JP5324390B2 - Laminated electronic components - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated electronic component that is improved in electric characteristics and is reduced in size. <P>SOLUTION: The present invention relates to a laminated thermistor element including an element body 10 in a cubic shape that has a ceramic layer 4 and internal electrode layers 6a to 8b laminated alternately, an insulating film 11 formed at least on four entire side faces of the element body 10, a pair of first external electrode films 12a and 12b formed on a pair of end faces of the element body 10 except the four side faces and coming into contact with one of the internal electrode layers 6a to 8b, and a pair of second external electrode films 14a and 14b covering the respective first external electrode films 12a and 12b and covering ends of the insulating film 11 formed on the four side faces within a prescribed overlap range L1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to the structure of multilayer electronic components such as thermistors, varistors, inductors, and capacitors.

  For example, a laminated thermistor element has a rectangular parallelepiped element body in which ceramic layers and internal electrode layers are alternately laminated. External electrodes are formed on both end faces of the element body, and the external electrodes are connected to the alternately stacked internal electrodes. Inside the element body, a ceramic layer sandwiched between a pair of internal electrodes serves as a resistor layer to constitute a thermistor element.

  In the multilayer electronic component including the thermistor element, electrical characteristics are improved and the size can be reduced by increasing the overlapping area of the internal electrode layers stacked with the ceramic layer interposed therebetween. Therefore, an electrode pattern has been developed in which the width of the internal electrode layer is designed to be the same as the width of the element body (see Patent Document 1).

  However, when the width of the internal electrode layer is designed to be the same as the width of the element body, the side end in the width direction of the internal electrode layer is exposed from the element body. In consideration of the bondability when the electronic component is brazed with solder, the external electrode has a shape that covers the four side surfaces near the end surface from the end surface of the element body. Therefore, the other end (free end) of the internal electrode layer may be short-circuited with the other external electrode located on the opposite side to the one external electrode to which one end of the internal electrode layer is connected. .

  Therefore, the other end of the internal electrode layer cannot be extended to a position in contact with the other external electrode, which cannot increase the overlapping area of the internal electrode layers stacked with the ceramic layer interposed therebetween. It is the limit. Note that Patent Document 1 discloses that a side surface of an element body that is not covered with an external electrode is covered with an insulating protective film in order to improve moisture resistance. However, the insulating protective film described in Patent Document 1 is not formed between the external electrode and the element body.

JP 2001-250702 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a multilayer electronic component with improved electrical characteristics and reduced size.

In order to achieve the above object, the multilayer electronic component according to the present invention is
A rectangular parallelepiped element body in which ceramic layers and internal electrode layers are alternately laminated;
An insulating film formed on at least four side surfaces of the element body;
A pair of first external electrode films formed on a pair of opposed end faces excluding the four side surfaces of the element body, and connected to any of the internal electrode layers;
A pair of second external electrode films covering the first external electrode films and covering the end portions of the insulating film formed on the four side surfaces within a predetermined overlapping range.

  In the multilayer electronic component according to the present invention, insulating films are formed on the four side surfaces of the element body. Therefore, even if the width of the internal electrode layer is set to be the same as the width of the element body, the side end in the width direction of the internal electrode layer is not exposed from the side surface of the element body.

  Also, a first external electrode film is formed on the opposing end surface of the element body, and the second external electrode film connected to the first external electrode film is formed so as to cover the end of the insulating film within a predetermined overlapping range. It is. Therefore, in the element main body, the free end of the internal electrode can be extended to the vicinity of the first external electrode film without being connected to the first external electrode film. As a result, the overlapping area of the internal electrode layers laminated with the ceramic layer interposed therebetween can be maximized. Therefore, the electrical characteristics of the electronic component are improved and the number of internal electrode layers stacked can be reduced, contributing to downsizing of the electronic component. If the number of stacked internal electrode layers can be reduced, variation in characteristics due to stacking deviation can be suppressed, and electrical characteristics can be stabilized.

  In addition, the area of the internal electrode layer can be maximized inside the element body, and the side end of the internal electrode layer can be positioned near the surface of the element body, so The amount of heat that can be released to the outside of the element body also increases. Moreover, the amount of heat generated inside the element body can be released to the outside of the element body also through the external electrode film located near the side edge of the internal electrode layer. If the heat dissipation from the element body is improved, the rated power of the electronic component can be increased. Moreover, self-heating is reduced by improving heat dissipation, and resistance error during operation is also reduced.

