a is connected to the lower surface of the solid electrolyte 23, but in this embodiment, the cathode lead wire 23a is connected to the upper surface of the sensor substrate 27 . Therefore, the limiting current type oxygen sensor 20 'according to the present embodiment has a structure in which the process of connecting the cathode lead 23a is easier.

FIG. 6 is a sectional view showing the structure of a limiting current type oxygen sensor 20 'according to another embodiment of the present invention, and FIG. 7 is a top plan view showing the essential internal structure of the limiting current type oxygen sensor 20' to be. In Fig. 7, the lower and right side views of the upper perspective view are cross-sectional views taken along lines I-I 'and II-II', respectively.

The limit current type oxygen sensor 20 'disclosed in Fig. 6 has a structure in which a layer of the spacer S is separately interposed between the solid electrolyte 23 and the sensor substrate 24 and the cathode lead wire 30 is provided with the spacer S, Layer, and the remaining configuration is substantially the same as that of the oxygen sensor disclosed in Fig.

The layer of the spacer S may be the same size as the sensor substrate 24, and a through hole corresponding to a flat space B ₁ may be provided in the center portion.

The limiting current type oxygen sensor 20 'disclosed in Fig. 6 can be manufactured by the process disclosed in Fig.

Hereinafter, a method of manufacturing the limiting current type oxygen sensor 20 shown in FIG. 2 including the line-shaped pinhole (B ₂ ) as the diffusion path of the oxygen gas will be described in more detail.

FIG. 8 is a process flow chart sequentially showing the manufacturing method of the limiting current type oxygen sensor 20 shown in FIG.

Referring to FIG. 8, first, a green sheet 30 for a solid electrolyte is prepared (process 1). The green sheet for a solid electrolyte 30 is prepared by finely pulverizing a mixture containing a raw material powder, a binder, a plasticizer and a solvent, which are made of a solid electrolyte, with a ball miller to obtain a slurry for tape casting on a suspension, To form a sheet and then drying it.

Preferably, the solid electrolyte powder may be a YSZ powder. Of course, the above-mentioned solid electrolyte green sheet 30 may be used by purchasing a commercially available product. The solid electrolyte green sheet 30 has a thickness of about 50-300 um.

The above green sheet forming method is disclosed in detail in the following reference documents, and the disclosure of that document can be incorporated as a part of this specification.

[Reference literature]

YJ. Oh and DYLee, "Fabrication and Characteristics of Limit-Current Type Oxygen Sensor with Monolith Aperture Structure ", J. K. Sens.Soc., Vol. 17, no. 4, pp. 273-280, 2008.

Next, the electrode paste is screen-printed on the upper and lower surfaces of the green sheet 30 for solid electrolyte and then dried to form the anode electrode 31 and the cathode electrode 32 in the form of a porous thin film ②).

Preferably, the anode electrode 31 and the cathode electrode 32 are formed to a thickness of 5-40 um. In one aspect, a portion of the cathode electrode 32 must be exposed to the outside, so that the size of the cathode electrode 32 is made larger than the size of the anode electrode 31. One side of the cathode electrode 32 may be formed so that the cathode electrode 32 is formed larger than the anode electrode 31 so that at least a portion of the cathode electrode 32 can contact one side of the green sheet 30 for a solid electrolyte can do.

The anode electrode 31 and the cathode electrode 32 may be formed by an inkjet printing method or a spraying method widely used in the electrode process of the limiting current type oxygen sensor in addition to the screen printing method.

Preferably, the electrode paste may be a platinum (Pt) paste.

10, a green sheet 33 for a sensor substrate is prepared, a combustible sheet slice 34 is placed at a position where a flat space region B ₁ is to be formed, and a diffusion barrier The green sheet 30 for a solid electrolyte, on which the electrodes 31 and 32 are respectively attached to the upper and lower surfaces after the flammable wire 35 is placed at the point where the line-shaped pinhole B ₂ to be used as the sensor is to be formed, (Green sheet 33) to form a laminated structure (process 3). At this time, one end of the combustible wire 35 overlaps with a part of the area of the combustible sheet section 34.

On the other hand, the green sheet 33 for a sensor substrate may have a cut-out portion D on one side. The cut-out portion D exposes a part of the cathode electrode 32 formed on the lower surface of the solid electrolyte green sheet 30 to the outside. A lead wire may be connected to the exposed electrode portion in a process to be described later.

Since the materials of the combustible sheet section 34 and the combustible wire 35 have been described in detail in the foregoing, repetitive description thereof will be omitted.

