JP4299260B2 - Multilayer NTC thermistor - Google Patents

Description

  The present invention relates to a stacked NTC thermistor.

  In general, in an NTC thermistor having a predetermined B constant, the output voltage changes in a curve with respect to temperature, so that a microcomputer is required to process the output voltage, and the circuit becomes complicated. There was a problem to do.

In order to solve such a problem, a composite in which an NTC thermistor having a first B constant and an NTC thermistor having a second B constant different from the first B constant are connected in parallel or in series. A type NTC thermistor has been proposed (see, for example, Patent Document 1). According to such a composite NTC thermistor, the output voltage changes linearly with respect to temperature, so that the circuit can be simplified.
JP 2003-272904 A

  By the way, recently, it has been required to implement the composite NTC thermistor as described above with a single element.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a stacked NTC thermistor capable of obtaining an output voltage that changes linearly with respect to temperature.

In order to achieve the above object, a stacked NTC thermistor according to the present invention is a stacked NTC thermistor in which a plurality of thermistor layers are stacked, and includes a first thermistor layer having a first B constant, A second thermistor layer disposed on both sides of the one thermistor layer and having a second B constant lower than the first B constant; a first internal electrode disposed in one second thermistor layer; At the interface between the first external electrode connected to the first internal electrode and the first thermistor layer, the other second thermistor layer, or the first thermistor layer and the other second thermistor layer. And a second external electrode connected to the second internal electrode, and sandwiched between the first internal electrode and the second internal electrode in the stacking direction of the thermistor layer. The thickness of the second thermistor layer is Characterized in that it is thicker than the thickness of one of the thermistor layer. The multilayer NTC thermistor according to the present invention is a multilayer NTC thermistor formed by laminating a plurality of thermistor layers, and includes a first thermistor layer having a first B constant and both sides of the first thermistor layer. A second thermistor layer having a second B constant higher than the first B constant, a first internal electrode disposed in one second thermistor layer, and a first internal electrode, A second external electrode disposed at the interface between the connected first external electrode and the first thermistor layer, the other second thermistor layer, or the first thermistor layer and the other second thermistor layer. An internal electrode and a second external electrode connected to the second internal electrode, and in a region sandwiched between the first internal electrode and the second internal electrode in the stacking direction of the thermistor layer, The thermistor layer thickness of the first thermistor layer Characterized in that it is thinner than is.

  In this stacked NTC thermistor, the second thermistor layer is disposed on both sides of the first thermistor layer. The first internal electrode connected to the first external electrode is disposed in one second thermistor layer, and the second internal electrode connected to the second external electrode is the first In the other thermistor layer, or in the interface between the first thermistor layer and the other second thermistor layer. Accordingly, at least the first internal electrode, a part of one second thermistor layer, a part of the first thermistor layer, and the second part between the first external electrode and the second external electrode. The internal electrodes are connected in series. Here, the first B constant of the first thermistor layer and the second B constant of the second thermistor layer are different from each other. Therefore, according to this stacked NTC thermistor, the output voltage can be linearly changed with respect to the temperature. In addition, since the second thermistor layer is disposed on both sides of the first thermistor layer, deformation due to firing can be suppressed.

  The second thermistor layer is preferably arranged on both sides of the first thermistor layer so as to be point-symmetric with respect to the center of the first thermistor layer. Further, the second internal electrode is preferably disposed in the other second thermistor layer. At this time, the first internal electrode and the second internal electrode may be disposed on both sides of the first thermistor layer so as to be point-symmetric with respect to the center of the first thermistor layer. preferable. As a result, deformation due to firing can be further suppressed.

  In addition, a third internal electrode may be disposed at the interface between the first thermistor layer and the second thermistor layer so as to be positioned between the first internal electrode and the second internal electrode. preferable. Accordingly, diffusion at the boundary between the first thermistor layer and the second thermistor layer between the first internal electrode and the second internal electrode (the component of one thermistor layer is transferred to the other thermistor layer). Diffusion), and an output voltage that changes linearly with respect to temperature can be obtained with certainty.

  According to the multilayer NTC thermistor according to the present invention, an output voltage that changes linearly with respect to temperature can be obtained.

Hereinafter, a preferred embodiment of a multilayer NTC thermistor according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
[First Embodiment]

  As shown in FIG. 1, the stacked NTC thermistor 1 </ b> A includes a rectangular parallelepiped thermistor body 2 in which a plurality of ceramic layers are stacked. The thermistor body 2 includes a thermistor layer (first thermistor layer) 3 formed by laminating a plurality of ceramic layers having a B constant (first B constant) B1, and a B constant (second second) lower than the B constant B1. A thermistor layer (second thermistor layer) 4 formed by laminating a plurality of ceramic layers having B2. The ceramic layer constituting the thermistor layer 3 is formed of a perovskite-type metal oxide containing, for example, Mn and Co as main components and further containing at least one of Ni, Ca, Zr, Al, Cu, and Fe. The ceramic layer constituting the thermistor layer 4 is mainly composed of, for example, Mn and Ca, and further includes Zn, Co, Ti, Sm, Mg, Al, Ni, Zr, Nb, Sn, La, and Ta. It is made of a perovskite type metal oxide containing at least one kind.

