JP2000114006A - Resistance element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a short circuit between internal electrodes and to adjust a resistance value by specifying positive/negative of a distance between first and second planes, that between end parts of an external electrode which is on the side closer to a counter part, and that in the direction connecting first and second end surfaces between tip ends of an internal electrode. SOLUTION: A thermister element body 2 of semiconductor ceramics of negative temperature characteristics comprises first and second end surfaces 2a and 2b facing each other, and first and second internal electrodes 3 and 4 are formed on first and second planes at different level, respectively, in the element body 2. Related to the first and second internal electrodes 3 and 4, they overlap each other in thickness direction as shown with a diagonal-line part A, so that a distance between them is a distance L in the direction connecting the first and second end surfaces 2a and 2b. The distance L between tip ends 3a and 4a is negative when overlapped each other while positive when not overlapped. With an absolute value L of a distance connecting between first and second end surfaces of a region A set smaller than an inter-plane distance H, a resistance adjustment range of the thermister element 1 is enlarged, with an inter-end-part distance(d)of external electrodes 5 and 6 being larger than L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resistance element such as a negative temperature coefficient thermistor (NTC) element, a positive temperature coefficient thermistor (PTC) element or a varistor, and more particularly to a resistance element having a plurality of internal electrodes.

[0002]

2. Description of the Related Art Conventionally, various types of chip-type resistive elements that can be surface-mounted such as a printed circuit board have been proposed. For example, Japanese Patent Laying-Open No. 4-283902 discloses a chip type thermistor element shown in FIG.

The thermistor element 51 has a thermistor element 52 made of semiconductor ceramics. The thermistor body 52 has opposed end faces 52a and 52b. A first internal electrode 53 is formed in the thermistor body 52 so as to be drawn out to the end face 52a. End face 5
A second internal electrode 54 is formed so as to be drawn out to 2b.

[0004] The first and second internal electrodes 53 and 54 are formed at the same height position, that is, on the same plane, and a front end 53a and a front end 54a are opposed to each other with a predetermined distance X therebetween. External electrodes 55 and 56 are formed on the end surfaces 52a and 52b, respectively. External electrodes 55, 5
6 is formed so as to reach not only the end surfaces 52a and 52b but also both surfaces, a lower surface and both side surfaces of the thermistor body 52.

In the thermistor element 51, the resistance value can be easily adjusted by adjusting the distance X between the tips 53a, 54a of the first and second internal electrodes 53, 54.

On the other hand, Japanese Patent Application Laid-Open No. Sho 62-137804 discloses that a plurality of internal electrodes are arranged so as to overlap in the thickness direction via a thermistor element layer.
A thermistor element capable of reducing the resistance is disclosed.
FIG. 9 is a cross-sectional view showing a thermistor element described in the related art.

In the thermistor element 57, a thermistor body 58 made of semiconductor ceramics is used. The thermistor body 58 has opposed end faces 58a and 58b. In the thermistor body 58, internal electrodes 59a to 59d are formed at different height positions. The internal electrodes 59a and 59c are drawn out to the end face 58a,
On the other hand, the internal electrodes 59b and 59d are extended to the end face 58b.

The internal electrodes 59a to 59d are overlapped in the thickness direction at the front end portion with the thermistor element layer interposed therebetween within a range of a distance Y shown in FIG. The end face 58a
An external electrode 60 is formed on the upper surface.
Are connected to the internal electrodes 59a and 59c. Similarly,
An external electrode 61 is formed on the end face 58b, and the external electrode 61 is connected to the internal electrodes 59b and 59d.

In the thermistor element 57, as described above,
By arranging the plurality of internal electrodes 59a to 59d so as to overlap in the thickness direction via the thermistor body layer,
It is said that resistance can be reduced.

[0010]

In the thermistor element 51 shown in FIG. 8, tips 53a, 5a of internal electrodes 53, 54 are provided.
Although the resistance value can be adjusted by adjusting the distance X between the electrodes 4a, when the distance X is shortened, there is a possibility that the internal electrodes 53 and 54 may be short-circuited. Therefore, it is necessary to select the distance X so as to reliably prevent a short circuit, and the adjustment range of the resistance value is limited.

In addition, according to the experiment of the present inventor, according to the experiment of the present invention, the covering depth of the external electrodes 55 and 56 on the thermistor body 52, that is, the upper and lower surfaces and both side surfaces of the thermistor body 52 of the external electrodes 55 and 56 are shown. It was confirmed that depending on the length of the reaching portion, the resistance value could not be sufficiently changed even if the distance X between the first and second internal electrodes 53 and 54 was changed.

