JPH09266103A - Chip thermistor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the range of resistance and thermistor characteristic of B value by increasing the adjustment range of resistance, to easily obtain the characteristics of low resistance and high B vale, and to obtain an enough mechanical strength by preventing micro cracks or the like. SOLUTION: A rectangular parallelepiped thermistor element 12 is formed by stocking and bonding several thin plate materials 11 of ceramic sintered compact. Several electrodes 13 for resistance adjustment are formed on the surface or in the thermistor element 12. These electrodes 13 are exposed at the ends of the thermisotor element 12. Several thin plate materials 11 are stacked and bonded by an insulating adhesive 16. An insulating ceramic board material 15 is adhered to two of the four sides of the thermistor 12 through an insulating adhesive 16. The other two sides are covered with insulating polymer film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type thermistor suitable for a temperature compensating thermistor of various electronic devices and a sensor for measuring a surface temperature, and a manufacturing method thereof. More specifically, the present invention relates to a chip type thermistor surface-mounted on a printed circuit board or the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a method of manufacturing a chip type thermistor of this type, the present applicant has formed a resistance value adjusting electrode by printing a conductive paste in a strip shape on the surface of a thin plate material made of a ceramic sintered body, By cutting the thin plate material in a direction orthogonal to the longitudinal direction of the resistance value adjusting electrode to produce a strip, by cutting the strip along the center line in the width direction of the resistance adjusting electrode. A chip-shaped thermistor element body in which one end of the resistance value adjusting electrode is located at each end is prepared,
Further, a patent application was filed for a method of manufacturing a chip type thermistor in which terminal electrodes electrically connected to the resistance value adjusting electrodes are formed on both end surfaces of the thermistor body (Japanese Patent Laid-Open No. 12740/1992).
1).

This chip type thermistor is specifically manufactured by the following method. First, a conductive paste is formed in a strip shape on both sides or one side of a thin plate material made of a ceramic sintered body, printed with a screen printing method or a roll transfer printing method, and then dried to adjust resistance values in a large number of rows. Forming electrodes. Next, an insulating inorganic material layer is formed by printing, spraying or immersing a paste containing an insulating inorganic material such as glass on both sides of this thin plate material and then firing it.
After cutting a thin plate material whose both surfaces are covered with an insulating inorganic material layer in a strip shape in a direction orthogonal to the longitudinal direction of the resistance adjusting electrode, a paste containing an insulating inorganic material on a cut surface of the strip material is formed. The insulating inorganic material layer is formed on the cut surface by printing, spraying or dipping and firing. Next, by cutting this strip in the direction orthogonal to its longitudinal direction, a chip-like thermistor element is produced, and a conductive paste is applied to both ends including both end surfaces that are cut surfaces of the thermistor element. A baked electrode layer is formed by applying and baking. Further, by forming a plating layer on the surface of this baked electrode layer, a chip type thermistor having terminal electrodes composed of the baked electrode layer and the plated layer at both ends is obtained.

In the method of manufacturing the chip type thermistor configured as described above, the resistance value adjusting electrode is formed on the surface of the thin plate material by the screen printing method, the roll transfer printing method or the like. The dimensional accuracy is higher than the method in which the thermistor element body is dipped therein. As a result, the resistance value adjusting electrodes can be formed with high accuracy, so that the interval between the resistance value adjusting electrodes can be formed with high dimensional accuracy. Further, since the resistance value adjusting electrode is formed on a ceramic sintered body, that is, on a thin plate material that has already been sintered, it is possible to prevent variation in dimensional accuracy due to firing shrinkage of the thin plate material.

On the other hand, thin plate materials having resistance value adjusting electrodes on both sides are laminated, and the resistance value adjusting electrodes are connected to terminal electrodes so that the resistance value adjusting electrodes are connected in parallel. A laminated type thermistor is disclosed (Japanese Patent Publication No. 50-11585). In this laminated thermistor,
The initial resistance value can be reduced without changing the B constant of the thermistor. That is, a thermistor having a small initial resistance value and a large B constant can be obtained.

