JPH11224805A - Thermistor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-resistance thermistor element the resistance value fluctuations of which are caused by lamination slippage is small. SOLUTION: A thermistor element is constituted by forming first and second internal electrodes 3a and 4a, which are respectively extended inward from the facing and faces 2a and 2b of an elemental thermistor body 2 on which external electrodes 5a and 5b are formed, a first floating electrode 3b which is made to face to the inside end of the first internal electrode 3a at a prescribed distance, and a second floating electrode 4b which is made to face to the inside end of the second internal electrode 4a at a prescribed distance in the elemental thermistor body 2, with the floating electrodes 3b and 4b being made to overlap each other with an elemental thermistor layer 2c in between. The lengths l1 and l2 and widths w1 and w2 of the floating electrodes 3b and 4b are adjusted so as to satisfy relations, l1 >l2 and w1 >w2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor element used for detecting an ambient temperature, a solid temperature, or the like, or for performing temperature compensation of an electronic circuit or the like. The present invention relates to a laminated thermistor element formed by:

[0002]

2. Description of the Related Art Conventionally, various thermistor elements have been widely used for temperature detection and temperature compensation. In some applications, a low-resistance thermistor is required, and a chip-type laminated thermistor element shown in FIG. 6 has been proposed to reduce the resistance.

As shown in FIGS. 6A and 6B, a thermistor element 61 has a plurality of internal electrodes 63a to 63e overlapped with a thermistor element body 62 made of a semiconductor ceramic material via a thermistor element layer. It has the structure arranged in. The internal electrodes 63a, 63c, 63e are end faces 62a.
And is connected to an external electrode 64a formed on the end face 62a. On the other hand, the internal electrodes 63b, 63
d is drawn out to the end face 62b and is connected to the external electrode 64b formed on the end face 62b.

In the thermistor element 61, the internal electrodes 63a, 63c,
The width of the internal electrode 63e is different from that of the internal electrodes 63b and 63d. This will be described with reference to FIG. 6B on behalf of the internal electrodes 63b and 63c.

The internal electrode 63b and the internal electrode 63c are
Overlap in the range of the length L _1. However, in comparison with the width W ₁ of the inner electrode 63 b, the width W ₂ of the internal electrode 63c is small.

Accordingly, in manufacturing the thermistor element 61, when laminating the green sheets having the internal electrodes 63a to 63e formed on the upper surface, even if a misalignment occurs in the width direction, the internal electrode 63c is not 63
as long as it is arranged in a region that it is included in the b width W ₁ of, variation in the resistance value hardly occurs.

However, the internal electrodes 63 b, and the width W ₁ of the 63d, the internal electrodes 63a, 63c, even when made different from the width W ₂ of 63e, longitudinal, i.e. opposite second end faces 62a, 62b, If the stacking deviation occurs in the connecting direction, the length L of the region where the internal electrodes overlap
₁ variation, there is a problem that also the resistance value varies.

On the other hand, JP-A-6-53008 discloses that
A multilayer thermistor element capable of reducing variation in resistance value caused by stacking deviation in the length direction connecting the two opposite end surfaces of the thermistor body is disclosed. The structure of the multilayer thermistor element will be described with reference to FIG.

In the thermistor element 71, first and second internal electrodes 73a and 73b are formed so as to extend from the two opposing end surfaces 72a and 72b of the thermistor body 72 toward the center. The first and second internal electrodes 73a,
73b is opposed at a predetermined distance at the center. The internal electrodes 73a and 73b are respectively
a, 72b are connected to external electrodes 74a, 74b.

The third internal electrode 7 is overlapped with the internal electrodes 73a and 73b via the thermistor body layer.
3c is buried. The internal electrode 73c is
4a, 74b are not connected.

In the thermistor element 71, since the third internal electrode 73c overlaps the first and second internal electrodes 73a and 73b, the green sheet on which the internal electrodes 73a and 73b are formed and the internal electrode 73c are formed. In stacking the laminated green sheets, even if the stacking misalignment occurs in the length direction, that is, the direction connecting the two opposing end surfaces 72a and 72b, it is possible to reduce the variation in the resistance value caused by the stacking misalignment.