Preferably, the laminated structure may be pressed into a Warm Isostatic Press at a temperature of 50-75 degrees and a pressure of 50-300 bar for 1-10 minutes. Then, the interfaces of the elements constituting the laminated structure can be tightly bonded together.

The forming method of the green sheet 33 for sensor substrate is substantially the same as that described above. However, the kind of the ceramic powder to be included in the green sheet can be changed.

Preferably, the green sheet 33 for a sensor substrate may be made of the same material as the green sheet 30 for a solid electrolyte. In this case, cracks can be prevented from occurring at the interface because the mutual bonding green sheets have the same thermal expansion coefficient. However, the green sheet 33 for the sensor substrate may be thicker than the green sheet 30 for solid electrolyte in order to secure the mechanical rigidity of the sensor. Preferably, the green sheet 33 for the sensor substrate may have a thickness of approximately 200-800 um. However, the present invention is not limited by the material and the thickness of the green sheet 33 for a sensor substrate.

In the next step, the laminated structure obtained in the step (3) is loaded into the firing chamber, and co-firing is performed for 1 to 6 hours under an atmospheric atmosphere and a temperature condition of 1400 to 1600 degrees (step (4)).

In the co-firing process, the green sheet 30 for a solid electrolyte and the green sheet 33 for a sensor substrate are sintered together, and the combustible sheet segment 34 and the combustible wire 34 are burnt together, A flat void region B ₁ and a line-shaped pinhole B ₂ are formed. One end of the line-shaped pinhole B ₂ is opened toward the outside air to be measured for oxygen concentration, and the other end communicates with the gap area B ₁ (see FIGS. 2 and 3).

In the next step, a heater substrate 37 made of a ceramic material to which the thin film type line heater 36 is attached is prepared, and the resultant product obtained in the step (4) is bonded thereon with a ceramic adhesive or the like (step (5)).

Preferably, the heater substrate 37 may be made of alumina (Al ₂ O ₃ ), and the thin film line heater 36 may be made of platinum (Pt). The thin film type line heater 36 can be formed by printing and drying a metal paste by a screen printing method. The heater substrate 37 has a thickness of 200-800 um. However, the present invention is not limited by the material and thickness of the thin film type line heater 36 and the heater substrate 37. [

In the final step, the lead wires 38, 39, 40, and 41 are connected to the anode electrode 31 and the cathode electrode 32 attached to the upper and lower surfaces of the solid electrolyte 30 and the thin film type line heater 36 . Preferably, the lead wires 38, 39, 40, and 41 may be made of platinum (Pt).

On the other hand, among the above-described processes, the processes (5) and (6) can be omitted by the manufacturer because they can be performed by a manufacturer who modularizes the limiting current type oxygen sensor.

As a modification of the above process, a green sheet for a heater substrate is prepared, a thin film line heater is screen-printed on the lower surface, and a green sheet for a heater substrate is formed on the lower part of the laminated structure obtained in the step And the sensor structure obtained in step (5) can be formed at one time by performing the simultaneous firing process. In the case of this modification, since the solid electrolyte, the sensor substrate, and the green sheets constituting the heater substrate are sintered together, the step (5) can be omitted. Therefore, the manufacturing process of the limiting current type oxygen sensor is further simplified.

Among the above-mentioned processes, another modification of the process (3) is shown in Fig. 12, a solid electrolyte green sheet 30 in which an anode electrode 31 and a cathode electrode 32 are formed on an upper surface and a lower surface to define the void region B ₁ , A spacer S having a through hole corresponding to the gap region B ₁ can be sandwiched between the sheets 33. In this case, the combustible wire 35 can be sandwiched between the green sheet 30 for a solid electrolyte and the green sheet 33 for a sensor substrate so that one end overlaps the through-hole.

The spacer S may be made of the same material as the solid electrolyte green sheet 30 and the sensor substrate green sheet 33, preferably made of a non-combustible insulating material. For example, the spacer S may be formed of a green sheet including YSZ.

When the laminated structure is obtained by the process disclosed in Fig. 12, the laminated structure can be pressed using the hot isostatic press, and the subsequent processes described above can proceed substantially the same.

Particularly, in step (4), when the co-firing process proceeds, the respective green sheets constituting the laminated structure are simultaneously sintered. Further, a space (B ₁ ) is defined by the spacer (S), and a line-shaped pinhole (B ₂ ) communicating with the space (B ₁ ) is formed in the place where the combustible wire (35) is burnt.