A method for manufacturing this laminated type thermistor was applied to the thermistor filed by the present applicant (Japanese Patent Laid-Open No. 6-231906).
Will be described with reference to the specification and drawings. First, a conductive paste is printed and dried on the upper surface of the ceramic green sheet to form a resistance value adjusting electrode, and then a plurality of green sheets are stacked to form a sheet-like laminated body, and the laminated body is fired to form a sintered sheet. Then, glass paste is printed on both surfaces of the sintered sheet and fired to form a glass layer made of insulating crystallized glass. Next, after cutting the sintered sheet whose both surfaces are covered with a glass layer into strips in a direction orthogonal to the column direction of the electrodes, glass paste is printed and fired on the cut surfaces on both sides of this strip in the same manner as above. To form a glass layer made of crystallized glass. Next, the strip is finely cut in a direction perpendicular to the cut surface and along the center line in the width direction of the electrode to form a thermistor body. A conductive paste is applied to both ends of the thermistor body so as to wrap the cut surface of the thermistor body, and is baked to form an electrode layer. Further, by using this baked electrode layer as a base electrode layer, a plating layer is formed on the surface of the baked electrode layer to obtain a laminated thermistor having end-stop electrodes composed of the baked electrode layer and the plated layer.

[0007]

However, in the above-mentioned conventional method for manufacturing a chip type thermistor, since the resistance value adjusting electrodes are formed only on the two side surfaces of the thermistor element body facing each other, the resistance value of the thermistor is reduced. There is a limit to the reduction. As a result, the range of thermistor characteristics (combination of resistance value and B constant) becomes relatively narrow, so that there has been a problem that a thermistor having a low resistance and a high B constant, which has been increasingly demanded in recent years, cannot be obtained. . Further, in the above-described conventional method of manufacturing a chip type thermistor, since the thin plate material is cut into strips in a state where the insulating inorganic material layer such as glass is formed on the surface of the thin plate material, the thermal expansion coefficient of the thin plate material and the insulating inorganic material layer. Due to the thermal stress caused by the difference (this thermal stress remains inside), micro cracks etc. occur in the thin plate material or the insulating inorganic material layer at the time of the above cutting, and the mechanical strength of the chip type thermistor can be sufficiently obtained. There was no problem. As a result, there has been a problem that sufficient performance cannot be obtained even in reliability tests regarding the strength of the chip type thermistor such as a substrate bending resistance test and a temperature cycle test. On the other hand, in the above conventional laminated type thermistor, since the green sheet and the conductive paste are simultaneously fired, sufficient dimensional accuracy can be obtained under the influence of variations due to shrinkage of the green sheet or the conductive paste during firing. However, there is a problem in that the resistance value of the thermistor varies. Further, in the conventional laminated thermistor, the glass layer covering the surface of the thermistor element body is fired at a relatively high temperature, which causes a problem of varying the characteristics of the thermistor element body.

The object of the present invention is to widen the range of resistance value and B constant thermistor characteristics by expanding the adjustment range of resistance value, and to easily obtain the characteristics of low resistance and high B constant. Another object of the present invention is to provide a chip type thermistor that can obtain sufficient mechanical strength by preventing the generation of microcracks and the like, and a manufacturing method thereof. Another object of the present invention is to improve the original function accuracy of the thermistor by suppressing variations in resistance value, and to reduce fluctuations in thermistor characteristics during heat curing of the coating that covers the surface of the thermistor body. And to provide a manufacturing method thereof.

[0009]

The invention according to claim 1 is
As shown in FIG. 5, a thermistor element body 12 formed into a rectangular parallelepiped shape by laminating and adhering a plurality of thin plate materials 11 made of a ceramic sintered body, and a thermistor element body formed on the surface and inside of the thermistor element body 12. A plurality of resistance adjusting electrodes 13 exposed at the end faces of the thermistor 12; and terminal electrodes 14 provided at both ends of the thermistor body 12 including both end faces and electrically connected to the resistance adjusting electrodes 13. This is an improvement of the chip type thermistor. Its characteristic structure is the thin plate material 1
1 is laminated and adhered by an insulating adhesive 16, and the insulating ceramic plate material is interposed between the two side surfaces of the thermistor element body 12 which face each other and on which the resistance adjusting electrode 13 is formed, through the insulating adhesive 16. 15 is adhered, and two of the four side surfaces of the thermistor element body 12 other than the two side surfaces are covered with the polymer film 17 having an insulating property.