That is, the first internal electrode 73a and the third
If the length b _{1 of the} portion overlapping with the internal electrode 73 c becomes smaller due to lamination displacement, on the contrary, the second internal electrode 73 is reduced by the reduced length b _1.
and b, overlapping length b ₂ regions are larger in the third inner electrode 73c. Therefore, it is possible to reduce the variation in the resistance value due to the stacking deviation in the length direction. Further, in order to reduce the variation in the resistance value due to the lamination misalignment in the horizontal direction, the width dimension of the internal electrodes 73a and 73b and the internal electrode 73c may be made different, and the thermistor element 61 shown in FIG. The same effect can be obtained. However, since the electrode overlap dimension (b ₁ + b ₂ ) is smaller than L ₁ and in series, the resistance value is much larger than that of the thermistor element 61 in FIG. 6, and it is difficult to reduce the resistance.

[0013]

As described above, in the multilayer thermistor element 71 shown in FIG. 7, although the variation in the resistance value due to the lamination shift can be reduced, the resistance value becomes large. The low resistance value could not be set. Although the thermistor element 61 shown in FIG. 6 can reduce the resistance value, the variation in the resistance value due to the lamination misalignment along the width direction can be reduced.
It was not possible to suppress the variation in the resistance value due to the stacking deviation in the length direction.

An object of the present invention is to provide a laminated thermistor capable of reducing the resistance, which can suppress the variation in the electrode overlap area due to the lamination shift, and has a low resistance.
Another object of the present invention is to provide a thermistor element having high resistance value accuracy.

[0015]

According to the first aspect of the present invention,
Such a thermistor element has opposing first and second end faces.
A thermistor body, and a first thermistor body
A first internal electrode extended to an end face, and a first internal electrode
With a predetermined distance from the tip of the
A first floating electrode embedded in the body
And the second end face of the thermistor body drawn out
2 and a predetermined distance from the tip of the second internal electrode
And buried in the thermistor body
Second floating electrode, and first and second
And first and second external electrodes formed on the end face.
The first and second floating electrodes are located inside the thermistor body.
And are arranged so as to overlap in the thickness direction, and
The length and width of the first and second floating electrodes
Each, l₁, W₁, And l_Two, W_TwoAnd l ₁
> L_TwoAnd w₁> W_TwoIt is characterized by that.

According to the second aspect of the present invention, the first and second floating electrodes are formed in a region not overlapping the first and second internal electrodes in the thickness direction.
According to the third aspect of the present invention, at least one of the first and second floating electrodes is divided so as to have a plurality of floating electrode portions arranged at a predetermined distance from each other.

According to the fourth aspect of the present invention, the first internal electrode and the first floating electrode are formed at different height positions. In the invention described in claim 5, the second internal electrode and the second floating electrode are formed at different height positions.

In the invention described in claim 6, a first electrode pair comprising the first internal electrode and the first floating electrode, and a second electrode comprising the second internal electrode and the second floating electrode. At least one of the pairs is formed in plurality.

[0019]

1 (a) and 1 (b) are a longitudinal sectional view and a plan sectional view for explaining a chip type thermistor element according to a first embodiment of the present invention. Note that the chip-type thermistor element 1 of the present embodiment is configured using a thermistor element 2 having a negative resistance-temperature characteristic.
Therefore, it is configured to operate with the NTC thermistor element.

The thermistor body 2 is made of semiconductor ceramics having negative resistance temperature characteristics, and has a rectangular parallelepiped shape having two opposite end faces 2a and 2b. In the following, the end faces 2a, 2 of the thermistor body 2 will be described.
The direction connecting b is the length direction, the direction orthogonal to the length direction and parallel to the upper and lower surfaces of the thermistor body 2 is the width direction, and the direction connecting the upper and lower surfaces of the thermistor body 2 is the height direction. .

A first internal electrode 3a is formed to extend from the end face 2a into the thermistor body 2. A tip or inner end of the first inner electrodes 3a, the first floating electrode 3b with a predetermined gap length g ₁ is formed.

A second internal electrode 4a is formed inward from the end face 2b. The tip of the second internal electrodes 4a, the second floating electrode 4b by a gap of length g ₂ is formed.

In this embodiment, the first internal electrode 3a and the first floating electrode 3b are formed at the same height. The second internal electrode 4a and the second floating electrode 4b are formed at the same height. The first and second floating electrodes 3b and 4b are formed so as to overlap in the thickness direction via the thermistor body layer 2c.

As apparent from FIG. 1B, the length l ₁ and width w ₁ of the first floating electrode 3b are larger than the length l ₂ and width w _{2 of} the second floating electrode 4b.
It is configured to satisfy the relations of l ₁ > l ₂ and w ₁ > w ₂ .

