JP2000077207A - Resistance element and method of adjusting resistance of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resistance element which has low dispersion in resistance and can accurately and easily perform adjustment of the resistance. SOLUTION: In this thermistor element 1, a first and a second surface electrodes 3 and 4 are formed facing each other on the upper surface 2a of a thermistor element 2 as resistance element, the first and the second surface electrodes 3 and 4 have structures in which a plurality of electrode layers 3a, 3b and 4a, 4b are sequentially laminated, respectively, a portion in which the surface electrodes 3 and 4 face each other is of least two-step shaped structure, each of the electrode layers 3a-3d and 4a-4d in each step have a structure in which a second metal thin film is laminated on a first metal thin film, and the first and the second metal thin films are formed of a first and a second metals, respectively, each of which has an etchant which dissolves one metal thin film but not the other metal thin film each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance element such as a chip thermistor element and a method of adjusting the resistance value thereof, and more particularly, to a first and a second resistance element which are opposed to each other on one principal surface of a resistance element body. And a method of adjusting the resistance value of the resistance element having the surface electrode.

[0002]

2. Description of the Related Art Conventionally, chip type thermistors have been widely used for temperature compensation circuits and temperature detectors.

FIG. 12 is a sectional view showing an example of a conventional chip thermistor element. Chip type thermistor element 5
1 is a thermistor element 52 made of semiconductor ceramics.
It is configured using A first external electrode 53a is formed to cover one end surface 52a of the thermistor body 52. A second external electrode 53b is formed to cover the other end surface 52b of the thermistor body 52.

The external electrodes 53a and 53b are formed by immersing the ends of the thermistor body 52 in a conductive paste and then baking the ends. Therefore, the external electrode 5
The lengths of the portions 3a and 53b reaching the upper surface, the lower surface, and both side surfaces of the thermistor body 52 tend to vary.
In addition, the specific resistance itself of the thermistor body 52 also tends to vary. Therefore, in the thermistor element 51, there is a problem that the variation in the resistance value is large.

To solve the above-mentioned problem, Japanese Patent Application Laid-Open No. 3-250603 discloses a thermistor element 54 shown in FIG. In the thermistor element 54, a glass coating layer 56 is formed so as to cover the upper surface, the lower surface, and both side surfaces of the thermistor element 55. A first external electrode 57a is formed so as to cover one end face 55a of the thermistor body 55, and an external electrode 57b is formed so as to cover the other end face 55b.

In the thermistor element 54, the glass coating layer 5
6 is formed, the resistance value of the external electrodes 57a,
It is determined by the portion existing on the end faces 55a and 55b of the 57b. Therefore, resistance values are not affected by variations in lengths of the external electrodes 57a and 57b reaching the upper surface, the lower surface, and the side surface of the thermistor body 55.

However, when the external electrodes 57a and 57b are formed by applying and baking a conductive paste, the material forming the glass coating layer 56 and the external electrodes 57a and 57b
57b tended to diffuse with each other. For this reason, a part of the glass coating layer 56 may be lost due to mutual diffusion, and the external electrode 57b may directly contact the thermistor body 55 on the lower surface of the thermistor body 55 or the like.

[0008] It is difficult to control the above-mentioned interdiffusion, and there is a problem that the resistance value tends to deviate from the design value. In addition, the resistance value variation of the thermistor body 55 itself still exists, and therefore, it is very difficult to obtain the thermistor element 54 having a desired resistance value with high accuracy.

Further, thermistor elements 5 having various resistance values
In the case of trying to manufacture No. 4, for each desired resistance value,
The thermistor body 55 having a different specific resistance has to be prepared. Therefore, it has been difficult to supply thermistor elements 54 having various resistance values.

Therefore, Japanese Patent Application Laid-Open No. 4-130702 proposes a chip thermistor element 58 shown in FIG. In the chip-type thermistor element 58, first and second internal electrodes 60 and 61 are arranged in a thermistor body 59. The internal electrodes 60 and 61 are formed at the same height position, and the front end 60a and the front end 61a are opposed to each other at a predetermined distance. Internal electrodes 60, 61
Are drawn out to end surfaces 59a and 59b, respectively, and are electrically connected to external electrodes 62a and 62b, respectively.

