JPH06295803A - Chip type thermister and production thereof - Google Patents

Abstract

PURPOSE:To produce a highly reliable chip type thermister excellent in solderability and soldering heat resistance in which fluctuation of resistance due to plating of enclosing electrode is suppressed easily at low cost. CONSTITUTION:A chip body stamped out from a green sheet for thermister is fired to produce a thermister body 10 and internal electrodes 11 are formed at the opposite ends of the body 10 while wrapping them. The body 10 is then coated with a dielectric inorganic layer 14 of 0.1-10mum thick over the entire surface thereof. A conductive paste containing a metal powder and an inorganic coupler is applied to the opposite end parts of the body 10 while wrapping them over an area smaller than the internal electrode and then the paste is fired at a temperature lower than the melting point or softening point of the inorganic layer. Consequently, a part of the underlying inorganic layer is fused to the inorganic coupler in the paste thus forming an external electrode 16. Subsequently, plating layers 18, 19 are formed on the surface of the external electrode.

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 sensor for temperature compensation of various electronic devices and a sensor for measuring a surface temperature. For more details,
Chip-type NTC that is surface-mounted on a printed circuit board, etc.
The present invention relates to a thermistor such as a thermistor and a PTC thermistor, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in a chip type thermistor, terminal electrodes containing silver-palladium as a main component are printed on both ends of a thermistor body. The reason for containing palladium in addition to silver in the electrode component is to prevent the silver from eluting and disappearing in the solder when soldering the chip type thermistor to the substrate, and to obtain the solder heat resistance of the electrode. is there. However, when the palladium content is increased, the solder adhesion of the electrode is reduced and the thermistor adhesion to the substrate is weakened, so the palladium content has a certain limit. Therefore, when the electrodes are soldered at a high temperature for a long time, the conventional chip type thermistor still has insufficient solder heat resistance.

In order to improve the solder heat resistance and the solder adhesion, it is conceivable to provide a plating layer on the surface of the baking electrode as in the case of the chip type capacitor. However, the thermistor element body is a ceramic element body for capacitors. Since the thermistor element has different conductivity, if the thermistor element is plated with the element exposed, plating will adhere to the element surface and the resistance of the thermistor will be different from the desired value, and the thermistor element will be eroded by the plating solution. As a result, the reliability of the thermistor is deteriorated and other problems occur.

For the purpose of eliminating the problem at the time of the plating treatment and allowing a wide selection of materials for the terminal electrodes, the applicant of the present invention has formed an insulating inorganic material layer over the entire surface of the thermistor element body having internal electrodes formed on both end surfaces. After coating, both ends of this thermistor body were wrapped with an outer envelope electrode, and a chip type thermistor in which a plating layer was formed on the surface of the outer envelope electrode was applied for a patent (Japanese Patent Application No. 3-355048). The insulating inorganic material layer of this thermistor has a melting point or a softening point higher than the firing temperature when forming the outer envelope electrode, and when forming the outer envelope electrode, a part of the inorganic layer corresponding to the base portion of the conductive paste is conductive. The inorganic binder contained in the paste is melted by reaction and absorbed by the outer envelope electrode to disappear. The inorganic layer is formed to have an extremely thin thickness of 2 to 10 μm in order to absorb and extinguish it by the outer envelope electrode.

[0005]

However, the above-mentioned chip type thermistor has the following problems. (a) When the thickness of the insulating inorganic material layer is less than 2 μm due to variations in manufacturing conditions, etc., the inorganic binder in the end-encapsulating portion of the thermistor element is not compatible with the inorganic material layer when forming the outer envelope electrode. Since the end-wrapped portion of the outer-wrapping electrode comes into direct contact with the thermistor element body after being melted and electrically connected to the thermistor element body, the resistance value of the chip type thermistor varies. (b) As a result, the thickness of the insulating inorganic material layer is limited to 2 μm or more, and even if the thickness of the inorganic material layer is 2 μm or more, depending on the type of the inorganic binder contained in the conductive paste and the type of the inorganic material layer. The same phenomenon is still observed, and the resistance value of the thermistor may vary.