The first and second floating electrodes 3
Although b and 4b are configured to have a rectangular shape in FIG. 1, they may have other shapes than the rectangle.
That is, when the second floating electrode 4b is projected downward, as long as it is formed in a shape included in the region where the first floating electrode 3b is formed, the shapes of both are particularly limited. Not something.

The first and second floating electrodes 3
b and 4b correspond to the first and second internal electrodes 3a and 4a, respectively.
It is formed in a region that does not overlap in the thickness direction. Reference numerals 5a and 5b denote first and second external electrodes, respectively, which are formed so as to cover the end faces 2a and 2b.

In manufacturing the thermistor element 1, first, a green sheet on which a first internal electrode 3a and a first floating electrode 3b are printed, and a second internal electrode 4a and a second floating electrode 4b are printed. The obtained green sheet is laminated together with a plain green sheet, and the obtained laminate is pressed and then fired to obtain the thermistor body 2. Therefore, similarly to the thermistor elements 61 and 71 of the related art, there is a problem of variation in the resistance value due to the misalignment of the green sheets.

However, in the thermistor element 1, the first and second layers overlap with each other via the thermistor body layer.
The second floating electrodes 3b and 4b are configured so that the first and second floating electrodes 3b and 4b have the above-described specific dimensional relationship. Even if a stacking shift occurs, as long as the second floating electrode 4b is included in the area where the first floating electrode 3b is projected upward, the resistance value does not change due to the stacking shift.

Therefore, it is possible to provide a thermistor element 1 in which a variation in resistance value due to a lamination shift is unlikely to occur. The thermistor body 2 can be formed using an appropriate semiconductor ceramic having a negative resistance temperature characteristic. However, in order to form a PTC thermistor, a semiconductor ceramic having a positive resistance temperature characteristic is used. The thermistor body 2 may be configured. Also, the first and second internal electrodes 3a, 4a and the floating electrode 3b,
About 4b, it can comprise using suitable electroconductive materials, such as Ag and Ag-Pd, and it is not specifically limited.

Further, regarding the external electrodes 5a and 5b,
A conductive paste such as Ag paste is applied so as to cover the end faces 2a and 2b of the thermistor element body 2 and baked, or a conductive material such as Ag or Ag-Pd is plated, vapor-deposited or sputtered to form the end faces 2a and 2b. Can be formed.

The external electrodes 5a and 5b may have a laminated structure in which a Sn plating layer is formed on an external electrode made of Ag or Ag-Pd via a Ni plating layer in order to enhance solderability. , External electrodes 5a, 5b
Are not particularly limited, either.

Next, specific experimental examples will be described. M
A binder resin, a dispersant, and a surfactant are mixed with a ceramic powder having a negative resistance temperature characteristic obtained by mixing transition metal oxides such as n, Ni, and Co to prepare a ceramic slurry. Used, thickness 50
A μm ceramic green sheet was obtained. Next, the above ceramic green sheet is punched into a predetermined rectangular shape,
A plurality of rectangular mother ceramic green sheets were obtained.

An Ag-Pd paste was printed on one mother ceramic green sheet, and the first internal electrodes 3 were printed.
a and a plurality of first floating electrodes 3b were formed in a matrix. Also, a plurality of second internal electrodes 4a and second floating electrodes 4b were formed in a matrix on another mother ceramic green sheet. The first and second mother ceramic green sheets are
Lamination displacement was adjusted as described below together with another appropriate number of mother ceramic green sheets, and the layers were pressed in the thickness direction and pressed to obtain a mother laminate.

Thereafter, the mother laminate was cut in the thickness direction to obtain a laminate chip for each thermistor element, and the laminate chip was fired to obtain a thermistor body 2. An Ag paste is applied to the end surfaces 2a, 2b of the thermistor body 2 and baked to form the external electrodes 5a, 5b.
b was formed.

As described above, the thermistor body 2 having the dimensions of 1.6 mm length × 0.8 mm width × 0.8 mm thickness
And the width w ₁ = 0.5 mm, l ₁ = 0.
8 mm, w ₂ = 0.3 mm, l ₂ = 0.6 mm, g ₁ =
A chip-type thermistor element of the example in which 0.1 mm and g ₂ = 0.2 mm was obtained.

The resistance values R and B constants of the chip type thermistor element of the embodiment obtained as described above were measured. The results are shown in Table 1 below together with variations in the resistance values R and B constants.