  The thermistor layer 4 is laminated on both sides of the thermistor layer 3 so as to be point symmetric with respect to the center of the thermistor layer 3. That is, the thickness of the thermistor layer 4 in the stacking direction of the thermistor layers 3 and 4 (hereinafter simply referred to as “stacking direction”) is substantially the same on both sides of the thermistor layer 3.

  A rectangular internal electrode (first internal electrode) 5 is formed in one thermistor layer 4, and a rectangular internal electrode (second internal electrode) 6 is formed in the other thermistor layer 4. Is formed. These internal electrodes 5 and 6 are formed in each thermistor layer 4 laminated on both sides of the thermistor layer 3 so as to be point-symmetric with respect to the center of the thermistor layer 3. The internal electrodes 5 and 6 are made of, for example, Ag, Pd, or an Ag—Pd alloy.

  The inner end portion 5a of the internal electrode 5 does not reach the side surface 2b of the side surfaces 2a and 2b of the thermistor body 2 facing each other in the direction orthogonal to the stacking direction, and the outer end portion 5b of the internal electrode 5 The side 2a of the element body 2 is reached. On the other hand, the inner end 6 a of the internal electrode 6 does not reach the side surface 2 a of the thermistor body 2, and the outer end 6 b of the internal electrode 6 reaches the side 2 b of the thermistor body 2. Further, a part 5c on the inner end part 5a side of the internal electrode 5 and a part 6c on the inner end part 6a side of the internal electrode 6 are a part of one thermistor layer 4, a part of the thermistor layer 3, and the other part. The thermistor layers 4 face each other in the stacking direction.

  In a region A sandwiched between a part 5c of the internal electrode 5 and a part 6c of the internal electrode 6, a thickness of a part of one thermistor layer 4 in the stacking direction and one of the other thermistor layers 4 in the stacking direction. The thickness of the portion is substantially the same, and is thicker than the thickness of a part of the thermistor layer 3 in the stacking direction.

  An external electrode (first external electrode) 7 connected to the outer end 5 b of the internal electrode 5 is formed on the side surface 2 a of the thermistor body 2, and the internal electrode is formed on the side surface 2 b of the thermistor body 2. An external electrode (second external electrode) 8 connected to the outer end portion 6b of 6 is formed. These external electrodes 7 and 8 function as terminal electrodes. The external electrodes 7 and 8 are made of, for example, Ag, Pd, or an Ag—Pd alloy.

  Next, a manufacturing method of the stacked NTC thermistor 1A will be described.

  First, the oxide or carbonate raw materials are wet mixed so that the metal element ratios of Mn, Co, and Ni are 45 mol%, 45 mol%, and 10 mol%, respectively, and the uniformly mixed ceramic material is dried. And further calcined to obtain a calcined powder. The calcined powder is wet pulverized, and a binder is added to the pulverized calcined powder to form a slurry. Then, the slurry is formed into a sheet shape by a doctor blade method or a screen printing method, and then dried to obtain a green sheet that becomes a ceramic layer constituting the thermistor layer 3. Similarly, a green sheet that becomes a ceramic layer constituting the thermistor layer 4 is obtained using a green sheet containing a material containing 45 mol%, 45 mol%, and 10 mol% of Mn, Ca, and Co in the metal element ratio, respectively. . Then, on a predetermined green sheet serving as a ceramic layer constituting the thermistor layer 4, a conductive paste having Pd as a main component is screen-printed to form electrodes to be the internal electrodes 5 and 6.

  The green sheets thus obtained are laminated in a predetermined order, and pressure is applied to press the green sheets together to form a green sheet laminate. After the green sheet laminate is dried, it is cut into a predetermined size by a dicing saw or the like to obtain a laminate chip. And this laminated body chip | tip is baked at the temperature of 1100 degreeC-1200 degreeC, and the thermistor body 2 in which the internal electrodes 5 and 6 were formed is obtained. Subsequently, a conductive paste mainly composed of Ag is applied to the side surfaces 2a and 2b of the thermistor body 2 facing in the direction orthogonal to the laminating direction by a transfer method and baked to form the external electrodes 7 and 8. A type NTC thermistor 1A is completed.