  Furthermore, it is preferable that a plating film is formed outside the second external electrode film, but when forming the plating film, both ends of the insulating film formed on the side surface of the element body are the second external electrode film. Therefore, the plating solution is less likely to enter the element body.

  Preferably, each of the predetermined overlapping ranges has a length of 1/20 to 1/7, more preferably a length of 1/12 to 1/6 with respect to the distance between the end faces of the element body. . By setting it as such a range, the overlapping area of an internal electrode layer can be enlarged, preventing a short circuit. In addition, the strength at the time of soldering can be improved.

  Preferably, the first external electrode film is an electrode film formed by baking, and the second external electrode film is a resin-containing paste film. By forming the second external electrode film as a resin-containing paste film, an electrode film is formed on the insulating film formed on the side surface of the element body while ensuring electrical connection to the first external electrode film. It's easy to do.

  In addition, by using the first external electrode film as an electrode film formed by baking, a so-called Kirkendall effect occurs due to the high temperature during firing, and the metal is included in the internal electrode layer and the first external electrode film. Metals diffused to each other and are firmly connected. In order to effectively generate the Kirkendall effect, the internal electrode layer and the first external electrode film contain different kinds of metals having a face-centered cubic crystal structure such as Ag, Pd, and Pt. Is preferred.

  Preferably, the insulating film covers the end surface in addition to the four side surfaces of the element body, and the end portion of the internal electrode layer penetrates the insulating film and is connected to the first external electrode film on the end surface. It is. If the Kirkendall effect occurs, even if a thin insulating film is formed up to the end face of the element body, the metal diffuses between the internal electrode layer and the first external electrode film through the insulating film. As a result, one end of the internal electrode layer protrudes and extends to the first external electrode film.

Preferably, the internal electrode layer is
A pair of first internal electrode layers each having an end connected to the first external electrode film;
A floating electrode layer that is formed in the same plane as these first internal electrode layers and is not connected to these first internal electrode layers;
A pair of second internal electrode layers that are laminated to a part of the floating electrode layer and the first internal electrode layer via the ceramic layer, and are connected to the first external electrode film but not to each other. And having.

  The pattern of the internal electrode layer having the floating electrode layer can reduce variation in characteristics compared to the pattern of the internal electrode layer not having the floating electrode layer.

  Preferably, both free ends of the floating electrode layer (ends extending in the direction of the end face of the element body) are respectively located within the predetermined overlapping range. By extending the free end of the floating electrode layer to such a range, the overlapping area of the electrodes can be increased, and there is no short circuit between the pair of external electrode films.

Alternatively, the internal electrode layer is
A first internal electrode layer connected at one end to one of the first external electrode films;
The first internal electrode layer may be laminated via the ceramic layer, and the other first external electrode film and a second internal electrode layer connected at one end may be included.

  In this case, preferably, in the first internal electrode layer and the second internal electrode layer, free ends opposite to one end connected to the first external electrode film are positioned within the predetermined overlapping range. By extending the free ends of these internal electrode layers to such a range, the overlapping area of the electrodes can be increased, and there is no short circuit between the pair of external electrode films.

FIG. 1 is a schematic cross-sectional view of a laminated thermistor element according to an embodiment of the present invention. 2A is a schematic cross-sectional view showing the element body of the laminated thermistor element shown in FIG. 1, and FIG. 2B is a schematic cross-sectional view taken along the line IIB-IIB shown in FIG. 3A is a schematic cross-sectional view taken along line IIIA-IIIA shown in FIG. 2A, and FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB shown in FIG. FIG. 4 is a schematic cross-sectional view showing a usage state of the laminated thermistor element shown in FIG. FIG. 5 is a schematic cross-sectional view of a laminated thermistor element according to another embodiment of the present invention.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
First embodiment

  As shown in FIG. 1, a laminated thermistor element 2 as a laminated electronic component according to an embodiment of the present invention has ceramic layers 4 and internal electrode layers 6a to 6c, 7a to 7b, and 8a to 8b alternately laminated. It has a certain element body 10. In the present embodiment, the element body 4 has a rectangular parallelepiped shape having a long side direction in the X-axis direction, a short side direction in the Y-axis direction, and a stacking direction in the Z-axis direction.

