JP2001189201A - Chip thermistor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip thermistor, which is small and thin but has small resistance and satisfactory reliability, and to provide a method for manufacturing the same. SOLUTION: A chip thermistor comprises, on one surface of a thermistor element assembly, two electrodes for mounting a substrate with a distance therebetween. A third electrode is provide on a portion or the entire reverse surface of the thermistor element assembly. The third electrode and either one of the two electrodes for mounting the substrate are connected with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip thermistor mounted on a circuit board or the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art As electronic components and circuit boards have become more precise in recent years, demands for smaller and thinner chip-type thermistors have been increasing.

However, when the chip type thermistor is reduced in size and thickness, there is a problem that it is generally difficult to reduce the resistance.

[0004] Therefore, chip-type thermistors having various electrode structures have been conventionally studied in order to realize a low resistance even by miniaturization and thinning. That is, based on the double-sided electrode structure type shown in FIG. 1 as a basic type, a double-sided electrode structure type as shown in FIG. 2 and a double-sided electrode / single-sided resistance adjusting electrode structure type as shown in FIG. JP-A-6-61011) and a double-ended / double-sided resistance adjusting electrode structure type as shown in FIG. 4 (for example, JP-A-10-106808). Also,
A single-sided resistance adjusting electrode / single-sided floating electrode type as shown in FIG. 5 (for example, JP-A-6-302406 and JP-A-11-54301) has been studied.

[0005]

The various electrode structures which have been studied in the past, especially the improved types shown in FIGS. 3, 4 and 5, are smaller and thinner than the basic structure shown in FIG. To some extent. However,
Resistance reduction is not yet sufficient, and further reduction in resistance is required in practical use. Further, further improvement is required in terms of prevention of a bridge between electrodes and prevention of mechanical and thermal deterioration.

Particularly, in recent years, the size of the chip type thermistor has been changed from 2115 size (2.0 mm × 1.25 mm) to 1608 size (1.6 mm × 0.8 mm), and further, 1005 size (1.0 mm × 0.5 mm). ) Is further downsized.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a chip type thermistor which can exhibit a low resistance without changing the specific resistance of the thermistor body even if it is small and thin, and which is more reliable and a method of manufacturing the same. To provide.

[0008]

Means for Solving the Problems The present inventor has made intensive studies to solve the above problems. As a result, only one of the two spaced electrodes provided on the same surface of the thermistor element body and the third electrode provided on a part or all of the opposite surface thereof are provided.
It has been found that all of the above-mentioned problems can be solved by adopting a structure for connecting the electrodes.

That is, a chip-type thermistor according to the present invention is a chip-type thermistor in which two substrate mounting electrodes are provided on the same surface of the thermistor body at a distance from each other. And a third electrode is provided on a part or the entirety of the substrate, and the third electrode is connected to one of the two substrate mounting electrodes.

Further, the method of manufacturing a chip type thermistor according to the present invention comprises the steps of (a) forming a substrate mounting electrode on one surface of a thermistor body at a distance; and (b)
(A) forming an electrode on the surface opposite to the electrode surface; (c) forming an insulating layer between the substrate mounting electrodes formed in (a); and (d) forming the insulating layer. Dicing on a strip so that the two substrate mounting electrodes are positioned at the edges through the intermediary, and forming electrodes on one side surface of the dicing surface of the strip obtained in (e) and (d). Process and (f)
(E) dicing the strip obtained in (e) into a desired chip size.

Further, another method of manufacturing a chip-type thermistor according to the present invention comprises the steps of (a) forming an electrode on one surface of a thermistor body, and (b) forming a processed body obtained in (a). Fixing the electrode surface to the heat-resistant plate with the electrode surface on the lower side,
(C) a step of dicing at a pitch of two desired chip thermistors in the longitudinal direction using a blade having a thickness of 100 to 300 μm, and (d) a conductive paste in a gap obtained by dicing in (c). Is formed by screen-printing a conductive paste to form a substrate mounting electrode, and forming an insulating layer between the substrate mounting electrodes formed in steps (e) and (d). Process and
(F) A thickness of 50 to 50 mm is obtained along the center of the gap obtained by dicing in (c) and coated with the conductive paste in (d).
Dicing using a 100 μm blade.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION [Chip type thermistor] In the present invention, the term "thermistor body" refers to a fired body having thermistor characteristics, that is, a characteristic in which a resistance value changes depending on temperature. Add metal oxide to oxides such as nickel and cobalt,
Baking.

