JP2009206498A - Thermistor element, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermistor element and a manufacturing method thereof, in which peeling is suppressed against a thermal shock even with a structure having dissimilar materials laminated. <P>SOLUTION: The thermistor element includes a first thermistor layer 2A composed of a mixed sintered body consisting of two or more kinds of materials, a second thermistor layer 2B laminated on the first thermistor layer 2A and composed of a mixed sintered body consisting of two or more kinds of materials and having a resistance value and a B constant different from those of the first thermistor layer 2A, and a pair of lead wires each having one end portion connected to both the first thermistor layer 2A and the second thermistor layer 2B, the first thermistor layer 2A and the second thermistor layer 2B having one or more kinds of mutually common materials 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermistor element used for temperature measurement such as in automobiles and a method for manufacturing the thermistor element.

  Generally, a thermistor temperature sensor is employed as a temperature sensor for measuring the catalyst temperature around the automobile engine, the exhaust system temperature, and the like. The thermistor element used in this thermistor temperature sensor is, for example, used as a temperature sensor for the above-mentioned automobile-related technology, information equipment, communication equipment, medical equipment, housing equipment, etc., and is an oxide semiconductor having a large negative temperature coefficient. A sintered element is used.

In recent years, there has been an increasing demand for thermistor elements capable of measuring from room temperature to high temperatures. In particular, in order to measure the catalyst temperature and the like around an automobile engine, a thermistor element capable of measuring up to a high temperature around 900 ° C. is required. As such a thermistor element material that can be measured up to a high temperature, Y (Cr, Mn) O ₃ -based perovskite oxide is known as described in Non-Patent Document 1 and Patent Document 1, for example.

  However, while it is possible to measure from around room temperature to around 900 ° C., there is a problem that measurement accuracy deteriorates because the change in resistance at a high temperature range is small. Thus, for the purpose of improving the sensitivity in a high temperature range, for example, Patent Document 2 proposes a thermistor structure in which materials having two or more different resistance values and B constants are stacked. In this technique, desired characteristics can be obtained in a wide temperature range by combining two or more materials.

Kurano, “Development of catalyst temperature sensor for NOx catalyst control”, Denso Technical Review, Vol. 5, no. 2, 2000 Japanese Patent No. 3362651 Japanese Patent Laid-Open No. 5-34208

The following problems remain in the conventional technology.
That is, when a structure in which different materials of the thermistor material are laminated is employed, there are disadvantages such as separation of the bonded layers during thermal shock due to differences in thermal expansion coefficients due to bonding of different materials and insufficient adhesion at the interface.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a thermistor element that can suppress delamination against thermal shock and a method of manufacturing the thermistor element even in a structure in which different kinds of materials are laminated. .

The present invention employs the following configuration in order to solve the above problems.
That is, the thermistor element of the present invention includes a first thermistor layer composed of a mixed sintered body made of two or more materials, and two or more materials laminated on the first thermistor layer and the first thermistor layer. One end is connected to both the first thermistor layer and the second thermistor layer, and the second thermistor layer composed of a mixed sintered body having a resistance value and a B constant different from those of the first thermistor layer. A pair of lead wires, wherein the first thermistor layer and the second thermistor layer have one or more kinds of materials common to each other.

  That is, in this thermistor element, the laminated first thermistor layer and the second thermistor layer have one or more kinds of materials that are common to each other. The material can serve as a binder to improve the bonding strength. In addition, by increasing the ratio of the common material, the thermal expansion coefficient can be made closer and the bonding strength can be increased.

In the thermistor element of the present invention, the first thermistor layer is a complex oxide represented by a general formula: (1-z) Y (Cr _x Mn _1-x ) O ₃ + zY ₂ O ₃ , The second thermistor layer is a composite oxide represented by a general formula: (1-z) Y (Cr _y Mn _1-y ) O ₃ + zY ₂ O ₃ (where x ≠ y) . That is, in this thermistor element, the first thermistor layer and the second thermistor layer are thermistor materials of Y (Cr, Mn) O ₃ based perovskite oxide and Y ₂ O ₃ as a common material. Therefore, it is possible to measure up to a high temperature around 900 ° C., and the thermal expansion coefficient becomes closer and a high bonding strength can be obtained. Furthermore, not only the binder effect but also the resistance value can be adjusted by the amount of Y ₂ O ₃ which is an insulating material.