  The element body 10 has two side surfaces that face each other in the Y-axis direction, two side surfaces that face each other in the Z-axis direction, and two end surfaces that face each other in the Z-axis direction. These four side surfaces and two end surfaces are covered with an insulating film 11. The insulating film 11 is composed of, for example, a silicon oxide film, an aluminum oxide film, a zirconium oxide film, a titanium oxide film, a magnesium oxide film, or the like. The insulating film 11 is formed on the entire outer peripheral surface of the element body 10 by, for example, a solution dipping method, a spin coating method, a sputtering method, or the like.

  The thickness of the insulating film 11 is preferably 0.05 to 10 μm on the four side surfaces of the element body 10, and preferably 0 to 2 μm on the two end faces of the element body 10. The thickness of the insulating film 11 may be the same or different between the four side surfaces and the two end surfaces of the element body 10. Although the thickness of the insulating film 11 may be zero on the two end surfaces of the element body 10, the end portions of the internal electrode layers 6 a to 8 a and 6 b to 8 b are not insulated from each other due to the Kirkendall effect. 11 is connected to the terminal electrodes 15a and 15b.

  A pair of terminal electrodes 15a and 15b are formed at both ends of the element body 10 in the X-axis direction. Each terminal electrode 15a is composed of three layers of external electrode films 12a, 14a, 16a and 12b, 14b, 16b. The innermost first external electrode films 12 a and 12 b are formed only on the end surface of the element body 10, and hardly extend to the side surface of the element body 10.

  The outer sides of the first external electrode films 12a and 12b cover the first external electrode films 12a and 12b, and the end portions in the X-axis direction of the insulating film 11 located on the four side surfaces of the element body 10 are respectively in the X-axis direction. A pair of second external electrode films 14a and 14b are formed to cover the predetermined overlapping range L1. A pair of third external electrode films 16a and 16b are formed on the outer sides of the second external electrode films 14a and 14b, respectively, so as to entirely cover these films.

  The internal electrode layers 6a to 6c on the same plane located substantially in the center in the Z-axis direction inside the element body 10 are sandwiched by the internal electrode layers 7a to 7b and 8a to 8b via the ceramic layer 4. . The internal electrode layers 6a to 6c are formed on the same plane as the first internal electrode layers 6a and 6b that penetrate the insulating film 11 and are connected to the first external electrode films 12a and 12b, respectively. The floating electrode layer 6c is not connected to the first internal electrode layers 6a and 6b.

  Both ends (free ends) in the X-axis direction of the floating electrode layer 6c are insulated from the first internal electrode layers 6a and 6b by the first gap pattern 3, and are positioned within a predetermined overlapping range L1. ing. The second internal electrode layers 7a and 7b are respectively laminated on a part of the floating electrode layer 6c and the first internal electrode layers 6a and 6b via the ceramic layer 4, and are respectively formed on the first external electrode films 12a and 12b. Although they are connected, they are not connected to each other by the second gap pattern 5. The second internal electrode layers 8a and 8b are the same as the second internal electrode layers 7a and 7b.

  As shown in FIGS. 3A and 3B, the first gap pattern 5 and the second gap pattern 7 extend linearly along the Y-axis direction, and their widths d1 and d2 in the X-axis direction. Are preferably the same as each other, but may be different, and preferably 30 to 100 μm. All the internal electrode layers 6a to 6c, 7a to 7b, and 8a to 8b have a width in the Y-axis direction of the element body 10 as shown in FIG. 2 (b), FIG. 3 (a), and FIG. 3 (b). 1 is exposed from the side surface of the element body 10 in a state where the insulating film 11 shown in FIG. 1 is not formed.

  The ceramic layer 4 is composed of a semiconductor ceramic such as an NTC thermistor layer, and is composed of two or more elements selected from transition metal elements such as manganese, nickel, cobalt, and iron, and spinel. It is comprised with the material which contains the complex oxide which has a structure as a main component. Further, the ceramic layer 4 may contain subcomponents for improving the characteristics. What is necessary is just to determine suitably a composition and content of a main component and a subcomponent according to a desired characteristic.