(C) Further, when the inorganic layer having a thickness of more than 2 μm is formed on the entire surface by sputtering,
The formation time of the inorganic layer becomes long and the productivity of the thermistor is poor. (d) If the thickness of the inorganic layer is appropriate and the end-wrapping part of the outer-wrapping electrode does not directly contact the thermistor body, the contact area of the inner-wrapping electrode with the thermistor body determines the resistance value of the thermistor. Although it is determined, since this internal electrode has only the both end surfaces of the thermistor element body, variations occur in the dimensions of the thermistor element body, or when the conductive paste drips from the end surface to the side surface during the formation of the internal electrode, The resistance value of the thermistor tends to deviate from the expected value.

An object of the present invention is to provide a chip type thermistor which is excellent in solder heat resistance and solder adhesion, has no change in resistance value due to electrode plating, and has high reliability. Another object of the present invention is to provide a chip type thermistor which can obtain desired characteristics even if electrodes on both ends of a conductive thermistor body are plated.

Another object of the present invention is to provide a chip type thermistor in which variations in resistance value are small and the material of the outer envelope electrode can be widely selected. Still another object of the present invention is to
It is an object of the present invention to provide a method for manufacturing a chip-type thermistor suitable for mass production, in which the excellent chip-type thermistor can be manufactured relatively easily and inexpensively.

[0009]

As shown in FIGS. 1 and 2, a chip type thermistor of the present invention comprises a thermistor body 10 and internal electrodes 11 provided at both ends of the thermistor body 10. An insulating inorganic material layer 14 covering the entire surface of the thermistor element body 10 on which the internal electrode 11 is formed,
The thermistor element body 10 covering the inorganic layer 14 is provided with outer envelope electrodes 16 provided at both ends, and plating layers 18 and 19 formed on the surfaces of the outer envelope electrode 16. The characteristic configuration is that the internal electrode 11 has the thermistor element body 1.
0 is formed so as to enclose both ends, and the outer envelope electrode 16 includes a conductive paste containing a metal powder and an inorganic binding material.
It is formed by coating and baking both ends of the thermistor element body 10 with a wrapping area less than 1.
The inorganic layer 14 has a thickness of 0.1 to 10 μm, has a melting point or a softening point higher than the firing temperature for forming the outer envelope electrode 16, and a part of the inorganic layer of the base portion of the paste is the outer envelope. This is because when the electrode 16 was formed, it was reacted and melted with the inorganic binder to be absorbed by the outer envelope electrode 16 and disappeared.

As shown in FIGS. 3 to 6, the method of manufacturing a chip type thermistor according to the present invention comprises the steps of preparing a slurry by mixing a metal oxide powder and a binder, and drying the slurry to form a film. To form a green sheet, a step of punching the chip body 2 from the green sheet, a step of firing the chip body 2 to form the thermistor body 10, and the both ends on both end faces of the thermistor body 10. Of forming the internal electrode 11 so as to enclose the part, and the internal electrode 11
The thermistor element body 10 having the formed
A step of coating the insulating inorganic layer 14 of 10 μm, and a wrapping area smaller than that of the inclusion electrode 11 with the conductive paste 30 containing the metal powder and the inorganic binder 32 at both ends of the thermistor element body 10 coated with the inorganic layer 14. And the step of applying so as to wrap both ends thereof, and the thermistor element body 10 applied with this paste 30 is fired at a temperature lower than the melting point or softening point of the inorganic material layer 14 to apply the inorganic binder 3 of the applied paste.
2, a step of extinguishing a part of the inorganic layer of the base portion of the paste by reaction melting to form the outer envelope electrode 16, and plating layers 18, 19 on the surface of the outer envelope electrode 16.
And a step of forming.

