JP6983199B2 - Drying method, manufacturing method of ceramic parts, and drying system - Google Patents

Description

The present invention relates to a drying method, a method for manufacturing ceramic parts, and a drying system.

Conventionally, ceramic parts having a ceramic substrate and a conductor such as an electrode formed on the substrate are known. For example, Patent Document 1 describes a method for manufacturing a sensor element which is a kind of such ceramic parts and detects a predetermined gas concentration in a gas to be measured. Specifically, first, a plurality of green sheets are prepared, a predetermined pattern such as an electrode is printed on the prepared green sheet, and the pattern is dried. Subsequently, the green sheets on which the patterns are printed are laminated in a predetermined order and pressed to form a laminate. Then, the laminated body is cut into individual units of the sensor element and then fired to obtain a sensor element. Further, Patent Document 2 describes that hot air drying is performed as a method of drying a pattern such as an electrode after printing.

Japanese Unexamined Patent Publication No. 2011-225434 Japanese Unexamined Patent Publication No. 2011-247725

However, when a pattern such as an electrode made of a conductive paste is dried with hot air, it is necessary to provide a closed space so as not to let the hot air escape, and there is a problem that the drying time becomes long because the entire space is heated.

The present invention has been made to solve such a problem, and an object of the present invention is to efficiently dry a conductive paste.

The present invention has taken the following measures to achieve the above-mentioned main object.

The drying method of the present invention
A green structure having one or more ceramic green sheets and at least partially coated with a conductive paste is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to obtain the conductive paste. Drying process to dry,
Is included.

In this drying method, the conductive paste is dried by irradiating an infrared ray having a peak wavelength in a wavelength region of 0.8 μm to 4 μm. Here, infrared rays (near infrared rays) having a wavelength of 0.8 μm to 4 μm are excellent in the ability to break hydrogen bonds in molecules such as water and solvents contained in the conductive paste. Therefore, in the drying method of the present invention, it is possible to efficiently perform drying in a short time as compared with the case of performing hot air drying, for example.

In the drying method of the present invention, in the drying step, the green structure may be cooled by a cooling gas while irradiating the infrared rays. By doing so, it is possible to suppress defects due to overheating of the green structure due to infrared irradiation. Examples of defects due to overheating include the occurrence of uneven firing and warpage in the subsequent firing step due to the partial firing of the green sheet in the drying step.

In this case, in the drying step, the green structure is placed on the mounting member having the through holes so that at least a part of the conductive paste is overlapped with the region where the through holes are present when viewed from the green structure side. The cooling gas may be circulated in the through hole while irradiating the infrared rays in the state where the paste is placed. By doing so, the cooling gas can be centrally distributed in the vicinity of the conductive paste through the through holes of the mounting member, so that the green structure can be efficiently cooled.

In this case, the green structure has a long rectangular shape, and in the drying step, a plurality of the green structures are formed on the above-mentioned placing member at least in the conductive paste when viewed from the side of each green structure. In a state where a part of the green structure is placed so as to overlap with the region where the through hole exists and the plurality of green structures are placed with a gap along the direction perpendicular to the longitudinal direction of the green structure. The infrared rays may be irradiated. In this way, long rectangular parallelepiped green structures are lined up with a gap along the direction perpendicular to the longitudinal direction, so cooling gas is circulated through the gap to efficiently cool multiple green structures at the same time. The conductive paste can be dried. Therefore, the conductive pastes of a plurality of green structures can be efficiently dried together.

In the drying method of the present invention in the embodiment using a mounting member, the green structure has a long rectangular parallelepiped shape cut out by cutting a laminated body of a plurality of ceramic green sheets, and has at least a cut surface. A part may be coated with the conductive paste. Here, when the cut surface of the green structure is coated with the conductive paste, it cannot be coated with the conductive paste before cutting out the laminate, and the coating and drying with the conductive paste are performed after cutting out from the laminate. It will be. The above-mentioned drying method using a mounting member having a through hole is suitable for drying in this case.

In the drying method of the present invention, an infrared heater is used in the drying step so that the output P [W] of the infrared heater and the infrared irradiation time T [sec] both satisfy the following equations (1) and (2). May be irradiated with the infrared rays. In this way, the conductive paste can be sufficiently dried. If the irradiation time T is made as small as possible within the range in which both the formulas (1) and (2) are satisfied, the conductive paste can be sufficiently dried while shortening the drying time as much as possible.

T ≧ (-20/13) P + 380 equation (1)
T ≧ (-2/3) P + (596/3) Equation (2)

In the drying method of the present invention, in the drying step, a part of the region of the green structure containing the conductive paste may be irradiated with the infrared rays. By doing so, it is possible to suppress the irradiation of the unnecessary region where there is no conductive paste with infrared rays, and it is possible to suppress the overheating of the green structure.

In the drying method of the present invention, in the drying step, the infrared rays may be irradiated without sealing the conductive paste. In the drying method of the present invention, since the drying is performed using infrared rays, it is not necessary to heat the entire space and it is not necessary to seal the space. By performing the drying process in a non-sealed state, for example, it is not necessary to carry in and out the green structure into the furnace (sealed space), and the work efficiency is improved.

The method for manufacturing a ceramic component of the present invention is as follows.
A preparatory step of preparing a green structure having one or more ceramic green sheets, and a coating step of covering at least a part of the green structure with a conductive paste after the preparatory step.
After the coating step, the green structure is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to dry the conductive paste.
After the drying step, a firing step of firing the green structure to obtain ceramic parts,
Is included.

In this production method, similarly to the drying method of the present invention described above, the conductive paste is dried by irradiating an infrared ray having a peak wavelength in a wavelength region of 0.8 μm to 4 μm in the drying step. Therefore, it is possible to efficiently perform drying in a short time as compared with the case of performing hot air drying, for example. Therefore, ceramic parts can be efficiently manufactured. In each step of the method for manufacturing the ceramic component, various aspects of the above-mentioned drying method may be adopted, or a step corresponding to the above-mentioned drying method may be added.

The drying system of the present invention is
A first coating device that covers at least a part of the upper surface of a rectangular parallelepiped green structure having one or more ceramic green sheets with a conductive paste.
A first drying device that irradiates the upper surface of the green structure with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm.
An inversion device that inverts the green structure upside down,
A second coating device that covers at least a part of the upper surface of the green structure after inversion with a conductive paste.
A second drying device that irradiates the upper surface of the green structure after inversion with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm.
A transport device for transporting the green structure to the first printing device, the first drying device, the reversing device, the second printing device, and the second drying device in this order.
It is equipped with.

In this drying system, similarly to the drying method of the present invention described above, the first drying device and the second drying device irradiate infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to dry the conductive paste. Let me. Therefore, it is possible to efficiently perform drying in a short time as compared with the case of performing hot air drying, for example. Further, in this drying system, after coating and drying the conductive paste on the upper surface of the green structure, the inversion device inverts the green structure upside down, and the upper surface after inversion (lower surface before inversion) is conductive. Cover and dry the paste. Therefore, it is possible to automatically coat and dry the conductive paste on both sides (two sides) of the rectangular parallelepiped green structure. In this drying system, various aspects of the above-mentioned drying method may be adopted, or a configuration may be added to realize each function of the above-mentioned drying method.

Schematic diagram of a cross section of the gas sensor 100. A view of FIG. A perspective view of the periphery of the upper connector pad 91 of the sensor element 101 as viewed from the third surface 101c side. A perspective view of the periphery of the upper connector pad 91 of the sensor element 101 as viewed from the fourth surface 101d side. Explanatory drawing which shows the outline of the structure of the drying system 200. The perspective view of the mounting member 270. The top view which shows the state which the green structure 109 was mounted on the mounting member 270. FIG. 5 is a sectional view taken along the line CC of the infrared heater 220 of FIG. An enlarged top view showing the green structure 109 after inversion mounted on the mounting member 270. A graph plotting the evaluation of the dry state with respect to the output P and the irradiation time T.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a gas sensor 100 provided with a sensor element 101 according to an embodiment of the ceramic component of the present invention. FIG. 2 is a view A of FIG. 1. FIG. 3 is a perspective view of the periphery of the upper connector pad 91 of the sensor element 101 as viewed from the third surface 101c side. FIG. 4 is a perspective view of the periphery of the upper connector pad 91 of the sensor element 101 as viewed from the fourth surface 101d side. The cross section of the sensor element 101 in FIG. 1 corresponds to the cross section taken along the line BB in FIG.

The gas sensor 100 includes a sensor element 101 that detects the concentration of a specific gas (NOx in this embodiment) in the gas to be measured. The sensor element 101 has a long rectangular shape, the longitudinal direction of the sensor element 101 (horizontal direction in FIG. 1) is the front-rear direction, and the thickness direction of the sensor element 101 (vertical direction in FIG. 1) is the vertical direction. do. Further, the width direction (direction perpendicular to the front-rear direction and the vertical direction) of the sensor element 101 is defined as the left-right direction (vertical direction in FIG. 2). Since the sensor element 101 is a rectangular parallelepiped, as shown in FIGS. 1 to 4, the outer surface of the solid electrolyte layer of the sensor element 101 is the first surface 101a (upper surface), the second surface 101b (lower surface), and the third surface 101c. It has six surfaces: (left side surface), fourth surface 101d (right side surface), fifth surface 101e (front end surface), and sixth surface 101f (rear end surface).

The sensor element 101 includes a first substrate layer 1, a second substrate layer 2, a third substrate layer 3, and a first solid electrolyte layer 4 _{, each of which is composed of an oxygen ion conductive solid electrolyte layer such as zirconia (ZrO 2).} The element has a structure in which six layers of the spacer layer 5 and the second solid electrolyte layer 6 are laminated in this order from the lower side in the drawing. Further, the solid electrolyte forming these six layers is a dense airtight one. The sensor element 101 is manufactured, for example, by performing predetermined processing, printing of a circuit pattern, or the like on a ceramic green sheet corresponding to each layer, laminating them, and further firing and integrating them.

A gas introduction port 10, a first diffusion rate controlling unit 11, and a buffer space between the lower surface of the second solid electrolyte layer 6 and the upper surface of the first solid electrolyte layer 4, which is one tip of the sensor element 101. 12, the second diffusion rate controlling unit 13, the first internal space 20, the third diffusion rate controlling unit 30, and the second internal space 40 are formed adjacent to each other in this order.