  The method for producing the thermistor element of the present invention includes a first green sheet forming step of forming a mixed calcined powder made of two or more materials into a slurry and then forming the first green sheet. A second green sheet forming step of forming a mixed calcined powder composed of two or more materials having a resistance value and a B constant different from those of a sintered body of the green sheet into a slurry and then forming the second green sheet; A laminated sheet forming step in which a green sheet and the second green sheet are laminated together to form a laminated sheet, and a pair of lead wires with one end connected to both the first green sheet and the second green sheet Firing the laminated sheet to produce a thermistor element in which a first thermistor layer and a second thermistor layer are laminated, and the first green Sheet and the second green sheet, characterized in that it contains one or more materials that are common to each other.

  That is, in this method of manufacturing the thermistor element, the first green sheet and the second green sheet containing one or more kinds of materials common to each other are laminated to form a laminated sheet, and thermistor element is produced by sintering. The thermistor layers of different materials can be easily stacked, and the thickness of each layer can be controlled with high accuracy, so that high productivity can be obtained.

  Further, in the method for producing the thermistor element of the present invention, the firing step is performed in a state where the laminated sheet is cut into a plurality of chip-shaped molded bodies, and groove portions are formed on both side surfaces of the molded body, The lead wire is connected in a state of being fitted into the groove. That is, in this method of manufacturing the thermistor element, the groove portions are formed on both side surfaces of the molded body, so that the lead wire is connected in a state of being fitted into the groove portion, and the groove portion and the lead wire fitted into the groove portion are connected. Contacting at a plurality of locations increases the contact area, and the high bonding strength can prevent element destruction due to heat cycle. The connection of the lead wire to the groove portion may be before or after firing.

The present invention has the following effects.
That is, according to the thermistor element and the manufacturing method thereof according to the present invention, the stacked first thermistor layer and second thermistor layer have one or more kinds of materials common to each other. As the expansion coefficient becomes close, the bonding strength can be improved, and it is difficult to peel off against thermal shock or the like due to repeated use, and high reliability can be obtained.
Thus, since the thermistor element of the present invention has high reliability with a suitable resistance value in a wide temperature range, it is particularly suitable as a high-temperature measurement sensor for detecting the catalyst temperature around the automobile engine and the exhaust system temperature.

  A first embodiment of a thermistor element and a manufacturing method thereof according to the present invention will be described below with reference to FIGS.

  As shown in FIGS. 1 and 2, the thermistor element 1 of the present embodiment includes a first thermistor layer 2A composed of a mixed sintered body made of two or more materials, and the first thermistor layer 2A. A second thermistor layer 2B made of a mixed sintered body made of two or more materials and having a resistance value and a B constant different from those of the first thermistor layer 2A, and the first thermistor layer 2A and the second thermistor layer 2A. A pair of lead wires 3 having one end connected to both of the thermistor layers 2B. The first thermistor layer 2A and the second thermistor layer 2B constitute the element body 2.

The first thermistor layer 2A and the second thermistor layer 2B are composed of a mixed sintered body of a metal oxide sintered body that is a thermistor material and an insulator material. Further, the first thermistor layer 2A and the second thermistor layer 2B have one or more kinds of materials common to each other.
That is, the first thermistor layer 2A is composed of the first thermistor material 4 of the metal oxide sintered body and the common material 5 of the insulator material, and the second thermistor layer 2B is made of the metal oxide sintered body. It is comprised by the 2nd thermistor material 6 and the common material 5 of an insulator material.

For example, in the present embodiment, the first thermistor layer 2A is a composite oxide represented by the general formula: (1-z) Y (Cr _x Mn _1-x ) O ₃ + zY ₂ O ₃ , The thermistor layer 2B is a composite oxide represented by the general formula: (1-z) Y (Cr _y Mn _1-y ) O ₃ + zY ₂ O ₃ (where x ≠ y). That is, the first thermistor layer 2A has Y (Cr _x Mn _1-x ) O ₃ as the first thermistor material 4, and the second thermistor layer 2B has Y (Cr _y Mn as the second thermistor material 6. and a _{1-y) O 3.} Further, Y ₂ O ₃ is adopted as a common material 5 for the first thermistor layer 2A and the second thermistor layer 2B.