The present invention will be described in detail below. (a) Production of thermistor element body The thermistor element body of the present invention is produced by the following method. First, one kind or two or more kinds of oxide powders of metals such as Mn, Fe, Co, Ni, Cu and Al are sampled and mixed. When two or more kinds are mixed, each metal oxide is weighed so as to have a predetermined metal atomic ratio. After calcining and pulverizing this mixture, an organic binder and a solvent are added and kneaded to prepare a slurry.
Then, this slurry is dried by a doctor blade method or the like to form a green sheet. A chip body 2 shown in FIG. 3A is punched out from this green sheet, and is fired to form a chip-like thermistor body 10 shown in FIG. 3B.
To get

(B) Formation of Encapsulating Electrode As shown in FIG. 3 (c), the conductive paste is applied to both ends of the thermistor element body so as to wrap both ends, and then the encapsulating electrode is dried and baked. 11 is formed. The application is preferably a dipping method in which both ends of the thermistor element body are dipped in a conductive paste. The metal powder contained in this paste is not particularly limited as long as it maintains conductivity with the thermistor element body 10. Examples of this include noble metals such as Ag, Au, Pd and Pt, or powders obtained by mixing these.

(C) Coating of Insulating Inorganic Material Layer on Thermistor Element Body The entire surface of the thermistor element body 10 on which the inclusion electrode 11 is formed is coated with an insulating inorganic material layer having a thickness of 0.1 to 10 μm (see FIG. 3 (d)). When the thickness is more than 10 μm, the inorganic layer melted during the formation of the external electrode described later is not completely absorbed in the external electrode, and the inorganic layer remains as an insulating film at the interface between the external electrode and the internal electrode, so that the external electrode and the internal electrode And do not connect. When the thickness is less than 0.1 μm, the function of protecting the thermistor element during the plating treatment described later and after the plating treatment is poor. As an example of this insulating inorganic material layer 14 (FIGS. 1 and 2), a SiO ₂ film, or 50 wt% or more of SiO ₂ and the balance of Al ₂ O ₃ , MgO, ZrO ₂ and TiO _{2 is used.}
Thin film composed of one or more oxides of _2,
Alternatively, a thin film made of glass containing one or more oxides of SiO ₂ , B ₂ O ₃ , Na ₂ O, PbO, ZnO and BaO as a main component may be mentioned. This inorganic layer 1
No. 4 needs to have a melting point or softening point higher than the firing temperature when forming the envelope electrode described later. For example,
When an Ag paste is baked as the envelope electrode, the baking temperature is 600 to 850 ° C., and therefore a material having a melting point or a softening point higher than this temperature is selected. The reason for this is that if the melting point or softening point is significantly lower than the baking temperature of the paste, the inorganic material layer floats up on the electrode surface during paste baking, or the thermistor element bodies or the element body and the firing jig adhere to each other and yield increases. Is easily reduced.

Other than this requirement, the inorganic layer 14 is not particularly limited as long as it has resistance to plating and has a property of reacting with an inorganic binder contained in a conductive paste described later and melting. Or may be amorphous. However, the glass is crystalline and the inorganic layer 1
When 4 is crystallized glass, the bending strength of the thermistor is increased, which is preferable. The thermistor body is coated with an inorganic layer by a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method (C).
VD method). Among these, the sputtering method is preferable because it is suitable for mass production. For mass production by this method, as shown in FIG. 4, a stainless steel basket 22 rotatable around a horizontal shaft 20 is prepared, and a large number of thermistor bodies 10 are housed therein. The basket 22 is put in a sputtering device (not shown). A target 24 for obtaining a desired inorganic layer is mounted in the apparatus. For example, if the inorganic layer is a SiO ₂ film, quartz glass is used, and SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ are used.
_{In the case of} a composite oxide film of ₂ , B ₂ O ₃ , Na ₂ O, PbO, ZnO, BaO, etc., these are formed into a disk shape by powder metallurgy, or they are melted and cooled to form a disk-shaped composite glass. To use. When the sputtering is performed while swinging the basket 22 around the horizontal axis 20, the target material knocked out from the target 24 is condensed on the entire surface of the thermistor element body 10, and the inorganic material layer 14 made of the target material is formed.

(D) Formation of outer electrode As shown in FIG. 3 (e), a conductive paste 30 containing a metal powder and an inorganic binder is applied to both ends of the thermistor element body 10 covered with the insulating inorganic material layer 14. To do. This application is performed so that the conductive paste 30 wraps the both ends of the thermistor element body in a wrapping area smaller than that of the internal electrode 11. This coating is preferably a dipping method in which both ends of the thermistor element body are dipped in a conductive paste, similar to the method of forming the internal electrodes. Further, the metal powder contained in the conductive paste may be a noble metal such as Ag, Au, Pd, or Pt which is the same type as the inclusion electrode, or a powder obtained by mixing these. As an example of the inorganic binder contained in the conductive paste 30, SiO ₂ , B ₂ O ₃ ,
Glasses such as borosilicate glass, zinc borate glass, cadmium borate glass, lead zinc silicate glass, which contain one or more oxides of Na ₂ O, PbO, ZnO and BaO as main components. Examples include fine particles.