In this chip type thermistor, the resistance value adjusting electrode 13 is provided on the surface and inside of the thermistor element body 12, so that the resistance value can be adjusted, that is, the resistance value can be easily reduced, and the resistance and the resistance can be increased. The thermistor 10 having the thermistor characteristic of B constant can be obtained relatively easily. Further, since the surface of the thermistor body 12 is covered with the polymer film 17 which can be heat-cured at a relatively low temperature, the thermal load on the thermistor body 12 is small, and the fluctuations of the thermistor characteristics such as the resistance value and the B constant are small. You can Furthermore, since the insulating ceramic plate material 15 having excellent mechanical strength is adhered to two of the four side surfaces of the thermistor body 12, the strength of the thermistor 10 can be improved.

The invention according to claim 2 is the invention according to claim 1, wherein a plurality of thin plate members are Mn, Co, Cu, F.
A ceramic sintered body containing one or more metal oxides selected from the group consisting of metal oxides containing e, Al and Ni, wherein the composition ratio of the metal oxides for each thin plate material is It is characterized by being configured differently.

In the invention according to claim 3, as shown in FIGS. 1 and 5, a large number of resistance value adjusting electrodes 13 are provided in parallel on the surface of the thin plate material 11 made of a ceramic sintered body at a predetermined interval. Insulating the plurality of thin plate members 11 and the pair of insulating ceramic plate members 15 with the plurality of thin plate members 11 on which the resistance adjusting electrodes 13 are formed being sandwiched by the pair of insulating ceramic plate members 15. Forming a laminated body 18 by laminating and adhering with a conductive adhesive 16, a step of cutting the laminated body 18 into a strip shape in a direction orthogonal to the longitudinal direction of the resistance value adjusting electrode 13, and a cut surface of the strip-shaped material 21. A step of applying the insulating polymer paste to the substrate, drying it, and curing it by heating to form a strip 22 with a coating, and strip 22 with a coating along the center of each resistance value adjusting electrode 13 in the width direction. Both ends by cutting A step of forming the thermistor element body 12 in which the resistance value adjusting electrodes 13 are respectively exposed, and electrodes on both ends of the thermistor element body 12 including both end surfaces of the thermistor element body 12 and one end surfaces of the plurality of resistance value adjusting electrodes 13. Layer 23
And a step of forming the plating layer 24 on the surface of the electrode layer 23 to form the terminal electrode 1 including the electrode layer 23 and the plating layer 24.
4 is a step of forming a chip thermistor.

In the method of manufacturing the chip type thermistor,
After sintering the thin plate material 11, the resistance value adjusting electrode 13 is formed on the surface of the thin plate material 11, and the thin plate material 11 is further formed.
Since the electrodes are laminated and adhered, the distance between the resistance value adjusting electrodes 13 becomes accurate, and a highly accurate thermistor with a small resistance value variation can be obtained. Further, since the coating film 17 that covers the surface of the thermistor body 12 is formed of a polymer material that can be heat-cured at a relatively low temperature, the thermal load on the thermistor body 12 is small, and the thermistor characteristics such as the resistance value and the B constant vary. Can be made smaller. Further, since the polymer coating 17 has excellent denseness and high performance in terms of strength, when the surface of the thermistor body 12 is covered with the polymer coating 17, no microcracks or the like are generated, and the thermistor 10 has It is possible to improve the mechanical strength.

[0014]

Next, a first embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 3 and 5, the chip-type thermistor 10 of the present invention includes a thermistor element body 12 formed in a chip shape by laminating and adhering two thin plate members 11 made of a ceramic sintered body.
Eight resistance value adjusting electrodes 13 formed on the surface and inside of the thermistor element body 12 and a pair of terminal electrodes 14 and 14 provided at both ends including both end surfaces of the thermistor element body 12 are provided. The eight resistance value adjusting electrodes 13 are exposed on either one of the end faces of the thermistor element body 12,
The pair of end stop electrodes 14, 14 are electrically connected to the resistance value adjusting electrode 13.