The chip-type thermistor element 58 is obtained by using a well-known integrated ceramic firing technique. In this case, the first and second internal electrodes 60 and 61 are formed by printing a conductive paste on the same ceramic green sheet. Therefore, the distance between the tip 60a of the first and second internal electrodes 60 and the tip 61a of the second internal electrode 61 can be easily controlled by screen printing. Therefore, by controlling the above-mentioned interval using the same thermistor element body 59, thermistor elements 58 having various resistance values can be easily realized.

However, in practice, the edges of the internal electrodes 60 and 61 may be distorted due to bleeding of the conductive paste. In addition, since the ceramic green sheets on which the conductive paste is printed and a plurality of ceramic green sheets on which the conductive paste is not printed are laminated and integrally fired, the internal electrodes 60 and 50 may be affected by variations in shrinkage during firing. 61 tended to vary.
Therefore, the resistance value tends to deviate from the design value,
It has been difficult to obtain a chip thermistor element 58 having a resistance value as designed, with high accuracy.

Japanese Patent Application Laid-Open No. 6-61101 proposes a chip-type thermistor element capable of reducing the variation in resistance value as described above. As shown in FIGS. 15A and 15B, in the chip type thermistor element 63, rectangular first and second surface electrodes 65 and 66 are formed on the upper surface of the thermistor body 64. The tips of the first and second surface electrodes 65 and 66 are opposed to each other at a predetermined distance in the center of the upper surface of the thermistor body 64. Further, the surface electrodes 65 and 66 are extended to the edges formed by the end surfaces 64a and 64b and the upper surface of the thermistor body 64, respectively.

The external electrodes 67a and 67b cover the end faces 64a and 64b of the thermistor body 64, respectively.
Further, it is formed so as to reach a pair of side surfaces, an upper surface, and a lower surface. The external electrode 67a is connected to the first surface electrode 65,
The external electrode 67a is electrically connected to the second surface electrode 66.

Further, first and second surface electrodes 65 and 66 are provided.
An insulating layer 68 is formed so as to cover the opposing region and the vicinity of the tip. The surface electrodes 65 and 66 can be formed on the upper surface of the thermistor body 64 by a thin film forming method such as plating, vapor deposition, or sputtering. Therefore, the surface electrode 65,
66 can be formed in an accurate shape, and it is possible to reduce variation in the resistance value of the thermistor element 63.

[0016]

As described above, in the conventional chip type thermistor elements 51, 54 and 58, it is difficult to reduce the variation in the resistance value, and the thermistor elements having the resistance value as designed. Could not be obtained with high precision.

On the other hand, a chip type thermistor element is usually
Since it is used for temperature detection and temperature compensation, it is strongly desired that the resistance value has very high accuracy.

In view of the above, in view of the large variation in the resistance value of a large number of chip thermistor elements conventionally manufactured,
A complicated operation of measuring the resistance value of a chip-type thermistor element manufactured in large quantities and selecting a resistance value close to a design value has been required. Therefore, there is a problem that the cost is higher by the amount required for the sorting operation than other electronic components.

On the other hand, in the chip type thermistor element 63 shown in FIG. 15, the surface electrodes 65 and 66 can be formed accurately. Further, since the insulating layer 68 is formed so as to cover the opposing regions of the surface electrodes 65 and 66 and the vicinity of the tip, the external electrodes 6 formed by using the dipping method are formed.
Surface electrode 6 formed with higher precision than 7a and 67b
The majority of the resistance value is determined by 5,66. Therefore,
It is possible to temporarily reduce the variation in the resistance value.

However, when the surface electrodes 65 and 66 were formed by screen printing of a conductive paste, graphic distortion was caused by bleeding, and the precision of the resistance value was not so high.

Further, when the surface electrodes 65 and 66 are formed by photolithography, the surface electrodes 6 are formed by over-etching at the time of etching.
In some cases, the shapes of the 5, 66 edges are varied, and the variation in the resistance value is also increased. If the film thickness of the surface electrodes 65 and 66 is reduced, the above-mentioned over-etching can be avoided, but the resistance value of the electrode itself increases, which again causes a variation in the resistance value.

On the other hand, as a method of adjusting the resistance value, there has been conventionally known a method of trimming a part of an electrode using a laser. However, in processing by laser, it was difficult to control the portion to be removed in units of several microns. That is, it was difficult to adjust the resistance value with high accuracy.

An object of the present invention is to reduce the variation in the resistance value, so that the complicated operation of selecting the resistance value after manufacturing can be simplified, and the adjustment of the resistance value can be performed easily and accurately. An object of the present invention is to provide a chip-type resistance element and a method for adjusting a resistance value of the chip-type resistance element.