The gas introduction port 10, the buffer space 12, the first internal vacant space 20, and the second internal vacant space 40 are provided in such a manner that the spacer layer 5 is hollowed out, and the upper portion thereof is the lower surface of the second solid electrolyte layer 6. The lower part is the upper surface of the first solid electrolyte layer 4, and the side part is the space inside the sensor element 101 partitioned by the side surface of the spacer layer 5.

The first diffusion rate control section 11, the second diffusion rate control section 13, and the third diffusion rate control section 30 are all provided as two horizontally long slits (openings have a longitudinal direction in the direction perpendicular to the drawing). .. The portion from the gas introduction port 10 to the second internal vacant space 40 is also referred to as a gas distribution section.

Further, at a position far from the tip side of the gas flow portion, the side portion is partitioned between the upper surface of the third substrate layer 3 and the lower surface of the spacer layer 5 by the side surface of the first solid electrolyte layer 4. A reference gas introduction space 43 is provided at such a position. For example, the atmosphere is introduced into the reference gas introduction space 43 as a reference gas for measuring the NOx concentration.

The atmosphere introduction layer 48 is a layer made of porous ceramics, and the reference gas is introduced into the atmosphere introduction layer 48 through the reference gas introduction space 43. Further, the atmosphere introduction layer 48 is formed so as to cover the reference electrode 42.

The reference electrode 42 is an electrode formed in such a manner that it is sandwiched between the upper surface of the third substrate layer 3 and the first solid electrolyte layer 4, and as described above, the reference electrode 42 is connected to the reference gas introduction space 43 around the reference electrode 42. An atmosphere introduction layer 48 is provided. Further, as will be described later, it is possible to measure the oxygen concentration (oxygen partial pressure) in the first internal space 20 and the second internal space 40 using the reference electrode 42.

In the gas flow section, the gas introduction port 10 is a portion that is open to the external space, and the gas to be measured is taken into the sensor element 101 from the external space through the gas introduction port 10. The first diffusion rate-controlling unit 11 is a portion that imparts a predetermined diffusion resistance to the gas to be measured taken in from the gas introduction port 10. The buffer space 12 is a space provided for guiding the gas to be measured introduced from the first diffusion rate control unit 11 to the second diffusion rate control unit 13. The second diffusion rate controlling unit 13 is a portion that imparts a predetermined diffusion resistance to the gas to be measured introduced from the buffer space 12 into the first internal space 20. When the gas to be measured is introduced from the outside of the sensor element 101 to the inside of the first internal space 20, the pressure fluctuation of the gas to be measured in the external space (if the gas to be measured is the exhaust gas of an automobile, the pulsation of the exhaust pressure). ), The gas to be measured that is suddenly taken into the inside of the sensor element 101 from the gas introduction port 10 is not directly introduced into the first internal space 20, but the first diffusion rate controlling unit 11, the buffer space 12, and the second. After the fluctuation in the concentration of the gas to be measured is canceled through the diffusion rate controlling unit 13, the gas is introduced into the first internal space 20. As a result, the concentration fluctuation of the measured gas introduced into the first internal space 20 becomes almost negligible. The first internal space 20 is provided as a space for adjusting the oxygen partial pressure in the gas to be measured introduced through the second diffusion rate controlling unit 13. The oxygen partial pressure is adjusted by operating the main pump cell 21.

The main pump cell 21 has an inner pump electrode 22 having a ceiling electrode portion 22a provided on substantially the entire lower surface of the lower surface of the second solid electrolyte layer 6 facing the first internal space 20, and the upper surface of the second solid electrolyte layer 6. An electrochemical pump cell composed of an outer pump electrode 23 provided in a region corresponding to the ceiling electrode portion 22a so as to be exposed to an external space, and a second solid electrolyte layer 6 sandwiched between these electrodes. be.

The inner pump electrode 22 is formed so as to straddle the upper and lower solid electrolyte layers (second solid electrolyte layer 6 and first solid electrolyte layer 4) that partition the first internal space 20 and the spacer layer 5 that provides the side wall. There is. Specifically, a ceiling electrode portion 22a is formed on the lower surface of the second solid electrolyte layer 6 that provides the ceiling surface of the first internal space 20, and a bottom portion is formed on the upper surface of the first solid electrolyte layer 4 that provides the bottom surface. The electrode portion 22b is formed, and the side electrode portion (not shown) constitutes a spacer layer on both side walls of the first internal space 20 so as to connect the ceiling electrode portion 22a and the bottom electrode portion 22b. It is formed on the side wall surface (inner surface) of 5, and is arranged in a structure in the form of a tunnel at the arrangement portion of the side electrode portion.

The inner pump electrode 22 and the outer pump electrode 23 are formed as a porous cermet electrode (for example, a cermet electrode of Pt containing 1% Au and ZrO ₂ ). The inner pump electrode 22 that comes into contact with the gas to be measured is formed by using a material having a weakened reducing ability for the NOx component in the gas to be measured.

In the main pump cell 21, a desired pump voltage Vp0 is applied between the inner pump electrode 22 and the outer pump electrode 23, and a pump current is applied in the positive or negative direction between the inner pump electrode 22 and the outer pump electrode 23. By flowing Ip0, the oxygen in the first internal space 20 can be pumped into the external space, or the oxygen in the external space can be pumped into the first internal space 20.

Further, in order to detect the oxygen concentration (oxygen partial pressure) in the atmosphere in the first internal space 20, the inner pump electrode 22, the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte layer 4 are used. The third substrate layer 3 and the reference electrode 42 constitute an electrochemical sensor cell, that is, an oxygen partial pressure detection sensor cell 80 for controlling a main pump.

By measuring the electromotive force V0 in the oxygen partial pressure detection sensor cell 80 for controlling the main pump, the oxygen concentration (oxygen partial pressure) in the first internal space 20 can be known. Further, the pump current Ip0 is controlled by feedback-controlling the pump voltage Vp0 of the variable power supply 24 so that the electromotive force V0 becomes constant. As a result, the oxygen concentration in the first internal space 20 can be maintained at a predetermined constant value.

The third diffusion rate controlling unit 30 imparts a predetermined diffusion resistance to the measured gas whose oxygen concentration (oxygen partial pressure) is controlled by the operation of the main pump cell 21 in the first internal space 20, and transfers the measured gas. It is a part leading to the second internal vacant space 40.

The second internal space 40 is provided as a space for performing a process related to the measurement of the nitrogen oxide (NOx) concentration in the gas to be measured introduced through the third diffusion rate controlling unit 30. The NOx concentration is mainly measured in the second internal vacant space 40 in which the oxygen concentration is adjusted by the auxiliary pump cell 50, and further, the NOx concentration is measured by the operation of the measurement pump cell 41.

In the second internal space 40, after the oxygen concentration (oxygen partial pressure) is adjusted in advance in the first internal space 20, the auxiliary pump cell 50 is further applied to the gas to be measured introduced through the third diffusion rate controlling unit 30. The oxygen partial pressure is adjusted by. As a result, the oxygen concentration in the second internal space 40 can be kept constant with high accuracy, so that the NOx concentration can be measured with high accuracy in the gas sensor 100.

The auxiliary pump cell 50 has an auxiliary pump electrode 51 having a ceiling electrode portion 51a provided on substantially the entire lower surface of the second solid electrolyte layer 6 facing the second internal space 40, and an outer pump electrode 23 (outer pump electrode 23). It is an auxiliary electrochemical pump cell composed of a sensor element 101 and an appropriate electrode on the outside) and a second solid electrolyte layer 6.

The auxiliary pump electrode 51 is arranged in the second internal space 40 in a structure having a tunnel shape similar to that of the inner pump electrode 22 provided in the first internal space 20. That is, the ceiling electrode portion 51a is formed on the second solid electrolyte layer 6 that provides the ceiling surface of the second internal space 40, and the first solid electrolyte layer 4 that provides the bottom surface of the second internal space 40 is formed. , The bottom electrode portion 51b is formed, and the side electrode portion (not shown) connecting the ceiling electrode portion 51a and the bottom electrode portion 51b provides a side wall of the second internal space 40 of the spacer layer 5. It has a tunnel-like structure formed on both walls. The auxiliary pump electrode 51 is also formed by using a material having a weakened reducing ability for the NOx component in the gas to be measured, similarly to the inner pump electrode 22.

In the auxiliary pump cell 50, by applying a desired voltage Vp1 between the auxiliary pump electrode 51 and the outer pump electrode 23, oxygen in the atmosphere in the second internal space 40 is pumped out to the external space or outside. It is possible to pump from the space into the second internal space 40.

Further, in order to control the oxygen partial pressure in the atmosphere in the second internal space 40, the auxiliary pump electrode 51, the reference electrode 42, the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte are used. The layer 4 and the third substrate layer 3 constitute an electrochemical sensor cell, that is, an oxygen partial pressure detection sensor cell 81 for controlling an auxiliary pump.

The auxiliary pump cell 50 pumps at the variable power supply 52 whose voltage is controlled based on the electromotive force V1 detected by the auxiliary pump control oxygen partial pressure detection sensor cell 81. As a result, the oxygen partial pressure in the atmosphere in the second internal space 40 is controlled to a low partial pressure that does not substantially affect the measurement of NOx.

At the same time, the pump current Ip1 is used to control the electromotive force of the oxygen partial pressure detection sensor cell 80 for controlling the main pump. Specifically, the pump current Ip1 is input to the oxygen partial pressure detection sensor cell 80 for main pump control as a control signal, and the electromotive force V0 is controlled so that the third diffusion rate control unit 30 to the second internal vacant space. The gradient of the oxygen partial pressure in the gas to be measured introduced into the 40 is controlled to be always constant. When used as a NOx sensor, the oxygen concentration in the second internal space 40 is maintained at a constant value of about 0.001 ppm by the action of the main pump cell 21 and the auxiliary pump cell 50.