  For example, as shown in FIGS. 2 (a) and 2 (b), the ceramic layer 4 is obtained by firing together one or more green sheets together with the internal electrode layers 6a to 6c, 7a to 7b, and 8a to 8b. can get. The thickness of the ceramic layer 4 is not particularly limited, but is preferably about 10 to 100 μm between the internal electrode layers 6a to 6c, 7a to 7b, and 8a to 8b in the present embodiment. In the present embodiment, the number of electrode layers stacked is not particularly limited, and the electrode layers 6a to 6c and 7a to 7b may be repeated as many units through the ceramic layer 4 as repeating units.

  The conductive material that constitutes the internal electrode layers 6a to 6c, 7a to 7b, and 8a to 8b is not particularly limited. Or it is comprised with base metals, such as Cu and Ni, and these alloys. However, from the viewpoint of improving the bonding property with the first external electrode films 12a and 12b by the Kirkendall effect described later, it is more preferable that the metal film is made of a dissimilar metal having a face-centered cubic crystal structure.

  Further, the material of the first external electrode films 12a and 12b in the terminal electrodes 15a and 15b is not particularly limited, and the same material as the conductive material constituting the internal electrodes can be used. However, the first external electrode films 12a and 12b are electrode films formed by baking, and have an effect of improving the bonding property with the internal electrode layers 6a, 6b, 7a, 7b, 8a, and 8b by the Kirkendall effect described later. In order to promote, it is more preferable that it is made of a dissimilar metal having a face-centered cubic crystal structure. From such a viewpoint, the first external electrode films 12a and 12b preferably include silver or an alloy containing silver as a main component, and the internal electrode layers 6a to 6c, 7a to 7b, and 8a to 8b include palladium or platinum. Or it is more preferable that it contains the alloy which has these metals as a main component.

  That is, in such a case, the so-called Kirkendole in which these metals diffuse through the insulating film 11 due to the high temperature when the first external electrode films 12a and 12b are baked on the end face of the element body 10 is used. The effect comes to occur. When this Kirkendall effect occurs, the metal contained in the internal electrode layers 6a to 6b, 7a to 7b, and 8a to 8b diffuses toward the first external electrode films 12a and 12b, and accompanying this diffusion, the internal electrode layer 6a. One end of ˜6b, 7a˜7b, 8a˜8b protrudes toward the first external electrodes 12a, 12b, and both are closely joined.

  The second external electrode films 14a and 14b formed on the outside of the first external electrode films 12a and 12b are resin-containing paste films and do not require heat treatment at a high temperature, and are formed at the side end portions of the element body 10. It adheres well to the surface of the insulating film 11. Although it does not specifically limit as a metal contained in a resin containing paste film | membrane, Preferably it is silver, palladium, a silver palladium alloy, gold | metal | money, platinum, and a gold platinum alloy. The resin contained in the resin-containing paste film is not particularly limited, but is preferably an epoxy resin, a silicon resin, or a polyimide resin.

  The third external electrode films 16a and 16b are preferably formed outside the second external electrode films 14a and 14b. The third external electrode films 16a and 16b may be a multilayer film of Ni plating and Sn plating, or Cu It may be a multilayer film of plating, Ni plating, or Sn plating. By forming the third external electrode films 16a and 16b made of a plating film, the terminal electrodes 15a and 15b of the laminated thermistor element 2 are joined to the land pattern 26 of the circuit board 26 by solder 20 as shown in FIG. In this case, it is possible to effectively prevent solder erosion.

  In the present embodiment, the thickness of each of the first external electrode films 12a and 12b is preferably 5 to 50 μm, and the thickness of each of the second external electrode films 14a and 14b is preferably 5 to 50 μm. Each thickness of the electrode films 16a and 16b is preferably 1 to 10 μm.

  The dimension of the laminated thermistor element 2 is not particularly limited, and may be an appropriate dimension depending on the application. Usually, the X-axis direction dimension (dimension L0 shown in FIG. 1) is 0.4 to 1.6 mm. The Y-axis direction dimension is 0.2 to 0.8 mm, and the Z-axis direction dimension is about 0.2 to 0.8 mm.

  The length L2 in the X-axis direction of each terminal electrode 15a, 15b is a length obtained by adding the thickness of each terminal electrode 15a, 15b to the above-described predetermined overlapping range L1 in the X-axis direction. In the present embodiment, the predetermined overlapping range L1 is preferably 0.01 to 0.5 mm, and more preferably 0.03 to 0.5 mm. Further, since the thickness of each terminal electrode 15a, 15b is sufficiently smaller than the length L0 of the element 2, the length L0 of the element 2 is equal to the distance between the end faces of the element body 10. The ratio L1 / L0 is preferably 1/2 to 1/3, more preferably 1/5 to 2/5.