[0024]

According to a first aspect of the present invention, there is provided a resistance element, comprising: a resistor element; first and second surface electrodes formed on one surface of the resistor element so as to face each other; First and second external electrodes formed at both ends of the element body and electrically connected to the first and second surface electrodes, respectively, wherein the first and second surface electrodes are a plurality of electrodes. The first and second surface electrodes have a stepped structure with at least two steps, and each of the electrode films further has a stepped structure. It has a structure in which a second metal thin film is laminated on one metal thin film, and the first and second metal thin films each have an etchant that dissolves one but not the other with each other. It is characterized by being made of metal.

According to the second aspect of the present invention, except for the portion where the first and second surface electrodes are opposed to each other, the first and second surface electrodes are not limited to each other.
An insulating layer is formed so as to cover the second surface electrode. According to the third aspect of the invention, the first and second external electrodes are extended from both ends of the resistor body to the resistor body surface on which the first and second surface electrodes are formed. And is laminated on the insulating layer on the surface of the resistor body.

In the invention described in claim 4, the resistor element has a rectangular parallelepiped shape having a pair of main surfaces, a pair of side surfaces, and a pair of end surfaces, and the first and second surface electrodes are , Formed on at least one main surface.

[0027] In the invention described in claim 5, the first and second metal thin films are constituted by metal thin films formed by a photolithography method. According to the invention described in claim 6, the resistor element is a thermistor element made of a semiconductor ceramic having positive or negative resistance-temperature characteristics, thereby forming a thermistor element as a resistance element.

According to a seventh aspect of the present invention, there is provided a method for adjusting a resistance value of a resistance element according to the present invention, wherein the first and second surface electrodes are opposed to each other at a portion where the first and second surface electrodes face each other. The resistance value is adjusted by etching a step-like structure of the surface electrode.

In the invention described in claim 8, the etching step for adjusting the resistance value includes etching the second metal thin film using an etchant that dissolves the second metal but does not dissolve the first metal. Next, the etching is performed by etching the first metal thin film using an etchant that dissolves the first metal thin film but does not dissolve the second metal thin film.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip type thermistor according to an embodiment of the present invention will be described with reference to FIGS.

The chip type thermistor element 1 is constituted by using a thermistor element body 2 having a rectangular parallelepiped shape. The thermistor body 2 is made of a semiconductor ceramic having a positive or negative resistance temperature characteristic.

First and second surface electrodes 3 and 4 are formed on the upper surface 2a of the thermistor body 2 so as to face each other. The surface electrodes 3 and 4 include a plurality of electrode films 3a to 3
d, 4a to 4d. In addition, each of the electrode films 3a to 3d and 4a to 4d is a first and a second, respectively.
And a laminated metal film formed by laminating the above metal thin films. That is, as shown in FIG. 3 by enlarging the portion indicated by C upward, the electrode films 4a to 4d
Are the _first and _second metal thin films 4a1, 4a2 to 4a2, respectively.
It is constituted by laminating 4d ₁ and 4d ₂ .
For example, the electrode film 4a is the first on the thin metal film 4a _1, having a structure formed by laminating a second metal film 4a _2. Similarly, the electrode films 3a to 3d of the first and second surface electrodes 3 are also formed by laminating the first and second metal thin films.

Further, as it is clear from FIGS. 1 to 3, a first metal thin film 4a ₁ and the second metal thin film 4a ₂ in the electrode film 4a is the same planar shape. In the remaining electrode films, the first and second metal thin films have the same rectangular shape.

However, the area of the first and second surface electrodes 3 and 4 is reduced from the electrode films 3a and 4a to the upper electrode film, so that the surface electrodes 3 and 4 face each other. In each of the portions where they meet each other, a four-step stair-like structure is formed.

In this embodiment, the surface electrodes 3 and 4 have the above-mentioned step-like structure at all edges except the edges reaching the end faces 2c and 2d of the thermistor body 2. Note that, in this specification, a step-like structure refers to a structure in which an edge is drawn inward as a lower electrode film goes to an upper electrode film.

Accordingly, the opposing distance between the rectangular surface electrodes 3 and 4 is the opposing distance between the lowermost electrode films 3a and 4a. In the present specification, the facing distance between the first and second surface electrodes means the distance between both of the portions where the surface electrode 3 and the surface electrode 4 face each other, as the facing distance d shown in FIG. It refers to the shortest distance.