As shown in FIG. 5, the inorganic binder 32 is uniformly dispersed in the applied conductive paste 30.
The inorganic binder 32 needs to have a property of reacting with the inorganic layer 14 that comes into contact with the paste 30 during baking of the conductive paste to melt and extinguish a part of the inorganic layer 14 as shown in FIG. . As shown in FIGS. 3 (f) and 6, the conductive paste 30 is baked to cover the outer electrode 1.
6 is generated, and the outer electrode 16 is electrically connected to the inner electrode 11 due to the disappearance of a part of the inorganic layer 14 during the baking.

(E) Formation of Plating Layer A plating layer is formed on the surface of the envelope electrode 16. This plating layer preferably has a double structure by forming a Ni plating layer 18 as shown in FIG. 3 (g) and then forming an Sn plating layer 19 as shown in FIG. 3 (h). Ni plating layer 1
8 improves solder heat resistance, prevents electrode erosion of the outer envelope electrode by solder, and the Sn plating layer 19 improves solder adhesion. Inner electrode 11, outer electrode 16, plating layer 1
The terminal electrode 12 is formed by 8 and 19 (FIGS. 1 and 2).

[0018]

When the thermistor element body coated with the conductive paste for the envelope electrode is fired at a temperature lower than the melting point or softening point of the inorganic layer, the envelope electrode 1 as shown in FIG. 3 (f) and FIG.
6 is formed. That is, during the firing, the inorganic binder 32 uniformly dispersed in the paste reacts with a part of the inorganic layer 14 to melt it. The fluidized inorganic substance of the inorganic substance layer 14 penetrates into the pores in the outer envelope electrode 16 formed when the metal is sintered. Since the thickness of the inorganic material layer 14 is set to 0.1 to 10 μm, a part of the inorganic material layer 14 is absorbed in the pores during the firing process and partially disappears from the surface of the inclusion electrode 11. As a result, the outer electrode 16 and the inner electrode 11
Are directly bonded through the disappeared portion of the inorganic layer 14 and are electrically connected to each other. Since the inner electrode 11 is formed so as to maintain conductivity with the thermistor body 10, the outer electrode 16 and the thermistor body 10 are electrically connected.

Since the wrapping area of both ends of the outer envelope electrode 16 is smaller than the wrapping area of the inner envelope electrode 11, the outer envelope electrode 1
6 does not cover the part of the inorganic layer 14 where the internal electrode 11 does not exist. Therefore, even if the thickness of the inorganic layer 14 is as thin as 0.1 μm, which is the lower limit value, the outer envelope electrode 16 does not directly contact the thermistor element body 10, and the current is the outer envelope electrode 16, the inner envelope electrode 11, It flows through the thermistor body 10. On the other hand, even if the paste of the inorganic layer 14 to which the conductive paste for the envelope electrode is not applied is baked, the melting point or softening point of the inorganic layer is higher than the baking temperature.
It remains on the surface of the thermistor element body 10 without any change and maintains its insulation protection function.

[0020]

As described above, in the conventional manufacturing method, the number of steps is large and complicated, but according to the manufacturing method of the present invention, the terminal electrode of the chip type thermistor can be relatively easily manufactured with a small number of steps. Since it can be formed, it is suitable for mass production and the cost for forming electrodes is low. Further, in the chip type thermistor of the present invention, the thermistor element body is covered with the insulating inorganic material layer except for the portion where the outer envelope electrode is in contact, and the thermistor element body is protected by this inorganic material layer, so that plating is performed even if plating There is no change in properties due to erosion of the liquid on the element body or plating adhesion. By forming a plating layer on the surface of the envelope electrode,
It has excellent effects on solder heat resistance and solder adhesion. In particular, since the wrapping area of the external electrode is smaller than the wrapping area of the internal electrode, the resistance value of the thermistor can be accurately set by this internal electrode because the internal electrode is provided, and the material of the external electrode can be widely selected. Further, by this, the thickness of the insulating inorganic material layer can be made extremely thin, and when the inorganic material layer is formed by the vapor deposition method, the formation time of the inorganic material layer is shortened and the thermistor productivity is improved.