In the case of this modified example, the heater substrate attaching step and the lead wire forming step may be omitted, and the above-described application example in which the green sheet for heater substrate is simultaneously fired can be similarly applied.

FIG. 9 is a process flow chart sequentially showing the method of manufacturing the limiting current type oxygen sensor 20 'disclosed in FIG.

Referring to FIG. 9, the step (1 ') is substantially the same as the step (1) of FIG. 8 in the step of preparing the green sheet (30) for a solid electrolyte. The step 2 'is substantially the same as the step 2 of FIG. 8 except that the size of the cathode electrode 32 is adjusted to almost the same size as that of the anode electrode 31.

8, a green sheet 33 for a sensor substrate is prepared, and an electrode paste is coated on the upper surface by a screen printing method to form a cathode lead wire pad 42 Process. Preferably, platinum (Pt) paste may be used as the electrode paste. The cathode lead line pad 42 is formed to have a size that can be at least overlapped with the cathode electrode 32. The cathode lead wire pad 42 is formed so that one side thereof is in contact with one side of the green sheet 33 for the sensor substrate.

The step (4) 'is a step similar to the step (3) in FIG. 8, and will be described with reference to FIG. 9 and FIG. First, the cathode lead pads 42 are formed in the sensor substrate green sheet 33 is a flat air gap area (B ₁₎ is placed a combustible sheet sections (34) on the branch to be formed line-shaped pin holes (B ₂₎ in a surface area for the Place the flammable wire 35 at the point where it should be formed. Then, a green sheet 30 for a solid electrolyte, on which an anode 31 and a cathode 32 are formed on the upper and lower surfaces, is laminated on the green sheet 33 for the sensor substrate to form a laminated structure. At this time, the cathode lead pad 42 formed on the green sheet 33 for the sensor substrate is exposed to the outside through the cut-out portion D formed on one side of the green sheet 30 for solid electrolyte. The exposed portion may be connected to a lead wire in a subsequent process.

Preferably, in order to improve the interfacial bonding property of the laminated structure, the laminated structure can be pressed using the hot isostatic press as described in step (3) of FIG.

Referring back to FIG. 9, step 5 'is a step of simultaneously firing the laminated structure obtained in step 4' in the same manner as step 4 in FIG. 8. When the process is completed, the solid electrolyte 30 and the sensor substrate 33 A flat void region B ₁ on the interface and a line-shaped pinhole B ₂ communicating with the void region B ₁ are formed.

Processes (6) 'and (7)' are substantially the same processes as the processes (5) and (6) of FIG. 8, and correspond to the heater structure forming process and the lead wire wiring process, respectively.

On the other hand, in the process (7 '), the wiring of the cathode lead wire (39) is performed through the cathode lead wire pad (42) exposed to the outside toward the top, so that the wiring process is easier than in the above embodiment.

Also in the manufacturing method described with reference to FIG. 9, steps 6 'and 7' can be omitted because they can be performed by the manufacturer who modularizes the limiting current type oxygen sensor.

Also, before proceeding with the co-firing process of step 5 ', a green sheet for a heater substrate in which a thin film type line heater 36 is formed on the lower surface can be attached to the lower surface of the green sheet 33 for sensor substrate. At this time, the interfacial adhesion property can be improved by pressing the laminated structure using a hot isostatic press. Then, in the step < 5 > ', the entire structure of the limiting current type oxygen sensor excluding the lead wire can be formed by one simultaneous firing process.

Among the above-described processes, another modification of the process ④ 'is disclosed in FIG. 13, a solid electrolyte green sheet 30 in which an anode electrode 31 and a cathode electrode 32 are formed on an upper surface and a lower surface to define the void region B ₁ , A spacer (S) layer having a through hole corresponding to the void region (B ₁ ) between the sheets (33) and having a cathode lead pad (42) formed on one edge can be sandwiched. In one example, the spacer (S) layer may be substantially the same size as the green sheet 33 for the sensor substrate. In this case, the combustible wire 35 can be sandwiched between the green sheet 30 for a solid electrolyte and the green sheet 33 for a sensor substrate so that one end overlaps the through-hole.

The spacer (S) layer is made of a non-combustible insulating material, and may preferably be made of the same material as the green sheet 30 for a solid electrolyte and the green sheet 33 for a sensor substrate. For example, the spacer S may be formed of a green sheet including YSZ.

When the laminated structure is obtained by the process disclosed in Fig. 13, the laminated structure can be pressed by using the hot isostatic press, and the subsequent processes described above can proceed substantially the same.