The characteristic structure of the present embodiment is that two thin plate members 11 and 11 are laminated and adhered by an insulating adhesive 16 and are opposed to each other among the four side surfaces of the thermistor element body 12 and a resistance value adjusting electrode. Insulating ceramic plate material 15 is adhered to the two side surfaces on which 13 is formed via an insulating adhesive 16, and the remaining two side surfaces of the thermistor element body 12 are covered with a polymer film 17 (FIG. 3) having an insulating property. It is in the place where it was done. In addition, three or more thin plate materials may be laminated and bonded,
The resistance value adjusting electrode may be formed in seven or less pieces or in nine or more pieces in order to obtain a desired resistance value.

A method of manufacturing the chip type thermistor having the above structure will be described with reference to FIGS. (A) Preparation of thin plate material 11 made of ceramic sintered body First, one or more kinds of oxide powders of metals such as Mn, Co, Cu, Fe, Al, and Ni are used, and the metal atomic ratio becomes a predetermined ratio. As weigh each and
Mix for 20 hours, dehydrate and dry. Then, the mixture is calcined under atmospheric pressure at 500 to 1000 ° C. for 1 to 10 hours,
It is pulverized again with a ball mill or the like, dehydrated and dried. Next, an organic binder or the like is added to this crushed product, and the crushed product is granulated to have a particle size of about 30 to 200 μm using a spray dryer or the like, and compression-molded into a rectangular parallelepiped by a hydraulic press or the like. Furthermore, this molded product is 1000 to 1300 ° C. under atmospheric pressure.
By firing for 2 to 10 hours, a ceramic sintered block having a predetermined size is manufactured, and this block is cut to a predetermined thickness using a band saw or the like to manufacture the thin plate material 11 (Fig. 1 (a )).

(A) Formation of the resistance adjusting electrode 13 on the surface of the thin plate member 11 A strip-shaped conductive paste having a width of 0.2 to 2.8 mm is formed on both surfaces of the thin plate member 11 in the width direction by 0.1 to 0.1 mm. Print and dry at 1.4 mm intervals. At this time, printing is performed so that the conductive pastes on both surfaces of the thin plate member 11 face each other with the thin plate member 11 interposed therebetween. This thin plate material 11 is heated to 750 to 850 at atmospheric pressure.
The temperature is maintained at 0 ° C., and the resistance value adjusting electrodes 13 having a thickness of 3 to 5 μm are formed on both surfaces of the thin plate member 11 (FIG. 1A).
The conductive paste is Ag paste or Ag-P.
A d-paste or the like is used, and the conductive paste may be printed on one side of the thin plate material instead of both sides. Further, a thin film electrode having a thickness of 0.1 to 1 μm may be formed by using a resinate paste such as Au.

(C) Preparation of Insulating Ceramic Plate 15 A slip prepared by mixing an insulating ceramic powder such as alumina (silica as a sintering aid, magnesia) with a binder, a plasticizer, a solvent and the like is used as a doctor blade. Method to form a green sheet having a predetermined thickness, and the green sheet is fired in a predetermined atmosphere at 1300 to 1700 ° C. for 10 to 20 hours to produce an insulating ceramic plate material 15 having a thickness of 0.15 to 0.20 mm. (FIG. 1 (a)). (D) Laminate adhesion of thin plate material 11 and insulating ceramic plate material 15 A plurality of thin plate materials 11 having resistance value adjusting electrodes 13 formed thereon are prepared, and the pattern of the resistance value adjusting electrodes 13 formed on these thin plate materials 11 is Each of them is positioned and stacked so as to have a predetermined position, and these thin plate members 11 are sandwiched by two insulating ceramic plate members 15 and 15 to form an insulating adhesive 1.
6 is laminated and adhered to form a laminated body 18 (FIG. 1).
(B) and FIG. 2). As the insulating adhesive 16, it is preferable to use a thermosetting adhesive such as an epoxy adhesive. Further, in order to ensure the above-mentioned adhesion, it is preferable to apply a predetermined pressure to the thin plate member 11 and the insulating ceramic plate member 15 laminated before the adhesive 16 is cured.