The first thermistor layer 2A, for example _Y and _{(Cr 0.5 Mn} 0.5) _{O 3} to 30 _mol%, a mixed layer of sintered Y and the 2 _{O 3} 70 mol%, and the second The thermistor layer 2B is, for example, a layer obtained by mixing and sintering 30 mol% of YCrO ₃ and 70 mol% of Y ₂ O ₃ . The first thermistor layer 2A has a resistance value of 200 kΩ at 25 ° C. and a B constant of 2000K, and the second thermistor layer 2B has a resistance value of 1 GΩ and a B constant of 7000 K at 25 ° C. In addition, by increasing the proportion of Y ₂ O ₃ that is the common material 5, the thermal expansion coefficient can be made closer and the bonding strength can be increased.

A manufacturing method of the thermistor element 1 and a manufacturing method and a structure of a thermistor temperature sensor using the thermistor element 1 will be described below with reference to FIGS.
First, as raw materials for the first thermistor layer 2A, each powder of Y ₂ O ₃ , Cr ₂ O ₃ and MnO ₂ was weighed in a molar ratio of 25: 12.5: 25 and then placed in a ball mill, Mix with pure water for about 24 hours. The mixed material was taken out and dried, and then calcined at 1300 ° C. for 5 hours, and calcined Y (Cr _0.5 Mn _0.5 ) O ₃ in the above general formula x = 0.5 Get. Next, the calcined powder is pulverized with a ball mill using Zr balls and pure water, and then dried.

Further, Y ₂ O ₃ was added to this calcined powder so that Y (Cr _0.5 Mn _0.5 ) O ₃ and Y ₂ O ₃ were in a molar ratio of 30:70, and mixed by a ball mill, Dry into mixed calcined powder. Next, PVB, a solvent, a dispersant, and a plasticizer are added to the mixed calcined powder and mixed with a ball mill to produce a slurry. This slurry is formed into a first green sheet having a thickness of 500 μm by a doctor blade method (first green sheet forming step).

On the other hand, as a raw material for the second thermistor layer 2B, each powder of Y ₂ O ₃ and Cr ₂ O ₃ is weighed in a molar ratio of 50:50 and then placed in a ball mill, and an appropriate amount of Zr balls and pure water are added. Mix for about 24 hours. The mixed material is taken out and dried, and then fired at 1300 ° C. for 5 hours to obtain YCrO ₃ calcined powder in which y = 1.0 in the above general formula. Next, the calcined powder is pulverized with a ball mill using Zr balls and pure water, and then dried.

Further, Y ₂ O ₃ is added to the calcined powder such that YCrO ₃ and Y ₂ O ₃ are in a molar ratio of 30:70, mixed by a ball mill, and dried to obtain a mixed calcined powder. Next, PVB, a solvent, a dispersant, and a plasticizer are added to the mixed calcined powder and mixed with a ball mill to produce a slurry. This slurry is formed into a second green sheet having a thickness of 500 μm by a doctor blade method (second green sheet forming step).

  Next, the first green sheet and the second green sheet were laminated by a thermocompression press and adhered (laminated sheet forming step), then punched out with a φ2.0 mm mold, diameter 2.0 mm, thickness 1 A pre-firing element body 2 having a disc shape of 0 mm is produced. After that, a hole with a diameter of 0.3 mm was drilled through the first green sheet and the second green sheet with a precision drill in two places, and one end of a Pt (platinum) wire with a diameter of 0.3 mm was inserted into these holes. Insert the lead wire 3.

  The element body 2 in which the first thermistor layer 2 </ b> A and the second thermistor layer 2 </ b> B are laminated by firing the molded article in this state after debinding treatment at 1600 ° C. for 5 hours, and the element A thermistor element 1 having two lead wires 3 connected at one end to the main body 2 is obtained (firing process).

  Next, as shown in FIG. 3, a tube 7 made of an insulating ceramic is fitted so as to wrap around the element body 2 of the thermistor element 1. Further, the two lead wires 3 are inserted into the respective holes 8a of the two-hole insulating tube 8 made of alumina, and the lead wires 3 are protected to the root by the two-hole insulating tube 8. Then, the thermistor temperature sensor 10 is obtained by putting the thermistor element 1 in this state into a cylindrical stainless steel case 9 whose tip is closed to ensure hermeticity.