Particularly, in step < 5 >', when the co-firing process proceeds, the respective green sheets constituting the laminated structure are simultaneously sintered. In addition, the gap area (B ₁₎ by a spacer (S) layer defined place with a combustible wire 35 burning, the line-shaped pin holes (B ₂₎ is in communication with the gap region (B ₁₎ is formed.

Experimental Example

14 is a graph showing the results of measurement of oxygen concentration using the limiting current type oxygen sensor manufactured by the process shown in FIG.

In the oxygen sensor manufactured in this experiment, the diameter of the line-shaped pinhole (B ₂ ) was measured in the range of 5-10 μm along the longitudinal direction of the pinhole. A polyethylene yarn was used as a combustible wire to form the line-shaped pinhole (B ₂ ). The effective area of the anode electrode and the cathode electrode was adjusted to 3 * 3 mm ² . The area of the flat void region (B ₁ ) was adjusted to about 70% of the effective area of the cathode electrode. A flat void region (B ₁ ) was formed by burning flammable paper slices. The material of the solid electrolyte and the sensor substrate was unified with YSZ, and the material of the anode electrode, the cathode electrode, and the lead wire was selected as platinum (Pt) material. A dc voltage source of 1.25V was used as the pumping voltage, and a dc voltage source of 5.3V was used as the voltage source of the heater. The shunt resistor for measuring the limiting current was a resistance element having a resistance value of 1 kΩ.

In the present experimental example, the limit current type oxygen sensor is loaded in a chamber capable of precisely controlling the oxygen concentration, the heater substrate is connected to a DC voltage source for the heater power supply, and the cathode electrode and the anode electrode of the limit current type oxygen sensor are connected to a DC voltage source Respectively. Then, the magnitude of the voltage applied across the shunt resistor was measured while adjusting the oxygen concentration in the chamber. The voltage measured through the shunt resistor can be converted to the magnitude of the limiting current by Ohm's law.

Referring to FIG. 14, it can be seen that the voltage measured through the shunt resistor shows a good linear change characteristic according to the change of the oxygen concentration. Therefore, it can be seen that the flat void region and the line-shaped pinhole formed inside the limiting current type oxygen sensor function well as a diffusion barrier ensuring a leak-tight gas diffusion.

The experimental results obtained through the graph of FIG. 14 can be used as a look-up table to measure the oxygen concentration. That is, by using the look-up table, it is possible to map the oxygen concentration corresponding to an arbitrary voltage measured using the limiting current type oxygen sensor.

Alternatively, a linear function indicating the relationship between the oxygen concentration and the voltage may be obtained from the graph of Fig. 14, and then the corresponding linear function may be utilized for measuring the oxygen concentration. That is, the oxygen concentration corresponding to an arbitrary voltage measured by using the limiting current type oxygen sensor can be calculated using the above-mentioned linear function.

Figs. 15 and 16 are photographs taken at 1000 times magnification and 2000 times magnification, respectively, of the structure of the line-shaped pinhole using an electron microscope.

Referring to FIG. 15, it can be seen that the boundaries of the green sheets completely disappeared as crystal grains were grown near the interface in the process of simultaneously firing the solid electrolyte green sheet and the sensor substrate green sheet. Also, it can be confirmed that the line-shaped pinhole is well opened in the outside direction, and it can be confirmed that the inner wall of the cylindrical structure is well developed toward the inside of the oxygen sensor.

Referring to FIG. 16, it can be seen that the boundary of the crystal grains is exposed toward the outside air on the inner wall of the line-shaped pinhole.

17 is an electron micrograph showing a cross-sectional structure when the limiting current type oxygen sensor is cut along the line I-I 'in FIG.

Referring to FIG. 17, it can be confirmed that a flat air gap region is well formed by the combustion of the combustible paper. The void region communicates with the line-shaped pinhole shown in FIG. 15, and serves to diffuse oxygen toward the cathode electrode together with the line-shaped pinhole.

As seen in the above embodiments, the present invention can form a diffusion barrier structure of a limiting current type oxygen sensor including a flat void region and a line-shaped pinhole by a simple process. Also, since the space occupied by the diffusion barrier structure is minimized, it is possible to reduce the thickness of the oxygen sensor. In addition, the manufacturing cost of the oxygen sensor can be reduced by simplifying the process. In addition, it is possible to manufacture a limiting current type oxygen sensor in which the oxygen concentration exhibits a linear dependence on the magnitude of the limiting current over a wide range of oxygen concentration.