The measurement pump cell 41 measures the NOx concentration in the gas to be measured in the second internal space 40. The measurement pump cell 41 includes a measurement electrode 44 provided on the upper surface of the first solid electrolyte layer 4 facing the second internal space 40 and at a position separated from the third diffusion rate controlling unit 30, and an outer pump electrode 23. , The electrochemical pump cell composed of the second solid electrolyte layer 6, the spacer layer 5, and the first solid electrolyte layer 4.

The measuring electrode 44 is a porous cermet electrode. The measurement electrode 44 also functions as a NOx reduction catalyst that reduces NOx existing in the atmosphere in the second internal space 40. Further, the measurement electrode 44 is covered with the fourth diffusion rate controlling portion 45.

The fourth diffusion rate controlling unit 45 is a film made of a porous ceramic body. The fourth diffusion rate controlling unit 45 plays a role of limiting the amount of NOx flowing into the measuring electrode 44, and also functions as a protective film of the measuring electrode 44. In the measurement pump cell 41, oxygen generated by the decomposition of nitrogen oxides in the atmosphere around the measurement electrode 44 can be pumped out, and the amount generated can be detected as the pump current Ip2.

Further, in order to detect the oxygen partial pressure around the measurement electrode 44, an electrochemical sensor cell, that is, a reference electrode 42 is provided by the first solid electrolyte layer 4, the third substrate layer 3, the measurement electrode 44, and the reference electrode 42. The oxygen partial pressure detection sensor cell 82 for controlling the measurement pump is configured. The variable power supply 46 is controlled based on the electromotive force V2 detected by the oxygen partial pressure detection sensor cell 82 for controlling the measurement pump.

The gas to be measured guided into the second internal space 40 reaches the measurement electrode 44 through the fourth diffusion rate controlling unit 45 under the condition that the oxygen partial pressure is controlled. Nitrogen oxides in the gas to be measured around the measurement electrode 44 are reduced (2NO → N ₂ + O ₂ ) to generate oxygen. The generated oxygen is pumped by the measurement pump cell 41, and at that time, a variable power source is used so that the control voltage V2 detected by the measurement pump control oxygen partial pressure detection sensor cell 82 becomes constant. The voltage Vp2 of 46 is controlled. Since the amount of oxygen generated around the measurement electrode 44 is proportional to the concentration of nitrogen oxides in the gas to be measured, the nitrogen oxides in the gas to be measured are used by using the pump current Ip2 in the pump cell 41 for measurement. The concentration will be calculated.

Further, if the measuring electrode 44, the first solid electrolyte layer 4, the third substrate layer 3 and the reference electrode 42 are combined to form an oxygen partial pressure detecting means as an electrochemical sensor cell, the measuring electrode 44 can be formed. It is possible to detect the electromotive force according to the difference between the amount of oxygen generated by the reduction of the NOx component in the surrounding atmosphere and the amount of oxygen contained in the reference atmosphere, thereby the concentration of the NOx component in the measured gas. It is also possible to ask for.

Further, the electrochemical sensor cell 83 is composed of the second solid electrolyte layer 6, the spacer layer 5, the first solid electrolyte layer 4, the third substrate layer 3, the outer pump electrode 23, and the reference electrode 42. The electromotive force Vref obtained by the sensor cell 83 makes it possible to detect the oxygen partial pressure in the measured gas outside the sensor.

In the gas sensor 100 having such a configuration, the oxygen partial pressure is always kept at a constant low value (a value that does not substantially affect the measurement of NOx) by operating the main pump cell 21 and the auxiliary pump cell 50. The gas to be measured is supplied to the measurement pump cell 41. Therefore, the NOx concentration in the measured gas is determined based on the pump current Ip2 that flows when oxygen generated by the reduction of NOx is pumped out from the measurement pump cell 41 in substantially proportional to the concentration of NOx in the measured gas. You can know it.

Further, the sensor element 101 includes a heater unit 70 which plays a role of temperature adjustment for heating and keeping the sensor element 101 warm in order to enhance the oxygen ion conductivity of the solid electrolyte. The heater unit 70 includes a heater 72, a heater insulating layer 74, and a pressure dissipation hole 75.

The heater 72 is an electric resistor formed by being sandwiched between the second substrate layer 2 and the third substrate layer 3 from above and below. The heater 72 generates heat by being supplied with power from the outside, and heats and keeps the solid electrolyte forming the sensor element 101.

Further, the heater 72 is embedded over the entire area from the first internal space 20 to the second internal space 40, and the entire sensor element 101 can be adjusted to a temperature at which the solid electrolyte is activated. ing.

The heater insulating layer 74 is an insulating layer formed on the upper and lower surfaces of the heater 72 by an insulator such as alumina. The heater insulating layer 74 is formed for the purpose of obtaining electrical insulation between the second substrate layer 2 and the heater 72 and electrical insulation between the third substrate layer 3 and the heater 72.

The pressure dissipation hole 75 is a portion provided so as to penetrate the third substrate layer 3 and communicate with the reference gas introduction space 43, and for the purpose of alleviating the increase in internal pressure due to the temperature rise in the heater insulating layer 74. It is formed.

Further, an upper connector pad 91, a lower connector pad 92, and a side conduction portion 95 are arranged on the sixth surface 101f side (rear end side) of the sensor element 101. The upper connector pad 91 is arranged on the rear end side of the first surface 101a and functions as a connector electrode for electrically conducting the sensor element 101 and the outside. A plurality of (four in this embodiment) upper connector pads 91 are arranged, and specifically, the first to fourth upper connector pads 91a to 91d are arranged in order from the left side of the sensor element 101. The lower connector pad 92 is arranged on the rear end side of the second surface 101b, and functions as a connector electrode for electrically conducting the sensor element 101 and the outside. A plurality of (four in this embodiment) lower connector pads 92 are arranged, and specifically, the first to fourth lower connector pads 92a to 92d are arranged in order from the left side of the sensor element 101. The side conducting portion 95 is arranged on the rear end side of the third and fourth surfaces 101c and 101d, and is a lead that electrically conducts each electrode inside the sensor element 101 with the upper connector pad 91 and the lower connector pad 92. Acts as part of the line. A plurality of side conductive portions 95 (five in this embodiment) are arranged. Specifically, the first and second side surface conductive portions 95a and 95b are arranged on the third surface 101c (FIG. 3), and the third to fifth side surface conductive portions 95c to 95e are arranged on the fourth surface 101d. It is installed (Fig. 4).

The connection between the upper connector pad 91 and the lower connector pad 92 and each electrode and the like will be described. The first upper connector pad 91a is electrically conductive with the measurement electrode 44 via the second side surface conduction portion 95b and the measurement electrode lead wire 44a. The measurement electrode lead wire 44a is arranged between the first solid electrolyte layer 4 and the spacer layer 5 from the measurement electrode 44 to the third surface 101c, and is an end portion on the third surface 101c side (FIG. 3). (See the broken line portion of) is connected to the second side surface conductive portion 95b. The second side surface conductive portion 95b connects the measurement electrode lead wire 44a and the first upper connector pad 91a.

The second upper connector pad 91b is electrically connected to the outer pump electrode 23 via the lead wire 23a for the outer pump electrode arranged on the first surface 101a of the second solid electrolyte layer 6.

The third upper connector pad 91c is electrically connected to the auxiliary pump electrode 51 via the auxiliary pump electrode lead wire 51d, the fifth side surface conduction portion 95e, and the auxiliary pump electrode lead wire 51c. The auxiliary pump electrode lead wire 51c is arranged between the spacer layer 5 and the second solid electrolyte layer 6 from the auxiliary pump electrode 51 to the fourth surface 101d, and is arranged at the end portion on the fourth surface 101d side (the auxiliary pump electrode lead wire 51c). (See the broken line portion in FIG. 4) is connected to the fifth side surface conductive portion 95e. The fifth side surface conductive portion 95e connects the auxiliary pump electrode lead wire 51c and the auxiliary pump electrode lead wire 51d arranged on the first surface 101a.

The fourth upper connector pad 91d is electrically connected to the inner pump electrode 22 via the fourth side surface conductive portion 95d and the inner pump electrode lead wire 22c. The inner pump electrode lead wire 22c is arranged between the spacer layer 5 and the second solid electrolyte layer 6 from the inner pump electrode 22 to the fourth surface 101d, and is arranged at the end portion on the fourth surface 101d side (the inner pump electrode lead wire 22c). (See the broken line portion in FIG. 4) is connected to the fourth side surface conductive portion 95d. The fourth side surface conductive portion 95d connects the inner pump electrode lead wire 22c and the fourth upper connector pad 91d.

The first lower connector pad 92a is electrically connected to the heater 72 via the first side surface conductive portion 95a and the heater lead wire 76b. The heater lead wire 76b is arranged between the second substrate layer 2 and the third substrate layer 3 from the heater 72 to the third surface 101c, and is an end portion on the third surface 101c side (FIG. 3). (See the broken line portion of) is connected to the first side surface conductive portion 95a. The first side surface conductive portion 95a connects the heater lead wire 76b and the first lower connector pad 92a.

The second lower connector pad 92b is connected to the heater 72 via the through hole 73 and the heater lead wire 76a (see FIG. 1). Like the second lower connector pad 92b, the third lower connector pad 92c is also connected to the heater 72 via a through hole (not shown) and a lead wire for a heater.

The fourth lower connector pad 92d is electrically connected to the reference electrode 42 via the third side surface conductive portion 95c and the reference electrode lead wire 42a. The reference electrode lead wire 42a is disposed between the third substrate layer 3 and the first solid electrolyte layer 4 from the reference electrode 42 to the fourth surface 101d, and is an end portion on the fourth surface 101d side (the reference electrode lead wire 42a). (See the broken line portion in FIG. 4) is connected to the third side surface conductive portion 95c. The third side surface conductive portion 95c connects the reference electrode lead wire 42a and the fourth lower connector pad 92d.

The sensor element 101 is connected to each electrode (inner pump electrode 22, outer pump electrode 23, reference electrode 42, measurement electrode 44, auxiliary) from the outside via these upper connector pads 91, lower connector pads 92, side conduction portions 95, and the like. It is possible to apply a voltage or current to the pump electrode 51) and measure the voltage or current of each electrode. The application of voltage by the variable power supply 24, the variable power supply 46, and the variable power supply 52 described above, the detection of the pump currents Ip1, the electromotive forces V0, V1, and V2 are actually performed via the upper connector pad 91 and the lower connector pad 92. .. Further, the heater 72 is electrically connected to the first to third lower connector pads 92a to 92c as described above, and by connecting the first to third lower connector pads 92a to 92c to an external power source. , It is possible to supply power to the heater unit 70 from the outside.