The first metal forming the first metal thin film and the second metal forming the second metal thin film are different types having an etchant which dissolves each other but does not dissolve the other. Of metal. For example, when a Ni—Cr alloy is used as the first metal and Ag is used as the second metal, the Ni—Cr alloy becomes
Although etching can be performed with an aqueous iron solution, Ag cannot be etched with a ferric chloride aqueous solution. Conversely, A
g can be etched with ferric nitrate aqueous solution, but Ni-C
The r alloy cannot be etched with ferric nitrate aqueous solution.

As described above, the first and second metals constituting the first and second metal thin films are composed of different metals having an etchant that dissolves one but does not dissolve the other.

In the present embodiment, the planar shape of the surface electrodes 3 and 4 is rectangular, but may be various shapes such as a semicircle. Further, each of the surface electrodes 3 and 4 may be composed of a comb-shaped electrode having a plurality of electrode fingers. Can be enlarged.

The insulating layers 5 and 5 cover the surface electrodes 3 and 4 except for the portions where the surface electrodes 3 and 4 face each other.
6 are formed. The insulating layers 5 and 6 can be made of an appropriate insulating resin such as polyimide or epoxy resin. The insulating layers 5 and 6 are formed so as to reach an edge formed by the upper surface 2a and the end surface 2c or the end surface 2d.
In this embodiment, the insulating layer 7 is also formed on the lower surface 2b of the thermistor body 2. The insulating layer 7 can be made of the same material as the insulating layers 5 and 6, and the insulating layer 7 is formed so as to reach an edge formed by the lower surface 2b and the end surface 2c or the end surface 2d.

At both ends of the thermistor body 2, end faces 2c,
First and second external electrodes 8 and 9 are formed so as to cover 2d, respectively. The external electrodes 8 and 9 are connected to the end face 2
It is formed so as to reach not only c and 2d but also the upper and lower surfaces of the thermistor body 2. However, the portions of the external electrodes 8 and 9 reaching the upper surface 2a of the thermistor body 2 are stacked on the upper surfaces of the four insulating layers 5, 6. Similarly, portions of the external electrodes 8, 9 reaching the lower surface 2 b of the thermistor body 2 are laminated on the insulating layer 7.

Therefore, in the chip type thermistor element 1,
The resistance value extracted between the external electrodes 8 and 9 is not affected by the length of the portions of the external electrodes 8 and 9 reaching the upper surface 2a and the lower surface 2b of the thermistor body 2.

In the chip type thermistor element 1 of this embodiment, the surface electrodes 3 and 4 have a structure in which the electrode films 3a to 3d and 4a to 4d formed by stacking the first and second metal thin films are stacked. The first and second metal thin films can be formed with high precision by photolithography.
Therefore, variation in resistance value can be reduced.

Further, in this embodiment, each electrode film is formed of the first,
Each of the surface electrodes 3 and 4 has a structure in which four layers of electrode films are stacked. Therefore, since the electric resistance of the surface electrodes 3 and 4 itself is low, the variation in the resistance value is also reduced.

In addition, since the first and second metal thin films are formed using the first and second metals, the resistance value can be adjusted with high precision by etching. This will be described with reference to FIGS.

After the chip type thermistor element 1 is obtained, if its resistance value is smaller than a desired resistance value,
By etching the portions where the second metal thin films 3 and 4 are opposed to each other, it is possible to increase the facing distance d between the first and second surface electrodes 3 and 4 so as to increase the resistance value. it can.

That is, the insulating layers 5 and 6 are
4 does not cover the portion where the surface electrodes 3 and 4 face each other, so that the portion where the surface electrodes 3 and 4 face each other is exposed.
Therefore, after the chip type thermistor element 1 is obtained, the opposing portions of the surface electrodes 3 and 4 can be easily etched.

Moreover, each electrode film is formed by the first and second electrodes described above.
First, the second metal thin film is etched using an etchant that does not dissolve the first metal thin film but dissolves the second metal thin film. Next, the first metal thin film is etched using an etchant that does not dissolve the second metal thin film but dissolves the first metal thin film. As a result, as shown in FIG. 4, the opposing portions of the surface electrodes 3 and 4 are etched, and the opposing distance between the first and second surface electrodes 3 and 4 is increased. That is, opposing distance d ₁ in FIG. 4 is larger than the opposing distance d shown in FIG. Further, when it is desired to further increase the resistance value, the etching method described above is repeated once again to increase the etching amount so as to increase the facing distance d ₂ as shown in FIG. Good.

