JP2002141204A - Thermistor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a thermistor being regulated in its resistance by normally changing its material, but the change of its material is accompanied with a change in a B constant, making it difficult that the thermistors of the same B constant to are connected in series. SOLUTION: An electrode layer 7 is sandwiched between a thermistor body 3 and a protective film 4, the electrode layer 7 is connected electrically to a primary electrode 5, and a contact area between the electrode layer 7 and the thermistor body 3 is controlled, so as to regulate a thermistor 1 in resistance value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor and a method of manufacturing the same, for example, a chip type thermistor and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing an appearance of a chip type thermistor 1, and FIG. 2 is a diagram showing a cross section taken along line AA of FIG.

[0003] On the side surface along the longitudinal direction of the thermistor body 3, a protective film 4 of inorganic composite crystallized glass is overcoated to protect the thermistor body 3. And
On both end surfaces of the thermistor body 3 in the longitudinal direction, a primary electrode 5 baked with silver and a secondary electrode 6 such as Ni formed by electrolytic plating are formed, and function as the electrode 2.

[0004]

The resistance value of the thermistor having a configuration as shown in FIG. 2 and called a single-plate type or a non-laminated type, is such that if the material of the thermistor body 3 is the same, the electrode 2 and the thermistor body 3 Contact area, that is, thermistor body
Determined by the area of the end face of 3. Therefore, the resistance value of the thermistor 1 is adjusted by changing the thermistor material or the size of the thermistor body 3.

However, since the change of the thermistor material involves a change in the B constant, it is difficult to series the resistance values at the same B constant. If we stick to the same B constant, we have to change the shape.

The present invention has been made to solve the above-described problem, and has as its object to arbitrarily set the resistance of a thermistor.

[0007]

The present invention has the following arrangement as one means for achieving the above object.

[0008] The thermistor according to the present invention comprises at least two first electrode layers formed on a surface along a longitudinal direction of the thermistor body, and a surface of the thermistor body and the first electrode layer on the surface along the longitudinal direction. A protective film that substantially covers the electrode layer, and second electrodes formed on both end surfaces in the longitudinal direction, wherein the first electrode layers are each electrically connected to one of the second electrodes. It is characterized by being.

Further, at least two first electrode layers formed on at least both end faces in the longitudinal direction from a surface along the longitudinal direction of the thermistor body, and a surface of the thermistor body on a surface along the longitudinal direction. It is characterized in that it has a protective film that substantially covers the first electrode layer, and a second electrode that covers the first electrode near the both end faces.

[0010] The method for manufacturing a thermistor according to the present invention comprises:
Form at least two first electrode layers on the surface along the longitudinal direction of the thermistor body, on the surface along the longitudinal direction,
Forming a protective film that substantially covers the surface of the thermistor body and the first electrode layer, forming second electrodes on both end surfaces in the longitudinal direction, and forming the first electrode layers on the second electrode respectively. Is electrically connected to one of the terminals.

Also, a strip-shaped thermistor body is formed,
Forming two first electrode layers from a first surface facing each other along a longitudinal direction of the thermistor body to at least a second surface adjacent to the first surface and facing each other; Forming a protective film that substantially covers the surface of the thermistor body and the first electrode layer, and forming a second electrode that covers the first electrode on the second surface; The body is divided in the longitudinal direction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a chip thermistor according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a sectional view of a chip type thermistor capable of adjusting the resistance value. In FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 3 differs from FIG. 2 in that an electrode layer 7 for adjusting a resistance value is interposed between the thermistor body 3 and the protective film 4. That is, by sandwiching the electrode layer 7 between the thermistor body 3 and the protective film 7 and electrically connecting the electrode layer 7 to the primary electrode 5, the contact area between the electrode layer 7 and the thermistor body 3 is controlled. Thus, the resistance value of the thermistor 1 can be adjusted.

FIG. 3 shows an example in which the electrode layer 7 is formed on each of the two opposing surfaces. However, the electrode layers 7 may be formed on not only the two opposing surfaces but also on two adjacent surfaces or on four surfaces.
Further, the number of the electrode layers 7 connected to one electrode 2 is not limited to one, but may be plural.

Next, a description will be given of a chip thermistor obtained by further developing the configuration of FIG. FIG. 4 is a flowchart showing an example of a procedure for manufacturing a chip thermistor.

In step S1, the baked thermistor wafer 11 is cut into a predetermined width to form a strip-shaped thermistor body 12 (see FIG. 5). The material of the thermistor body 12 is
It is not particularly limited.

Next, in step S2, an electrode layer 13 is formed as a primary electrode on the side surface along the longitudinal direction of the thermistor body 12 (see FIG. 6). The electrode layer 13 is formed by stacking a metal layer of a desired shape such as Ag on the thermistor body 12 by, for example, sputtering or screen printing using a metal mask. FIG. 6 shows an example in which two electrode layers 13 are formed from one side surface along the longitudinal direction to the opposite side surface.
As shown in (c), the electrode layer 13 may be formed only from one side surface along the longitudinal direction to the adjacent (perpendicular) side surface.