The side conduction portion 95 contains, for example, a noble metal such as platinum or a material such as a refractory metal such as tungsten or molybdenum. Further, the side conducting portion 95 may be a porous cermet like the above-mentioned electrodes. Further, the first to fifth side surface conductive portions 95a to 95d may be made of the same material as the electrodes or the like to which each conducts. In the present embodiment, the side conduction portion 95 is a cermet of _{Pt and ZrO 2.} The same material as that of the side conductive portion 95 can be used for the upper connector pad 91, the lower connector pad 92, and each lead wire. Further, although not particularly limited to this, the thickness of the upper connector pad 91, the lower connector pad 92, the side conducting portion 95, and each lead wire is, for example, 5 to 50 μm.

Next, an example of a method for manufacturing the sensor element 101 of the gas sensor 100 will be described below. The method for manufacturing the sensor element 101 of the present embodiment is as follows.
A preparatory step for preparing a green structure 109 having one or more ceramic green sheets (see FIGS. 5 and 9 described later), and
After the preparatory step, a coating step of coating at least a part of the green structure 109 with a conductive paste 195 (see FIGS. 9 and 10 described later) which becomes a side conductive portion 95 after firing, and a coating step.
After the coating step, the green structure 109 is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to dry the conductive paste 195, and a drying step.
After the drying step, the green structure 109 is fired to obtain the sensor element 101, and the firing step.
including.

First, the preparation process will be described. In the preparatory step, first, six unfired ceramic green sheets containing an oxygen ion conductive solid electrolyte such as zirconia as a ceramic component are prepared. A plurality of sheet holes and necessary through holes used for positioning during printing and laminating are formed in advance on this green sheet. Further, a space serving as a gas distribution section is provided in advance on the green sheet serving as the spacer layer 5 by punching or the like. Similarly, the green sheet serving as the first solid electrolyte layer 4 is also provided with a space serving as a reference gas introduction space 43. Then, corresponding to each of the first substrate layer 1, the second substrate layer 2, the third substrate layer 3, the first solid electrolyte layer 4, the spacer layer 5, and the second solid electrolyte layer 6, respectively. Pattern printing and drying are performed to form various patterns on the ceramic green sheet. Specifically, the pattern to be formed is, for example, a pattern of each of the above-mentioned electrodes and lead wires, an atmosphere introduction layer 48, a heater portion 70, an upper connector pad 91, a lower connector pad 92, and the like. Pattern printing is performed by applying a pattern forming paste prepared according to the characteristics required for each forming target onto a green sheet using a known screen printing technique. The drying treatment is also performed using a known drying means. After pattern printing and drying are completed, the adhesive paste for laminating and adhering the green sheets corresponding to each layer is printed and dried. Then, the green sheets on which the adhesive paste is formed are laminated in a predetermined order while being positioned by the sheet holes, and crimped by applying predetermined temperature and pressure conditions to form a single laminated body. The laminated body thus obtained includes a plurality of green structures 109 which become sensor elements 101 after firing. By cutting the laminate and cutting it into the size of the sensor element 101, a plurality of green structures 109 are obtained. The green structure 109 is in a printed and dried state except for the patterns that need to be formed on the cut surfaces (third and fourth surfaces 101c, 10d) of the laminated body. More specifically, the green structure 109 has a conductive paste 195 (first to fifth conductive pastes 195a to 195e) that becomes side conductive portions 95 (first to fifth side conductive portions 95a to 95e) after firing. , Details described later) are not formed, but the other upper connector pad 91, lower connector pad 92, each electrode, each lead wire, and the like are in a printed and dried state.

Next, the coating process and the drying process will be described. In the present embodiment, the coating step and the drying step are performed using the drying system 200. FIG. 5 is an explanatory diagram showing an outline of the configuration of the drying system 200. FIG. 6 is a perspective view of the mounting member 270. FIG. 7 is a top view showing a state in which the green structure 109 is mounted on the mounting member 270. FIG. 8 is a sectional view taken along the line CC of the infrared heater 220 of FIG. FIG. 9 is an enlarged top view showing the green structure 109 after inversion mounted on the mounting member 270. In the description of the drying system 200, the left-right direction, the front-back direction, and the up-down direction are as shown in FIGS. 5 to 9.

The drying system 200 is configured as a green structure processing line that automatically carries out a coating process and a drying process by transporting the green structure 109 mounted on the mounting member 270 from the front to the rear. The drying system 200 includes a first printing device 201 (corresponding to the first coating device of the present invention), a first inspection device 203, a first drying device 211, a reversing device 240, and a second printing device 202 (the present invention). (Corresponding to the second covering device) and the second inspection device 204, and these devices are arranged in this order along the transport direction. Further, the drying system 200 includes a transport device 250 and a control device 260. The transport device 250 includes a plurality of (five in this embodiment) belt conveyors (first to fifth belt conveyors 251a to 251e), which are continuously arranged in this order. Each of the first to fifth belt conveyors 251a to 251e has rollers 252 and 252 at both front and rear ends and a pair of left and right belts 253 and 253 hung and hung on the rollers 252 and 252 (enlarged perspective in the lower part of FIG. 5). (See figure) and. The mounting member 270 is arranged on the belt 253 and is conveyed from the front to the rear by the first to fifth belt conveyors 251a to 251e. The first belt conveyor 251a conveys the mounting member 270 before and after the first printing device 201 and the first inspection device 203. The second belt conveyor 251b conveys the mounting member 270 before and after the first drying device 211. The third belt conveyor 251c conveys the mounting member 270 before and after the reversing device 240. The fourth belt conveyor 251d conveys the mounting member 270 before and after the second printing device 202 and the second inspection device 204. The fifth belt conveyor 251e conveys the mounting member 270 before and after the second drying device 212.

The mounting member 270 is, for example, a substantially flat plate-shaped member made of metal. The mounting member 270 is preferably made of a material having high infrared reflectance such as aluminum or SUS. The mounting member 270 is arranged and conveyed on the belt 253 in the orientation shown in FIG. The mounting member 270 includes through holes 271,272, recesses 273, a plurality of protrusions 274, and a plurality of protrusions 275. The through hole 271 is formed near the left end portion of the mounting member 270, and the through hole 272 is formed near the right end portion of the mounting member 270. The through holes 271,272 penetrate the mounting member 270 up and down, and are opened in a rectangular shape with rounded corners in the longitudinal direction along the front-rear direction. The recess 273 has a rectangular shape with rounded corners along the front-rear direction in the longitudinal direction, and is formed between the through hole 271 and the through hole 272 in the left-right direction. The protrusion 274 is arranged between the through hole 271 and the recess 273 in the left-right direction, and a plurality of protrusions 274 are arranged at equal intervals along the front-rear direction. As shown in the enlarged view of FIG. 6, a groove 278 is formed between the adjacent protrusions 274. The groove 278 is formed by facing side portions 276, 276 of adjacent protrusions 274 and a bottom portion 277 between them. In the present embodiment, 46 protrusions 274 are arranged, thereby forming 45 grooves 278. A plurality of protrusions 275 (46 in this embodiment) are arranged in the same manner as the protrusions 274, except that the protrusions 275 are arranged between the through holes 272 and the recesses 273 in the left-right direction. A plurality of (45) grooves 279 are formed by the plurality of protrusions 275, similarly to the grooves 278. Each of the plurality of grooves 278 has a one-to-one correspondence with the groove 279 on the right side, and the corresponding grooves 278 and 279 have the same position in the front-rear direction. By mounting the green structure 109 so as to straddle the corresponding grooves 278, 279 (see FIG. 7), the mounting member 270 places the green structure 109 on the sides and bottom of the grooves 278, 279. It can be supported by. Therefore, in the present embodiment, the mounting member 270 arranges each of the 45 green structures 109 so that the longitudinal direction is along the left-right direction, and mounts the plurality of green structures 109 at equal intervals in the front-rear direction. It is possible. The distance between the green structures 109, that is, the width of the protrusions 274 and 275 in the front-rear direction is, for example, 1 mm or more. The upper limit is not particularly limited, but if the width is too large, the quality is not affected, but the number of treatments is reduced, so 3 mm or less is preferable. The mounting member 270 has a front-back symmetry and a left-right symmetry shape. Further, the mounting member 270 has a shape that is twice symmetrical with the axis in the vertical direction passing through the center of the front, back, left, and right as the rotation axis.

The first printing device 201 is a device that covers at least a part of the upper surface of the green structure 109 mounted on the mounting member 270 with the conductive paste 195. In the present embodiment, the first printing apparatus 201 is configured as a known screen printing machine that applies a pattern of a conductive paste 195 that becomes a side conductive portion 95 after drying and baking to a green structure 109. The second printing apparatus 202 is configured as the same apparatus as the first printing apparatus 201 except that screen printing is performed on the green structure 109 after being inverted upside down by the inversion device 240.

The first inspection device 203 is a device that inspects the pattern of the conductive paste 195 printed by the first printing device 201. The first inspection device 203 includes a camera capable of capturing an image below. The first inspection device 203 performs an inspection process as follows, for example. First, the first inspection device 203 takes an image of the upper surface of the green structure 109 mounted on the mounting member 270 as it passes below. Next, the position and shape of the conductive paste 195 are detected from the obtained image data. Then, the presence or absence of abnormality is inspected by comparing the conductive paste 195 stored in advance with the reference position and the reference shape. If there is an abnormality in any of the plurality of green structures 109 mounted on the mounting member 270, information for identifying the green structure 109 determined to be abnormal (for example, the position on the mounting member 270). Is output to the control device 260. The second inspection device 204 is configured as the same device as the first inspection device 203 except that the pattern of the conductive paste 195 printed by the second printing device 202 is inspected.