  In the thermistor element 1 and the thermistor temperature sensor 10 including the thermistor element 1, the resistance value changes from about 200 kΩ to about 100 Ω at a high temperature from room temperature to about 900 ° C., and can be measured in a wide temperature range. In addition, since the first thermistor layer 2A and the second thermistor layer 2B, which are two kinds of thermistor materials having different characteristics, are connected in parallel by a pair of lead wires 3, as shown in FIG. The change in resistance value is large, and measurement can be performed with higher sensitivity.

  As described above, in the present embodiment, the laminated first thermistor layer 2A and the second thermistor layer 2B have one or more kinds of materials common to each other, so that the thermal expansion coefficients are close to each other. The common material plays a role of a binder and can improve the bonding strength.

Further, since the first thermistor layer 2A and the second thermistor layer 2B are thermistor materials of Y (Cr, Mn) O ₃ -based perovskite oxide and use Y ₂ O ₃ as a common material, 900 It can be measured up to a high temperature of about 0 ° C., and the thermal expansion coefficient becomes closer and higher bonding strength can be obtained. Furthermore, not only the binder effect but also the resistance value can be adjusted by the amount of Y ₂ O ₃ which is an insulating material.

  Furthermore, in the manufacturing method of the thermistor element 1, the first green sheet and the second green sheet containing one or more kinds of common materials are laminated to form a laminated sheet, and the thermistor element 1 is manufactured by sintering. Therefore, the first thermistor layer 2A and the second thermistor layer 2B made of different materials can be easily stacked, and the thickness of each layer can be controlled with high accuracy, so that high productivity can be obtained.

  Next, a second embodiment of the thermistor element and the manufacturing method thereof according to the present invention will be described below with reference to FIGS. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that in the first embodiment, a pair of lead wires 3 are inserted into a pair of through-holes and fired together, whereas the first embodiment is connected to the first embodiment. In the thermistor element of 2 embodiment and its manufacturing method, as shown in FIGS. 5-7, the groove part 22a is each formed in the both sides | surfaces of the laminated molded object 22, and the lead wire 25 is inserted in the groove part 22a after baking. Are connected.

That is, in the second embodiment, as shown in FIG. 5, first, the ceramic green sheets 21 of the first green sheet and the second green sheet are first formed (green sheet forming step), as in the first embodiment. Next, a plurality of ceramic green sheets 21 of the first green sheets and ceramic green sheets 21 of the second green sheets are laminated to form a laminated sheet 23 (lamination process).
Next, as shown in FIG. 5, a portion that becomes the groove portion 22a of the molded body 22 of the laminated sheet 23 is punched into a circular shape with a pin having a predetermined diameter, and cut into a lattice shape so as to pass through the center of the circle. The groove portions 22 a are respectively formed on the side surfaces of the adjacent molded bodies 22. As shown in FIGS. 6 (a) and 6 (b), a molded body 22 in which groove portions 22a are respectively formed on a plurality of both side surfaces is formed from the laminated sheet 3 (molded body cutting process, molded body forming process).

The groove 22 a is formed in a circular arc shape corresponding to the outer peripheral surface of the lead wire 25. In the present embodiment, a groove portion 22a having a substantially semicircular cross section is formed. The size of the semicircle is set in consideration of the shrinkage of ceramics during firing. In addition, the resistance value can be adjusted by adjusting the punching position and cutting position of the circle. (The resistance value can also be adjusted by adjusting the thickness of the sheet.)
Further, instead of cutting the molded body 22, the molded body 22 may be extracted by punching with a mold having a predetermined shape.
In this way, for example, a molded body 22 in which semicircular grooves are provided on both side surfaces of a chip-shaped molded body having a thickness of 1 mm and a 1.2 mm square is obtained. After the ceramic is fired, the lead wire with a diameter of 0.3 mmΦ is adjusted by adjusting the size of the semicircular groove of the molded body before firing so that it becomes a semicircular groove with a diameter of 0.3 mm when the electrode paste 26 is applied. 25 can be attached.

  Further, as shown in FIG. 7, the molded body 22 is fired to form a metal oxide sintered body 24 (firing step), and a pair of lead wires 25 are connected to both side surfaces of the metal oxide sintered body 24 ( Electrode wire connecting step). At this time, the lead wire 25 is connected in a state of being fitted into the groove 22a.

  The lead wire 25 is connected by fitting the lead wire 25 into the groove portion 22a in a state where a heat resistant electrode paste 26 such as Pt paste or the like is applied to the groove portion 22a, and baking the electrode paste 26 in this state. The lead wire 25 is joined to the groove 22a. In order to further strengthen the electrode wire bonding, the electrode paste 26 may be bonded so as to cover the lead wire 25. Further, the lead wire 25 may be connected by welding or the like.

