JPH1092606A - Chip thermistor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a chip thermistor which has high accuracy, a high environmental resistance, and highly reliable mechanical strength and temperature cycle performance, etc., at high mass-productivity. SOLUTION: External electrodes 2 on both end faces of a chip-like thermistor blank body 1 are respectively constituted in laminated structures of conductive metallic layers 2a, conductive resin layers 2b, and plated-meal layers 2c. After glass layers 3 are formed on the four side faces of a prism-like thermistor blank body obtained by cutting a thermistor wafer into strip-like bodies, the thermistor blank body 1 is obtained by cutting the prism-like blank body and the external electrodes 2 are formed on both end faces of the blank body 1. Therefore, the cracking of the blank body 1 is prevented, because the mechanical stress or thermal stress given to the electrodes 2 when the thermistor body 1 is mounted on a substrate or the blank body 1 is subjected to a temperature cycle can be relieved by means of the soft resin layers 2b.

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 surface-mounted on a printed circuit board or the like and a method for manufacturing the same, and more particularly, to a chip type thermistor having excellent mechanical strength, high accuracy and high reliability. The present invention relates to a method of manufacturing a simple chip thermistor at low cost.

[0002]

2. Description of the Related Art As a typical product of a chip type thermistor surface-mounted on a printed circuit board or the like, as shown in FIG. Baking terminal electrode 2A and plating layer 2 covering its surface to improve adhesion
B is formed, and a structure other than the surface on which the external electrodes 2 are formed is covered with an insulating inorganic layer such as a glass layer 3.

Conventionally, such a chip type thermistor 4
Is manufactured as follows. That is, first, a glass paste is printed and applied to both plate surfaces of a thin plate-shaped thermistor element body (hereinafter sometimes referred to as a “thermistor wafer”) made of a ceramic sintered body, and then fired to form an insulating glass layer. Form. Next, the thermistor wafer whose both surfaces are covered with the glass layer is cut out in a strip shape, and then the glass layer is formed on the cut surface by printing and applying a glass paste in the same manner as described above. The thus obtained prismatic thermistor body having glass layers on four sides is cut in a direction perpendicular to the longitudinal direction (a direction perpendicular to the cut surface) to obtain a chip-like thermistor body. A conductive paste is applied to the cut surfaces (both end surfaces) of the chip-shaped thermistor body and baked to form baked terminal electrodes. Further, a plating layer is formed on the surface of the terminal electrode to obtain a chip type thermistor 4 shown in FIG.
250603). The prism-shaped thermistor element having glass layers on the four sides can also be manufactured by cutting a thermistor wafer as it is into a strip shape, applying a glass paste on the four sides, and firing.

In the above chip type thermistor,
There is also provided a chip thermistor element in which a surface electrode for adjusting a resistance value is formed on a side surface of the chip thermistor body. Such a chip thermistor is prepared by applying a conductive base to both surfaces of a thermistor wafer in advance. It is manufactured by the same method as described above except that a surface electrode for adjusting the value is formed (Japanese Patent Laid-Open No. 4-127401).

[0005] As described above, a plurality of chip-shaped thermistor bodies are manufactured by cutting the prism-shaped thermistor body whose four side surfaces are covered with a glass layer, and the chip-shaped thermistor body is manufactured by dipping or the like. The conventional method of manufacturing a chip-type thermistor, in which a conductive paste for forming an electrode is simultaneously applied to the cut surfaces at both ends and fired, is extremely excellent in mass productivity, and the obtained product is cut into chips to obtain dimensional accuracy. Excellent. In addition, since the connection surface between the thermistor element and the electrode is set in advance at the time of processing, irrespective of the coating shape of the electrode, variation in the resistance value is extremely small. Moreover, since the entire surface of the element body is covered with the glass layer and the electrode layer, there are various advantages such as excellent environmental resistance.

[0006]

Since the chip-shaped thermistor body of the chip-type thermistor manufactured by the above-mentioned conventional manufacturing method is manufactured by cutting, the apex corners of its four side surfaces and both end surfaces are sharp. It becomes a pyramid shape. For this reason, when mounted on a circuit board, the mechanical stress resulting from bending when the board is cut or the like, or the thermal stress resulting from the difference in the coefficient of thermal expansion of the thermistor body, electrodes, solder, board, etc. during a temperature cycle passes through the external electrodes. The chip concentrates on the apical corner of the chip body, and cracks are likely to occur.

