JP2001044022A - Thermistor element and thermistor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermisotr element and a thermisotr using it, which comprises such electrode structure as a current capacity is large, while being strong in contacting a spring terminal for preventing migration, when energized. SOLUTION: A plate-like thermistor element assembly, an Ag electrode 13a so formed as to almost cover the both main surfaces of it, an Ag-Pd center electrode 13b formed at the central part on both main surfaces of the thermistor element assembly 12 over the Ag electrode, and an Ag-Pd outer perimeter electrode 23b formed in annular form striding over the outer edge of the Ag electrode, are provided to a thermistor element 11. The thermistor element 11 is clamped with a pair of spring terminals connected electrically to the Ag-Pd center electrode 13b, while being attached internally in an insulating case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor element, and more particularly to a thermistor element sandwiched between spring terminals and a case-type thermistor using the same.

[0002]

2. Description of the Related Art A thermistor element, here, a negative characteristic thermistor element will be described.

The negative characteristic thermistor element is incorporated in a power supply circuit of an electronic device by utilizing a function that the resistance value decreases as the temperature rises as compared with the resistance value at normal temperature, and a power switch of the electronic device is used. It is used as a circuit element that suppresses an inrush current flowing in a power supply circuit at the moment of being turned on.

FIG. 7 is a plan view showing a general structure of the negative temperature coefficient thermistor element 1. As shown in FIG. Negative characteristic thermistor element 1
Is composed of a disk-shaped negative characteristic thermistor element body 2 and circular electrodes 3 and 3 formed on opposing main surfaces of the negative characteristic thermistor element body 2.

FIG. 8 is a sectional view showing a general structure of a case type negative characteristic thermistor 4 for suppressing an inrush current.
The negative characteristic thermistor 4 has spring terminals 5, 5 electrically connected to the electrodes 3, 3 on both main surfaces of the disk-shaped negative characteristic thermistor element 1, and further has the negative characteristic thermistor element 1 and the spring terminals 5, 5. Are housed in a heat-resistant insulating case 6. The negative characteristic thermistor element 1 is elastically clamped at one end side of the spring terminals 5 and 5 in the internal space of the case 6, and the other ends of the spring terminals 5 and 5 pass through the case 6 and are led out to the outside. I have.

[0006]

The electrodes 3, 3 of the above-mentioned negative characteristic thermistor element 1 are coated with Ag or Ag-Pd paste so as to cover almost both of the main surfaces of the negative characteristic thermistor element 2, and then fired. It is formed by attaching.

The electrodes 3 and 3 made of Ag have a low specific resistance and can realize a large current capacity. However, it is easy to be scraped off by friction with the spring terminals 5 and 5, and a spark may be generated between the electrodes 3 and 3 and the spring terminals 5 and 5 when an inrush current is applied. In addition, migration between the electrodes is likely to occur, that is, when electricity is supplied, Ag of the electrodes 3, 3 on one main surface is increased.
May move toward the electrodes 3 on the other main surface, and a short circuit may occur on the side surface of the negative temperature coefficient thermistor body 2.

The electrodes 3, 3 made of an Ag—Pd alloy are
g, and is less likely to be scraped off by friction with the spring terminals 5,5. However, the specific resistance is high, and the sheet resistance of the electrodes 3 becomes large. Then, sparks may be generated between the electrodes 3 and 3 and the spring terminals 5 and 5 when the inrush current is applied. In addition, since it is more expensive than Ag, there is a problem that the cost is increased.

An object of the present invention is to provide a thermistor element and a thermistor using the same, which have a large current capacity, are resistant to contact with a spring terminal, and have an electrode structure for preventing migration during energization. .

[0010]

The thermistor element according to the first invention comprises a plate-like thermistor element, an Ag electrode formed so as to substantially cover both main surfaces of the thermistor element, And a Ag-Pd center electrode formed at the center of both main surfaces of the thermistor body.

The thermistor element according to the second aspect of the present invention includes a plate-shaped thermistor element, an Ag electrode formed so as to substantially cover both main surfaces of the thermistor element,
An Ag-Pd outer peripheral electrode formed annularly over the outer peripheral edge of the electrode.