First, the structure of a chip type thermistor according to the present invention will be described with reference to FIGS.

The chip-type thermistor according to the present invention comprises a thermistor element (11) and two substrate mounting electrodes (12a, 12b) formed on the same surface (11a) of the thermistor element (11) at an interval. ), Thermistor body (11)
The third electrode (13) formed on a part or the whole of the surface (11b) on the opposite side is a constituent element, and one of the two substrate mounting electrodes (12a, 12b) (FIG. 6, FIG. In the example of 7, 12a) is connected to the third electrode (13). As shown in FIGS. 6 and 7, the form of the connection may be via a connection electrode (14) formed on the end face (11c) of the thermistor body, or via another circuit or conductor. You may. Also, as shown in FIGS.
An insulating layer (15) is provided so as to cover the opposing edges of the two substrate mounting electrodes (12a, 12b) and the surface of the space.

One of the substrate mounting electrodes (12a in FIGS. 6 and 7), the connection electrode (14), and the third electrode (1
3) may be an integrated electrode or a form in which each unit is connected.

[0016] Substrate mounting electrodes (12a, 12b), third
The electrode (13) and the connection electrode (14) are formed of a conductive paste as a thick film or a metal or a noble metal as a thin film. For a thick film, for example, by screen printing, and for a thin film, for example, evaporation, sputtering. Formed by Preferably, it is screen printing.

The conductive paste used for forming the electrodes is composed of a noble metal powder, glass fine particles, and an organic vehicle, and examples thereof include a gold paste, a silver paste, a silver / palladium paste, and a copper paste.

The insulating layer (15) is formed by using an insulating paste as a thick film, for example, by screen printing.

The insulating paste used for forming the insulating layer is not particularly limited as long as it has an insulating property, but is preferably a glass paste or a resin paste.

As the glass paste, lead borosilicate glass, zinc borosilicate glass, borosilicate Bi glass and the like can be used.

As the resin paste, acrylic resin,
Examples thereof include a polyimide resin and a polyparaxylene resin.

The chip-type thermistor according to the present invention has substrate mounting electrodes (12a, 12b) separated by an insulating layer on one surface of a thermistor body, as shown in FIGS. Although the third electrode (13) is provided on the surface on the side, it is particularly important that one of the substrate mounting electrodes is further connected to the third electrode. The resistance of the thermistor is proportional to the distance between the electrodes and inversely proportional to the electrode area. In the case of a double-sided electrode, the smaller and thinner the electrode area becomes, the higher the resistance value becomes. According to the connection of the present invention, the resistance R of the thermistor is increased in parallel with the resistance R1 of the electrode surface on the substrate mounting electrode side and the parallel resistance of the electrode surface R2 on the third electrode side. The same effect as described above is obtained.
This makes it possible to provide a chip thermistor that can exhibit low resistance and that is more reliable.

Specifically, according to the chip type thermistor according to the present invention, a 1608 size (length 1.6 mm × width 0.8 mm), a 1005 size (length 1.0 mm × width 0.5 mm), or It can be smaller than that. Preferably, the thermistor size (thermistor length x thermistor width) is 1.0 mm x 0.5 mm or less. Further, the thickness of the thermistor is preferably 500 μm.
The thickness can be set to 400 μm or less, more preferably 300 μm or less.

According to the chip type thermistor of the present invention, the thermistor size is 1005 size (1.0 m).
m × 0.5 mm) or less, and the thickness of the thermistor is 500 μm
The resistance can be set to preferably 100 Ω or less, more preferably 80 Ω or less, and further preferably 50 Ω or less in the following small and thin size. Further, in the same small and thin size, the B constant can be preferably 2000K or more, more preferably 2200K or more, and further preferably 2500 or more.

The chip type thermistor according to the present invention further comprises changing the distance between the substrate mounting electrodes (12a, 12b) and the area of the third electrode (13) on the element body surface (11b). Also, there is an advantage that the resistance can be freely adjusted.

The chip-type thermistor according to the present invention may have a part or all of a surface other than the surface on which the two substrate mounting electrodes are provided in accordance with operating conditions such as actual substrate mounting. May be provided with an insulating layer. This insulating layer may be formed by a method similar to the method of forming the insulating layer (5) described above. [Method of Manufacturing Chip-Type Thermistor] Hereinafter, two types of manufacturing methods (manufacturing methods 1 and 2) of the chip-type thermistor of the present invention will be described. The chip-type thermistor of the present invention may be manufactured by a method other than these manufacturing methods. However, the following manufacturing method of the present invention is a preferable mode particularly due to its ease of manufacturing. (Manufacturing Method 1) First, a conductive paste is screen-printed so as to form spaced electrodes (12) on one surface (11a) of the thermistor body (11) (FIG. 8).