Conventionally, efforts have been made to reduce the stress by optimizing the coefficient of thermal expansion of an inorganic layer such as glass with respect to the thermistor body, but this has not been completely solved. In addition, it is also possible to round the corners of the chip-shaped thermistor body by post-processing, but in this method, the processing shape tends to vary, and the chip size becomes smaller due to processing,
There is a problem that the manufacturing cost increases.

The present invention solves the above-mentioned conventional problems, and provides a chip type thermistor having high accuracy, excellent environmental resistance, and excellent reliability such as mechanical strength and temperature cycle performance at low cost and with good productivity. It is intended to do so.

[0009]

According to the present invention, there is provided a chip-type thermistor according to the present invention, comprising: a rectangular parallelepiped chip-shaped thermistor element made of a ceramic sintered body; external electrodes formed on both end surfaces of the chip-shaped thermistor element; In a chip-type thermistor having a coating layer made of an insulating inorganic material covering four side surfaces other than the both end surfaces, the external electrode includes a conductive metal layer in contact with an end surface of the chip-shaped thermistor body, and the conductive metal layer. It is characterized by comprising a conductive resin layer formed thereon and a metal plating layer formed on the conductive resin layer.

In the chip type thermistor of the present invention, when mounted on a circuit board, mechanical stress caused by bending when the board is cut, or thermistor element during a temperature cycle,
When thermal stresses due to differences in the coefficients of thermal expansion of the electrodes, solder, substrate, etc., are transmitted to the external electrodes, these stresses are relieved by the flexible conductive resin layer in the intermediate layer of the external electrodes. For this reason, generation of cracks in the chip-shaped thermistor body due to these stresses is prevented.

The conductive metal layer as the lower electrode layer of the external electrode is effective for sufficient electrical connection with the thermistor body and strong mechanical connection with the thermistor body and an inorganic coating layer such as glass. Since the conductive metal layer and the conductive resin layer have extremely low resistance, their electrical connection is also good.

The metal plating layer preferably comprises a nickel plating layer and a solder plating layer formed on the nickel plating layer from the viewpoints of solder wettability and heat resistance required for mounting on a substrate. Even without a layer, the conductive resin layer can sufficiently withstand solder erosion. Therefore, the nickel plating layer can be omitted, and the product price can be reduced.

In the chip type thermistor of the present invention, a step of forming an insulating inorganic layer on four side surfaces extending in the longitudinal direction of a prismatic thermistor element made of a ceramic sintered body, and forming the insulating inorganic layer. Cutting the prism-shaped thermistor body in a direction perpendicular to the longitudinal direction to form a chip-shaped thermistor body, and forming external electrodes on both end surfaces of the chip-shaped thermistor body that are not covered with the inorganic layer. In the method of manufacturing a chip-type thermistor having, in forming the external electrode, after forming a conductive metal layer on both end surfaces of the chip-shaped thermistor body by sintering, forming a conductive resin layer on the conductive metal layer It can be manufactured by forming and then forming a metal plating layer on the conductive resin layer.

The chip-type thermistor according to the present invention may be one in which surface electrodes for adjusting a resistance value are formed on side surfaces other than both end surfaces of the chip-like thermistor body. Is a step of forming an insulating inorganic layer on four side surfaces of a prismatic thermistor element body formed of a ceramic sintered body and having a surface electrode formed on a side surface extending in a longitudinal direction, A step of forming a chip-shaped thermistor body by cutting the prismatic thermistor body on which the insulating inorganic layer is formed in a direction perpendicular to the longitudinal direction, and both end faces of the chip-shaped thermistor body not covered with the inorganic layer In the method for manufacturing a chip-type thermistor having a step of forming an external electrode, a conductive metal layer is formed by sintering both end surfaces of the chip-shaped thermistor body in forming the external electrode After form, to form a conductive resin layer on the conductive metal layer, then it can be produced by forming a metal plating layer on the conductive resin layer.

In the present invention, the metal plating layer may be composed of a nickel plating layer and a solder plating layer formed on the nickel plating layer, or may be composed of only the solder plating layer. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip type thermistor and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

1 to 4 are cross-sectional views showing one embodiment of the chip type thermistor of the present invention.
Members having the same functions as the members shown in FIG. 7 are denoted by the same reference numerals.

The chip type thermistor 10A shown in FIG.
A rectangular parallelepiped chip-shaped thermistor body 1 made of a ceramic sintered body, external electrodes 2 formed on both end faces of the chip-shaped thermistor body 1, and four side faces other than the both end faces are provided. And an insulating inorganic layer such as a glass layer 3.