[0021]

EXAMPLES The present invention will now be described based on examples in order to show specific embodiments of the present invention. The examples described below do not limit the technical scope of the present invention. Example 1 A chip type thermistor shown in FIGS. 1 and 2 was manufactured by the following method. First, commercially available manganese carbonate, nickel carbonate, and cobalt carbonate were used as starting materials, and M
Converted to nO ₂ : NiO: CoO, the metal atom ratio is 3: 1:
Each was weighed in the ratio of 2. Weigh 1 with ball mill
After uniformly mixing for 6 hours, it was dehydrated and dried. Next, this mixture was calcined at 900 ° C. for 2 hours, and the calcined product was again pulverized with a ball mill and dehydrated and dried. Polyvinyl butyral 6% by weight, ethanol 30% with respect to 100% by weight of pulverized product
Binders of 30% by weight and 30% by weight of butanol were added and uniformly mixed to prepare a slurry. The slurry was dried by a doctor blade method to form a green sheet having a thickness of 0.80 mm. 2.34 mm from this sheet
A chip body with a size of 1.48 mm was punched out and fired at 1200 ° C. for 4 hours under atmospheric pressure to obtain a sintered body having a length of 1.9 mm, a width of 1.2 mm and a thickness of 0.65 mm.

This sintered body was used as the thermistor body 10 shown in FIG. 3B, and silver paste was applied to both ends of this thermistor body by a dipping method. After the silver paste on both ends was dried, it was baked at 800 ° C. under atmospheric pressure to form the internal electrode 11 (FIG. 3C).

Next, the thermistor element body 10 having the encapsulated electrode 11 formed thereon was formed with an insulating inorganic material layer made of a SiO ₂ film on the entire surface thereof by using the sputtering apparatus shown in FIG. That is, a stainless steel cage 22 containing a large number of thermistor bodies 10 is set in a sputtering device using a quartz glass as a target 24, and the thermistor body 1 is subjected to sputtering while rocking the cage 22.
A SiO ₂ film having a thickness of 2 μm was formed on the entire surface of No. 0 (FIG. 3D).

Further, terminal electrodes 12 are provided on both ends of the thermistor element body 10 whose entire surface is covered with the SiO ₂ film 14. The terminal electrode 12 includes an inner electrode 11, an outer electrode 16 and Ni.
It is composed of the plating layer 18 and the Sn plating layer 19. First, a conductive paste was applied by a dipping method to both ends of the thermistor element body on which the inorganic layer 14 was formed (FIG. 3).
(E)). This application was performed so that both ends of the thermistor element body were covered with the conductive paste with a smaller covering area than the inclusion electrode 11. The conductive paste is a commercially available silver paste (JPN-1176J manufactured by DuPont), and Ag powder, glass fine particles composed of SiO ₂ , TiO ₂ , B ₂ O ₃ , Na ₂ O and K ₂ O, and an organic vehicle. Consists of. After drying the thermistor element coated with the conductive paste under atmospheric pressure, the temperature is raised to 820 ° C. at a rate of 30 ° C./minute, held there for 10 minutes, and then lowered to room temperature at a rate of 30 ° C./minute. An envelope electrode 16 made of Ag was obtained (FIG. 3 (f)). Next, the thickness of the electrode 16 is 2-3 μm by the electrolytic barrel plating method.
m Ni plating layer 18 is formed, and then the thickness is 1-2 μm.
The Sn plating layer 19 was formed. <Comparative Example 1> Example 1 described above except that the inner electrode was formed only on both end surfaces of the thermistor element body without enclosing the both end portions of the thermistor element body, and the outer electrode was formed by enclosing both end portions of the thermistor element body.
A chip type thermistor with a plated layer was produced by the same method as described above.