The first drying device 211 is a device that dries the conductive paste 195 printed by the first printing device 201. The first drying device 211 includes an infrared heater 220 that irradiates infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm, and exhaust ducts 215 and 216 that are arranged on the right and left sides of the infrared heater 220 and open downward, respectively. And an exhaust fan 217 that sucks and exhausts the atmosphere (atmosphere in this embodiment) around the green structure 109 upward through the exhaust ducts 215 and 216.

The infrared heater 220 includes a heater main body 222 formed so that a tube 224 surrounds a filament 223, which is a heating element, and a substantially rectangular parallelepiped casing 230 that covers the entire heater main body 222. The infrared heater 10 radiates infrared rays to the green structure 109 arranged so that the longitudinal direction of the filament 223 is along the front-rear direction and is arranged in the direction toward the protective plate 234 (downward) when viewed from the filament 223. ..

The heater main body 222 is configured as a halogen heater in this embodiment. The filament 223 is a heating element that radiates infrared rays when heated, and is made of W (tungsten) in this embodiment. Examples of the material of the filament 223 include Ni—Cr alloys, Mo, Ta, and Fe—Cr—Al alloys. Power is supplied to both ends of the filament 223 in the front-rear direction from a power supply source (not shown) arranged outside the casing 230. The tube 224 is a cylindrical tube and is made of a material (for example, quartz) that transmits 0.8 μm to 4 μm infrared rays. The inside of the tube 224 has an atmosphere in which a halogen gas is added to an argon gas.

The casing 230 closes the casing main body 231 that opens downward to cover the top and left and right of the heater main body 222, the reflector 232 arranged on the lower surface of the casing main body 231 and the lower opening of the casing main body 231 to close the heater main body. It is provided with a protective plate 234 that covers the lower part of the 222. The protective plate 234 is made of a material (for example, glass) that transmits infrared rays of 0.8 μm to 4 μm.

The reflector 232 is arranged on a surface (lower surface) of the casing main body 231 exposed to the space 238 in which the heater main body 222 is arranged. The reflector 232 is made of a metal such as SUS304 or aluminum, and its cross section perpendicular to the front-rear direction has a curved shape such as an elliptical arc or an arc. In the present embodiment, the curved surface shape of the reflector 232 and the arrangement of the filament 223 are determined so that the infrared rays from the filament 223 are intensively reflected toward a part of the lower region (see the broken line arrow in FIG. 8). It was supposed to be. As a result, the infrared heater 220 irradiates the infrared irradiation region 228 shown in FIGS. 7 and 8 of the mounting member 270 and the green structure 109 with infrared rays, and does not irradiate the other parts with infrared rays. There is.

The infrared heater 230 preferably has a cooling mechanism. In the present embodiment, the first refrigerant (for example, a liquid such as water) is circulated from the outside into the refrigerant flow path 237 formed inside the casing main body 231 and the second refrigerant (for example, air) is circulated from the outside into the space 238. The infrared heater 230 can be cooled by circulating the gas).

The first drying device 211 configured in this way irradiates the conductive paste 195 with infrared rays by the infrared heater 220, and uses the exhaust fan 217 and the exhaust ducts 215 and 216 to cool gas (flow of atmosphere, which is the present embodiment). Then, the green structure 109 is cooled by the atmosphere). The second drying device 212 has the same configuration as the first drying device 211 except that the conductive paste 195 printed by the second printing device 202 is dried. The first and second drying devices 211 and 212 irradiate the conductive paste 195 with infrared rays in a state where the green structure 109 and the conductive paste 195 are not sealed (atmosphere in the present embodiment).

The reversing device 240 is a device that flips the green structure 109 mounted on the mounting member 270 upside down and mounts it on another mounting member 270. The reversing device 240 includes a first and second arms 241,242, a pair of front and rear first holding portions 243, a pair of front and rear second holding portions 244, a rotating shaft 245, a support portion 246, and an elevating device 247. , And an elevating member 248. The first arm 241 is configured to be expandable and contractible in the front-rear direction by an actuator such as a cylinder or a slider. A first holding portion 243 is connected to both front and rear ends of the first arm 241. The pair of first holding portions 243 sandwich the mounting member 270 from the front-rear direction by expanding and contracting the first arm 241. The second arm 242 is configured to be expandable and contractible in the front-rear direction like the first arm 241 and is arranged on the side opposite to the first arm 241 (lower side in FIG. 5) with the rotation shaft 245 interposed therebetween. A second holding portion 244 is connected to both front and rear ends of the second arm 242, respectively. The pair of second holding portions 244 sandwich the mounting member 270 from the front-rear direction by expanding and contracting the second arm 242. The rotation shaft 245 is an axis along the left-right direction, and is supported by a support portion 246 so as to be rotatable (rotating). When the rotation shaft 245 is rotated by a servomotor (not shown), the first and second arms 241 and 242 and the first and second holding portions 243 and 244 are also rotated accordingly. The elevating device 247 is a mechanism for elevating and elevating the elevating member 248. The elevating member 248 is arranged at the center of the pair of belts 253 in the left-right direction, and is moved up and down by the elevating device 247. The width of the elevating member 248 in the left-right direction is smaller than the distance between the pair of belts 253 in the left-right direction. Raise and lower. The elevating member 248 has a positioning pin (not shown) on the upper surface. By inserting this positioning pin into a positioning hole (not shown) of the mounting member 270, the elevating member 248 can always hold the mounting member 270 at the same position.

The control device 260 is configured as a microprocessor centered on a CPU. The control device 260 includes exhaust fans 217, infrared heater 220, and reversing device 240 of the first and second printing devices 201 and 202, the first and second inspection devices 203, 204, and the first and second drying devices 211 and 212. And, signals and information are input and output to a drive motor (not shown) of each belt conveyor 251 of the transport device 250 to control and manage them. Further, the control device 260 includes a display operation unit such as a touch panel (not shown), and inputs an instruction from the operator or outputs information to the operator.

The operation of the drying system 200 configured in this way, and the coating process and the drying process by the operation will be described. First, the operator instructs the control device 260 to start the process, and the control device 260 that receives the instruction drives the transfer device 250. Further, as described above, the operator mounts the plurality (45) green structures 109 obtained in the preparation step in the plurality of grooves 278 and the grooves 279 of the mounting member 270, and mounts the front end of the first belt conveyor 251a. It is placed on the belt 253 and conveyed in sequence. As shown in the enlarged view in the middle of FIG. 7, the operator arranges all of the plurality of green structures 109 so that the third surface 101c is the upper surface and the sixth surface 101f is the left surface.

When the mounting member 270 on which the plurality of green structures 109 are mounted is conveyed to the first printing device 201, the first printing device 201 is transferred to the upper surface (third surface 101c) of the plurality of green structures 109. A coating step of applying the conductive paste by screen printing to form the conductive paste 195 is performed (see the lower part of FIG. 7). More specifically, the first conductive paste 195a is formed so as to connect the unfired first lower connector pad 192a of the green structure 109 and the lead wire 176b for the unfired heater. Further, the second conductive paste 195b is formed so as to connect the unfired first upper connector pad 191a and the unfired measurement electrode lead wire 144a. The unfired first lower connector pad 192a is a conductive paste (conducting paste after drying) that becomes the first lower connector pad 92a after firing. The same applies to the unfired measurement electrode lead wire 144a and the like, and individual description is omitted by adding a value 100 to the code of the component after firing and adding unfired to the name. Further, the first and second conductive pastes 195a and 195b become the first and second side conductive portions 95a and 95b after firing.

As the conductive paste 195, for example, the powder used as the material of the side conductive portion 95 described above is dispersed in a solvent such as acetone. It is preferable to add a sintering aid to the conductive paste 195. Further, when the side conductive portion 95 is made porous, it is preferable to add a pore-forming material. Examples of the sintering aid include silicon dioxide, calcium carbonate, and alumina. As the pore-forming material, a material that disappears during sintering can be used, and examples thereof include theobromine and acrylic resin. The particle size and the amount of the pore-forming material added are appropriately adjusted according to, for example, the porosity of the side conductive portion 95. Further, the viscosity of the conductive paste 195 is appropriately adjusted according to the thickness of the side conductive portion 95.

When the green structure 109 after the coating step is passed under the first inspection device 203, the conductive paste 195 (first and second conductive pastes 195a, 195b) and its surroundings are imaged. , The above-mentioned inspection process is performed. The result of the inspection process is stored in the storage unit of the control device 260. The control device 260 may stop the transfer by the first belt conveyor 251a at the time of imaging.

After the inspection process is performed, the green structure 109 is conveyed to the first drying device 211 by the second belt conveyor 251b. The control device 260 stops the second belt conveyor 251b when the mounting member 270 on which the green structure 109 is mounted is conveyed to a predetermined position (see FIGS. 5 and 8) directly below the first drying device 211. Further, the control device 260 controls the infrared heater 220 to energize the heater main body 222 to irradiate infrared rays, and controls the exhaust fan 217 to suck the atmosphere below the exhaust ducts 215 and 216. Have the drying device 211 perform the drying step. By this drying step, the conductive paste 195 (first and second conductive pastes 195a, 195b) is dried.

Here, the positional relationship between the first drying device 211 and the green structure 109 in the drying step will be described. As shown in FIGS. 7 and 8, the infrared irradiation region 228 on which the infrared heater 220 irradiates infrared rays is a partial region on the left side of the mounting member 270 including the through hole 271 in the top view. The position of the infrared heater 220 with respect to the belt 253, the shape of the reflector 232, the position of the green structure 109 on the mounting member 270, etc. are predetermined so that the infrared irradiation region 228 includes all the conductive paste 195 to be dried. Has been done. Further, in the present embodiment, the through hole 271 is located directly below the filament 223, and is located in the middle of the openings of the exhaust ducts 215 and 216 in the left-right direction. Here, the infrared heater 220 irradiates infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm as described above. Infrared rays (near infrared rays) having a wavelength of 0.8 μm to 4 μm are excellent in the ability to break hydrogen bonds in molecules such as water and solvents contained in the conductive paste 195. In addition, a solvent such as acetone is relatively easy to absorb near infrared rays. Therefore, the conductive paste 195 arranged in the infrared irradiation region 228 is efficiently dried in a short time as compared with the case of performing hot air drying, for example. Since it is not necessary to irradiate the region of the green structure 109 where the conductive paste 195 is not formed with infrared rays, such a region (for example, the right half of the green structure 109 in FIG. 7) is infrared rays. It is preferable to keep it away from the irradiation area 228. The vertical distance between the infrared heater 220 and the green structure 109 (in this embodiment, the distance between the protective plate 234 and the green structure 109) is not particularly limited, but is, for example, 10 mm to 80 mm. ..