On the other hand, in the present invention, the line-shaped pinhole B ₂ may not be formed on only one side of the flat void region B ₁ but may be formed on the other side. The point where the line-shaped pinhole B ₂ is further formed can be arbitrarily selected in the front, rear, left, and right directions with respect to the flat air gap region B ₁ .

For example, in the limiting current type oxygen sensor 20 shown in Fig. 2, the line-shaped pinhole structure can be additionally formed on the right side of the flat void region B ₁ and can be opened through the right side wall of the sensor. In this case, it is self-evident that the further formed line-shaped pinhole also communicates with the flat void region B ₁ .

The addition of such a line-shaped pinhole structure can be equally applied to the structure of the limiting current type oxygen sensor 20, 20 'disclosed in Figs. 4 and 6. The same is true of the case where the flat air gap B ₁ is defined by the layer of the spacer S or the spacer S as shown in Figs. 12 and 13. For example, the further formed line-shaped pinhole may penetrate to the right sidewall of the sensor along the interface between the solid electrolyte 21 and the cathode lead line pad 30.

In these variations, the oxygen gas can be diffused through the line-shaped pinhole formed in at least two directions with reference to the flat void region (B ₁ ). Therefore, it is useful for accurate measurement of oxygen concentration under very dilute oxygen concentration conditions.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Various changes and modifications will be possible.

20, 20 ': limiting current type oxygen sensor 21, 30: solid electrolyte
22, 31: anode electrode 23, 32: cathode electrode
24, 33: sensor substrate 27, 37: heater substrate
28, 36: thin-film heaters 22a, 38: anode leads
23a, 39: cathode lead line B ₁ : flat air gap region
B ₂ : Line-shaped pinhole 34: Flammable sheet intercept
35: combustible wire 30, 42: cathode lead wire pad
D: Cutting area S: Spacer

Claims

A solid electrolyte capable of pumping oxygen ions;
An anode electrode and a cathode electrode respectively formed on the upper and lower surfaces of the solid electrolyte; And
And a sensor substrate attached to the cathode electrode side in a face-
A line-shaped pinhole is formed at an interface between the solid electrolyte and the sensor substrate, the line-shaped pinhole being opened through a sidewall on which the interface is exposed so as to communicate with the gap region, and a flat void region for exposing at least a part of the cathode electrode Wherein the limit current type oxygen sensor comprises:

The method according to claim 1,
Wherein a spacer defining the flat void region is interposed at an interface between the solid electrolyte and the sensor substrate.

The method according to claim 1,
Wherein the line-shaped pinhole is left as a trace while the combustible wire is burned.

The method according to claim 1,
And a grain boundary of crystals constituting the solid electrolyte and the sensor substrate is exposed through an inner wall of the line-shaped pinhole.

The method of claim 3,
Wherein a combustion by-product of the combustible wire is present in an extremely small amount on the inner wall of the line-shaped pin hole.

The method according to claim 1,
Wherein the flat void region is left as a trace while the combustible sheet segment is burned.

The method according to claim 6,
Wherein a combustion by-product of the flammable sheet segment is present in a trace amount on the inner wall of the flat void region.

The method according to claim 1,
Wherein the solid electrolyte and the sensor substrate are made of stabilized zirconia (YSZ) to which yttria is added.

The method according to claim 1,
Further comprising a cathode lead pad interposed between the solid electrolyte and the sensor substrate so as to overlap with the cathode electrode and at least a part of which is exposed to the outside along an upper surface of the sensor substrate.

10. The method of claim 9,
Further comprising a cathode lead line connected to the cathode lead line pad and an anode lead line connected to the anode electrode.

The method according to claim 1,
Wherein the cathode electrode includes a portion exposed to the outside along a lower surface of the solid electrolyte,
Further comprising a cathode lead connected to the exposed portion and an anode lead connected to the anode electrode.

The method according to claim 1,
A heater substrate attached to a lower side of the sensor substrate; and a thin film line heater formed on a lower surface of the heater substrate.

(a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte;
(b) preparing a green sheet for a sensor substrate;
(c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for sensor substrate, the method comprising the steps of: (a) Inserting a combustible wire in the form of a line in contact with the other end exposed to the outside air between green sheets to prepare a laminated structure; And
(d) co-firing the laminated structure to simultaneously sinter the green sheet for a solid electrolyte and the green sheet for a sensor substrate to burn the combustible sheet segment and the combustible wire, And forming a line-shaped pinhole to be opened.