<Embodiment 2> The insulating inorganic material layer is made of SiO ₂ ,
A chip type thermistor with a plating layer was produced in the same manner as in Example 1 except that a PbO, K ₂ O based glass film was used and the firing temperature after applying the conductive paste for the outer envelope electrode was 600 ° C.

<Comparative Example 2> Except that the internal electrodes are formed only on both end surfaces of the thermistor element body without enclosing the both ends of the thermistor element body, and the outer electrode is formed by enclosing both end portions of the thermistor element body.
A chip type thermistor with a plated layer was produced in the same manner as in Example 2 above.

<Comparison Test and Results> Example 1, Example 2,
100 each of the thermistors of Comparative Example 1 and Comparative Example 2 were prepared. -Dispersion of resistance value The resistance value of each of these thermistors was measured, and the deviation of the resistance value was calculated from the deviation of the resistance value average value from the resistance reference value and the average value and standard deviation. The results are shown in Table 1.

Microscopic Observation of Polished Cross Section Each of these thermistors is polished so that the cross section shown in FIG. 2 appears, and the cross section is observed with a microscope to count the number of chips in which the outer electrode is directly connected to the thermistor body. did. The results are shown in Table 1. As is clear from Table 1, the thermistors of Example 1 and Example 2 are compared with the thermistors of Comparative Example 1 and Comparative Example 2.
None of the external electrodes were connected to the thermistor element body, and there were few deviations and variations in resistance values, and good characteristics were obtained.

[0029]

[Table 1]

[0030]

[Brief description of drawings]

FIG. 1 is a fragmentary perspective view of a chip type thermistor of the present invention.

FIG. 2 is a central sectional view thereof.

FIG. 3 is a perspective view of an element body in a process from the thermistor element body of the present invention to a chip type thermistor.

FIG. 4 is a schematic perspective view of a sputtering apparatus for coating the surface of the thermistor element body with an insulating inorganic material layer.

FIG. 5 is an enlarged cross-sectional view of a main part of the thermistor element body in which a conductive paste for an envelope electrode is applied.

FIG. 6 is an enlarged cross-sectional view of a main part in a state where the conductive paste is baked to form an outer envelope electrode.

[Explanation of symbols]

 2 Chip Body 10 Thermistor Element 11 Internal Electrode 12 Terminal Electrode 14 Insulating Inorganic Material Layer 16 External Encapsulation Electrode 18 Ni Plating Layer 19 Sn Plating Layer 30 Conductive Paste 32 Inorganic Binder

[Procedure amendment]

[Submission date] April 9, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The present invention will be described in detail below. (a) Production of thermistor element body The thermistor element body of the present invention is produced by the following method. First, one kind or two or more kinds of oxide powders of metals such as Mn, Fe, Co, Ni, Cu and Al are sampled and mixed. When two or more kinds are mixed, each metal oxide is weighed so as to have a predetermined metal atomic ratio. After calcining and pulverizing this mixture, an organic binder and a solvent are added and kneaded to prepare a slurry.
Then, this slurry is dried by a doctor blade method or the like to form a green sheet. A chip body 2 shown in FIG. 3A is punched out from this green sheet, and is fired to form a chip-like thermistor body 10 shown in FIG. 3B.
To get It is preferable that the thermistor element body 10 is barrel-polished in the same manner as the chip type multilayer capacitor to square off the thermistor element body.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

[0021]

EXAMPLES The present invention will now be described based on examples in order to show specific embodiments of the present invention. The examples described below do not limit the technical scope of the present invention. Example 1 A chip type thermistor shown in FIGS. 1 and 2 was manufactured by the following method. First, commercially available manganese carbonate, nickel carbonate, and cobalt carbonate were used as starting materials, and M
Converted to nO ₂ : NiO: CoO, the metal atom ratio is 3: 1:
Each was weighed in the ratio of 2. Weigh 1 with ball mill
After uniformly mixing for 6 hours, it was dehydrated and dried. Next, this mixture was calcined at 900 ° C. for 2 hours, and the calcined product was again pulverized with a ball mill and dehydrated and dried. Polyvinyl butyral 6% by weight, ethanol 30% with respect to 100% by weight of pulverized product
Binders of 30% by weight and 30% by weight of butanol were added and uniformly mixed to prepare a slurry. The slurry was dried by a doctor blade method to form a green sheet having a thickness of 0.80 mm. 2.34 mm from this sheet
A chip body with a size of 1.48 mm was punched out and fired at 1200 ° C. for 4 hours under atmospheric pressure to obtain a sintered body having a length of 1.9 mm, a width of 1.2 mm and a thickness of 0.65 mm. The sintered body was barrel-polished and the sintered body was chamfered.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