As shown in FIG. 6B, the electrode layer 13 can cover not only the two side surfaces of the thermistor body 12 but also the remaining two side surfaces while leaving a part thereof. The formation greatly affects the resistance value after completion of the thermistor. In other words, the contact area between the electrode layer 13 serving as the primary electrode and the thermistor body 12 can provide much greater design freedom than the contact area between the primary electrode 5 and the thermistor body 3 shown in FIG. it can. Therefore, the resistance value after completion of the thermistor can be adjusted by the contact area between the electrode layer 13 as the primary electrode and the thermistor body 12.

Next, in step S3, if necessary, the resistance between the two electrode layers 13 is adjusted by laser trimming or mechanically removing the electrode layer 13 in the longitudinal direction of the thermistor body 12. I do.

Next, in step S4, the surface of the thermistor body 13 exposed between the two electrode layers 13 and a part of the electrode layer 13 are covered with a protective layer 14 of inorganic composite crystallized glass (FIG. 7). reference). Next, in step S5, the electrode layer 15 such as Ni, Ni-Sn or solder is plated on the electrode layer 13 by electrolytic plating to form a secondary electrode (see FIG. 8).

Next, in step S6, a strip-shaped thermistor
The chip 16 is cut at a predetermined pitch (see FIG. 9), and a chip-type thermistor 17 is completed.

According to the method of manufacturing the thermistor 17 described with reference to FIGS. 4 to 9, the resistance value of the thermistor can be arbitrarily adjusted without changing the material of the thermistor. Different thermistors can be easily serialized. Further, as compared with the configuration of FIG. 3, there is no need to configure the electrode layer 7, so that the manufacturing process can be simplified.

[0024]

As described above, according to the present invention,
The resistance value of the thermistor can be set arbitrarily.

[Brief description of the drawings]

FIG. 1 is a diagram showing the appearance of a chip-type thermistor;

FIG. 2 is a diagram showing a cross section taken along line AA of FIG. 1;

FIG. 3 is a cross-sectional view of a chip thermistor capable of adjusting a resistance value.

FIG. 4 is a flowchart showing an example of a procedure for manufacturing a chip type thermistor;

FIG. 5 is a diagram illustrating a manufacturing procedure of a chip type thermistor;

FIG. 6 is a diagram illustrating a manufacturing procedure of the chip type thermistor;

FIG. 7 is a diagram illustrating a manufacturing procedure of a chip type thermistor;

FIG. 8 is a view for explaining a manufacturing procedure of the chip type thermistor;

FIG. 9 is a diagram illustrating a manufacturing procedure of the chip type thermistor.

[Explanation of symbols]

 3 Thermistor body 4 Protective film 5 Primary electrode 6 Secondary electrode 7 Electrode layer 12 Thermistor body 13 Electrode layer (primary electrode) 14 Protective film 15 Electrode layer (secondary electrode)

Claims (6)

[Claims] At least two first electrode layers formed on a surface along the longitudinal direction of the thermistor body, and the surface along the longitudinal direction substantially covers the surface of the thermistor body and the first electrode layer. It has a protective film and a second electrode formed on both end surfaces in the longitudinal direction, wherein the first electrode layer is electrically connected to one of the second electrodes, respectively. Thermistor. 2. The thermistor according to claim 1, wherein each of said first electrodes is formed on mutually facing surfaces of said thermistor body. 3. From the surface along the longitudinal direction of the thermistor body,
At least two first electrode layers formed on at least both end surfaces in the longitudinal direction; and a protective film that substantially covers the surface of the thermistor body and the first electrode layer on a surface along the longitudinal direction; A second electrode covering the first electrode in the vicinity of the surface. 4. The thermistor according to claim 3, wherein each of said first electrodes is formed from a surface of said thermistor body facing each other to one of said both end surfaces. 5. A protection device, wherein at least two first electrode layers are formed on a surface along the longitudinal direction of the thermistor body, and the surface along the longitudinal direction substantially covers the surface of the thermistor body and the first electrode layer. Forming a film, forming second electrodes on both end surfaces in the longitudinal direction, and electrically connecting the first electrode layers to one of the second electrodes, respectively. Method. 6. A strip-shaped thermistor body is formed, and two from a first surface facing each other along a longitudinal direction of the thermistor body to a second surface adjacent to the first surface and facing each other at least. Forming a first electrode layer; forming a protective film on the first surface to substantially cover the surface of the thermistor body and the first electrode layer; and forming the first electrode on the second surface. A method for manufacturing a thermistor, comprising: forming a second electrode to cover; and dividing the strip-shaped thermistor body in the longitudinal direction.