JPH10116707A - Chip type thermistor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability in mechanical strength or temperature cycle performance, etc., by a method wherein, in an external electrode, a conductive metal layer is brought into contact with an end face of a chip-like thermistor element, a conductive resin layer is formed on the conductive metal layer, and a metal plating layer is formed on the conductive resin layer. SOLUTION: A chip type thermistor 10A is formed with an external electrode 2 at both end faces of a rectangular parallelepiped chip-like thermistor element 1 composed of a ceramic sintered body, and an insulation inorganic substance layer of a glass layer 3, etc., is provided so as to cover two opposite side faces having a larger area among four side faces other than these both end faces. In an external electrode 2, a conductive metal layer 2a is brought into contact with an end face of the chip-like thermistor element 1, and a conductive resin layer 2b is formed thereon. A metal plating layer 2c is formed on the conductive resin layer 2b, and is a two-layer structure of a Ni plating layer 2d and a solder plating layer 2e. Thereby, it is possible to enhance mechanical strength and cycle performance, etc.

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 of manufacturing the same, and more particularly to a negative temperature coefficient thermistor whose resistance value decreases with a rise in temperature, and which has a mechanical strength The present invention relates to a chip-type thermistor having excellent reliability and high reliability and a method for manufacturing such a chip-type 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 two opposing sides of the four sides of the thermistor body 1 on which the external electrode 2 is not formed are covered with an insulating inorganic layer such as a glass layer 3. I have.

Conventionally, such a chip type thermistor 4
Is manufactured as follows. That is, first, an insulating glass layer is formed by printing and applying a glass paste on both main plate surfaces of a thin plate thermistor element body (thermistor wafer) made of a ceramic sintered body and firing it. Next, a thermistor wafer whose both main plate surfaces are covered with a glass layer is cut into strips, and a prismatic thermistor body having glass layers on two opposing side surfaces is obtained. A conductive paste is applied and baked on two side surfaces of the prismatic thermistor body not covered with the glass layer to form baked terminal electrodes. Further, a plating layer is formed on the surface of the terminal electrode to form an external electrode layer. Then, the chip type thermistor 4 shown in FIG. 7 is cut in a direction orthogonal to the longitudinal direction (a direction perpendicular to the cut surface).
Get.

In the above chip type thermistor,
There is also provided a chip thermistor element in which surface electrodes for adjusting a resistance value are formed on side surfaces of the chip thermistor body. Such a chip thermistor is prepared by applying a conductive base to both main plate surfaces of a thermistor wafer in advance. It is manufactured by the same method as described above except that a surface electrode for adjusting a value is formed.

[0005] A method of manufacturing a large number of chip-type thermistors by cutting the prism-shaped thermistor element body on which the external electrode layer is formed as described above is based on a method of manufacturing a chip-type thermistor.
Only the side surface is covered with a glass layer, and the remaining two side surfaces are slightly unreliable in terms of environmental resistance because the surface of the body is exposed. However, it is excellent in mass productivity and requires a small number of processes and low cost. This is an industrially advantageous method.

[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.

In particular, a prismatic thermistor element having a glass layer formed on two side surfaces and an external electrode layer formed on the remaining two side surfaces is cut, ie, an inorganic material for the glass layer and a semiconductor ceramic material for the thermistor element. In addition, since different materials such as a metal material for the external electrode layer are cut at the same time, stress is easily concentrated on the exposed surface of the element body, and particularly, microcracks are easily generated at the apex corners.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a chip thermistor excellent in reliability such as mechanical strength and temperature cycle performance at low cost and with good mass productivity.

[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; A chip-type thermistor having a coating layer made of an insulating inorganic material covering two opposing side surfaces of the four side surfaces other than the both end surfaces, wherein the external electrode is a conductive metal layer in contact with an end surface of the chip-like thermistor body. And a conductive resin layer formed on the conductive metal layer, 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.

The chip type thermistor according to the present invention is a step of forming an insulating inorganic layer on the front and back main plate surfaces of a thin plate thermistor element made of a ceramic sintered body, and a thin plate thermistor wafer having an insulating inorganic layer formed thereon. To form a prismatic thermistor body by cutting into a strip shape, and among the four side surfaces extending in the longitudinal direction of the prismatic thermistor body, the body is exposed because no insulating inorganic layer is formed. Forming an external electrode layer on the two side surfaces, and cutting the prism-shaped thermistor element body formed with the external electrode layers into chips in a direction orthogonal to the longitudinal direction to obtain a chip-type thermistor. In the method for manufacturing a thermistor, a conductive metal layer is formed on the two side surfaces where the element body is exposed by sintering, and then a conductive resin layer is formed on the conductive metal layer. Then, by forming a metal plating layer on the conductive resin layer, it can be manufactured at low cost with a small number of manufacturing steps.