Further, electrodes were provided on both ends of the thermistor body 10 whose entire surface was covered with the SiO ₂ film 14. As a result, the terminal electrode 12 including the inner electrode 11, the outer electrode 16, the Ni plating layer 18, and the Sn plating layer 19 was formed.
First, a conductive paste was applied by a dipping method to both ends of the thermistor element body on which the inorganic layer 14 was formed (FIG. 3).
(E)). This application was performed so that both ends of the thermistor element body were covered with the conductive paste with a smaller covering area than the inclusion electrode 11. The conductive paste is a commercially available silver paste (JPN-1176J manufactured by DuPont), and Ag powder, glass fine particles composed of SiO ₂ , TiO ₂ , B ₂ O ₃ , Na ₂ O and K ₂ O, and an organic vehicle. Consists of. After drying the thermistor element coated with the conductive paste under atmospheric pressure, the temperature is raised to 820 ° C. at a rate of 30 ° C./minute, held there for 10 minutes, and then lowered to room temperature at a rate of 30 ° C./minute. An envelope electrode 16 made of Ag was obtained (FIG. 3 (f)). Next, the thickness of the electrode 16 is 2-3 μm by the electrolytic barrel plating method.
m Ni plating layer 18 is formed, and then the thickness is 1-2 μm.
The Sn plating layer 19 was formed. <Comparative Example 1> Example 1 described above except that the inner electrode was formed only on both end surfaces of the thermistor element body without enclosing the both end portions of the thermistor element body, and the outer electrode was formed by enclosing both end portions of the thermistor element body.
A chip type thermistor with a plated layer was produced by the same method as described above. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

(C) Coating of Insulating Inorganic Material Layer on Thermistor Element Body The entire surface of the thermistor element body 10 on which the inclusion electrode 11 is formed is coated with an insulating inorganic material layer having a thickness of 0.1 to 10 μm (see FIG. 3 (d)). When the thickness is more than 10 μm, the inorganic layer melted during the formation of the external electrode described later is not completely absorbed in the external electrode, and the inorganic layer remains as an insulating film at the interface between the external electrode and the internal electrode, so that the external electrode and the internal electrode And do not connect. When the thickness is less than 0.1 μm, the function of protecting the thermistor element during the plating treatment described later and after the plating treatment is poor. As an example of the insulating inorganic material layer 14 (FIGS. 1 and 2), a SiO ₂ film, or 50 wt% or more of SiO ₂ and the balance of Al ₂ O ₃ , MgO, ZrO ₂ or TiO _{2 is used.}
Thin film constituted by any one or more oxides of _2, or _{SiO 2, B 2 O 3,} Na 2 O, PbO, Z
Examples of the thin film include glass containing, as a main component, one or more oxides of nO and BaO. The inorganic layer 14 needs to have a melting point or a softening point higher than the firing temperature when forming the envelope electrode described later. For example, when an Ag paste is baked as the envelope electrode, the baking temperature is 600 to 850 ° C., and therefore, a material having a melting point or a softening point higher than this temperature is selected. The reason for this is that if the melting point or softening point is significantly lower than the baking temperature of the paste, the inorganic material layer floats up on the electrode surface during paste baking, or the thermistor element bodies or the element body and the firing jig adhere to each other and yield increases. Is easily reduced.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

(D) Formation of outer electrode As shown in FIG. 3 (e), a conductive paste 30 containing a metal powder and an inorganic binder is applied to both ends of the thermistor element body 10 covered with the insulating inorganic material layer 14. To do. This application is performed so that the conductive paste 30 wraps the both ends of the thermistor element body in a wrapping area smaller than that of the internal electrode 11. This coating is preferably a dipping method in which both ends of the thermistor element body are dipped in a conductive paste, similar to the method of forming the internal electrodes. Further, the metal powder contained in the conductive paste may be a noble metal such as Ag, Au, Pd, or Pt which is the same type as the inclusion electrode, or a powder obtained by mixing these. As an example of the inorganic binder contained in the conductive paste 30, SiO ₂ , B ₂ O ₃ ,
Borosilicate-based glass, zinc borate-based glass, cadmium borate-based glass containing, as a main component, one or more oxides of Na ₂ O, PbO, ZnO, and BaO.
Examples thereof include fine glass particles such as lead zinc silicate based glass.