Next, a conductive paste is screen-printed on the entire surface or a part of the opposite surface (11b), and after drying,
Baking is performed to provide an electrode (13) (FIG. 9).

If necessary, an insulating paste may be further screen-printed on the opposite surface (11b) on which the electrodes are formed, dried, and baked.

Next, an insulating paste is screen-printed on the space between the electrodes (12) formed on the surface (11a) so as to cover the electrode-facing edge and the surface of the space, dried, and baked. Providing an insulating layer (15) (FIG. 1)
0).

Using a dicer, dicing is performed on a strip so that the two electrodes (12) are located at the edges via the insulating layer (15) (FIG. 11).

A conductive paste is applied to one side surface of the dicing surface of the diced strip, dried and baked to form a connection electrode (14) on the end surface (11c) of the thermistor body ( (FIG. 12).

The obtained strips are aligned and diced to a desired chip size to obtain a chip-type thermistor. (Production Example 2) First, a conductive paste is screen-printed on one surface (11b) of the thermistor body (11), dried and baked to provide an electrode (13) (FIG. 1).
3).

[0033] If necessary, an insulating paste may be screen-printed on the surface (11b) on which the electrode (13) is formed, dried, and baked.

The obtained processed body is fixed to the heat-resistant plate (16) with the surface of the electrode (13) facing downward. The heat-resistant plate used at this time is selected from those having a smooth surface and heat resistance higher than the baking temperature. The adhesive used for fixing has heat resistance higher than the drying temperature, has adhesive strength that does not separate during dicing, volatilizes and carbonizes at the baking temperature, and has a large amount of volatile components.

Next, using a blade having a thickness of 100 to 300 μm, dicing is performed at a pitch corresponding to two longitudinal directions of a desired chip type thermistor (FIGS. 14 and 15). further,
The surface is washed with pure water or the like and dried.

The conductive paste is screen-printed while the conductive paste is applied to the gaps obtained by the dicing to form electrodes (12) spaced apart (FIG. 16).

Next, an insulating paste is screen-printed on the space between the formed electrodes so as to cover the electrode facing edge and the surface of the space, dried and baked to form an insulating layer (1).
5) is provided (FIG. 17).

Dicing is performed along a central portion of each uncoated electrode portion using a blade having a thickness of 50 to 100 μm (FIG. 18).

The obtained strips are aligned and diced to a desired chip size to obtain a chip type thermistor.

[0040]

EXAMPLES The present invention will be described in detail below, but the present invention is not limited to these examples. [Examples 1 to 3] Chip type thermistor A obtained by the manufacturing method of the present invention (thermistor thickness = 0.25 mm, thermistor length = 1.3 mm, thermistor width = 0.61 m)
m, distance between electrodes = 0.3 mm), chip thermistor B
(Thermistor thickness = 0.25 mm, thermistor length =
1.3 mm, thermistor width = 0.49 mm, distance between electrodes = 0.3 mm, chip type thermistor C (thermistor thickness = 0.25 mm, thermistor length = 1.2 mm, thermistor width = 0.45 mm, distance between electrodes) = 0.3 mm) as a sample, and the resistance (R2
5) The resistance (R50) at 50 ° C. was measured, and the B constant (R25 / R50) was calculated. The results are shown in Table 1.

The "distance between electrodes" mentioned above refers to the distance between the two substrate mounting electrodes described with reference to FIGS. [Comparative Examples 1 to 8] Performed in the same manner as in Example, except that the chip-type thermistor used no electrode on the back surface (Comparative Examples 1 to 4) and the case of a backside floating electrode (Comparative Examples 5 to 8). Was. The results are shown in Table 1.

The above "case without an electrode on the back surface" refers to the case without the third electrode described with reference to FIGS. The “case of the back surface floating electrode” mentioned above means a case where there is no connection electrode described in FIGS. 6 and 7 (for example, the form of FIG. 5).

[Table 1]

[0043]

The chip type thermistor according to the present invention can exhibit low resistance even if it is small and thin, and has high reliability. Therefore, it is possible to provide a high-density mounting or a composite one-package component with another electronic component.