  The lead wire 25 may be a Pt wire, but it is preferable to employ another electrode wire that is inexpensive and has high heat resistance. For example, a metal wire (heat resistant alloy wire) having a heat resistance of 1000 ° C. or higher is used as the lead wire 25, and a JIS 310 SUS wire is particularly preferable. More preferably, the surface of the lead wire 25 is covered with Pt. That is, the lead wire 25 having the surface of SUS310S plated with Pt is employed. Moreover, you may employ | adopt the Pt-SUS clad wire by which the outer side was covered with Pt. Further, an Inconel (registered trademark) wire, a Ni alloy wire, a Pd alloy wire, or the like may be employed.

  In addition, as lead wire 25, it becomes possible to ensure heat resistance of 1000 ° C. or more by increasing the CrNi ratio in stainless steel like SUS310S wire. In the case of other SUS lines, for example, SUS316L line and SUS304 line are brittle, and other transition metal lines such as Mo and W lines are also oxidized and brittle at 1000 ° C.

  As a result, as shown in FIG. 7, a thermistor element 27 having a metal oxide sintered body 24 and two lead wires 25 is obtained.

As described above, in the method for manufacturing the thermistor element according to the second embodiment, since the lead wire 25 is connected in a state of being fitted into the groove 22a formed on both side surfaces of the metal oxide sintered body 24, the groove 22a The contact area is increased by contact with the lead wire 25 fitted in the groove 22a at a plurality of locations, and destruction of the device due to heat cycle can be prevented by high bonding strength.
In particular, since the groove portion 22a is formed in a cross-sectional arc shape corresponding to the outer peripheral surface of the lead wire 25, the contact area is further increased by the surface contact between the lead wire 25 having a circular cross-section and the groove portion 22a having a cross-sectional arc shape. Thus, higher bonding strength can be obtained.

Moreover, in the said manufacturing method, by producing with the sheet | seat method mentioned above, the thickness of the molded object 22 can be adjusted with the number of lamination | stacking of the green sheet 21, and resistance value dispersion | variation can be suppressed.
In addition, since the lead wire 25 is connected after the firing step, the lead wire 25 other than the Pt wire can be used without the heat resistance of 1400 ° C. or higher during firing.

  In addition, in the manufacturing method of the said 2nd Embodiment, although the green sheet 21 is laminated | stacked as an efficient method, the process of cutting out in chip shape and producing the some molded object 22 is employ | adopted as a molded object formation process. A plurality of sheet-like molded sheet bodies are cut out or extracted from the green sheet 21 in a predetermined shape (molded sheet body forming process), and a plurality of molded sheet bodies are stacked to form a chip-shaped molded body 22 (laminate process). May be adopted. In this case, grooves are formed on both side surfaces of the molded sheet body, and the groove portions extending in one direction are obtained on both side surfaces of the molded body 22 by laminating so that the groove portions of each molded sheet body are continuous. Can do.

  In addition, although the groove part with a circular arc cross section is preferable like the said 2nd Embodiment, as shown in FIG. 8, it is good also as the molded object 32 which employ | adopted the groove part 32a with a rectangular cross section. In this case, the lead wire 25 and the groove portion 32a are joined in line contact with each other at at least three locations. More preferably, the gap between the lead wire 25 and the ceramic of the groove 32a having a rectangular cross section is filled with an electrode paste to increase the electrode contact area.

  Moreover, in the said 2nd Embodiment, although the electrode wire was fitted and connected to the groove part of the metal oxide sintered compact after baking, it fired together in the state which fitted the electrode line in the groove part of the molding before baking. You can connect them. In this case, it is preferable to use a Pt wire (including a Pt alloy wire) that can withstand a firing temperature of 1400 ° C. or higher as the electrode wire, and use a Pt paste (including a Pt alloy paste) as the electrode paste.

  Next, the results of evaluation based on examples in which the thermistor element according to the present invention was actually manufactured will be specifically described.