In order to remove a part of the surface electrodes 3 and 4 with high accuracy when etching the surface electrodes 3 and 4,
It is necessary that the thickness of the electrode film is thin. That is, when the thickness of the electrode film is large, over-etching tends to occur and trimming cannot be performed with high accuracy. However, in this embodiment, the facing distance between the surface electrodes 3 and 4 is determined by the distance between the lowermost electrode films 3a and 4a. On the other hand, the lowermost electrodes 3a and 4a are thinner than the entire thickness of the surface electrodes 3 and 4. Therefore, the electrode films 3a and 4a can be etched with high precision.

Further, as described above, the electrode films 3a, 4a
Each has a structure in which the first and second metal thin films are stacked, and the first and second metal thin films may be etched in two stages as described above, so that the trimming is performed with even higher precision. can do.

Therefore, in the chip type thermistor element 1 of this embodiment, the resistance value can be adjusted with high accuracy by etching. Therefore, according to the present embodiment, it is possible to provide the chip-type thermistor element 1 capable of adjusting the resistance value with high accuracy, in addition to the small variation in the resistance value.

Next, a method of manufacturing the chip type thermistor element 1 will be described based on specific experimental examples. Mn compound, N
The i compound and the Co compound were kneaded with a binder to obtain a slurry. Using this slurry, 65mm x 65m
A green sheet having a planar shape of m was obtained.

Next, as shown in FIG. 6A, a plurality of the green sheets 11 are stacked, pressed in the thickness direction, and baked at 1300 ° C. to obtain a thermistor wafer 12 (FIG. 6A). FIG. 6 (b)).

Next, a Ni—Cr alloy and Ag are sequentially formed on the entire surface of the thermistor wafer 12 by sputtering to form a film having a thickness of 0.1 μm on the upper surface of the thermistor wafer 12.
A 1 μm Ni—Cr thin film and a 0.1 μm thick Ag thin film were laminated to form a mother electrode film 13.

Thereafter, a photoresist layer 14 having a thickness of 1.5 μm was formed on the mother electrode film 13 by spin coating (FIG. 6D). Next, a mask 15 was brought into contact with the photoresist layer 14, exposed, and developed with a solvent (FIG. 6E). Thus, a patterned photoresist layer 14A was formed (FIG. 7A).
Thereafter, etching is performed for 30 seconds using an aqueous ferric nitrate solution (pH = 2), the Ag thin film on the upper layer of the electrode film 13 is etched, and etching is performed using an aqueous ferric chloride solution (pH = 2). Etching for 2 seconds, Ni in the mother electrode film 13
-The Cr thin film was etched. Thus, the first-stage patterned electrode film 13A was formed (FIG. 7).
(B)). Next, the remaining photoresist layer was removed with a solvent (FIG. 7C). The adjacent electrode films 13A,
The distance between 13A was 100 μm.

Next, in order to form a second-stage electrode film,
In the same manner as the formation of the electrode film 13, a Ni-Cr alloy thin film and an Ag thin film are sequentially formed by sputtering,
The electrode film 16 was laminated (FIG. 7D).

After that, a thickness of 1.5
μm of the photoresist layer 17
(FIG. 7E). After a while, FIG.
As shown in (a), the mask 18 was brought into contact and exposed.
Note that a mask having an opening corresponding to a portion where the electrode film 16 is to be left was used as the mask 18. That is, in order to form a step-like structure, a mask 18 having a smaller opening area than the mask 15 was used.

In this case, the outer peripheral edge of the electrode film 13A is
The opening area of the mask 18 was adjusted so that the outer peripheral edge of the electrode film obtained after patterning the electrode film 16 was inside 20 μm.

Next, development was performed in the same manner as when the electrode film 13 was patterned, and the photoresist layer 17 was patterned to form a photoresist layer 17A (FIG. 8).
(B)). Thereafter, in the same manner as when the electrode film 13 is etched, the etched and patterned second
The electrode film 16A was formed (FIG. 8C). Further, the photoresist layer 17A was removed using a solvent (FIG. 8).
(D)).