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. Forming a surface electrode for resistance adjustment on the front and back main plate surfaces of a thin plate thermistor body made of a ceramic sintered body, and then forming an insulating inorganic layer, the thin plate having the insulating inorganic layer formed thereon Forming a prismatic thermistor body by cutting the prismatic thermistor body into strips, and, among the four side surfaces extending in the longitudinal direction of the prismatic thermistor body, an insulating inorganic layer is not formed Forming an external electrode layer on the two side surfaces where the element body is exposed, and cutting the prism-shaped thermistor element body formed with the external electrode layer into chips in a direction orthogonal to the longitudinal direction to obtain a chip-type thermistor. The method of manufacturing a chip-type thermistor having, per the formation of the external electrode layer, after forming a conductive metal layer by sintering the two sides body is exposed,
It can be manufactured by forming a conductive resin layer on the conductive metal layer and then 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 element 1 made of a ceramic sintered body, an external electrode 2 formed on both end faces of the chip-shaped thermistor element 1, and four opposing side faces other than both end faces facing each other having a large area An insulating inorganic layer such as a glass layer 3 provided so as to cover two side surfaces (main surfaces).

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 each have a surface electrode for adjusting a resistance value formed on the side surface of the chip-shaped thermistor body 1 covered with the glass layer 3. The chip-type thermistor 10B shown in FIG.
Surface electrodes 6A, 6 respectively connected to external electrodes 2 at both ends
B, 6C, and 6D are provided on two opposing side surfaces of the chip-like thermistor body 1, and an insulating inorganic layer such as a glass layer 3 is provided thereon.

In the chip type thermistor 10C shown in FIG. 3, surface electrodes 6E and 6F connected to the external electrodes 2 at both ends are provided on two opposing side surfaces of the chip-shaped thermistor body 1, and a glass layer 3 or the like is formed thereon. This is provided with an insulating inorganic layer.

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.

In the chip type thermistor 10D shown in FIG. 4, surface electrodes 6G and 6H which are not connected to the external electrode 2 are provided on two opposing side surfaces of the chip type thermistor body 1, and an insulating inorganic material such as a glass layer 3 is formed thereon. A layer is provided.

The chip 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, the main plate surfaces 11A on the front and back of the thin plate thermistor wafer 11 made of a ceramic sintered body shown in FIG.
11B, a glass layer 12 is formed as shown in FIG.

To form the glass layer, a glass powder paste adjusted to an appropriate viscosity is printed and applied to both main plate surfaces 11A and 11B of the thermistor wafer, dried, and baked.

Next, the thermistor wafer 11 on which the glass layer 12 is formed is cut into strips to obtain a prismatic thermistor body 13 shown in FIG. Then, of the four side surfaces extending in the longitudinal direction of the prismatic thermistor body 13,
As shown in FIG. 5D, an external electrode layer 14 is formed on the two side surfaces 13A and 13B that are not covered with the glass layer and on the other two side surfaces of the glass layer 12 near the two side surfaces.

Next, as shown in FIG. 5 (e), the prism-shaped thermistor element body 13 on which the external electrode layer 14 is formed is cut in a direction orthogonal to the longitudinal direction thereof so that the chip type thermistor 10 is formed.
A.

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 applied to both main plate surfaces 11A and 11B of a thin plate thermistor body (thermistor wafer) 11 made of a ceramic sintered body. By printing a belt-shaped pattern at appropriate intervals by screen printing method using
After drying, baking is performed to form the surface electrode layer 15. And
A glass layer is formed on both surfaces of the thermistor wafer 11 on which the surface electrode layer 15 is formed, in the same manner as described above, and then cut into strips to form a prismatic thermistor body 13 'shown in FIG. 6B. (However, the glass layer is not shown in FIG. 6B).

The external electrode layer is formed and cut in the same manner as described above on the two side surfaces of the prismatic thermistor element body 13 'on which the surface electrode 15 and the glass layer are formed without coating the glass layer. 10B, 10C, 10D
Get.

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 firing a conductive base containing a conductive metal powder such as Ag or Ag-Pd and a glass frit. This conductive metal layer is preferably formed to a thickness of about 5 to 80 μm, for example, when the final product chip has a length of about 1.6 mm. 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 in this manner is preferably 10 to 100 μm, for example, when the chip of the final product has a length of about 1.6 mm. 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, and if it exceeds 100 μm, it is the same as the case of the upper limit of the thickness of the conductive metal layer. This causes a problem of variation in chip dimensions. 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 thermistor body 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.

As a lower electrode layer, a conductive paste is applied to two side surfaces of the prism-shaped thermistor body not covered with the glass layer and the other two side glass layers near the two side surfaces,
By forming this by sintering at a high temperature, a sufficient electrical connection with the thermistor element and a strong mechanical connection with the thermistor element 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, the chip-type thermistor of the present invention can be manufactured in a small number of steps of forming and cutting a glass layer on a thermistor wafer, and forming and cutting external electrodes. However, as described above, the nickel plating layer can be omitted from the metal plating layer, so that the production cost can be further reduced.

[0042]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 According to the method of the present invention shown in FIG. 5, the chip thermistor shown in FIG. 1 was manufactured.