  As described above, both free ends in the X-axis direction of the floating electrode layer 6c are located within the predetermined overlapping range L1, and the overlapping range L3 is preferably at least 50 μm or less and the maximum is within the range. L1 or less. The length L4 in the X-axis direction on the side surface of the element body 10 where the terminal electrodes 15a and 15b are not formed is the length L2 in the X-axis direction of the terminal electrodes 15a and 15b from the length L0 in the X-axis direction of the element 2. It is the length that was drawn.

  Next, an example of a method for manufacturing the laminated thermistor 2 according to this embodiment will be described. A method for manufacturing the laminated thermistor according to the present embodiment is not particularly limited, and a known method may be used. However, in the following description, a case where a sheet method is used is illustrated.

  First, a green sheet on which an internal electrode paste film having a predetermined pattern for forming the internal electrode layers 6a to 8b and a green sheet not having the internal electrode layers 6a to 8b are prepared.

  The green sheet is formed of the material constituting the NTC thermistor layer described above. Note that this type of material may contain inevitable impurities such as Si, Na, and Ca in an amount of about 0.1 wt% or less.

  And a green sheet is manufactured by a well-known technique using such a material. Specifically, for example, first, the raw materials of the material constituting the NTC thermistor layer are uniformly mixed by means such as wet mixing and then dried. Next, calcination is performed under appropriately selected calcination conditions, and the calcination powder is wet pulverized. Then, a binder is added to the pulverized calcined powder to form a slurry. Next, the slurry is formed into a sheet by means such as a doctor blade method or a screen printing method, and then dried to obtain a green sheet.

  The internal electrode paste contains the various metals described above. By applying the internal electrode paste onto the green sheet by means such as a printing method, a green sheet on which an internal electrode paste film having a predetermined pattern is formed is obtained.

  Next, these green sheets are overlapped, pressure is applied and pressure-bonded, and after necessary steps such as a drying step, the green sheets are cut and the green element body 10 is taken out. Cutting can be performed using a dicing saw or the like.

  Next, after the green element body 10 taken out is baked under predetermined conditions, an insulating film 11 is formed on the outer surface of the element body 10. Thereafter, only the insulating film 11 formed on the end surface in the X-axis direction of the element body 10 is removed by polishing or the like, and without being removed, the first external electrode films 12a, 12b, 2 External electrode films 14a and 14b and third electrode films 16a and 16b are formed. As a result, as shown in FIG. 1, the laminated thermistor element 2 in which the terminal electrodes 15a and 15b are formed is obtained.

  In the laminated thermistor element 2 according to this embodiment, insulating films 11 are formed on the four side surfaces of the element body 10. Therefore, even if the widths of the internal electrode layers 6 a to 8 b are set to be the same as the width of the element body 10, the side edges in the width direction of the internal electrode layers 6 a to 8 b are not exposed from the side surfaces of the element body 10.

  In addition, first external electrode films 12a and 12b are formed on the opposing end faces of the element body 10, and the second external electrode films 14a and 14b connected to the first external electrode films 12a and 12b are respectively formed on the insulating film 11. Is formed so as to cover the side surface with a predetermined overlapping range L1. Therefore, in the element body 10, the free end of the floating electrode layer 6c in the X-axis direction can be extended to the vicinity of the first external electrode films 12a and 12b without being connected to the first external electrode films 12a and 12b. . As a result, the overlapping area of the internal electrode layers 6a to 8b stacked with the ceramic layer 4 interposed therebetween can be maximized. Therefore, the electrical characteristics of the laminated thermistor element 2 are improved and the number of laminated internal electrode layers 6a to 8b can be reduced, which contributes to the miniaturization of the element 2. If the number of stacked internal electrode layers 6a-8b can be reduced, variations in characteristics due to stacking deviation can be suppressed, and electrical characteristics can be stabilized.