(E) Cutting of laminated body 18 The laminated body 18 is cut by a dicing machine or the like in a width 0.70 in a direction orthogonal to the longitudinal direction of the resistance adjusting electrode 13.
A strip of 0.80 mm is cut out (Fig. 1 (c)). (F) Covering the cut surface of the strip 21 with the polymer film 17 After printing the polymer paste on the cut surface of the strip 21 by a screen printing method or the like, and drying it in a predetermined atmosphere at 200-
A strip-shaped article with a coating 2 coated with the polymer coating 17 by heating and curing at 250 ° C. for 10 to 30 minutes
2 is formed (FIG. 1 (d) and FIG. 3). As the polymer paste, it is preferable to use the same type of epoxy paste as the above.

(G) Cutting of the strip 22 with the coating The strip 22 with the coating is cut along the center of the resistance adjusting electrodes 13 in the width direction in a direction orthogonal to the longitudinal direction of the strip 22. It is cut into chips using a dicing machine or the like (FIG. 1 (e) and FIG. 4). By this cutting, the thermistor element body 12 in which both ends of the resistance value adjusting electrode 13 are exposed is obtained. It is preferable that the thermistor body 12 is formed to have a length of 1.50 to 1.58 mm. (H) Formation of the terminal electrodes 14 on both ends of the thermistor element body 12. First, the thermistor element body 12 including both end surfaces of the chip-like thermistor element body 12 and one end surface of the resistance value adjusting electrode 13 is formed.
A conductive paste of a resin-based frit containing a noble metal powder is applied to both ends of the electrode layer and heat-cured to form the electrode layer 23.
To form Next, the electrode layer 23 is used as a base electrode layer, and a plating layer 24 is formed on this surface to form the electrode layer 23 and the plating layer 2.
A chip type thermistor having the terminal electrodes 14 of 4 is obtained (FIG. 1 (f), FIG. 5).

FIG. 6 shows a second embodiment of the present invention.
6, the same reference numerals as those in FIG. 5 indicate the same parts. In this embodiment, the pattern of the resistance value adjusting electrodes 53 formed on both surfaces of the thin plate member 11 of the thermistor 50 is the thin plate member 11.
Are formed at different positions on the front and back. That is, the thin plate material 11
The resistance value adjusting electrode 53 formed on the front surface of the thermistor element body 12 is exposed at one end of the thermistor element body 12, and the resistance value adjusting electrode 53 formed on the back surface of the thin plate member 11 is exposed at the other end of the thermistor element body 12. And the resistance adjusting electrodes 53 have portions overlapping each other. The configuration other than the above is the same as that of the first embodiment. The resistance value adjusting electrode can be appropriately changed into various patterns and numbers in order to set the resistance value of the thermistor to a desired value. Therefore, the first
The pattern is not limited to the pattern of the second embodiment.

[0022]

Next, examples of the present invention will be described in detail together with comparative examples. <Embodiment 1> As shown in FIGS. 1 to 5, a chip type thermistor 10 manufactured by the following method was used as Embodiment 1. First, manganese carbonate, cobalt carbonate, and copper oxide are used as starting materials,
These were weighed so that the metal atomic ratio was a predetermined ratio, uniformly mixed in a ball mill for 16 hours, dehydrated and dried. This mixture was calcined at 900 ° C. under atmospheric pressure for 2 hours, ground again with a ball mill, dehydrated and dried. An organic binder was added to this pulverized product, and the pulverized product was granulated by a spray dryer so that the particle size was about 60 μm, and compression molded into a rectangular parallelepiped by a hydraulic press. This molded product was fired at 1100 ° C. under atmospheric pressure for 4 hours to produce ceramic sintered blocks having lengths, widths and thicknesses of 35 mm, 50 mm and 10 mm, respectively, and the blocks were cut with a band saw to obtain length, width and 35mm, 50mm and 0.20 thickness
A thin plate member 11 having a thickness of mm was produced (FIG. 1A).