It should be noted that, in Table 1, the stacking deviation 0
The lamination displacement of 0.05 mm corresponds to the case where the ceramic green sheets of the mother are laminated so as not to have a lamination displacement as shown in FIG. 1B, and the width direction and the length direction as shown in FIG. The results are shown in the case where the layers are stacked such that a stacking deviation of 0.05 mm occurs.

For comparison, the chip type thermistor is the same as in the above embodiment except that the dimensions of the first and second floating electrodes 3b and 4b are the same as those of the first floating electrode 3b. An element was manufactured. Table 1 below also shows the resistance values R and B constants of the thermistor element of this comparative example and their variations. Lamination displacement 0 and lamination displacement 0.05 mm in the comparative example have the same meaning as in the example.

In Table 1, 3CV = (3σ /
X) × 100 (%), where σ represents a standard deviation and X represents an average value.

[0040]

[Table 1]

As is apparent from Table 1, the chip type thermistor element of the embodiment has a length of 0.05 mm in the length direction and the width direction in comparison with the comparative example in which the dimensions of the first and second floating electrodes are the same. It can be seen that a chip-type thermistor element with almost no change in resistance value can be obtained even when a green sheet lamination shift occurs.

(Modification) In the chip type thermistor element 1 of the embodiment described above, the first and second floating electrodes 3
Although the b and 4b have been constituted by a single rectangular internal electrode, as shown in FIG. 3A, the thermistor element according to the present invention divides the floating electrode into a plurality of floating electrode portions. Is also good.

That is, in the thermistor element 11 shown in FIG. 3A, the second floating electrode 4b is divided into a plurality of floating electrode portions 4b ₁ and 4b ₂ . In this case, the floating electrode portions 4b ₁ and 4b
₂ are opposed to each other at a predetermined distance from each other,
Width w ₂ and length l ₂ of the floating electrode 4b of is the width and length of the region external to both, as shown, is formed.

In FIG. 3A, the floating electrode portions 4b ₁ and 4b ₂ are divided along the length direction, but may be divided along the width direction. FIG.
In the thermistor element 12 shown in (b), the floating electrode is not divided but a plurality of first and second floating electrodes are formed at the same height position. That is, a plurality of first floating electrodes 3b, 3b are formed at a predetermined distance at the same height position as the first internal electrode 3a. On the other hand,
Also for the second floating electrode, a plurality of second floating electrodes 4b, 4b are formed at the same height position as the second internal electrode 4a. In this case, first, the length and width of the second floating electrode, as indicated by l _1, l _2, w _1, w ₂ shown, determined by the length and width dimensions of the respective floating electrodes 3b, 4b Will be done.

In the thermistor element 1, the first and second
Are formed at the same height position as the corresponding first and second floating electrodes 3b and 4b, respectively, as shown in FIG.
a may be formed at a different height from the first floating electrode 3b, and similarly, the second internal electrode 4a
May also be formed at a different height from the second floating electrode 4b.

Although not particularly shown, only the first internal electrode 3a may be formed at a different height from the corresponding floating electrode 3b, or only the second internal electrode 4a may be formed at the corresponding floating electrode. 4b may be formed at a different height position.

Further, as shown in FIG. 5, a first electrode pair composed of a first internal electrode 3a and a first floating electrode 3b, and a second internal electrode 4a and a second floating electrode 4b. The second pair of electrodes to be
A plurality may be laminated in the thermistor body 2. Further, a plurality of only one of the electrode pairs may be stacked.

As shown in FIGS. 3 to 5, the structure of the internal electrode and the floating electrode in the thermistor element according to the present invention is such that the first and second floating electrodes satisfy the above-mentioned specific dimensional relationship. Various modifications can be made as long as they overlap in the thickness direction via the thermistor body.

The present invention relates to an NT having a negative resistance-temperature characteristic.
C thermistor element and PTC having positive resistance temperature characteristic
The invention can be applied to any of the thermistor elements. Further, since the first and second external electrodes are formed on the end surfaces of the two opposing surfaces, it can be used as a chip-type thermistor element that can be easily surface-mounted on a printed circuit board or the like.

[0050]

According to the first aspect of the present invention, the first and second internal electrodes and the first and second floating electrodes are formed in the thermistor body. In a configuration in which the floating electrodes overlap in the thickness direction via the thermistor element layer, the length l ₁ and width w ₁ of the first floating electrode and the lengths l ₂ and w _{2 of} the second floating electrode are different from each other. , L ₁ > l ₂ and w ₁ > w ₂
Therefore, it is possible to provide a thermistor element in which the resistance value hardly varies even if lamination misalignment occurs in any of the length direction and the width direction. Become.