  Further, the area of the internal electrode layers 6a to 8b can be maximized inside the element body 10, and the side ends of the internal electrode layers 6a to 8b can be positioned near the surface of the element body 10, The amount of heat that can be released to the outside of the element body 10 through the side edges of the internal electrode layers 6a to 8b is also increased. In addition, the amount of heat generated inside the element body 10 can be released to the outside of the element body 10 also through the external electrode films 14a, 14b, 16a, and 16b located near the side edges of the internal electrode layers 6a to 8b. If the heat radiation from the element body 10 is improved, the rated power of the element 2 can be increased. Moreover, self-heating is reduced by improving heat dissipation, and resistance error during operation is also reduced.

  Furthermore, in the present embodiment, the third external electrode films 16a and 16b made of a plating film are formed outside the second external electrode films 14a and 14b. Therefore, when forming the plating film, the element body 10 Since both ends of the insulating film 11 formed on the side surfaces are covered with the second external electrode films 14 a and 14 b, there is little possibility that the plating solution enters the element body 10.

  In the present embodiment, the first external electrode films 12a and 12b are electrode films formed by baking, and the second external electrode films 14a and 14b are resin-containing paste films. The electrode films 14a and 14b can be easily formed on the insulating film 11 formed on the side surface of the element body 10 while ensuring electrical connection to the films 12a and 12b.

Further, in the present embodiment, since the pattern of the internal electrode layer having the floating electrode layer 6c is used, variation in characteristics can be reduced as compared with the pattern of the internal electrode layer having no floating electrode layer. This is because, for example, when the green laminate is cut into a green chip, even if the cutting position in the X-axis direction is slightly shifted, the overlap area between the internal electrode layers 6a to 8b does not change in the chip. This is due to the fact that there is little variation in the overlapping area between them.
Second embodiment

  As shown in FIG. 5, the laminated thermistor element 102 according to the present embodiment changes the repeated pattern of the internal electrode layers 106 and 107 as compared with the internal electrode layers 6 a to 8 b shown in FIG. Except for the configuration, the embodiment has the same configuration as that of the embodiment shown in FIGS.

  In the present embodiment, the internal electrode layer positioned inside the element body 110 includes a first internal electrode layer 106 having one end connected to one first external electrode film 12 a and a ceramic layer with respect to the first internal electrode layer 106. 4 and a second internal electrode layer 107 having one end connected to the other first external electrode film 12b.

  In the first internal electrode layer 106 and the second internal electrode layer 107, the free ends on the opposite side to the one ends connected to the first external electrode films 12a and 12b are respectively located within the predetermined overlapping range L1. By extending the free ends of the internal electrode layers 106 and 107 to such a range L1, the overlapping area of the electrodes can be increased, and a short circuit occurs between the pair of external electrode films 12a and 12b. There is nothing.

In this embodiment, each terminal electrode 15a, 15b is composed of a two-layer film of a first external electrode film 12a, 12b and a second external electrode film 12b, 14b, respectively. Three external electrode films 16a and 16b may be formed respectively. Further, a large number of internal electrode layers 106 and 107 may be alternately stacked via the ceramic layer 4 inside the element body 110.
Other embodiments

  The present invention is not limited to the above-described embodiment, and can be variously modified.

  For example, the ceramic layer 4 is not limited to the thermistor layer, but may be a varistor layer, and the entire element is a multilayer varistor element. As the varistor layer, any varistor material can be used as long as it is composed of a varistor material capable of expressing varistor characteristics. More specifically, suitable examples include ZnO as a main component, and a rare earth element such as Pr, a subcomponent such as Bi, and a trace additive such as Al, etc., in the ZnO.

  Furthermore, the ceramic layer 4 may be a dielectric layer. In that case, the entire element may be a multilayer capacitor element, or may be another element. The structure of the present invention is particularly effective for thermistor elements and varistor elements in which the overlapping area of the internal electrode layers is important, and is particularly effective for small elements in which the dimension of the element 2 in the X-axis direction is small.

Next, the present invention will be described in more detail with reference to examples that further embody the embodiment of the present invention. However, the present invention is not limited to these examples.
Example 1

First, commercially available manganese trioxide (Mn ₃ O ₄ ), nickel oxide, cobalt oxide and iron oxide were prepared as raw materials for the material constituting the NTC thermistor layer. These raw materials were wet pulverized with a ball mill for 16 hours and dried to obtain raw materials for the NTC thermistor layer.