In the present invention, the external electrode 2 includes a conductive metal layer 2a in contact with the end face of the chip-shaped thermistor body, a conductive resin layer 2b formed on the conductive metal layer 2a, and a conductive resin layer 2b. And a metal plating layer 2c formed thereon. In the embodiment of FIG. 1, the metal plating layer 2c is made of Ni.
It has a two-layer structure of a plating layer 2d and a solder plating layer 2e.

The chip type thermistor 10 shown in FIGS.
B, 10C, and 10D have surface electrodes for adjusting the resistance value formed on the side surfaces of the chip-shaped thermistor body 1, and the chip-type thermistor 10B shown in FIG. Electrodes 6A, 6B, 6C, 6D
Are provided on two or four opposing sides of the chip-like thermistor body 1.

The chip-type thermistor 10C shown in FIG. 3 has surface electrodes 6E and 6F connected to the external electrodes 2 at both ends, respectively, provided on two opposite sides of the chip-like thermistor body 1. The surface electrode 6E is connected only to the external electrode on the left side of the figure, and the surface electrode 6F is connected only to the external electrode on the right side of the figure.

The chip-type thermistor 10D shown in FIG. 4 has surface electrodes 6G and 6H which are not connected to the external electrode 2 provided on two or four opposite sides of the chip-like thermistor body 1.

The chip type thermistor 10B, 1 shown in FIGS.
Other configurations of the chip thermistors 10C and 10D are the same as those of the chip thermistor 10A shown in FIG.

Hereinafter, a method for manufacturing the chip thermistors 10A to 10D of the present invention according to the method of the present invention will be described with reference to FIGS.

In manufacturing the chip-type thermistor 10A, first, a thin plate-like thermistor body (thermistor wafer) 11 made of a ceramic sintered body shown in FIG.
The rectangular thermistor body 12 shown in FIG. Next, the glass layer 3 is formed on four side surfaces (or the entire surface) extending in the longitudinal direction of the prismatic thermistor body 12.

For the formation of this glass layer, a glass powder paste adjusted to a sprayable viscosity is sprayed on the four side surfaces or the entire surface of the prismatic thermistor body, and after drying,
Perform baking. Alternatively, a thin film forming technique such as sputtering can be adopted.For example, a stainless steel cage containing a plurality of prismatic thermistor bodies is installed in a sputtering apparatus targeting a glass of a predetermined composition, The basket is oscillated, and sputtering is performed while rotating the prismatic thermistor body. This allows
As shown in FIG. 5 (c), the prismatic thermistor body 12
The glass layer 3 can be formed on the side surface or the entire surface.

Next, the prism-shaped thermistor element body 12 on which the glass layer 3 is formed is cut in a direction orthogonal to the longitudinal direction to form a chip-shaped thermistor element body 1 shown in FIG. As shown in FIG. 5 (e), external electrodes 2 are formed on both end surfaces 1A of the element body not covered with the glass layer 3 to obtain a chip type thermistor 10A.

Chip type thermistor 10 having surface electrodes
In order to manufacture B, 10C, and 10D, first, as shown in FIG. 6A, a conductive paste is used on both plate surfaces of a thin thermistor body (thermistor wafer) 11 made of a ceramic sintered body. A band-shaped pattern is printed at appropriate intervals by a screen printing method or the like, dried and baked to form the surface electrode 6. Then, the thermistor wafer 11 on which the surface electrode 6 is formed is cut into strips, and FIG.
The thermistor body 13 shown in FIG. 4 surface electrodes
When formed on the side surfaces, the surface electrodes are similarly formed on the two side surfaces on which the surface electrode 6 is not formed among the four side surfaces extending in the longitudinal direction of the prismatic thermistor body 13. .

Using the prismatic thermistor element 13 having the surface electrode 6 formed on the side surface in this manner, the formation and cutting of a chip-shaped thermistor element by cutting and cutting a glass layer and the formation of external electrodes are performed in the same manner as described above. Go to chip type thermistor 1
0B, 10C and 10D are obtained.

As described above, when a glass layer is formed on a prismatic thermistor body, the process of forming the glass layer only needs to be performed once, so that the production efficiency is improved and the manufacturing cost is reduced. It is possible. Moreover, before forming the glass layer,
Since the thermistor wafer is cut into strips, defects such as microcracks at the time of cutting are prevented, and a chip-type thermistor with high strength and high reliability can be manufactured. However, the chip-type thermistor of the present invention has a structure in which glass layers are formed on both plate surfaces of a thermistor wafer and then cut to form a prismatic thermistor body. It can also be manufactured by a method of performing glass coating by forming a layer.