In the thermistor element 57 shown in FIG. 9, when the distance Y in the direction connecting the first and second end faces 58a and 58b in the region where the internal electrodes 59a to 59d overlap each other increases, the internal electrodes 59a to 59d become larger. Even if the number of layers of 59d was reduced, the resistance value could not be changed much. That is, the resistance value can be largely changed only by increasing the number of stacked internal electrodes 59a to 59d.

[0013] The above-mentioned problem is similarly observed not only in thermistor elements but also in varistors and fixed resistance elements having a structure in which first and second internal electrodes facing each other and a plurality of internal electrodes are laminated. Was.

Accordingly, an object of the present invention is to solve the above-mentioned disadvantages of the prior art, to prevent a short circuit between internal electrodes from occurring, to make it possible to adjust a resistance value, and to provide a resistance element having a large resistance value adjustment range. Is to provide.

[0015]

According to a first aspect of the present invention, there is provided a resistor element having first and second end faces opposed to each other, and a first and second resistor element. A first and a second external electrode formed on the end face, and a first and a second internal electrode connected to the first and the second external electrode, respectively, and extended into the thermistor body; The first and second internal electrodes are formed on first and second planes at different height positions of the resistor element, respectively, and a distance between the first and second planes is H, When the distance between the ends of the second external electrodes closer to the other end is d, and the distance along the direction connecting the first and second end surfaces between the tips of the first and second internal electrodes is L. , L is negative, H> | L |, and if L is positive, d>
L.

In the resistance element according to the first aspect of the present invention, the widths of the first and second internal electrodes do not necessarily have to be the same, but may be different. In addition, the first
A plurality of second internal electrodes may be provided, and in this case, the first and second internal electrodes may be alternately arranged in the thickness direction in the resistor element.

The resistance element according to the present invention can be suitably applied to a negative-characteristic thermistor element using a resistor element made of semiconductor ceramics having a negative resistance-temperature characteristic. And various resistance elements such as fixed resistors.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be clarified below by giving non-limiting embodiments of the present invention with reference to the drawings.

(First Embodiment) FIGS. 1A and 1B
FIG. 2 is a plan sectional view and a front sectional view for explaining a resistance element according to a first example of the present invention, and FIG. 2 is a perspective view showing an appearance.

The NTC element 1 of this embodiment has a thermistor element 2 as a resistance element. The thermistor body 2 is
It is made of a semiconductor ceramic having a negative resistance temperature characteristic.

The thermistor body 2 has first and second end faces 2a and 2b facing each other. In the thermistor body 2, a first internal electrode 3 and a second internal electrode 4 are formed on first and second planes at different height positions of the thermistor body 2, respectively. The first and second planes are planes on which the internal electrodes 3 and 4 are formed, respectively.

The first internal electrode 3 is extended to the end face 2a, while the second internal electrode 4 is extended to the end face 2b. As shown in FIG. 1A, the internal electrodes 3 and 4 are formed of rectangular metal films having the same width. The first and second internal electrodes 3 and 4 overlap in the thickness direction via the thermistor body layer.
That is, the first and second internal electrodes 3 and 4 are arranged in the thickness direction such that the distance along the direction connecting the first and second end faces 2a and 2b between the tip 3a and the tip 4a is L. Overlapping.

The distance L between the tips 3a and 4a is negative when the internal electrodes 3 and 4 overlap as shown in the figure.
If they do not overlap, it shall be positive. FIG. 1 (a)
In FIG. 5, a region A where the first internal electrode 3 and the second internal electrode 4 overlap in the thickness direction is indicated by hatching.

A first external electrode 5 is formed on the end face 2a, and is electrically connected to the first internal electrode 3. The first external electrode 5 is provided not only on the end face 2a, but also on the upper face 2c, the lower face 2d, and both side faces 2e and 2e of the thermistor body 2.
It is formed so as to reach f.

Similarly, a second external electrode 6 is formed on the end face 2b, and is electrically connected to the second internal electrode 4. The second external electrode 6 is also formed so as to reach not only the end face 2b but also the upper face 2c, the lower face 2d, and both side faces 2e and 2f.

The first and second internal electrodes 3 and 4 are made of Ag or A
It can be made of g-Pd or an appropriate metal material such as Ni or Cu. Further, the first and second external electrodes 5 and 6 can also be made of an appropriate metal material such as Ag or Ag-Pd. In addition, external electrodes 5,
6 may have a structure in which a plurality of metal layers are stacked.