The third-stage and fourth-stage electrode films were formed in substantially the same manner as the process of forming the first-stage and second-stage patterned electrode films 13A and 16A. However, 3
When forming the electrode films of the fourth and fourth stages, 3
A mask was used in which the outer peripheral edge of the second-stage electrode film was positioned 20 μm inside the outer peripheral edge of the second-stage electrode film 16A. Further, when forming the fourth-stage electrode film,
A mask was used that was formed so that the outer peripheral edge of the fourth-stage electrode film was located 20 μm inside the outer peripheral edge of the third electrode film.

As described above, a structure in which the electrode films 13A, 16A, 19A and 20A are stacked as shown in FIG. 8E was obtained. Next, as shown in FIG. 9A, a photosensitive polyimide film 21 having a thickness of 3 μm was formed on the entire upper surface of the thermistor wafer 12.

Thereafter, as shown in FIG. 9B, the polyimide film 21 was patterned by exposing and developing using a mask 22. As shown in FIG. 9C, the patterned polyimide film 21A is shaped such that its edge is located 50 μm inward from the opposing edge of the fourth-stage electrode film 20A. Te

Thereafter, as shown in FIG. 9D, a polyimide film 23 was formed on the entire lower surface of the thermistor wafer 12 as well. The thermistor wafer 12 thus obtained was cut along the dashed-dotted lines E, E in FIG. 9D to obtain a 1.6 mm wide strip-shaped wafer divided body. This divided wafer is shown in FIG. In FIG. 10, the length direction L of the wafer divided body 12A corresponds to the paper surface-paper back direction in FIG. 9D.

Thereafter, a Ni—Cr alloy film is formed on both sides of the divided wafer body 12A by sputtering.
A Ni film and a Sn film were sequentially formed on the Ni-Cr alloy film by wet electrolytic plating. Thus, the mother external electrodes 24 and 25 shown in FIG. 11 were formed.

Thereafter, the wafer divided body 12A was further cut to a width of 0.8 mm as shown by a dashed line F, F in FIG. 11 to obtain chips for each chip-type thermistor element. The resistance values of a large number of chip-type thermistor elements 1 obtained as described above were measured and classified into another group. Of course, the grouping may be divided into five or more groups or three or less groups according to the measured thermistor elements. In this case, a group, a group, a group, and a group are set in order from the largest resistance value range.

Then, the thermistor elements of the group having a lower resistance value than the group were etched for 30 seconds using an aqueous ferric nitrate solution (pH = 2), and the electrode films 3a to 4d of the surface electrodes 3 and 4 were etched. The upper Ag thin film in the inside was etched, and subsequently, an aqueous solution of ferric hydrochloride (pH =
Etching for 30 seconds using 2), the respective electrode films 3a to 4
The lower Ni-Cr thin film in d was etched. By this etching, the facing distance between the surface electrodes 3 and 4 was increased, and the resistance value could be increased.

After the etching, the resistance value of the thermistor element was measured again, and the resistance value of the thermistor element lower than the resistance value of the group was increased by repeating the above etching.

As described above, by repeating etching without forming a mask or a photoresist layer,
The resistance value of the obtained thermistor element 1 can be increased stepwise, and a thermistor element having a desired resistance value can be obtained. After the resistance value was adjusted by etching as described above, the variation 3CV in the resistance value of the chip type thermistor element (the number of tests was 1,000) was 0.4%.

For comparison, the conventional thermistor elements 51, 54, 58, and 58 are similar to the thermistor element of the above embodiment except that the electrode structure is different.
63 were manufactured, and the resistance value variation 3 CV (the number of tests was 1000) was measured. The results are shown in Table 1 below.

The thermistor element 63 has a resistance value variation of 3 CV after trimming by laser.
Are also shown.

[0071]

[Table 1]

As is clear from Table 1, in the chip type thermistor element 1 of this embodiment, the resistance value variation 3CV can be significantly reduced by trimming by etching as compared with the conventional example.

In the above embodiment, the resistance element is
Although the thermistor element is shown, the present invention can be applied to other resistance elements such as a fixed resistance element and a varistor.

[0074]

In the resistance element according to the first aspect of the present invention, the first and second surface electrodes are opposed to each other on one surface of the resistor element, and each of the first and second surface electrodes has a plurality of surfaces. And the opposing portions have a step-like structure of at least two steps. Each of the electrode films has a structure in which a second metal thin film is laminated on a first metal thin film. Therefore, when the first and second surface electrodes are formed, an electrode film formed by stacking the first and second metal thin films may be stacked in a plurality of stages. The surface electrode can be formed with high precision.