14. The method of claim 13,
Wherein the combustible wire is a synthetic resin yarn, a paper yarn, an animal fiber yarn, or a carbon fiber.

14. The method of claim 13,
Wherein the combustible sheet slice is made of synthetic resin, paper or carbon.

14. The method of claim 13, wherein before step (d)
And pressing the stacked structure using a hot isostatic press. &Lt; RTI ID = 0.0 > 21. < / RTI >

14. The method of claim 13,
Wherein the green sheet for a solid electrolyte and the green sheet for a sensor substrate comprise stabilized zirconia particles to which yttria is added.

14. The method of claim 13, further comprising, between step (b) and step (c)
And forming a cathode lead line pad on the upper surface of the green sheet for the sensor substrate, one end of which overlaps with the cathode electrode and the other end is exposed to the outside along the surface of the green sheet for the sensor substrate. A method of manufacturing a current type oxygen sensor.

19. The method of claim 18,
And connecting the cathode lead and the anode lead to the exposed portion of the cathode lead line pad and the anode electrode, respectively.

14. The method according to claim 13, wherein in the step (a)
Wherein the cathode electrode is formed such that a part of the cathode electrode is exposed to the outside along the lower surface of the green sheet for solid electrolyte.

21. The method of claim 20,
Further comprising the steps of: connecting a cathode lead line and an anode lead line to the exposed portion of the cathode electrode and the anode electrode, respectively.

14. The method of claim 13,
Preparing a heater substrate having a thin film line heater formed on a lower surface thereof; And
Further comprising the step of fixing the laminated structure having the flat void region and the line-shaped pinhole to the heater substrate.

(a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte;
(b) preparing a green sheet for a sensor substrate;
(c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for a sensor substrate, wherein a spacer having a through hole formed in the inside thereof so as to expose a central portion of the cathode electrode Inserting a line-shaped combustible wire having one end into contact with the through-hole and the other end exposed to the outside air between the green sheets to prepare a laminated structure; And
(d) co-firing the laminated structure to simultaneously sinter the green sheet for a solid electrolyte and the green sheet for a sensor substrate to burn the combustible sheet segment and the combustible wire, And forming a line-shaped pinhole to be opened.

24. The method of claim 23, wherein between step (b) and step (c)
Further comprising forming a cathode lead pad on an upper surface of the green sheet for the sensor substrate, the cathode lead pad being overlapped with a part of the cathode electrode.

(a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte;
(b) preparing a green sheet for a sensor substrate;
(c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for sensor substrate, the method comprising the steps of: (a) Inserting a combustible wire in the form of a line in contact with the other end exposed to the outside air between green sheets to prepare a laminated structure;
(d) fixing the laminated structure on a green sheet for a heater substrate on which a thin film line heater is formed; And
(e) simultaneously firing the green sheet for a heater substrate to which the laminated structure is fixed, simultaneously sintering the green sheet for a solid electrolyte, the green sheet for a sensor substrate and the green sheet for a heater substrate, And burning the wire to form a flat void region and a line-shaped pinhole in its place.

26. The method of claim 25, wherein between step (b) and step (c)
Further comprising forming a cathode lead pad on an upper surface of the green sheet for the sensor substrate, the cathode lead pad being overlapped with a part of the cathode electrode.

(a) forming an anode electrode and a cathode electrode on a top surface and a bottom surface of a green sheet for a solid electrolyte;
(b) preparing a green sheet for a sensor substrate;
(c) stacking the green sheet for a solid electrolyte so that the cathode electrode faces the upper surface of the green sheet for a sensor substrate, wherein a spacer having a through hole formed in the inside thereof so as to expose a central portion of the cathode electrode Inserting a line-shaped combustible wire having one end into contact with the through-hole and the other end exposed to the outside air between the green sheets to prepare a laminated structure;
(d) fixing the laminated structure on a green sheet for a heater substrate on which a thin film line heater is formed; And
(e) simultaneously firing the green sheet for a heater substrate to which the laminated structure is fixed, simultaneously sintering the green sheet for a solid electrolyte, the green sheet for a sensor substrate and the green sheet for a heater substrate, And forming a line-shaped pinhole communicating with the flat through-hole to open to the outside air.

28. The method of claim 27, further comprising, between step (b) and step (c)
Further comprising forming a cathode lead pad on an upper surface of the green sheet for the sensor substrate, the cathode lead pad being overlapped with a part of the cathode electrode.