The feature of the thermistor element 1 of this embodiment is that the first and second regions of the region where the internal electrodes 3 and 4 overlap each other are described.
The absolute value L of the distance along the direction connecting the end faces of the
Is smaller than the distance H between the first and second planes on which the internal electrodes 3 and 4 are formed. In this embodiment, H>
By | L |, the resistance value adjustment range of the thermistor element 1 is expanded.

(Second Embodiment) FIGS. 3A and 3B
FIG. 3 is a plan sectional view and a front sectional view of a thermistor element according to a second embodiment of the present invention.

The thermistor element 11 has the same structure as the thermistor element 1 in the first embodiment, except for the internal electrode structure. Therefore, the same portions are denoted by the same reference numerals, and the description thereof in the first embodiment is omitted to omit the description.

In the thermistor element 11, the first and second internal electrodes 3 and 4 do not overlap in the thickness direction in the thermistor body 2. That is, the first internal electrode 3
A distance L in the direction connecting the first and second end faces 2a and 2b.
(L> 0).

When the distance between the ends 5a and 6a of the first and second external electrodes 5 and 6 near the other side is d, d
> L. In the thermistor element 11, since d> L, the resistance value adjustment range is widened as is clear from an experimental example described later.

(Experimental Example) Next, based on specific experimental examples, thermistor elements 1 and 11 according to the first and second embodiments will be described.
The fact that the resistance value adjustment range can be widened will be described.

(First Experimental Example) As the thermistor element 2, an element of Mn, Ni, Co, and Al having a length of 2.0 mm, a width of 1.25 mm and a thickness of 0.9 mm was prepared. . In the thermistor body 2, the second internal electrode 4 is placed on a second plane located at a height of 0.3 mm from the lower surface by a first plane that is 0.3 mm higher than the second internal electrode 4. Then, the first internal electrode 3 was formed. Therefore, H =
0.3 mm.

The length of the second internal electrode 4, that is, the length from the end face 2 b to the tip 4 a is 1.0 mm, and the length of the first internal electrode 3, that is, the length from the end face 2 a to the tip 3 a
The length of the first 3a, 4a,
Various thermistor elements were manufactured by changing the distance L along the direction connecting the second end faces.

The first and second portions between the tips 3a and 4a
When the distance L along the direction connecting the end faces 2a and 2b of the
The tips 3a and 4a are located at the same position when viewed in the thickness direction. When the distance L is a positive value, the tips 3a and 4a are separated from each other, which corresponds to the second embodiment. When the distance L is negative, the first and second internal electrodes 3 and 4 overlap in the thickness direction. This corresponds to one embodiment.

The external electrodes 5 and 6 are made of Ag-
It is formed by applying and baking a Pd conductive paste, and the distance d between the tips 5a, 6a of the external electrodes 5, 6 is defined as:
1.4 mm.

The resistance values between the external electrodes 5 and 6 of the various thermistor elements obtained as described above were measured. FIG. 4 shows the results. As is clear from FIG. 4, when the distance L on the horizontal axis is negative, the resistance value greatly changes substantially in proportion to the distance L in the range of -0.3 to 0.0, and when the distance L is -0.3 or less. Shows that the resistance value does not change much. Therefore, in the thermistor element 1 according to the first embodiment, it can be seen that the resistance adjustment range can be expanded by setting H> | L | as compared with the case where H ≦ | L |.

As is apparent from FIG. 4, in a region where the distance L is a positive value, the resistance value largely changes in proportion to the distance L within a range where the distance L is smaller than 1.4 mm and is 1.4 mm.
It can be seen that the resistance value does not change much when the above is reached.

Therefore, by making the distance L smaller than the distance d between the ends 5a and 6a of the external electrodes 5 and 6, the resistance value can be adjusted in a wide range only by changing the distance L. Understand.

That is, in the thermistor element of this experimental example where H = 0.3 mm, when L is negative, | L |
Is smaller than the distance H, and when the distance L is positive, the distance L is smaller than the distance d, whereby the resistance value can be largely changed substantially in proportion to the distance | L |. It can be seen that it can be enlarged.

(Experimental Example 2) As the thermistor body 2, M
Made of oxides of n, Ni, Co and Al, 2.0 m long
m × 1.25 mm × 0.9 mm thickness was prepared. In the thermistor body 2, the lower surface is set at 0.
The second internal electrode 4 is placed on the second plane at a height of 41 mm by 0.08 mm higher than the second internal electrode 4.
The first internal electrode 3 was formed in the plane of FIG.