Next, a width of 2.7 m is applied to both sides of the thin plate material 11.
m band-shaped Ag paste was printed by a screen printing method at intervals of 0.20 mm in the width direction and dried. At this time, the Ag paste on both surfaces of the thin plate member 11 was printed so as to face each other with the thin plate member 11 interposed therebetween. This thin plate material 11
Was held at 820 ° C. under atmospheric pressure, and the Ag paste was baked on the thin plate material 11 to form a plurality of rows of resistance value adjusting electrodes 13 having a thickness of about 5 μm (FIG. 1A). On the other hand, a slip prepared by mixing a binder, a plasticizer, a solvent and the like with alumina powder is formed into a green sheet having a predetermined thickness by a doctor blade method, and this green sheet is fired at 1500 ° C. for 15 hours in the atmosphere. An insulating ceramic plate material 15 having a length, width, and thickness of 35 mm, 50 mm, and 0.20 mm was produced (FIG. 1A).

Two thin plate members 11 on which the resistance value adjusting electrodes 13 are formed are prepared and positioned so that the patterns of the resistance value adjusting electrodes 13 formed on these thin plate members 11 are at predetermined positions. Stacked and further these thin plate materials 1
1 was sandwiched between two insulating ceramic plate materials 15 and laminated and adhered with an insulating adhesive 16 such as an epoxy adhesive to form a laminated body 18 (FIGS. 1B and 2). At this time, in order to ensure the above-mentioned adhesion, a predetermined pressure was applied to the two thin plate members 11, 11 laminated before the adhesive 16 was cured.

This laminated body 18 is cut into a strip shape having a width of 0.75 mm in a direction orthogonal to the longitudinal direction of the resistance value adjusting electrode 13 by a dicing machine (FIG. 1 (c)), and a cut surface of the strip 21 is cut. After printing the polymer paste on screen by the screen printing method and drying, at 20 ℃ in air atmosphere
By heating and curing for a minute, a strip 22 with a coating coated with the polymer coating 17 was formed (FIG. 1).
(D)). The coated strip 22 is cut into chips in a direction orthogonal to the longitudinal direction of the strip 22 along the center of the resistance value adjusting electrodes 13 in the width direction, and is cut into a length of 1 A thermistor element body 12 having a chip shape of 0.52 mm was produced (FIGS. 1E and 4). One end faces of the resistance value adjusting electrodes 13 are exposed at both ends of the thermistor body 12.

Further, Ag electrode paste of epoxy frit is applied to both ends of the thermistor body 12 including both end faces of the thermistor body 12 and one end face of the resistance adjusting electrode 13 by a dipping method, and then at 250 ° C. 30 The electrode layers 23 were formed on both ends of the thermistor element body 12 by heat curing for a minute. A plating layer 24 was formed on the surface of the electrode layer 23 (FIG. 5). The plating layer 24 is the electrode layer 2 described above.
2-5μ formed on the surface of No. 3 by electrolytic barrel method
m of the Ni plating layer 24a and a solder plating layer 24b having a thickness of 3 to 7 μm formed on the surface of the Ni plating layer 24a. Thus, the chip type thermistor 10 shown in FIGS. 1F and 5 was obtained.

<Comparative Example 1> Although not shown, the above-mentioned Example 1 was used.
Except that the thermistor element body having the same size as that of the thermistor element body is formed of a single thin plate material, and the resistance value adjusting electrodes of Example 1 are formed on the upper surface and the lower surface of the thermistor element body. A chip type thermistor manufactured in the same manner as in Example 1 was used as Comparative Example 1. That is, no resistance value adjusting electrode is formed inside the chip type thermistor of Comparative Example 1.

<Comparative Example 2> Although not shown, the above Comparative Example 1
Comparative Example 2 was a chip-type thermistor manufactured in the same manner as in Comparative Example 1 except that the resistance value adjusting electrodes were not formed on the upper and lower surfaces of the thermistor element body. That is, in the chip type thermistor of Comparative Example 2, no resistance value adjusting electrode was formed.

<Comparative Test and Evaluation> Example 1, Comparative Example 1
The resistance values of the chip type thermistors Nos. 2 and 2 were measured. Table 1 shows the results. In Table 1, the resistance value reduction rate refers to the resistance value reduction rate of Example 1 and Comparative Example 1 with respect to the resistance value of Comparative Example 2.