  Then, 100 parts by weight of the obtained raw material, 10 parts by weight of polyvinyl butyral resin, 5 parts by weight of dioctyl phthalate (DOP) as a plasticizer, and 100 parts by weight of alcohol as a solvent are mixed with a ball mill to form a paste. An NTC thermistor layer paste was obtained.

  Then, using the NTC thermistor layer paste prepared above and the internal electrode paste, the laminated thermistor 2 shown in FIG. 1 was manufactured as follows. In this example, a commercially available electrode paste containing Pd as the conductive material was used as the internal electrode layer paste.

  First, a green sheet was formed on a PET film by a doctor blade method using the obtained NTC thermistor layer paste. Next, an internal electrode pattern film was printed on the green sheet by screen printing using an internal electrode paste, and a green sheet on which the internal electrode pattern film was printed was manufactured. Next, separately from the above green sheet, a green sheet on which an internal electrode pattern film was not printed on a PET film was manufactured by a doctor blade method using NTC thermistor layer paste.

  And each green sheet manufactured above was laminated | stacked alternately, and the green chip | tip was manufactured by heating and pressurizing the obtained laminated body.

  Next, the obtained green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing under the following conditions to obtain a multilayer ceramic fired body.

  The binder removal treatment conditions were temperature rising rate: 30 ° C./hour, holding temperature: 300 to 400 ° C., temperature holding time: 8 hours, atmosphere: in air.

  The firing conditions were temperature rising rate: 200 ° C./hour, holding temperature: 1000-1400 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmosphere: in air.

  The annealing conditions were temperature rising rate: 200 ° C./hour, holding temperature: 600 to 800 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmosphere: in air.

Next, the insulating film 11 was formed on the outer surface of the obtained multilayer ceramic fired body by sputtering. The insulating film 11 was made of SiO ₂ and had a thickness of 0.05 to 10 μm.

  Next, the first external electrode films 12 a and 12 b containing silver were baked on the end face of the obtained element body 10. The baking temperature was 600 to 900 ° C. The thicknesses of the first external electrode films 12a and 12b were 5 to 50 μm, respectively.

  Thereafter, second electrode films 14a and 14b made of a resin-containing electrode film were formed so as to cover the first external electrode films 12a and 12b. The resin-containing electrode film contained silver as a metal and an epoxy resin as a resin. The second electrode films 14a and 14b made of the resin-containing electrode film were dried by heat treatment. The heat treatment temperature was 100 to 300 ° C. The thickness of the second external electrode films 14a and 14b was 5 to 50 μm.

  Next, third external electrode films 16a and 16b made of a Ni plating film and a multilayer film of Sn plating were formed by plating so as to cover the second external electrode films 14a and 14b, respectively. The thicknesses of the third external electrode films 16a and 16b were 1 to 10 μm, respectively.

The dimensional relationship shown in FIG. 1 for the obtained element 2 was as follows. L0 = 1.6 mm, L1 = 0.3 mm, L3 = 0.24 mm, the number of laminated internal electrode layers was 34, and the thickness of the ceramic layer sandwiched between them was 20 μm.
Example 2

A laminated thermistor element was manufactured in the same manner as in Example 1 except that the element body 110 had a laminated structure having a repeated pattern of the internal electrode layers 106 and 107 shown in FIG. The dimensional relationship shown in FIG. 5 was as follows. L0 = 1.6 mm, L1 = 0.3 mm, L3 = 0.24 mm, the number of laminated internal electrode layers was 34, and the thickness of the ceramic layer sandwiched between them was 20 μm.
Example 3

L0 = 1.0 mm, L1 = 0.22 mm, L3 = 0.16 mm, the number of laminated internal electrode layers was 18, and a laminated thermistor element was produced in the same manner as in Example 1.
Example 4

A laminated thermistor element was produced in the same manner as in Example 2, except that L0 = 1.0 mm, L1 = 0.22 mm, L3 = 0.16 mm, and the number of laminated internal electrode layers was 18.
Comparative Example 1

In FIG. 5, the insulating film 11 is not formed, and the free ends of the internal electrode layers 106 and 107 are not located in the overlapping range L1 but in the length L4, and the overlapping range L3 is minus 0. A laminated thermistor element was manufactured in the same manner as in Example 2 except that the thickness was 06 mm.
Comparative Example 2

In FIG. 5, the insulating film 11 is not formed, and the free ends of the internal electrode layers 106 and 107 are not positioned within the overlapping range L1, but are positioned within the length L4, and the overlapping range L3 is minus 0.0. A laminated thermistor element was manufactured in the same manner as in Example 4 except that the thickness was 06 mm.
Evaluation

  100 samples according to Examples 1 to 4 and Comparative Examples 1 to 2 were prepared, and the resistance between the terminal electrodes 15a and 45b and the variation in resistance were examined. When Examples 1 and 2 and Comparative Example 1 having the same element size are compared, the average resistance value of Example 2 can be reduced by 10% compared to the average resistance value of Comparative Example 1. 1 was confirmed to be reduced by 5%.