Next, a preferred method for forming an external electrode comprising a conductive metal layer, a conductive resin layer, and a metal plating layer of the chip-type thermistor of the present invention will be described.

The conductive metal layer is formed by applying and baking a conductive base containing a conductive metal powder such as Ag, Ag-Pd and glass frit. For example, when the chip has a length of about 1.6 mm, the conductive metal layer is preferably formed to have a thickness of about 5 to 80 μm. When the thickness of the conductive metal layer is less than 5 μm, the adhesive strength and electrical connection between the external electrode and the inorganic coating layer such as the chip and the glass layer are insufficient, and when the thickness exceeds 80 μm, the conductive resin formed on the upper portion thereof When the thickness of the layer is added, the chip dimensions vary, and the chip components cannot be packaged by taping. Alternatively, the operation rate of the device during mounting on a substrate is reduced. Note that if the chip size increases, the upper limit may be increased accordingly.

The conductive resin layer on the conductive metal layer is formed by applying a conductive resin paste obtained by forming a conductive metal powder and a thermosetting resin into a paste with an organic solvent, followed by drying and heat curing. .

The ratio between the metal powder of the conductive resin paste and the thermosetting resin used here is 70 to 95% by weight of the metal powder in order to secure conductivity and flexibility as an electrode layer. The thermosetting resin is preferably 30 to 5% by weight. When the proportion of the metal powder is less than 70% by weight, the electrical connection with the lower conductive metal layer becomes insufficient, and when the plating film is formed by the electrolytic plating method, the conductivity of the surface decreases, and the plating film is reduced. Formation becomes difficult. If the proportion of the metal powder exceeds 95% by weight, the effect of relieving stress is reduced, which is not preferable.

As the metal powder, a noble metal powder such as Ag or Pd or Ni powder can be used. As the thermosetting resin, epoxy, phenol, xylene, urethane resin and the like can be mentioned.

The thickness of the conductive resin layer formed as described above is preferably 10 to 100 μm when the chip has a length of about 1.6 mm, for example. If the thickness of the conductive resin layer is less than 10 μm, the effect of stress relaxation by forming the conductive resin layer is not sufficient.
If it exceeds 00 μm, a problem of chip size variation occurs as in the case of the upper limit of the thickness of the conductive metal layer. Note that if the chip size increases, the upper limit may be increased accordingly.

The metal plating layer formed on the conductive resin layer is composed of a Ni plating layer and a solder plating layer formed on the Ni plating layer. More preferred from the viewpoint of heat resistance,
Even if there is no Ni plating layer, the conductive resin layer can sufficiently withstand solder erosion, so that the Ni plating layer can be omitted. When a Ni plating layer and a solder plating layer are formed as metal plating layers, the thickness of the Ni plating layer is
It is preferable to set the thickness to 5 μm and the solder plating layer to 2 to 10 μm. When the Ni plating layer is omitted, the thickness of the solder plating layer is preferably 3 to 10 μm.

In the chip-type thermistor of the present invention, when mounted on a circuit board, mechanical stress caused by bending when the board is cut, or a thermistor element during a temperature cycle,
When thermal stresses due to differences in the coefficients of thermal expansion of the electrodes, solder, substrate, etc., are transmitted to the external electrodes, these stresses are relieved by the flexible conductive resin layer in the intermediate layer of the external electrodes. For this reason, generation of cracks in the chip-shaped thermistor body due to these stresses is prevented.

Further, as a lower electrode layer, a conductive paste is applied to both end surfaces of the chip-shaped thermistor element not covered with the glass layer and the four side glass layers near the both end surfaces, and sintered at a high temperature. By this, a sufficient electrical connection with the thermistor body and a strong mechanical connection with the thermistor body and the glass layer can be obtained. And since both the glass layer and the metal layer are covered with what was sintered at high temperature, the thermistor body becomes highly accurate and excellent in environmental resistance. Since the conductive metal layer and the conductive resin layer have extremely low resistance, there is no problem in electrical connection between them.
Further, in the present invention, as described above, among the metal plating layers,
Since the nickel plating layer can be omitted, the manufacturing cost can be reduced.