Therefore, the laminated thermistor element can reduce the resistance, and can effectively increase the resistance value accuracy. According to the second aspect of the present invention, the first and second floating electrodes are formed so as not to overlap the first and second internal electrodes in the thickness direction. It is possible to provide a thermistor element in which variation in resistance value due to overlapping of the floating electrode and the first and second internal electrodes hardly occurs and variation in resistance value is further reduced.

According to the third aspect of the present invention, at least one of the first and second floating electrodes is divided so as to have a plurality of floating electrode portions, respectively. By using the method, it is possible to provide a thermistor element having various resistance values and having a small variation in the resistance value.

According to the fourth aspect of the present invention, the first internal electrode and the first floating electrode are formed at different heights. According to the fifth aspect of the present invention, the second internal electrode and the first floating electrode are formed at different heights. And the second floating electrode are formed at different height positions. By adjusting the distance between each internal electrode and the floating electrode, respectively, the same thermistor element body is used to obtain various resistance values. It is possible to provide a thermistor element which has a small variation in resistance value.

According to the sixth aspect of the present invention, the first electrode pair consisting of the first internal electrode and the first floating electrode and the second electrode pair consisting of the second internal electrode and the second floating electrode are formed. Since at least one of them is formed in plural, it is possible to provide a thermistor element having further lower resistance and less variation in resistance value.

[Brief description of the drawings]

FIGS. 1A and 1B are a longitudinal sectional view and a plan sectional view of a thermistor element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of a chip-type thermistor element of an example manufactured in a specific experimental example, showing a case where a stacking deviation of 0.05 mm occurs in the length direction and the width direction.

FIGS. 3A and 3B are cross-sectional plan views showing modifications of the thermistor element according to the present invention.

FIG. 4 is a longitudinal sectional view for explaining still another modified example of the thermistor element of the present invention.

FIG. 5 is a longitudinal sectional view for explaining another modification of the thermistor element according to the present invention.

FIGS. 6A and 6B are a longitudinal sectional view and a plan sectional view for explaining an example of a conventional chip type thermistor element.

7A and 7B are a longitudinal sectional view and a plan sectional view for explaining another example of a conventional chip-type thermistor element.

[Explanation of symbols]

1 ... thermistor element 2 ... thermistor element 2a, 2b ... end surface 2c ... thermistor body layer 3a ... first internal electrode 3b ... first floating electrode 4a ... second internal electrode 4b ... second floating electrodes 4b ₁ , 4b ₂ ... floating electrode part 11, 12 ... thermistor element

Claims (6)

[Claims] 1. A semiconductor device having first and second end faces facing each other.
First thermistor body, and a first end face of the thermistor body drawn out.
The internal electrode is opposed to the tip of the first internal electrode at a predetermined distance.
And a first flow path embedded in the thermistor body.
And a second electrode drawn out to a second end face of the thermistor body.
An internal electrode, opposed to the tip of the second internal electrode at a predetermined distance
And embedded in the thermistor body
A floating electrode; first and second external electrodes formed on the first and second end faces;
Wherein the first and second floating electrodes are provided in the thermistor body.
Are arranged so as to overlap in the thickness direction.
The length and width of the first and second floating electrodes
Each l₁, W₁, And l_Two, W_TwoAnd l
₁> L_TwoAnd w ₁> W_TwoIt is characterized by being
A thermistor element. 2. The thermistor element according to claim 1, wherein the first and second floating electrodes are formed in a region that does not overlap with the first and second internal electrodes in a thickness direction. 3. The method according to claim 1, wherein at least one of the first and second floating electrodes is divided so as to have a plurality of floating electrode portions separated by a predetermined distance. The thermistor element as described. 4. The thermistor element according to claim 1, wherein said first internal electrode and said first floating electrode are formed at different height positions. 5. The thermistor element according to claim 1, wherein said second internal electrode and said second floating electrode are formed at different height positions. 6. A method according to claim 1, wherein at least one of the first pair of electrodes including the first internal electrode and the first floating electrode and the second pair of electrodes including the second internal electrode and the second floating electrode includes a plurality of pairs. Claim 1 which is formed.
5. The thermistor element according to any one of 5.