Further, the thickness of the entire first and second surface electrodes can be made sufficient by adjusting the number of laminated electrode films, thereby reducing the electric resistance of the surface electrodes themselves. Can be.

Therefore, the first and second surface electrodes can be formed with high precision and the electric resistance of the surface electrodes themselves can be reduced, so that the variation in the resistance value can be effectively reduced. .

Further, the first and second metal thin films have a stepped structure in which the opposing portions have at least two steps, and each of the first and second metal thin films has an etchant that dissolves one of the other but does not dissolve the other. And the first and second metals. On the other hand, the facing distance between the first and second surface electrodes is determined by the facing distance between the lowermost electrode films.
Therefore, the second metal thin film is etched using an etchant that dissolves the second metal thin film but does not dissolve the first metal thin film, and then dissolves the first metal thin film but removes the second metal thin film. By re-etching using an etchant that does not dissolve, the facing distance of the lowermost electrode film can be easily increased. In this case, since the first and second metal thin films constituting the lowermost electrode film can be formed extremely thin, the facing distance between the first and second surface electrodes can be precisely determined by the etching. Can be trimmed,
Thereby, the resistance value can be adjusted with high precision.
Also, according to the number of steps of the first and second metal thin films,
Etching can be performed without using a new mask, and the resistance value can be adjusted stepwise.

According to the second aspect of the invention, the first and second surface electrodes are removed except for the portion where the first and second surface electrodes face each other.
An insulating layer is formed so as to cover the surface electrode.
Also in this case, since the portion where the first and second surface electrodes face each other is not covered with the insulating layer and is exposed, the resistance value can be easily adjusted by the etching. .

According to the third aspect of the present invention, the first and second external electrodes extend from both ends of the resistor body to the resistor body surface on which the first and second surface electrodes are formed. However, the first and second external electrodes are stacked on the insulating layer on the surface of the resistor element. Accordingly, the resistance value is hardly affected by the fogging depth of the first and second external electrodes, that is, the length of the portion extending from both ends of the resistor body to the surface of the resistor body. Therefore, variation in the resistance value can be reduced more effectively.

According to the fourth aspect of the present invention, the resistance element is:
Since it has a rectangular parallelepiped shape and the first and second surface electrodes are formed on at least one main surface, the first and second surface electrodes can be easily formed on the main surface having a relatively large area. Can be formed.

According to the fifth aspect of the present invention, since the first and second metal thin films are constituted by metal thin films formed by photolithography, the first and second metal thin films can be formed with high precision. Can be formed, whereby variation in resistance value can be reduced.

According to the sixth aspect of the present invention, since the thermistor element made of a semiconductor ceramic having positive or negative resistance-temperature characteristics is used as the resistor element, the resistance value is less varied and the resistance value can be adjusted. An easy thermistor element can be provided. In particular, in a thermistor element using semiconductor ceramics, it is difficult to reduce the variation in the resistance value, and in the thermistor element, it is strongly required to control the resistance value with high accuracy. According to this, it becomes possible to stably and easily provide a thermistor element satisfying such a requirement. Therefore, it is possible to omit or simplify the conventional complicated resistance value selection work.

According to the seventh aspect of the present invention, the first and second surface electrodes are etched at portions where the first and second surface electrodes face each other. Thereby, the first and second surface electrodes can be trimmed with high precision. Therefore, the resistance value of the resistance element can be easily and accurately adjusted in the direction in which the resistance value increases.

In the invention according to claim 8, the second metal thin film is etched using an etchant that dissolves the second metal but does not dissolve the first metal, and then dissolves the first metal thin film. However, the resistance value is adjusted by etching the first metal thin film using an etchant that does not dissolve the second metal thin film. In this case, since the first and second metal thin films are extremely thin compared to the thickness of the entire surface electrode, the first and second metal thin films can be trimmed with high precision and easily by the above-described etching. . Therefore, the resistance value of the resistance element can be easily and accurately adjusted.

[Brief description of the drawings]

FIG. 1 is a plan view showing a thermistor element according to one embodiment of the present invention.

FIG. 2 is a side view of the thermistor element of the embodiment shown in FIG.

FIG. 3 is a side sectional view of the thermistor element of the embodiment shown in FIG.

FIG. 4 is a side sectional view showing a result of adjusting a resistance value in the thermistor element according to the embodiment.