[Brief description of the drawings]

FIG. 1 is a sectional view of a conventional double-sided electrode structure type thermistor.

FIG. 2 is a cross-sectional view of a conventional thermistor with a double-sided electrode structure.

FIG. 3 is a cross-sectional view of a conventional thermistor having both end electrodes / one-side resistance adjustment electrode structure.

FIG. 4 is a cross-sectional view of a conventional thermistor having both end electrodes / double-sided resistance adjusting electrode structure.

FIG. 5 is a cross-sectional view of a conventional one-sided resistance adjusting electrode / one-sided floating electrode type thermistor.

FIG. 6 is an external perspective view of an example of a chip thermistor according to the present invention.

FIG. 7 is a cross-sectional view of an example of a chip thermistor of the present invention.

FIG. 8 is a perspective view showing a state where an electrode (12) is formed on a thermistor body (11).

FIG. 9 is a perspective view showing a state in which an electrode (13) is formed on the body shown in FIG. 8;

FIG. 10 is a perspective view showing a state in which an insulating layer (15) is formed on the body shown in FIG. 9;

FIG. 11 is a perspective view showing a dicing portion of the body shown in FIG. 10;

FIG. 12 is a view showing a connection electrode (1) on a strip obtained by dicing.
The perspective view showing the state where 4) was formed.

FIG. 13 is a perspective view showing a state where an electrode (13) is formed on the thermistor body (11).

FIG. 14 is a perspective view showing a dicing portion, in which the element body of FIG. 13 is fixed to a heat-resistant plate (16) with the surface of an electrode (13) facing downward.

FIG. 15 is a perspective view showing a state after dicing of the body shown in FIG. 14;

FIG. 16 is a sectional view of the element body, showing a state in which an electrode (12) is formed on the element body of FIG. 15;

FIG. 17 is a cross-sectional view of the element body, showing a state where an insulating layer (15) is formed on the element body of FIG. 16;

FIG. 18 is a sectional view of the element body, showing a dicing portion of the element body of FIG. 17;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor body 2 Electrode 3 Insulating layer 11 Thermistor body 11a One surface of the thermistor body 11b One surface of the thermistor body 11c Side surface of the thermistor body 12 Electrode 12a Board mounting electrode 12b Board mounting electrode 13 Third Electrode 14 connection electrode 15 insulating layer 16 heat-resistant plate

Claims (6)

[Claims] 1. A chip-type thermistor having two substrate mounting electrodes provided on the same surface of a thermistor body at an interval, and a third or third part of the thermistor body is provided on a part or the entire surface on the opposite side of the thermistor body. A chip type thermistor, wherein an electrode is provided, and a third electrode thereof is connected to one of the two substrate mounting electrodes. 2. The chip type thermistor according to claim 1, wherein said connection is made via an electrode provided on one side surface of said thermistor body. 3. The chip thermistor according to claim 1, further comprising an insulating layer between the two board mounting electrodes spaced apart from each other. 4. The chip type according to claim 1, wherein an insulating layer is provided on a part or all of a surface other than the surface on which the two substrate mounting electrodes are provided apart from each other. Thermistor. 5. A method for manufacturing a chip-type thermistor according to claim 1, wherein: (a) forming electrodes for mounting a substrate at an interval on one surface of the thermistor body; (B) forming an electrode on the surface opposite to the electrode surface of (a); and (c) forming an insulating layer between the substrate mounting electrodes formed in (a). (D) a step of dicing on a strip so that the two substrate mounting electrodes are located at the edges via the insulating layer; and (e) one side of the dicing surface of the strip obtained in (d). A method for manufacturing a chip-type thermistor, comprising: a step of forming an electrode on a side surface; and (f) a step of dicing the strip obtained in (e) into a desired chip size. 6. A method for manufacturing a chip-type thermistor according to claim 1, wherein (a) forming an electrode on one surface of the thermistor body; a) fixing the processed body obtained in a) to a heat-resistant plate with the electrode surface facing downward; and (c) using a blade having a thickness of 100 to 300 μm for a desired chip-type thermistor for two longitudinal directions. A step of dicing at a pitch; and (d) screen-printing the conductive paste while applying the conductive paste to the gaps obtained by the dicing in (c) to form spaced substrate mounting electrodes. (E) a step of forming an insulating layer between the substrate mounting electrodes formed in (d), and (f) obtained by dicing in (c), and a conductive paste applied in (d). Along the middle of the gap, 50
Dicing using a 100 μm blade.