Claims (6)

[Claims] 1. A thermistor element body (10), internal electrodes (11) provided at both ends of the thermistor element body (10), and a thermistor element body (10) on which the internal electrode (11) is formed. Insulating inorganic material layer (14) covering the entire surface of the thermistor and outer electrode provided on both ends of the thermistor element body (10) covering the inorganic material layer (14)
(16) and a plating layer formed on the surface of the outer electrode (16)
(18, 19) is a chip-type thermistor, wherein the inner electrode (11) is formed so as to enclose both ends of the thermistor body (10), the outer electrode (16) is a metal powder And a conductive paste containing an inorganic binder is formed by coating and baking so as to wrap both ends of the thermistor element body (10) in a wrapping area smaller than the inclusion electrode (11), the inorganic material layer (14) has a thickness of 0.1 to 10 μm,
The external electrode (16) has a melting point or a softening point higher than the firing temperature at the time of forming, and a part of the inorganic layer of the base portion of the paste is the inorganic binder when the external electrode (16) is formed. A chip-type thermistor, which is configured so as to react with and melt into the outer envelope electrode (16) and disappear. 2. The insulating inorganic material layer (14) is made of SiO ₂ or 50.
% By weight of SiO ₂ and the balance Al ₂ O ₃ , MgO, Z
is constituted by the one or more oxides of and rO ₂ and TiO _2, SiO ₂ inorganic binder contained in the conductive paste for forming the envelope electrode _{(16), B 2 O 3} , Na 2 O,
A glass fine particle containing, as a main component, one or more oxides of PbO, ZnO and BaO.
The described chip type thermistor. 3. The insulating inorganic layer (14) comprises SiO ₂ , B.
Inorganic contained in the conductive paste for forming the envelope electrode (16), which is composed of glass containing one or more oxides of ₂ O ₃ , Na ₂ O, PbO, ZnO and BaO as a main component. The binder is SiO ₂ , B ₂ O ₃ , Na ₂ O, Pb
The chip type thermistor according to claim 1, wherein the chip type thermistor is composed of glass fine particles containing at least one oxide of O, ZnO and BaO as a main component. 4. The chip type thermistor according to claim 3, wherein the insulating inorganic material layer (14) is made of crystallized glass. 5. A step of preparing a slurry by mixing a metal oxide powder and a binder, a step of film-forming and drying the slurry to form a green sheet, and a step of forming a chip body (2) from the green sheet. A step of punching, a step of firing the chip body (2) to form a thermistor element body (10), and an encapsulating electrode (11) so as to wrap both ends of the thermistor element body (10). And a step of forming the thermistor element body (10) on which the internal electrode (11) is formed.
A step of coating an insulating inorganic layer (14) having a thickness of 0.1 to 10 μm on the entire surface of the thermistor element body (10) coated with the inorganic layer (14) on both sides of the metal powder and the inorganic binder ( 32) Conductive paste (3
A step of applying 0) so as to wrap the both ends in a wrapping area smaller than the inclusion electrode (11), and a thermistor element body (10) coated with the paste (30) of the inorganic material layer (14) Firing at a temperature below the melting or softening point,
A step of forming the envelope electrode (16) by extinguishing a part of the inorganic layer of the base portion of the paste by reaction melting in the inorganic binder (32) of the applied paste, and the envelope electrode (16) And a step of forming a plating layer (18, 19) on the surface of the chip-type thermistor. 6. An insulating inorganic material layer for the thermistor element body (10)
The method for manufacturing a chip type thermistor according to claim 5, wherein the coating of (14) is performed by a physical vapor deposition method.