Further, the green structure 109 is mounted on the mounting member 270 so that at least a part of the conductive paste 195 overlaps with the region where the through hole 271 exists when viewed from the green structure 109 side (= top view). It is preferable that it is placed. In the present embodiment, the green structure 109 is placed so that the conductive paste 195 (first and second conductive pastes 195a, 195b) is located in the region where the through hole 271 is present in the top view. (See the lower part of Fig. 7). Here, when the exhaust fan 217 sucks in a state where the through hole 271 is located below the exhaust ducts 215 and 216 as shown in FIG. 8, the cooling gas (atmosphere) that passes upward through the through hole 271 by suction A flow occurs (see the white arrow in FIG. 8). Therefore, the portion of the green structure 109 located in the region where the through hole 271 exists in the top view is efficiently cooled because the cooling gas flows intensively. The infrared irradiation region 228, the conductive paste 195 to be dried, and the surrounding area may be overheated by infrared rays from the infrared heater 220, but these are arranged so as to overlap with the through hole 271 to overheat. Can be suppressed. If the wind speed of the exhaust ducts 215 and 216 is low, the cooling effect is small, and if the wind speed is too high, the drying time is long. Therefore, the wind speed at the suction port of the exhaust ducts 215 and 216 is set to 0.5 m / sec to 10 m / sec. It is preferable to do so.

The output P [W] of the infrared heater 220 and the infrared irradiation time T [sec] in the drying step are stored in advance in the control device 260. The control device 260 energizes the filament 223 with the electric power of the output P based on the stored value, and also takes in air from the exhaust fan 217. Then, the control device 260 stops the energization of the filament 223 after the irradiation time T elapses, and conveys the dried green structure 109 toward the reversing device 240 by the second belt conveyor 251b. It is preferable that the output P [W] and the irradiation time T [sec] both satisfy the following equations (1) and (2).

T ≧ (-20/13) P + 380 equation (1)
T ≧ (-2/3) P + (596/3) Equation (2)

After the drying step is performed, the green structure 109 is turned upside down by the inversion device 240. The operation when the reversing device 240 reverses the green structure 109 will be described. First, the first holding portions 243 and 243 hold the mounting member 270 upside down in advance. Then, as shown in FIG. 7, when the mounting member 270 on which the plurality of green structures 109 are mounted is conveyed to directly above the elevating member 248 of the reversing device 240, the elevating device 247 raises the elevating member 248 and mounts it. The placement member 270 is raised to the same height as the second holding portions 244 and 244. As a result, the plurality of green structures 109 are sandwiched between the upper and lower mounting members 270 (see the enlarged view at the lower right of FIG. 5). More specifically, the upper portions of the plurality of green structures 109 mounted on the mounting member 270 raised by the elevating member 248 are the grooves 278, 279 of the mounting member 270 sandwiched by the first sandwiching portion 243. Is inserted inside. Next, as the second arm 242 contracts, the second holding portions 244 and 244 move in directions close to each other, and the raised mounting member 270 is sandwiched from the front and back. Subsequently, the elevating member 248 is lowered, and the rotating shaft 245 rotates 180 ° while maintaining the distance between the upper and lower mounting members 270. As a result, the first arm 241 and the second arm 242, the two upper and lower mounting members 270, and the green structure 109 are in a state of being turned upside down. After that, the elevating member 248 is raised and the pair of first sandwiching portions 243 and 243 are moved in a direction (front-back direction) away from each other, and mounted on the mounting member 270 sandwiched by the first sandwiching portion 243 and the mounting member 270. The placed green structure 109 is placed on the upper surface of the elevating member 248. Then, by lowering the elevating member 248, the mounting member 270 and the plurality of green structures 109 mounted on the mounting member 270 are mounted on the belt 253. As described above, the green structure 109 mounted on the mounting member 270 is another mounting member 270 in a state of being upside down (the mounting member 270 previously sandwiched by the first sandwiching portions 243 and 243). It will be placed on the belt 253 and returned on the belt 253. As a result, the dried third surface 101c (upper surface before inversion) becomes the lower surface, and the fourth surface 101d becomes the upper surface (see FIG. 9). Next, when another mounting member 270 is conveyed directly above the elevating member 248, the above-mentioned operation is performed upside down. That is, the transferred mounting member 270 is sandwiched by the first sandwiching portions 243 and 243, and the green structure 109 is mounted upside down on the mounting member 270 previously sandwiched by the second sandwiching portions 244 and 244. It is placed and put back on the belt 253.

The green structure 109 after being inverted by the inversion device 240 is sequentially conveyed to the second printing device 202, the second inspection device 204, and the second drying device 212, and has conductivity similar to the coating step and the drying step described above. The paste 195 is printed and dried. First, the second printing apparatus 202 performs a coating step of applying a conductive paste to the upper surfaces (fourth surface 101d) of the plurality of green structures 109 by screen printing to form the conductive paste 195 (lower part of FIG. 9). reference). More specifically, the third conductive paste 195c is formed so as to connect the unfired fourth lower connector pad 192d of the green structure 109 and the unfired reference electrode lead wire 42a. Further, the fourth conductive paste 195d is formed so as to connect the unfired fourth upper connector pad 191d and the unfired inner pump electrode lead wire 22c. Further, the fifth conductive paste 195e is formed so as to connect the unfired auxiliary pump electrode lead wires 151c and 151d. The third to fifth conductive pastes 195c to 195e become the third to fifth side surface conductive portions 95c to 195e after firing.

Subsequently, the second inspection device 204 inspects the conductive paste 195 (third to fifth side surface conductive portions 95c to 195e). Then, a drying step of drying the conductive paste 195 (third to fifth side surface conductive portions 95c to 195e) is performed by the second drying device 212. The positional relationship between the infrared irradiation region of the second drying device 212, the through hole 271 during the drying process, and the green structure 109 was the same as that of the first drying device 211. However, as shown in FIG. 9, a fifth conductive paste 195e is formed on the fourth surface 101d in addition to the third and fourth conductive pastes 195c and 195d. The third and fourth conductive pastes 195c and 195d are located in the region where the through hole 271 is present in the top view like the first and second conductive pastes 195a and 195b shown in FIG. 5 The conductive paste 195e does not overlap with the region where the through hole 271 exists in the top view. Further, it is preferable to perform the drying step so as to satisfy both the above formulas (1) and (2) in the case of the second drying device 212 as well. The output P [W] and the irradiation time T [sec] may be the same or different between the first drying device 211 and the second drying device 212.

When the drying process by the second drying device 212 is completed, the control device 260 controls the belt conveyor 251e to carry out the mounting member 270 from the drying system 200. By the above treatment, the coating step and the drying step are performed on each of the third and fourth surfaces 101c and 101d of the green structure 109 prepared in the preparation step, and the conductive paste 195 (first to fifth). The conductive pastes 195a to 195e are formed and dried.

After the above-mentioned coating step and drying step by the drying system 200, the operator removes the green structure 109 determined to be abnormal based on the inspection results of the first inspection device 203 and the second inspection device 204. Then, the green structure 109 that is not determined to be abnormal is fired at a predetermined firing temperature. As a result, each green sheet, the unbaked upper connector pad 91, the lower connector pad 92, each electrode, each lead wire, etc. are fired, and the conductive paste 195 (first to fifth conductive pastes 195a to 195e) is also fired. Then, it becomes the side conducting portion 95 (first to fifth side conducting portions 95a to 95e) described above, and obtains the sensor element 101. When the sensor element 101 is obtained in this way, the gas sensor 100 can be obtained by housing it in a predetermined housing and incorporating it into the main body (not shown) of the gas sensor 100.

In the drying method in the first and second drying devices 211 and 212 of the first embodiment described above in detail, infrared rays having a peak wavelength are irradiated in a wavelength region of 0.8 μm to 4 μm to cover a part of the green structure 109. The conductive paste 195 to be dried is dried. By using infrared rays (near infrared rays) having a wavelength of 0.8 μm to 4 μm, it is possible to efficiently perform drying in a short time as compared with the case of performing hot air drying, for example. For example, when hot air drying is performed in a batch furnace, there is a problem that it is difficult to incorporate it into the line of the drying system 200 because the size of the batch furnace is relatively large, and a temperature difference is likely to occur depending on the location in the furnace. In the present embodiment, by using the infrared heater 220, it is not necessary to carry the green structure 109 into the furnace and the drying can be performed in an open state, and the above-mentioned problems are less likely to occur. Further, when hot air drying is performed in a batch furnace, there is a problem that a waiting time is generated until the temperature rises to a temperature suitable for drying because the internal temperature drops when the green structure 109 is carried in and out of the batch furnace. In the present embodiment, since the infrared heater 220 can be used in a relatively short time after being energized, the waiting time is not long and it is suitable for incorporation into a line. Further, in the present embodiment, the conductive paste 195 becomes a porous cermet after firing. On the other hand, the ceramic green sheet of the green structure 109 becomes ceramics after firing. In general, porous cermets are darker in color than ceramics and tend to have a high absorption rate of infrared rays having a wavelength of 0.8 μm to 4 μm. Therefore, the infrared rays emitted from the filament 223 are efficiently absorbed by the conductive paste 195, but are relatively not absorbed by the main body (ceramics green sheet) of the green structure 109. Due to this difference in color, overheating of the main body of the green structure 109 is suppressed while efficiently drying the conductive paste 195. Further, for example, when hot air drying is performed in a batch furnace, it is necessary to raise the drying temperature to a high temperature, especially in order to perform drying in a short time, which may affect the element base (green structure 109 main body). .. In the present embodiment, the heating of the green structure 109 is suppressed, so that such an effect can be suppressed.