  In addition, it was confirmed that the average resistance variation of Example 1 can be reduced by 60% and that of Example 2 can be reduced by 40% with respect to the average resistance variation of Comparative Example 1.

  Further, when Examples 3 and 4 and Comparative Example 2 having the same element size are compared, the average resistance value of Example 3 can be reduced by 15% with respect to the average resistance value of Comparative Example 2. In Example 4, it was confirmed that the reduction was 30%.

  In addition, it was confirmed that the average resistance variation of Example 3 can be reduced by 70% compared to the average resistance variation of Comparative Example 2, and that 50% can be reduced by Example 4.

  As a result, as shown in Examples 3 and 4, the smaller the size, the smaller the absolute value of the resistance value and the smaller the variation of the resistance value compared to Comparative Example 2, and in particular, as shown in FIG. In the pattern (Example 3), the effect of reducing the absolute value of the resistance value and the effect of reducing the resistance variation were significant.

DESCRIPTION OF SYMBOLS 2 ... Laminated thermistor 4 ... Ceramic layer 6a, 6b, 106 ... 1st internal electrode layer 6c ... Floating electrode layer 7a, 7b, 8a, 8b, 107 ... 2nd internal electrode layer 10 ... Element main body 11 ... Insulating film 12a, 12b ... 1st external electrode film 14a, 14b ... 2nd external electrode film 16a, 16b ... 3rd external electrode film 15a, 15b ... Terminal electrode

Claims (8)

A rectangular parallelepiped element body in which the thermistor layers and internal electrode layers are alternately laminated;
An insulating film formed on at least four side surfaces of the element body;
A first external electrode film formed on a pair of opposed end faces excluding the four side surfaces of the element body, and formed by a pair of baking processes connected to any of the internal electrode layers;
Covering each of the first external electrode film, moreover have a, a second external electrode layer is a pair of resin-containing paste film covering a predetermined overlapping range an end portion of the insulating film is formed on the four side surfaces ,
The laminated thermistor , wherein the width of the internal electrode layer and the width of the element body are the same, and at least one of the free ends of the internal electrode layer is located within the predetermined overlapping range .   2. The stacked thermistor according to claim 1, wherein each of the predetermined overlapping ranges has a length of 1/20 to 1/7 with respect to a distance between the end faces of the element body. 3. The multilayer thermistor according to claim 1, wherein L3 is 50 μm or more and L1 or less, respectively, where L1 is the predetermined overlapping range and L3 is an overlapping range between the internal electrode layer and the predetermined overlapping range. The insulating film covers the end surface in addition to the four side surfaces of the element body, and the end portion of the internal electrode layer penetrates the insulating film and is connected to the first external electrode film on the end surface. laminated thermistor according to claim 1. The internal electrode layer is
A pair of first internal electrode layers each having an end connected to the first external electrode film;
A floating electrode layer that is formed in the same plane as these first internal electrode layers and is not connected to these first internal electrode layers;
A pair of second internal electrode layers stacked on the part of the floating electrode layer and the first internal electrode layer via the thermistor layer and connected to the first external electrode film but not connected to each other And a laminated thermistor according to any one of claims 1 to 4 . The multilayer thermistor according to claim 5 , wherein both free ends of the floating electrode layer are positioned within the predetermined overlapping range. The internal electrode layer is
A first internal electrode layer connected at one end to one of the first external electrode films;
The stacked via the thermistor layer to the first inner electrode layers, according to any of claims 1-4 in which the other of said first external electrode layer and the one end having a second inner electrode layer connected Laminated thermistor. 8. The stacked thermistor according to claim 7 , wherein in the first internal electrode layer and the second internal electrode layer, free ends opposite to one end connected to the first external electrode film are positioned within the predetermined overlapping range, respectively.

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