FIG. 5 is a side sectional view showing a state after adjusting a resistance value in the thermistor element of the embodiment shown in FIG. 1;

FIGS. 6A to 6E are side views for explaining respective steps of a method for manufacturing a chip-type thermistor element according to an embodiment. Note that the mask is a cross-sectional view.

FIGS. 7A to 7E are side views illustrating each step of a method for manufacturing a chip-type thermistor element according to an embodiment.

FIGS. 8A to 8E are side views for explaining each step of a method for manufacturing a chip-type thermistor element according to an embodiment. Note that the mask is a cross-sectional view.

FIGS. 9A to 9D are side views illustrating each step of a method for manufacturing a chip-type thermistor element according to an embodiment. Note that the mask is a cross-sectional view.

FIG. 10 is a partially cutaway plan view showing a divided wafer obtained by the method for manufacturing a thermistor element according to the embodiment.

FIG. 11 is a partially cutaway sectional view showing a state where mother external electrodes are formed so as to cover both side surfaces of the wafer divided body shown in FIG. 10;

FIG. 12 is a sectional view showing an example of a conventional chip thermistor element.

FIG. 13 is a sectional view showing another example of a conventional chip thermistor element.

FIG. 14 is a sectional view showing still another example of a conventional chip-type thermistor element.

15A and 15B are a plan view and a side sectional view showing another example of a conventional chip-type thermistor element.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chip type thermistor element 2 ... Thermistor body 2a ... Upper surface 2b ... Lower surface 2c, 2d ... First and second end surfaces 3, 4 ... First and second surface electrodes 3a-3d, 4a-4d ... Electrode film 4a ₁ , 4b ₁ , 4c ₁ , 4d ₁ .. 1st metal thin film 4a ₂ , 4b ₂ , 4c ₂ , 4d ₂ .. 2nd metal thin film 5, 6 ... insulating layer 7 ... insulating layer 8, 9 ... first , Second external electrode 12 ... thermistor wafer 13 ... mother electrode film 13A ... patterned electrode film 16 ... electrode film 16A, 19A, 20A ... electrode film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E028 AA10 BA23 BB09 BB10 CA02 DA04 EA23 JC02 JC05 JC11 JC12 5E032 BA23 BB09 BB10 CA02 CC14 CC16 TA03 TB20 5E034 AA09 AB01 BA09 BB01 DB12 DC01 DC03 DC09 DC10 DE14

Claims (8)

[Claims] A resistor element; first and second surface electrodes formed on one surface of the resistor element so as to face each other; and first and second electrodes formed at both ends of the resistor element. First and second external electrodes respectively electrically connected to the second surface electrode, the first and second surface electrodes having a structure in which a plurality of electrode films are stacked, and Opposing portions of the second surface electrode have at least two steps of a step-like structure, and each of the electrode films has a second metal thin film laminated on the first metal thin film. A resistive element having a structure, wherein each of the first and second metal thin films is formed of first and second metals having an etchant that dissolves one of the other but does not dissolve the other. . 2. The semiconductor device according to claim 1, further comprising an insulating layer formed so as to cover the first and second surface electrodes except for a portion where the first and second surface electrodes face each other. 3. The resistance element according to 1. 3. The first and second external electrodes extend from both ends of the resistive element to a resistive element surface on which first and second surface electrodes are formed. 3. The resistive element according to claim 2, wherein said resistive element is laminated on said insulating layer.
3. The resistance element according to 1. 4. The resistance element has a rectangular parallelepiped shape having a pair of main surfaces, a pair of side surfaces, and a pair of end surfaces, and the first and second surface electrodes are formed on at least one main surface. The resistance element according to claim 1, wherein the resistance element is formed. 5. The resistance element according to claim 1, wherein said first and second metal thin films are metal thin films formed by a photolithography method. 6. The resistance element according to claim 1, wherein the resistance element is a thermistor element made of a semiconductor ceramic having a positive or negative resistance-temperature characteristic. 7. The method for adjusting the resistance value of a resistance element according to claim 1, wherein the first and second surface electrodes face each other in a portion where the first and second surface electrodes face each other. The resistance value of the resistance element is adjusted by etching the surface electrode. 8. In etching for adjusting the resistance value, the second metal thin film is etched using an etchant that dissolves the second metal but does not dissolve the first metal, and then etches the first metal thin film. 8. The method for adjusting a resistance value of a resistance element according to claim 7, wherein the first metal thin film is etched using an etchant that dissolves but does not dissolve the second metal thin film.