Further, in the drying step by the first and second drying devices 211 and 212, the green structure 109 is cooled by the cooling gas using the exhaust fan 217 while irradiating infrared rays. As a result, it is possible to suppress defects due to overheating of the green structure 109 due to infrared irradiation. Examples of defects due to overheating include the occurrence of uneven firing and warpage in the subsequent firing step due to the partial firing of the green sheet of the green structure 109 in the drying step. Cooling the green structure 109 so that the temperature is 80 ° C. or lower is preferable because it can suppress defects in the above-mentioned firing step.

Further, in the drying step by the first and second drying devices 211 and 212, at least a part of the conductive paste 195 is a through hole on the mounting member 270 having the through hole 271 when viewed from the green structure 109 side (upper side). With the green structure 109 placed so as to overlap the region where 271 exists, the cooling gas is circulated in the through hole 271 while irradiating infrared rays. As a result, the cooling gas can be centrally distributed in the vicinity of the conductive paste 195 through the through hole 271 of the mounting member 270, so that the green structure 195 can be efficiently cooled.

The green structure 109 has a long rectangular parallelepiped shape. Then, in the drying step by the first and second drying devices 211 and 212, a plurality of green structures 109 are placed on the mounting member 270 at least one of the conductive pastes 195 when viewed from the green structure 109 side (upper side). A plurality of green structures 109 were placed with a gap along the direction (front-back direction) perpendicular to the longitudinal direction of the green structure 109 so that the portion overlapped with the area where the through hole 271 exists. In the state, irradiate infrared rays. In this way, in order to arrange the long rectangular parallelepiped green structures 109 with a gap in the direction perpendicular to the longitudinal direction, a cooling gas is circulated in the gap to efficiently cool the plurality of green structures 109 at the same time. While doing so, the conductive paste 195 can be dried. Therefore, the conductive paste 195 of the plurality of green structures 109 can be efficiently dried together.

Further, the green structure 109 has a long rectangular parallelepiped shape cut out by cutting a laminated body of a plurality of ceramic green sheets, and at least one of the cut surfaces (third and fourth surfaces 101c, 101d). The portion is covered with the conductive paste 195. Here, when the cut surface of the green structure 109 is coated with the conductive paste 195, it cannot be coated with the conductive paste 195 before cutting out the laminate, and it is coated with the conductive paste 195 after cutting out from the laminate. And will be dried. The drying method using the mounting member 270 having the through hole 271 described above is suitable for drying in this case.

Furthermore, in the drying step by the first and second drying devices 211 and 212, the infrared heater 220 is used, and the output P [W] of the infrared heater 220 and the infrared irradiation time T [sec] are the above equations (1). Irradiate infrared rays so as to satisfy both (2). As a result, the conductive paste 195 can be sufficiently dried. If the irradiation time T is made as small as possible within the range in which both the formulas (1) and (2) are satisfied, the conductive paste 195 can be sufficiently dried while shortening the drying time as much as possible. The upper limit of the irradiation time T is not particularly limited, but if it is too long, the number of treatments per unit time will be small. Therefore, for example, the irradiation time T may be 250 [sec] or less. Further, the larger of the values of T when the output P is substituted into the equations (1) and (2) may be Tmin, and the irradiation time T ≦ Tmin + 100 [sec] may be set.

Further, in the drying step by the first and second drying devices 211 and 212, the infrared irradiation region 228, which is a partial region of the green structure 109 including the conductive paste 195, is irradiated with infrared rays. As a result, it is possible to suppress irradiation of an unnecessary region without the conductive paste 195 with infrared rays, and it is possible to suppress overheating of the green structure 109. Further, by irradiating only a part of the region where the conductive paste 195 is present with infrared rays, the drying can be sufficiently performed even if the output of the infrared heater 220 is relatively small.

Further, in the drying step by the first and second drying devices 211 and 212, the conductive paste 195 is irradiated with infrared rays without being sealed. In the drying method of the present invention, since the drying is performed using infrared rays, it is not necessary to heat the entire space and it is not necessary to seal the space. By performing the drying step in a non-sealed state, for example, the green structure 195 does not need to be carried in and out of the furnace (sealed space), and the work efficiency is improved.

Further, in the drying system 200, after coating and drying the conductive paste 195 on the upper surface of the green structure 101, the inversion device 240 inverts the green structure 109 upside down, and the upper surface after inversion (before inversion). The lower surface) is coated with the conductive paste 195 and dried. Therefore, the conductive paste 195 on both sides (two sides) of the rectangular parallelepiped green structure 109 can be automatically coated and dried.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be carried out in various embodiments as long as it belongs to the technical scope of the present invention.

For example, in the above-described embodiment, the coating step and the drying step are performed using the drying system 200 shown in FIG. 5, but the present invention is not limited to this. For example, the drying system 200 may not be provided with the first and second inspection devices 203 and 204, and the inspection process may be omitted. Further, the drying system 200 may not be provided with the reversing device 240, and the operator may perform the vertical reversal of the green structure 109. Further, in the drying system 200, the reversing device 240, the second printing device 202, the second inspection device 204, and the second drying device 212 are omitted, and the coating process and the drying process for one surface of the green structure 109 are performed. , A coating step or a drying step may be performed using this. Alternatively, the operator may transport the green structure 109 between the transport devices 250 without the transport device 250. Further, although the first and second printing devices 201 and 202 are devices for coating the green structure 109 with the conductive paste 195 by screen printing, the coating method is not limited to screen printing. For example, coating may be performed using a method such as gravure printing or a doctor blade. The reversing device 240 is not limited to the device shown in FIG. 5, and it is sufficient that the green structure 109 can be flipped up and down. For example, the green structure 109 may be inverted one by one.

The first and second drying devices 211 and 212 may be any device as long as they irradiate infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to dry the conductive paste. For example, at least one of the first and second drying devices 211 and 212 may not be provided with the reflector 232. Further, at least one of the first and second drying devices 211 and 212 does not include the exhaust duct 215, the exhaust duct 216, and the exhaust fan 217, and it is not necessary to perform cooling during infrared irradiation. Alternatively, the entire green structure 109 may be included in the infrared irradiation region 228.

In the above-described embodiment, the green structure 109 is placed on the mounting member 270 shown in FIGS. 6 and 7 and the drying step is performed, but the present invention is not limited to this. For example, the mounting member 270 may or may not have a through hole through hole 272 or may not have a through hole 271. When the green structure 109 is not provided, for example, a cooling gas may be blown toward the upper surface of the green structure 109 to cool the green structure 109. Further, the shape of the through hole 271 is not limited to a rectangular shape with rounded corners, and may be any through hole. Further, although a plurality of green structures 109 are mounted on the mounting member 270, the present invention is not limited to this, and the green structure 109 may be mounted one by one and the drying step may be performed.

In the above-described embodiment, when the conductive paste 195 covering the third and fourth surfaces 101c and 101d, which are the cut surfaces of the green structure 109 from the laminated body, is dried, the peak is in the wavelength region of 0.8 μm to 4 μm. Irradiation with infrared rays having a wavelength is not limited to this. For example, for drying the pattern of the conductive paste such as electrodes and lead wires formed on the green sheet before laminating, or in the state of the laminated body before cutting, the pattern of the conductive paste such as electrodes and lead wires. For drying, infrared rays having a peak wavelength in the wavelength region of 0.8 μm to 4 μm may be used.

In the above-described embodiment, the first drying device 211 is provided with one infrared heater 220 (filament 223), but may be provided with a plurality of infrared heaters 220. In this case, the output P [W] is the total output of the plurality of infrared heaters 220.

In the above-described embodiment, the case of manufacturing the sensor element 101 as a ceramic component has been described, but the green structure having one or more ceramic green sheets and at least partially covered with the conductive paste is dried and then fired. The ceramic parts obtained by the above are not limited to this.

Hereinafter, an example in which the drying method of the present invention is specifically carried out will be described as an example. Experimental Examples 2, 7 to 9, 11, 14, 15, 20, 21, 23, 24, 27 to 29, 32 to 34, 38, 39, 41 to 46, 48, 50 correspond to the examples of the present invention. , Others correspond to comparative examples. The present invention is not limited to the following examples.

[Experimental Examples 1 to 50]
The conductive paste when the drying method of the present invention is carried out using the first drying apparatus 211 of the above-described embodiment and the output P [W] and the irradiation time T [sec] are variously changed as shown in Table 1. The dry state was examined and used as Experimental Examples 1 to 50. The wind speed of suction by the exhaust fan 217 was set to 2 m / sec at the suction ports of the exhaust ducts 215 and 216. The vertical distance between the protective plate 234 and the green structure 109 during drying was set to 30 mm. The peak wavelength of infrared rays from the filament 223 was about 1 μm.

The green structure and the conductive paste to be measured were prepared as follows. First, a laminated body in which six ceramic green sheets were laminated was prepared, and the laminated body was cut to prepare a green structure. The green structure has a length of 70 mm in the front-rear direction, a width of 6 mm in the left-right direction, and a thickness of 1.5 mm in the up-down direction. The six ceramic green sheets were formed by mixing zirconia particles to which 4 mol% of the stabilizer yttria was added, an organic binder, and an organic solvent, and tape molding. No pattern such as electrodes inside the green structure was formed.

Next, a pattern of the conductive paste was printed on the cut surface of the green structure cut out from the laminated body by screen printing, and a part of the cut surface was covered with the conductive paste. The conductive paste was adjusted as follows. Premixing is performed by adding a predetermined amount of Pt, a pore-forming material (alumina) having a particle size of 0.3 μm, and acetone as a solvent to the zirconia particles to which 4 mol% of the stabilizer yttria is added to obtain a premixed solution. rice field. A ratio of 50% by volume of the organic binder solution obtained by dissolving 15% by mass of polyvinyl butyral in 85% by mass of diethylene glycol butyl ether acetate with respect to the total volume of yttria partially stabilized zirconia and the pore-forming material in the premixed solution. After adding and mixing to the premixed liquid so as to be, a conductive paste was obtained by appropriately adding butyl carbitol to adjust the viscosity. The thickness of the conductive paste after printing was 15 μm, and the size was a rectangle of 1 mm × 1.5 mm.