[0030]

[Table 1]

As is clear from Table 1, the chip type thermistor of Example 1 was found to have a significantly reduced resistance value as compared with the chip type thermistors of Comparative Examples 1 and 2.

COMPARATIVE EXAMPLE 3 Although not shown, a chip type thermistor manufactured to have the same shape and size as the chip type thermistor of Example 1 by the following manufacturing method was used as Comparative Example 3.
First, a conductive paste is printed and dried on the upper surface of a ceramic green sheet to form a resistance value adjusting electrode, and then a plurality of green sheets are stacked to form a sheet-like laminated body, and the laminated body is fired to produce a sintered sheet. . Then, glass paste was printed on both surfaces of the sintered sheet and fired to form a glass layer made of insulating crystallized glass. Next, after cutting the sintered sheet whose both surfaces are covered with a glass layer into strips in a direction orthogonal to the column direction of the electrodes, glass paste is printed and fired on the cut surfaces on both sides of this strip in the same manner as above. To form a glass layer made of crystallized glass. Next, the strip was finely cut in a direction perpendicular to the cut surface and along the center line in the width direction of the electrode to prepare a thermistor body. A conductive paste was applied to both ends of the thermistor body so as to wrap the cut surface of the thermistor body and fired to form an electrode layer. Further, a plated layer was formed on the surface of this baked electrode layer as a base electrode layer to obtain a chip type thermistor having a termination electrode composed of the baked electrode layer and the plated layer.

<Comparative Test 2 and Evaluation> Thirty chip-type thermistors of Example 1 and Comparative Example 3 were produced and the variations in resistance values were compared. For the variation in resistance value, the standard deviation is s, and the average resistance value is Av. And when
3 × s / Av. The coefficient of variation (%) of the resistance value represented by was calculated and the coefficient of variation was compared. As a result, the coefficient of variation of the resistance value of Comparative Example 3 was 6.9%, whereas the coefficient of variation of the resistance value of Example 1 was as small as 1.5%. However, it was found that the variation in resistance value was extremely smaller than that of the chip type thermistor of Comparative Example 3.

[0034]

As described above, according to the present invention, a plurality of thin plate members made of a ceramic sintered body are laminated and adhered by an insulating adhesive, and the four side surfaces of the thermistor element body are opposed to each other and the resistance is increased. Since the insulating ceramic plate material is adhered to the two side surfaces on which the value adjusting electrodes are formed through the insulating adhesive, and the remaining two side surfaces of the four side surfaces of the thermistor body are covered with the insulating polymer film, Since the surface of the thermistor body is covered with a polymer film that can be heat-cured at a relatively low temperature, the thermal load on the thermistor body is small, and fluctuations in the resistance value and the B constant of the thermistor characteristics can be reduced. In addition, since the structure has resistance value adjusting electrodes on the surface and inside of the thermistor element body, the resistance value can be adjusted, that is, the resistance value can be easily decreased, and thermistors having low resistance and high B constant thermistor characteristics are compared. It can be easily obtained. Furthermore, since the insulating ceramic plate material having excellent mechanical strength is adhered to two of the four side surfaces of the thermistor body, the strength of the thermistor can be improved.

Further, a resistance value adjusting electrode is formed on the surface of a thin plate material made of a ceramic sintered body, and a plurality of thin plate materials are sandwiched between a pair of insulating ceramic plate materials and laminated and bonded by an insulating adhesive. To form a laminated body, and the laminated body is cut into strips, and an insulating polymer paste is applied to the cut surface, dried, and cured by heating to form a strip with a coating. The strip with a coating is formed. To form a chip thermistor body, and further form terminal electrodes consisting of an electrode layer and a plating layer at both ends of the thermistor body, by sintering the thin plate material and the insulating ceramic plate material, respectively. After the resistance value adjustment electrode is formed on the plate material, the thin plate material and the insulating ceramic plate material are laminated and adhered, so that the resistance value adjustment is not affected by variations such as shrinkage of the green sheet or conductive paste during firing. The distance between the electrodes is exactly, variations in resistance value can be obtain a small highly accurate thermistor.