  As described above, the thermistor layer 4 is disposed on both sides of the thermistor layer 3 in the stacked NTC thermistor 1A. The internal electrode 5 connected to the external electrode 7 is arranged in one thermistor layer 4, and the internal electrode 6 connected to the external electrode 8 is arranged in the other thermistor layer 4. Thereby, between the external electrode 7 and the external electrode 8, the internal electrode 5, a part of one thermistor layer 4, a part of the thermistor layer 3, a part of the other thermistor layer 4, and the internal electrode 6 are connected in series. Will be connected. Here, the B constant B2 of the thermistor layer 4 is lower than the B constant B1 of the thermistor layer 3. Therefore, according to the stacked NTC thermistor 1A, the output voltage can be linearly changed with respect to the temperature.

  In a region A sandwiched between the part 5c of the internal electrode 5 and the part 6c of the internal electrode 6, a part of the thermistor layer 4 in the stacking direction and the other thermistor layer 4 in the stacking direction. The thickness of a part of the thermistor layer 3 is substantially the same as that of the thermistor layer 3 in the stacking direction. Here, since the B constant B2 is lower than the B constant B1, the specific resistance of the thermistor layer 4 is generally lower than the specific resistance of the thermistor layer 3. However, according to the above-described configuration, since the electrical resistance of the thermistor layer 4 between the part 5c of the internal electrode 5 and the part 6c of the internal electrode 6 can be increased, it changes linearly with respect to temperature. It is possible to reliably obtain the output voltage to be performed.

  The thermistor layer 4 is laminated on both sides of the thermistor layer 3 so as to be point symmetric with respect to the center of the thermistor layer 3. Moreover, the internal electrode 5 and the internal electrode 6 are formed in each thermistor layer 4 laminated on both sides of the thermistor layer 3 so as to be point-symmetric with respect to the center of the thermistor layer 3. With such a configuration, deformation due to firing can be suppressed.

  In general, the characteristics of the surface layer of the thermistor body 2 have changed. However, in the stacked NTC thermistor 1A, the internal electrode 5, a part of one thermistor layer 4, and a part of the thermistor layer 3 are used. Since the output voltage characteristic with respect to temperature is taken inside the thermistor element body 2 such as a part of the other thermistor layer 4 and the internal electrode 6, the influence from the surface layer whose characteristics have changed is prevented.

  The stacked NTC thermistor 1A is not limited to the embodiment described above.

  For example, the B constant B2 of the thermistor layer 4 may not be completely the same on both sides of the thermistor layer 3, but may be substantially the same on both sides of the thermistor layer 3. Further, the B constant B1 of the thermistor layer 3 may be lower than the B constant B2 of the thermistor layer 4. In this case, in a region A sandwiched between the part 5c of the internal electrode 5 and the part 6c of the internal electrode 6, the thickness of a part of one thermistor layer 4 in the stacking direction and the other thermistor in the stacking direction. The thickness of a part of the layer 4 is preferably thinner than the thickness of a part of the thermistor layer 3 in the stacking direction.

  Moreover, the thickness of the thermistor layer 4 in the stacking direction may be different from each other on both sides of the thermistor layer 3 as shown in FIGS. Also in this case, it is possible to suppress deformation due to firing as compared with the case where the thermistor layer 4 is laminated only on one side of the thermistor layer 3. Moreover, each thermistor layer 3 and 4 may consist of a single ceramic layer.

Furthermore, the internal electrode 6 may be formed at the interface between the thermistor layer 3 and the other thermistor layer 4 as shown in FIG. 2, or formed in the thermistor layer 3 as shown in FIG. May be. Also in these cases, between the external electrode 7 and the external electrode 8, the internal electrode 5, a part of one thermistor layer 4, a part of the thermistor layer 3 and the internal electrode 6 are connected in series. Therefore, it becomes possible to change the output voltage linearly with respect to the temperature.
[Second Embodiment]

  As shown in FIG. 4, the stacked NTC thermistor 1 </ b> B has an internal structure that is positioned between the internal electrode 5 and the internal electrode 6 at the interface between the thermistor layer 3 and the thermistor layers 4 stacked on both sides thereof. This is different from the above-described stacked NTC thermistor 1A in that an electrode (third internal electrode) 9 is formed. Specifically, the internal electrode 9 is formed at the interface between the thermistor layer 3 and each thermistor layer 4 so as to block the part 5 c of the internal electrode 5 and the part 6 c of the internal electrode 6.

  Also in the multilayer NTC thermistor 1B configured as described above, the output voltage can be linearly changed with respect to the temperature for the same reason as in the multilayer NTC thermistor 1A described above.

  Further, diffusion at the boundary between the thermistor layer 3 and each thermistor layer 4 between the part 5c of the internal electrode 5 and the part 6c of the internal electrode 6 (the component of one thermistor layer is transferred to the other thermistor layer). Diffusion), and an output voltage that changes linearly with respect to temperature can be obtained with certainty.

  The present invention is not limited to the first and second embodiments described above.