The length of the second internal electrode 4, that is, the length from the end face 2 b to the tip 4 a is 1.0 mm, and the length of the first internal electrode 3, that is, the length from the end face 2 a to the tip 3 a
The length of the first 3a, 4a,
Various thermistor elements were manufactured by changing the distance L along the direction connecting the second end faces.

The first and second portions between the tips 3a and 4a
When the distance along the direction connecting the end surfaces 2a and 2b is 0, the tips 3a and 4a are located at the same position when viewed in the thickness direction, and when the distance is positive, they are separated from each other.
This corresponds to the second embodiment, and a negative value corresponds to the first embodiment.

The external electrodes 5 and 6 are made of Ag-
It is formed by applying and baking a Pd conductive paste, and the distance d between the tips 5a, 6a of the external electrodes 5, 6 is defined as:
0.3 mm.

The resistance values between the external electrodes 5 and 6 of the various thermistor elements obtained as described above were measured. FIG. 5 shows the results. As is clear from FIG. 5, when the distance L on the horizontal axis is in the range of −0.3 to 0.0, the resistance value largely changes in proportion to | L |. It can be seen that the resistance value does not change much. Therefore, in the thermistor element 1 of the first embodiment, it can be seen that the resistance adjustment range can be expanded by setting H> | L | as compared with the case where H ≦ L.

Further, as is apparent from FIG. 5, in the region where L is a positive value, the resistance value largely changes in proportion to the distance L within a range where L is less than 1.4 mm. It can be seen that the resistance value does not change so much when it becomes.

Therefore, by making the distance L smaller than the distance d between the ends 5a and 6a of the external electrodes 5 and 6, the resistance can be adjusted in a wide range only by changing the distance L. Understand.

That is, in the thermistor element of this experimental example where H = 0.08 mm, the distance L is smaller than the distance H when the distance L is negative and smaller than the distance d when the distance L is positive. It can be seen that by making the value smaller, the resistance value can be changed largely in proportion to | L | and the resistance value adjustment range can be expanded.

Therefore, as is clear from the first and second experimental examples, the distance L between the tips of the internal electrodes 3 and 4 can be increased by changing only the distance L within the above-mentioned specific range. A desired resistance value can be easily realized from the resistance value range. Therefore, the resistance value can be adjusted in a wide resistance value range without changing the composition of the thermistor body, the number of internal electrodes, and the distance H between the internal electrodes along the thickness direction.

(Modification) In the first and second embodiments, the first and second internal electrodes 3 and 4 are formed of rectangular metal films having the same width. 1st, 2nd
The width of the internal electrodes 3 and 4 may be different. That is, as shown in the plan sectional view and the front sectional view in FIGS. 6A and 6B, respectively, the width dimension W ₁ of the first internal electrode 3 is changed to the width dimension W of the second internal electrode 4. ₂ , and conversely, the width W ₂ of the second internal electrode 4 is
The width W1 of the _first internal electrode 3 may be larger than the width W1.

As described above, the first and second internal electrodes 3 and 4
If having different width dimensions, a first width direction, a stacked position of the second internal electrode is displaced, the first small side internal electrode 4 of the width dimension W ₂ is larger width dimension W ₁ The overlapping area (the area P shown by hatching in FIG. 6) does not change as long as the tip side portions overlap in the area where the internal electrode 3 is located. Therefore, the resistance value is determined only by the distance L along the direction connecting the first and second end surfaces 2a and 2b between the tips of the internal electrodes 3 and 4.

In the first and second embodiments, the first and second internal electrodes 3 and 4 are arranged in the thermistor body 2. However, a plurality of first and second internal electrodes are formed. May be. In the thermistor element 31 of the modified example shown in FIG. 7, two first internal electrodes 3 and 33 and two second internal electrodes 4 and 34 are arranged, and the first and second internal electrodes 3 and 4 are arranged. Are alternately arranged in the thickness direction.

As described above, the plurality of first internal electrodes 3
Even in the case of using the internal electrodes 33 and the second internal electrodes 4 and 34, as long as H> | L | or d> L according to the present invention, as in the first and second embodiments, a wide resistance value range Thus, a desired resistance value can be easily obtained.

By increasing the number of the first and second internal electrodes, a lower resistance value can be obtained even when the same thermistor body 2 is used.