Further, as a film for covering two of the four side faces of the thermistor body, an insulating polymer film which can be heat-cured at a relatively low temperature is used instead of the glass layer which needs to be baked at a relatively high temperature. As a result, the thermistor body can be coated without being exposed to high temperatures, so that the thermal load on the thermistor body is small and fluctuations in the thermistor characteristics can be reduced. Further, since the polymer material has a larger coefficient of thermal expansion than the glass material, the stress relationship between the thermistor body and the polymer film at the temperature at which the polymer cures after the film formation is such that the polymer film is different from the thermistor body. As a result, the compressive stress is applied, and the mechanical strength of the thermistor can be improved as compared with the case where the conventional glass layer applies tensile stress to the thermistor body. In addition, since the polymer coating has excellent compactness and high performance in terms of strength, when the thermistor element body is covered with the polymer coating, microcracks do not occur and the mechanical strength of the thermistor is improved. Can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a chip type thermistor according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along line CC of FIG. 1;

FIG. 5 is a sectional view taken along line DD of FIG. 1;

FIG. 6 is a sectional view illustrating a second embodiment of the present invention and corresponding to FIG. 5;

[Explanation of symbols]

 10, 50 Thermistor 11 Thin plate material 12 Thermistor element body 13, 53 Resistance value adjusting electrode 14 End stop electrode 15 Insulating ceramic plate material 16 Insulating adhesive 17 Polymer film 18 Laminated body 21 Strip-shaped article 22 Strip-shaped article with coating 23 Electrode layer 24 Plating layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Muraki 2270 Yokoze, Yokose-cho, Chichibu-gun, Saitama Sanryo Materials Co., Ltd.

Claims (3)

[Claims] 1. A plurality of thin plate materials made of a ceramic sintered body.
(11) a thermistor element body (12) formed in a rectangular parallelepiped shape by laminating and bonding, and a plurality of thermistor element bodies (12) formed on the surface and inside and exposed on the end surface of the thermistor element body (12) Of the resistance value adjusting electrode (13,53), and a terminal electrode electrically connected to the resistance value adjusting electrode (13,53) provided at both ends including both end surfaces of the thermistor element body (12) (14)
A thin plate material (11) is laminated and adhered by an insulating adhesive (16), and the resistance value adjusting electrodes face each other among the four side surfaces of the thermistor body (12). An insulating ceramic plate material (15) is adhered to the two side surfaces on which (13, 53) are formed via an insulating adhesive (16), and among the four side surfaces of the thermistor body (12) other than the two side surfaces. A chip type thermistor characterized in that two sides are covered with a polymer film (17) having an insulating property. 2. A plurality of thin plate materials are Mn, Co, Cu and F.
A ceramic sintered body containing one or more metal oxides selected from the group consisting of metal oxides containing e, Al and Ni, wherein the composition of the metal oxide is for each thin plate material. The chip type thermistor according to claim 1, wherein the ratio is different. 3. A step of forming a large number of resistance value adjusting electrodes (13) in parallel with each other at a predetermined interval on the surface of a thin plate material (11) made of a ceramic sintered body, and the resistance value adjusting electrode. A plurality of thin plate materials (1)
A plurality of thin plate materials (11) and a pair of insulating ceramic plate materials in a state that (1) is sandwiched by a pair of insulating ceramic plate materials (15)
Laminate (18) by laminating (15) with insulating adhesive (16)
And a step of cutting the laminate (18) into a strip shape in a direction orthogonal to the longitudinal direction of the resistance value adjusting electrode (13), and an insulating property on the cut surface of the strip (21). A step of forming a strip with coating (22) by coating a polymer paste, drying and heat curing, and the strip with coating (22) for each resistance adjustment electrode (13)
A step of forming the thermistor element body (12) in which the resistance value adjusting electrodes (13) are exposed at both ends by cutting along the center of the width direction, and both end surfaces of the thermistor element body (12) And the thermistor element body (12) including one end faces of the plurality of resistance value adjusting electrodes (13)
A step of forming an electrode layer (23) on both ends of the electrode layer (23) and a terminal electrode composed of the electrode layer (23) and the plating layer (24) by forming a plating layer (24) on the surface of the electrode layer (23) A method of manufacturing a chip type thermistor, including the step of forming (14).