After drying Experimental Examples 1 to 50, the dried state of the conductive paste was examined, and three stages of evaluation were performed: sufficient drying (◯), insufficient drying (Δ), and undried (×). The evaluation was performed by pressing the evaluation sheet (made of paper and PET) against the conductive paste at a constant pressure and checking whether the material component of the conductive paste adhered to the evaluation sheet side. When it did not adhere at all, it was evaluated as sufficiently dry, when it adhered slightly, it was evaluated as insufficiently dried, and when it adhered a lot, it was evaluated as undried. Table 1 summarizes the evaluation results of the output P [W], the irradiation time T [sec], and the dry state of Experimental Examples 1 to 50. Further, FIG. 10 is a graph plotting the evaluation of the dry state with respect to the output P and the irradiation time T. The irradiation time T was measured as the time from the time when the filament 223 was energized. The filament 223 became stable at the output P set almost at the same time as the start of energization.

As shown in FIG. 10, the higher the output P and the longer the irradiation time T, the more the dry state tends to be. Further, from the results of Experimental Examples 1 to 50, two straight lines A and B were drawn in the graph of FIG. 10 as the lower limit straight lines in which the dry state was not insufficient or undried. The equations of the straight lines A and B are as shown in the following equations (A) and (B). As can be seen from FIG. 10, if the irradiation time T is larger than any of the straight lines A and B (the shaded area in FIG. 10 including a part of the straight lines A and B), the dry state is sufficient. , Output P and irradiation time T were found to be a preferred combination. The above-mentioned equations (1) and (2) are equations representing this region. In any of Experimental Examples 1 to 50, the temperature of the green structure in the drying step did not exceed 80 ° C. Further, in Experimental Examples 1 to 50, the temperature difference of the green structure due to the length of the irradiation time T was small. It is considered that the temperature rise of the green structure is sufficiently suppressed by irradiating the green structure with infrared rays while cooling it.

T = (-20/13) P + 380 formula (A)
T = (-2/3) P + (596/3) Equation (B)

[Experimental Example 51]
The conductive paste was dried in the same manner as in Experimental Examples 1 to 51 except that the green structure was carried into the batch furnace and the conductive paste was dried with hot air at 80 ° C. In Experimental Example 51, it took a long time of 20 minutes until the drying was sufficient.

1 1st substrate layer, 2 2nd substrate layer, 3 3rd substrate layer, 4 1st solid electrolyte layer, 5 spacer layer, 6 2nd solid electrolyte layer, 6a upper closest part, 10 gas inlet, 11 1st Diffusion rate control section, 12 buffer space, 13 second diffusion rate control section, 20 first internal space, 21 main pump cell, 22 inner pump electrode, 22a ceiling electrode section, 22b bottom electrode section, 22c inner pump electrode lead wire, 23 outer side. Pump electrode, 23a outer pump electrode lead wire, 24 variable power supply, 30 third diffusion rate control part, 40 second internal space, 41 measurement pump cell, 42 reference electrode, 42a reference electrode lead wire, 43 reference gas introduction space, 44 Measurement electrode, 44a Measurement electrode lead wire, 45 4th diffusion rate control part, 46 variable power supply, 48 atmosphere introduction layer, 50 auxiliary pump cell, 51 auxiliary pump electrode, 51a ceiling electrode part, 51b bottom electrode part, 51c, 51d auxiliary pump electrode Lead wire, 52 variable power supply, 61 3rd internal space, 70 heater section, 72 heater, 73 through hole, 74 heater insulation layer, 75 pressure dissipation hole, 76a, 76b heater lead wire, 80 main pump control oxygen content Pressure detection sensor cell, 81 Auxiliary pump control oxygen partial pressure detection sensor cell, 82 Measurement pump control oxygen partial pressure detection sensor cell, 83 sensor cell, 91 upper connector pad, 91a to 91d 1st to 4th upper connector pads, 92 lower connector Pads, 92a to 92d 1st to 4th lower connector pads, 95 side conducting parts, 95a to 95e 1st to 5th side conducting parts, 100,300 gas sensors, 101 sensor elements, 101a to 101f 1st to 6th surfaces , 109 green structure, 122c unfired inner pump electrode lead wire, 142a unfired reference electrode lead wire, 151d unfired auxiliary pump electrode lead wire, 144a unfired measurement electrode lead wire, 176b unfired heater lead wire, 191a, 191d Unfired 1st and 4th Upper Connector Pads, 192a, 192d Unfired 1st and 4th Lower Connector Pads, 195 Conductive Pastes, 195a-195e 1st to 5th Conductive Pastes, 200 Drying Systems, 201, 202 1st and 2nd printing equipment, 203,204 1st and 2nd inspection equipment, 211,212 1st and 2nd drying equipment, 215, 216 exhaust duct, 217 exhaust fan, 220 infrared heater, 222 heater body, 223 filament, 224 tube, 228 infrared irradiation area, 230 casing, 231 casing body, 232 reflector, 234 protection Plate, 237 Refrigerant flow path, 238 space, 240 reversing device, 241,242 1st and 2nd arms, 243, 244 1st and 2nd pinching parts, 245 rotating shafts, 246 support parts, 247 lifting devices, 248 lifting members , 250 Conveyor, 251a to 251e 1st to 5th Belt Conveyors, 252 Rollers, 253 Belts, 260 Control Devices, 270 Mounting Members, 271,272 Through Holes, 273 Recesses, 274,275 Protrusions, 276 Sides, 277 bottom, 278,279 grooves.

Claims (15)

A green structure having one or more ceramic green sheets and at least partially coated with a conductive paste is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to obtain the conductive paste. Drying process to dry,
Including
In the drying step, the green structure is cooled by sucking the atmosphere around the green structure while irradiating the infrared rays.
How to dry the conductive paste. In the drying step, the cooling is performed by sucking the atmosphere around the green structure upward.
The method for drying a conductive paste according to claim 1. A green structure having one or more ceramic green sheets and at least partially coated with a conductive paste is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to obtain the conductive paste. Drying process to dry,
Including
In the drying step, the green structure is cooled by a cooling gas while irradiating the infrared rays.
In the drying step, the green structure is placed on a mounting member having a through hole so that at least a part of the conductive paste is overlapped with a region where the through hole is present when viewed from the green structure side. In this state, the cooling gas is circulated in the through hole by sucking the atmosphere around the green structure while irradiating the infrared rays.
How to dry the conductive paste. In the drying step, the wind speed at the suction port of the exhaust duct for performing the suction is set to 0.5 m / sec to 10 m / sec.
The method for drying a conductive paste according to claim 3. A green structure having one or more ceramic green sheets and at least partially coated with a conductive paste is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to obtain the conductive paste. Drying process to dry,
Including
In the drying step, the green structure is cooled by a cooling gas while irradiating the infrared rays.
In the drying step, the green structure is placed on a mounting member having a through hole so that at least a part of the conductive paste is overlapped with a region where the through hole is present when viewed from the green structure side. In this state, the cooling gas is circulated in the through hole while irradiating the infrared rays.
In the drying step, an infrared heater is used to irradiate the infrared rays with the through holes located directly below the filament of the infrared heater.
How to dry the conductive paste. A green structure having one or more ceramic green sheets and at least partially coated with a conductive paste is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to obtain the conductive paste. Drying process to dry,
Including
In the drying step, the green structure is cooled by a cooling gas while irradiating the infrared rays.
In the drying step, the green structure is placed on a mounting member having a through hole so that at least a part of the conductive paste is overlapped with a region where the through hole is present when viewed from the green structure side. In this state, the cooling gas is circulated in the through hole while irradiating the infrared rays.
In the drying step, an infrared heater is used, and the distance between the infrared heater and the green structure is set to 10 mm to 80 mm.
How to dry the conductive paste. The green structure has a long rectangular parallelepiped shape.
In the drying step, a plurality of the green structures are placed on the above-mentioned placing member so that at least a part of the conductive paste overlaps with the region where the through holes are present when viewed from the side of each green structure. Further, the infrared rays are irradiated in a state where the plurality of green structures are placed with a gap in the direction perpendicular to the longitudinal direction of the green structure.
The method for drying a conductive paste according to any one of claims 3 to 6. The green structure has a long rectangular parallelepiped shape cut out by cutting a laminate of a plurality of ceramic green sheets, and at least a part of the cut surface is covered with the conductive paste.
The method for drying a conductive paste according to any one of claims 3 to 7. In the drying step, an infrared heater is used to irradiate the infrared rays so that the output P [W] of the infrared heater and the infrared irradiation time T [sec] both satisfy the following formulas (1) and (2).
T ≧ (-20/13) P + 380 equation (1)
T ≧ (-2/3) P + (596/3) Equation (2)
The method for drying a conductive paste according to any one of claims 1 to 8. In the drying step, a part of the green structure containing the conductive paste is irradiated with the infrared rays.
The method for drying a conductive paste according to any one of claims 1 to 9. In the drying step, the infrared rays are irradiated without sealing the conductive paste.
The method for drying a conductive paste according to any one of claims 1 to 10. A preparatory step of preparing a green structure having one or more ceramic green sheets, and a coating step of covering at least a part of the green structure with a conductive paste after the preparatory step.
After the coating step, the green structure is irradiated with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm to dry the conductive paste.
After the drying step, a firing step of firing the green structure to obtain ceramic parts,
Including
In the drying step, the green structure is cooled by sucking the atmosphere around the green structure while irradiating the infrared rays.
Manufacturing method for ceramic parts. In the drying step, the cooling is performed by sucking the atmosphere around the green structure upward.
The method for manufacturing a ceramic component according to claim 12. A first coating device that covers at least a part of the upper surface of a rectangular parallelepiped green structure having one or more ceramic green sheets with a conductive paste.
A first drying device that irradiates the upper surface of the green structure with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm.
An inversion device that inverts the green structure upside down,
A second coating device that covers at least a part of the upper surface of the green structure after inversion with a conductive paste.
A second drying device that irradiates the upper surface of the green structure after inversion with infrared rays having a peak wavelength in a wavelength region of 0.8 μm to 4 μm.
A transport device for transporting the green structure to the first coating device, the first drying device, the reversing device, the second covering device, and the second drying device in this order.
Equipped with
At least one of the first drying device and the second drying device cools the green structure by sucking the atmosphere around the green structure while irradiating the infrared rays.
Drying system. At least one of the first drying device and the second drying device performs the cooling by sucking the atmosphere around the green structure upward.
The drying system according to claim 14.

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