[0040]

The present invention will be described more specifically with reference to the following examples.

Example 1 A chip-type thermistor shown in FIG. 1 was manufactured according to the method of the present invention shown in FIG.

Commercially available manganese carbonate, nickel carbonate, cobalt carbonate and copper oxide were used as starting materials, each of which was weighed so that the metal atomic ratio became a predetermined ratio, uniformly mixed in a ball mill for 16 hours, and then dehydrated and dried. . Next, this mixture was calcined at 900 ° C. under atmospheric pressure for 2 hours, and the calcined product was again pulverized by a ball mill and dehydrated and dried. An organic binder and the like were added to the pulverized product, granulated to have a particle size of about 60 μm by a spray drier, and compression-molded into a rectangular parallelepiped by a hydraulic press. This molded product is subjected to 120 atmospheric pressure.
Bake at 0 ° C for 4 hours, length 35mm, width 50mm, thickness 1
A 0 mm thermistor sintered block was made. Next, this block was cut into a thin plate with a band saw,
A thermistor wafer having a width of 50 mm, a width of 50 mm, and a thickness of 0.80 mm was obtained (FIG. 5A).

This thermistor wafer was cut into strips having a width of 0.80 mm by a dicing machine (FIG. 5).
(B)) on the four side surfaces of the obtained prismatic thermistor body,
A glass powder paste adjusted to a viscosity that can be sprayed is sprayed, dried and fired at 850 ° C. for about 10 minutes, and baked to obtain SiO ₂ , A having a thickness of about 20 μm.
An insulating glass layer made of an oxide such as l ₂ O ₃ , MgO, ZrO ₂ was formed (FIG. 5C). Then, the prism-shaped thermistor element body formed by coating the glass layer was formed with a length of 1.
It was cut out into a chip shape of 5 mm by a dicing machine (FIG. 5D).

Further, external electrodes were formed on both end surfaces of the chip-shaped thermistor body by the following method. First, a conductive base (a commercially available Ag paste containing a glass frit) is applied to both end surfaces of the chip-like thermistor body by dipping.
And baked at 820 ° C. for 10 minutes under atmospheric pressure. The thickness of the formed conductive metal layer is about 30 μm. Next, on this conductive metal layer, a conductive resin paste containing Ag powder (Ag powder: epoxy resin =
85:15 (% by weight) to which an organic solvent was added at 10% by weight) by a dipping method.
, And then heat-cured at 220 ° C. for 2 hours. The thickness of the formed conductive resin layer is about 50 μm.

Then, a Ni plating layer having a thickness of about 2 μm was formed on the surface of the conductive resin layer by an electrolytic barrel method, and a solder plating layer having a thickness of about 5 μm was formed thereon (FIG. 5).
(E)).

The chip type thermistor thus manufactured was subjected to a substrate bending resistance test and a temperature cycle test, and the results are shown in Table 1.

Comparative Example 1 A chip-type thermistor was prepared in the same manner as in Example 1 except that the conductive resin layer was not formed when forming the external electrodes. And a temperature cycle test, and the results are shown in Table 1.
It was shown to.

[0048]

[Table 1]

From the results shown in Table 1, the substrate bending resistance and the temperature cycle test (at -55 ° C. and 125 ° C. for 30 minutes each, air 500
With respect to the cycle, it can be seen that the chip thermistor of the present invention has improved characteristics as compared with the chip thermistor of the conventional example.

Example 2 In Example 1, both the surfaces of the thermistor wafer were
As shown in (a), the width is 0.6 mm and the interval in the width direction is 1.4.
Using a pattern of mm, the Ag paste was printed so that the electrodes on both sides of the wafer face each other, and then dried,
Then, the wafer was baked at 820 ° C. for 10 minutes to form a chip type thermistor 10 shown in FIG. 2 in the same manner except that a large number of rows of surface electrodes for resistance adjustment having a thickness of about 10 μm were formed.
B was prepared (the prism-shaped thermistor body was cut along the center line of the surface electrode).

With respect to this chip-type thermistor, the difference in characteristics due to the presence or absence of the conductive resin layer of the external electrode was examined in the same manner as in Example 1 and Comparative Example 1, and the chip-type thermistor of the present invention having a conductive resin layer was examined. It has been confirmed that the thermistor has improved characteristics as compared with the conventional chip thermistor.

Examples 3 and 4 The chip type thermistor 10 shown in FIG. 3 was manufactured in the same manner as in Example 2 except that the pattern for forming the surface electrodes was changed.
C and a chip type thermistor 10D shown in FIG. 4 were produced.