Table 1 shows the results of actually conducting a heat cycle test (HCT) and examining the presence or absence of cracks for the examples of the thermistor element 1 manufactured according to the first embodiment. As a comparison, Comparative Example 1 having an element body in which a thermistor layer made of a thermistor material of Mn—Ni—Cu series and a thermistor material made of a ZrO ₂ —Y ₂ O ₃ series was joined, and Mn—Co Comparative Example 2 having an element body in which a thermistor layer made of a thermistor material and a thermistor layer made of a ZrO ₂ —Y ₂ O ₃ thermistor material are joined, and Y (Cr _0.5 Mn _{0. 5} ) Comparative Example 3 having an element body in which a thermistor layer made of a thermistor material made of Y) and a thermistor layer made of a YCrO ₃ thermistor material are joined in the same manner, and a heat cycle test is conducted in the same manner to check for cracks. Table 1 also shows the results of the examination.

In addition, the said heat cycle test prepared 20 each of this Example and each comparative example, and performed 1000 cycles by alternating room temperature 6 minutes and 900 degreeC 6 minutes.
As can be seen from the test results, in Comparative Examples 1 to 3, all the cracks occurred or a part thereof, whereas in this example, no cracks occurred.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  As in the first embodiment, it is preferable to punch out each portion of the thermistor element 1 in a predetermined shape from the laminated sheet before debinding and firing, but after firing, the element body of the thermistor element 1 is fired. You may cut and produce the part used as 2 separately, respectively.

In the thermistor element of 1st Embodiment which concerns on this invention, and its manufacturing method, it is simple sectional drawing which shows a thermistor element. In 1st Embodiment, it is typical sectional drawing which shows the element main body of a thermistor element. In 1st Embodiment, it is sectional drawing which shows a thermistor temperature sensor. In 1st Embodiment, it is a graph which shows the resistance value with respect to the temperature in the 1st thermistor layer, the 2nd thermistor layer, and the element main body which joined these. It is a top view which shows the ceramic green sheet of a cutting state in 2nd Embodiment of the manufacturing method of the thermistor element which concerns on this invention, and a thermistor element. In 2nd Embodiment, it is the top view and side view which show a molded object. In 2nd Embodiment, it is the typical front view and side view which show a thermistor element. In 2nd Embodiment, it is a front view which shows the other example of a molded object.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,7 ... Thermistor element, 2 ... Element main body, 2A ... 1st thermistor layer, 2B ... 2nd thermistor layer, 3,25 ... Lead wire, 4 ... 1st thermistor material, 5 ... Common material, 6 ... 1st 2 thermistor material, 9 ... case, 10 ... thermistor temperature sensor, 21 ... ceramic green sheet, 22, 32 ... molded body, 22a, 32a ... groove, 23 ... laminated sheet

Claims (4)

A first thermistor layer composed of a mixed sintered body made of two or more materials;
A second thermistor layer made of a mixed sintered body made of two or more materials and having a resistance value and a B constant different from those of the first thermistor layer, laminated on the first thermistor layer;
A pair of lead wires having one end connected to both the first thermistor layer and the second thermistor layer;
The thermistor element, wherein the first thermistor layer and the second thermistor layer have one or more kinds of materials common to each other. The thermistor element according to claim 1,
The first thermistor layer is a composite oxide represented by a general formula: (1-z) Y (Cr _x Mn _1-x ) O ₃ + zY ₂ O ₃
The second thermistor layer is a composite oxide represented by a general formula: (1-z) Y (Cr _y Mn _1-y ) O ₃ + zY ₂ O ₃ (where x ≠ y) Thermistor element. A first green sheet forming step in which a mixed calcined powder made of two or more materials is made into a slurry and then formed into a first green sheet;
When sintered, the second green sheet is formed into a second green sheet after the mixed calcined powder composed of two or more materials having different resistance values and B constants from the sintered body of the first green sheet is made into a slurry. Sheet forming step;
A laminated sheet forming step of laminating the first green sheet and the second green sheet to form a laminated sheet;
The laminated sheet was fired with a pair of lead wires connected to both the first green sheet and the second green sheet, and the first thermistor layer and the second thermistor layer were laminated. A firing step for producing a thermistor element,
The method of manufacturing a thermistor element, wherein the first green sheet and the second green sheet contain one or more kinds of materials common to each other. In the manufacturing method of the thermistor element according to claim 3,
The firing step is performed in a state where the laminated sheet is cut into a plurality of chip-shaped molded bodies,
Grooves are formed on both side surfaces of the molded body,
A method for producing a thermistor element, wherein the lead wire is connected in a state of being fitted in the groove.

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