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).

A glass powder paste adjusted to a printable viscosity is printed on both main plate surfaces of the thermistor wafer, dried, baked at 850 ° C. for about 10 minutes, and baked to obtain a SiO 2 having a thickness of about 20 μm. ₂ , Al ₂ O ₃ , Mg
An insulating glass layer made of an oxide such as O or ZrO ₂ was formed (FIG. 5B). Then, the thermistor wafer on which the glass layer is formed is 0.8 mm wide by a dicing machine.
It was cut into strips of 0 mm (FIG. 5 (c)), and external electrodes were formed on the two side surfaces of the obtained prism-shaped thermistor body, which were not covered with a glass layer, by the following method.

First, a conductive paste (a commercially available Ag paste containing a glass frit) is adhered to the two side surfaces of the prism-shaped thermistor body by dipping, and the pressure is reduced to 8 at atmospheric pressure.
It was kept at 20 ° C. for 10 minutes and baked. 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),
An organic solvent was added thereto by 10% by weight), applied by dipping, and dried at 180 ° C. for 10 minutes.
The composition was cured by heating at 220 ° C. for 2 hours. The thickness of the formed conductive resin layer is about 50 μm.

Next, the prismatic thermistor body having the conductive resin layer formed thereon is immersed in a plating bath, and a Ni plating layer having a thickness of about 2 μm is formed on the surface of the conductive resin layer. A solder plating layer of about 5 μm was formed (FIG. 5).
(D)).

Thereafter, the length 1.
It was cut into a chip shape of 5 mm (FIG. 5E) to obtain a chip type thermistor.

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 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. The chip thermistor was subjected to a board bending resistance test. And a temperature cycle test, and the results are shown in Table 1.
It was shown to.

[0051]

[Table 1]

From the results shown in Table 1, the substrate bending resistance and the temperature cycle test (at -40.degree. C. and + 85.degree.
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.

Embodiment 2 In Embodiment 1, as shown in FIG. 6 (a), both the main plate surfaces of the thermistor wafer have a width of 0.6 mm and an interval in the width direction.
Using a 0 mm pattern, the Ag paste was printed so that the electrodes oppose each other on both main plate surfaces of the wafer, dried, and then baked at 820 ° C. for 10 minutes to form a multi-row of about 10 μm in thickness. The chip type thermistor 10B shown in FIG. 2 was manufactured in the same manner except that the surface electrode for adjusting the resistance value was formed. (Note that the cut-out of the prismatic thermistor body was performed along the center line of the surface electrode. Cut.)

The chip type thermistor was also examined for the difference in characteristics depending on the presence or absence of the conductive resin layer of the external electrode in the same manner as in Example 1 and Comparative Example 1. 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 formation pattern of the surface electrode 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 fabricated 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.

[0058]

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

[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 Glass layer 13, 13 'Prismatic thermistor element 14 External electrode layer 15 Surface electrode layer

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 two opposing side surfaces of the side surfaces, wherein the external electrode comprises: a conductive metal layer in contact with an end surface of the chip-shaped thermistor body; A chip thermistor comprising: a conductive resin layer formed on a 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 of the chip-shaped thermistor element body on which the coating layer is formed. 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 the front and back main plate surfaces of a thin sheet thermistor wafer made of a ceramic sintered body, and cutting the thin sheet thermistor wafer having the insulating inorganic layer formed thereon into strips. Forming a prismatic thermistor element; and, among the four side faces extending in the longitudinal direction of the prismatic thermistor element, external electrode layers on two side faces where the insulating body is not formed and the element body is exposed. And a method of manufacturing a chip-type thermistor having a step of obtaining a chip-type thermistor by cutting the prism-shaped thermistor body on which the external electrode layer is formed into chips in a direction orthogonal to the longitudinal direction. In forming the external electrode layer, a conductive metal layer is formed on the two side surfaces where the element body is exposed by sintering, and then a conductive resin layer is formed on the conductive metal layer. Up Method of manufacturing a chip-type thermistor, and forming a metal plating layer. 6. A step of forming a surface electrode layer for adjusting a resistance value on the front and back main plate surfaces of a thin plate thermistor wafer made of a ceramic sintered body, and then forming an insulating inorganic layer. A step of cutting the formed thin plate thermistor wafer into strips to form a prismatic thermistor body; and forming an insulating inorganic layer among four side surfaces extending in the longitudinal direction of the prismatic thermistor body. Forming an external electrode layer on the two side surfaces where the element body is exposed, and cutting the prism-shaped thermistor element formed with the external electrode layer into chips in a direction perpendicular to the longitudinal direction to form a chip-type thermistor. In the method of manufacturing a chip-type thermistor having a step of obtaining, in forming the external electrode layer, a conductive metal layer is formed on the two side surfaces where the element body is exposed by sintering, and then a conductive layer is formed on the conductive metal layer. sex Forming a lipid layer, then fabrication method of a chip type thermistor and forming a metal plating layer on the conductive resin layer.