With respect to these chip-type thermistors, the difference in characteristics depending on the presence or absence of the conductive resin layer of the external electrode was examined in the same manner as in Example 1 and Comparative Example 1, and the chip of the present invention having the conductive resin layer was examined. It was confirmed that the type thermistor had improved characteristics as compared with the conventional chip type thermistor.

Example 5 A chip-type thermistor was prepared in the same manner as in Example 1 except that the Ni plating layer was not formed, and the performance was evaluated. In the cycle test, it was confirmed that the same performance as that of Example 1 was exhibited, and that there was no problem in solder wettability and heat resistance.

[0055]

As described in detail above, according to the chip-type thermistor and the method of manufacturing the same according to the present invention, a chip having high accuracy, excellent environmental resistance, and excellent reliability such as mechanical strength and temperature cycle performance. A mold thermistor can be provided at low cost and with good mass productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a chip type thermistor of the present invention.

FIG. 2 is a sectional view showing another embodiment of the chip type thermistor of the present invention.

FIG. 3 is a sectional view showing another embodiment of the chip thermistor of the present invention.

FIG. 4 is a sectional view showing another embodiment of the chip type thermistor of the present invention.

FIG. 5 is a perspective view illustrating an example of a method for manufacturing a chip thermistor of the present invention.

FIG. 6 is a perspective view illustrating an example of a method for manufacturing a chip thermistor of the present invention.

FIG. 7 is a sectional view showing a conventional chip thermistor.

[Explanation of symbols]

1 chip-shaped thermistor element 2 external electrode 2a conductive metal layer 2b conductive resin layer 2c metal plating layer 2d Ni plating layer 2e solder plating layer 3 glass layer 6,6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H
Surface electrode 10A, 10B, 10C, 10D Chip type thermistor 11 Thermistor wafer 12, 13 Prismatic thermistor body

Claims (6)

[Claims] 1. A rectangular parallelepiped chip-shaped thermistor element made of a ceramic sintered body, external electrodes formed on both end faces of the chip-shaped thermistor element, and four electrodes other than the both end faces.
A chip-type thermistor having a coating layer made of an insulating inorganic material covering a side surface, wherein the external electrode comprises: a conductive metal layer in contact with an end face of the chip-shaped thermistor body; and a conductive layer formed on the conductive metal layer. A chip thermistor comprising: a conductive resin layer; and a metal plating layer formed on the conductive resin layer. 2. The chip thermistor according to claim 1, wherein a surface electrode for adjusting a resistance value is formed on a side surface other than the both end surfaces of the chip-shaped thermistor body. 3. The chip thermistor according to claim 1, wherein the metal plating layer comprises a nickel plating layer and a solder plating layer formed on the nickel plating layer. 4. The chip thermistor according to claim 1, wherein the metal plating layer comprises a solder plating layer. 5. A step of forming an insulating inorganic layer on four side surfaces extending in the longitudinal direction of a prism-shaped thermistor element made of a ceramic sintered body, comprising: forming a prism-shaped thermistor element having an insulating inorganic layer formed thereon; Production of a chip-type thermistor having a step of forming a chip-shaped thermistor body by cutting in a direction orthogonal to the longitudinal direction, and a step of forming external electrodes on both end surfaces of the chip-shaped thermistor body that are not coated with an inorganic material layer In the method, in forming the external electrode, after forming a conductive metal layer by sintering on both end surfaces of the chip-shaped thermistor element body, forming a conductive resin layer on the conductive metal layer, A method for producing a chip-type thermistor, comprising forming a metal plating layer on a conductive resin layer. 6. A prismatic thermistor element made of a ceramic sintered body, wherein insulating inorganic layers are formed on four side faces of a prismatic thermistor element body having surface electrodes formed on side faces extending in a longitudinal direction. Step, forming a chip-shaped thermistor body by cutting the prismatic thermistor body formed with an insulating inorganic layer in a direction perpendicular to the longitudinal direction, and
In a method for manufacturing a chip-type thermistor having a step of forming external electrodes on both end surfaces of the chip-shaped thermistor element body that are not covered with the inorganic layer, sintering is performed on both end surfaces of the chip-shaped thermistor element body in forming the external electrode. Forming a conductive metal layer on the conductive metal layer, forming a conductive resin layer on the conductive metal layer, and then forming a metal plating layer on the conductive resin layer. .