  For example, like the stacked NTC thermistor 1C shown in FIG. 5, the internal electrode 6 is formed in the thermistor layer 3, and the internal electrode 5 is formed in each thermistor layer 4 stacked on both sides of the thermistor layer 3. May be.

  Further, in the case where the thermistor layers 4 are laminated on both sides of each of the plurality of thermistor layers 3 as in the laminated NTC thermistor 1C shown in FIG. 6, the thermistors laminated between the adjacent thermistor layers 3 and 3 The internal electrode 6 may be formed in the layer 4, and the internal electrode 5 may be formed at the interface between each thermistor layer 3 of the adjacent thermistor layers 3 and 3 and the thermistor layer 4 laminated outside thereof.

  Further, as in the stacked NTC thermistor 1C shown in FIG. 7, the direction in which the internal electrode 5 formed in one thermistor layer 4 and the internal electrode 6 formed in the other thermistor layer 4 face each other is The direction is not limited to the direction orthogonal to the stacking direction, and may be a direction intersecting with both the direction orthogonal to the stacking direction and the stacking direction. A plurality of pairs of internal electrodes 5 and internal electrodes 6 facing each other in the direction orthogonal to the stacking direction and the direction crossing the stacking direction may be formed in the thermistor body 2. Even if the internal electrode 11 is formed in the thermistor layer 3 so as to be located between the internal electrode 5 and the internal electrode 6 facing each other in the direction orthogonal to the stacking direction and the direction intersecting with the stacking direction. Good.

1 is a cross-sectional view of a first embodiment of a multilayer NTC thermistor according to the present invention. It is sectional drawing of the modification of the laminated | stacked NTC thermistor shown by FIG. It is sectional drawing of the modification of the laminated | stacked NTC thermistor shown by FIG. It is sectional drawing of 2nd Embodiment of the laminated | stacked NTC thermistor which concerns on this invention. It is sectional drawing of the modification of the lamination type NTC thermistor which concerns on this invention. It is sectional drawing of the modification of the lamination type NTC thermistor which concerns on this invention. It is sectional drawing of the modification of the lamination type NTC thermistor which concerns on this invention.

Explanation of symbols

1A, 1B, 1C ... stacked NTC thermistor, 3 ... thermistor layer (first thermistor layer), 4 ... thermistor layer (second thermistor layer), 5 ... internal electrode (first internal electrode), 6 ... internal Electrode (second internal electrode), 7 ... external electrode (first external electrode), 8 ... external electrode (second external electrode), 9 ... internal electrode (third internal electrode).

Claims (6)

A laminated NTC thermistor in which a plurality of thermistor layers are laminated,
A first thermistor layer having a first B constant;
A second thermistor layer disposed on both sides of the first thermistor layer and having a second B constant lower than the first B constant;
A first internal electrode disposed in one of the second thermistor layers;
A first external electrode connected to the first internal electrode;
A second internal electrode disposed in the first thermistor layer, in the other second thermistor layer, or at the interface between the first thermistor layer and the other second thermistor layer;
A second external electrode connected to the second internal electrode ,
In the region sandwiched between the first internal electrode and the second internal electrode in the stacking direction of the thermistor layer, the thickness of the second thermistor layer is thicker than the thickness of the first thermistor layer. and laminated NTC thermistor, characterized in that are. A laminated NTC thermistor in which a plurality of thermistor layers are laminated,
A first thermistor layer having a first B constant;
A second thermistor layer disposed on both sides of the first thermistor layer and having a second B constant higher than the first B constant;
A first internal electrode disposed in one of the second thermistor layers;
A first external electrode connected to the first internal electrode;
A second internal electrode disposed in the first thermistor layer, in the other second thermistor layer, or at the interface between the first thermistor layer and the other second thermistor layer;
A second external electrode connected to the second internal electrode,
In the region sandwiched between the first internal electrode and the second internal electrode in the stacking direction of the thermistor layer, the thickness of the second thermistor layer is smaller than the thickness of the first thermistor layer. Multilayer NTC thermistor characterized by The second thermistor layer, wherein a center of the first thermistor layer so as to be point symmetric basis, according to claim 1 or 2, characterized in that disposed on both sides of the first thermistor layer Multilayer NTC thermistor.   4. The stacked NTC thermistor according to claim 1, wherein the second internal electrode is disposed in the other second thermistor layer. 5. The first internal electrode and the second internal electrode are arranged on both sides of the first thermistor layer so as to be point-symmetric with respect to the center of the first thermistor layer. The multilayer NTC thermistor according to claim 4 . A third internal electrode is disposed at the interface between the first thermistor layer and the second thermistor layer so as to be positioned between the first internal electrode and the second internal electrode. The multilayer NTC thermistor according to any one of claims 1 to 5 , wherein

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