[0055]

According to the resistance element according to the first aspect of the present invention, the first and second resistance elements at different heights of the thermistor element body are provided.
The first and second internal electrodes are formed on the respective planes, and the distance between the first and second planes is H, and the distance between the ends of the first and second external electrodes closer to the other side. To d, the first and second
When the distance L along the direction connecting the first and second end faces between the tips of the internal electrodes is L, L is negative and the tip side portions of the first and second internal electrodes overlap in the thickness direction. H> | L |, and if L is positive, that is, if the first and second internal electrodes do not overlap in the thickness direction, then d> L. The resistance value changes substantially in proportion to the absolute value | L | of the distance between the tips of the first and second internal electrodes. Therefore, even when the specific resistance value of the resistive element, that is, the composition, the number of internal electrodes, and the distance along the thickness direction between the internal electrodes are fixed, only by adjusting the distance L, a wide resistance value range can be obtained. The resistance value can be adjusted.

Accordingly, the resistance value of the resistance element having the first and second internal electrodes can be easily designed, the material cost and the number of steps can be reduced, and the resistance elements having various resistance values can be manufactured at low cost. Can be provided. In addition, since the first and second internal electrodes are arranged at different height positions of the resistance element, a short circuit between the first and second internal electrodes hardly occurs.

In the resistance element according to the second aspect of the present invention, since the widths of the first and second internal electrodes are different, the lamination positions of the first and second internal electrodes are shifted in the width direction. Even in this case, the resistance value does not change as long as the internal electrode having the smaller width dimension is arranged in the region of the internal electrode having the larger width dimension at the width direction position. Therefore, a desired resistance can be obtained in a wide resistance value range only by adjusting the distance L between the tips of the first and second internal electrodes without significantly increasing the lamination accuracy in the width direction of the first and second internal electrodes. A resistance value can be realized.

According to the third aspect of the present invention, a plurality of first
, And a plurality of second internal electrodes, and the first and second internal electrodes are alternately arranged in the thickness direction in the resistor element, so that the number of stacked internal electrodes is increased. Thus, a resistance element having a small resistance value can be provided, and the resistance value can be adjusted over a wide resistance value range only by adjusting the distance L between the tips between the first and second internal electrodes according to the present invention. be able to.

[Brief description of the drawings]

1 (a) and 1 (b) respectively show a first embodiment of the present invention.
FIGS. 3A and 3B are a plan cross-sectional view and a front cross-sectional view illustrating a thermistor element according to the example of FIG.

FIG. 2 is a perspective view showing the appearance of a thermistor element according to the first embodiment of the present invention.

FIGS. 3A and 3B are a plan sectional view and a front sectional view, respectively, of a thermistor element according to a second embodiment.

FIG. 4 is a diagram showing a result of the first experimental example, and showing a relationship between a distance L between tips of first and second internal electrodes and a resistance value.

FIG. 5 is a diagram showing a result of a second experimental example, and showing a relationship between a distance L between tips of first and second internal electrodes and a resistance value.

FIGS. 6A and 6B are a plan sectional view and a front sectional view, respectively, showing a modification of the resistance element of the present invention.

FIG. 7 is a front sectional view showing still another modified example of the resistance element of the present invention.

FIG. 8 is a front sectional view for explaining a conventional thermistor element.

FIG. 9 is a front sectional view showing another example of a conventional thermistor element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermistor element 2 ... Thermistor element body 2a, 2b ... 1st, 2nd end surface 2c ... Upper surface 2d ... Lower surface 2e, 2f ... Side surface 3 ... 1st internal electrode 4 ... 2nd internal electrode 3a, 4a ... Tip 5 First external electrode 6 Second external electrode 5a, 6a End 11 Thermistor element 21 Thermistor element 31 Thermistor element 33 First internal electrode 34 Second internal electrode

Claims (4)

[Claims] A resistor element having first and second end faces facing each other; first and second external electrodes formed on first and second end faces of the resistor element; , A second internal electrode connected to the second external electrode and extending inside the thermistor body, wherein the first and second internal electrodes have different heights of the resistance element body. The distance between the first and second planes is H, and the distance between the ends of the first and second external electrodes closer to the other side is H. d, where L is the distance along the direction connecting the first and second end faces between the tips of the first and second internal electrodes, and if L is negative, H> | L |, L
Is positive when d> L,
Resistance element. 2. The resistance element according to claim 1, wherein the first and second internal electrodes have different widths. 3. A plurality of first internal electrodes and a plurality of second internal electrodes, wherein the first and second internal electrodes are alternately arranged in the thickness direction in the resistor element. The resistance element according to claim 1, wherein: 4. The resistance element according to claim 1, wherein said resistance element is made of a semiconductor ceramic having a negative resistance temperature characteristic, and is a negative characteristic thermistor element.