The thermistor element according to the third aspect of the present invention includes a plate-like thermistor element, an Ag electrode formed so as to substantially cover both main surfaces of the thermistor element,
An Ag-Pd center electrode formed at the center of both main surfaces of the thermistor body on the electrode, and an Ag-Pd outer electrode formed annularly over the outer edge of the Ag electrode. Features.

The thermistor according to the fourth invention is a thermistor according to the first or third invention, and a pair of springs electrically connected to Ag-Pd center electrodes formed on both main surfaces of the thermistor. A terminal and an insulating case that houses the thermistor element are provided.

The thermistor according to a fifth aspect of the present invention includes the thermistor element according to the second aspect of the invention, and a pair of spring terminals electrically connected to Ag electrodes formed on both main surfaces of the thermistor element, respectively. An insulating case that houses the thermistor element.

Thus, it is possible to prevent electrode damage and migration between electrodes due to friction with the spring terminal without deteriorating current capacity characteristics.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

[0017]

Embodiment 1 A thermistor element according to one embodiment of the present invention is shown in FIG.
1 will be described. The negative-characteristic thermistor element 11 includes a disk-shaped negative-characteristic thermistor element 12 and Ag electrodes 13 a, 13 a formed on both main surfaces of the negative-characteristic thermistor element 12.
And Ag-Pd center electrodes 13b, 13b.

The negative characteristic thermistor body 12 is composed of Mn, N
It can be obtained by forming a disc-shaped molded body using a thermistor material mainly containing an oxide such as i, Co, Cu, Fe or the like, and firing it. The negative characteristic thermistor body 12 was a disk having a diameter of 7 mm and a thickness of 1.5 mm.

Ag electrodes 13a, 13a and Ag-Pd
The center electrodes 13b, 13b are connected to the negative characteristic thermistor element 12
Can be obtained by applying and baking an Ag paste and an Ag-Pd paste on both main surfaces.

The Ag electrodes 13a, 13a are formed in a circular shape having a diameter of 5 mm so as to substantially cover both main surfaces of the negative characteristic thermistor body 12.

The Ag-Pd center electrodes 13b, 13b are provided on both main surfaces of the negative characteristic thermistor body 12 with Ag electrodes 13a, 13b.
13a, a circular shape having a diameter of 2 mm is formed. That is, the Ag-Pd center electrode 13b is connected to the Ag electrode 13a.
Is formed in the center of the main surface of the negative characteristic thermistor element 11 on which the negative characteristic thermistor element body 12 and the Ag electrode 13a are concentrically arranged, and 1.5 mm in the vicinity of the outer peripheral edge of the Ag electrode 13a.
It is formed leaving a width gap.

The electrode is formed by applying an Ag paste,
After firing, the Ag-Pd paste may be applied and fired, or both electrodes may be fired simultaneously.

FIG. 2 shows a case-type negative characteristic thermistor using the negative characteristic thermistor element 12.
This will be described with reference to FIG. Negative characteristic thermistor 1 shown in FIG.
Reference numeral 4 denotes a structure in which both main surfaces of the negative characteristic thermistor element 11 are elastically sandwiched between spring terminals 15 and 15, and the negative characteristic thermistor element 11 is further housed in an insulating case 16.

The spring terminals 15, 15 are made of, for example, SUS, phosphor bronze, Cu-Ti alloy or the like, and are coated with a surface coating such as Ag or solder plating. Ag-Pd center electrodes 13b, 13b.

The insulating case 16 is made of, for example, PPS, phenol, PBT, or the like.
, The negative characteristic thermistor element 11 is protected from the external environment and the insulation property is maintained.

The negative-characteristic thermistor element 11 and the negative-characteristic thermistor 14 are formed with the Ag electrodes 13a, 13a so as to substantially cover both main surfaces of the negative-characteristic thermistor body 12, so that the sheet resistance is small and the current capacity is small. Is big. Further, when the spring terminals 15, 15 are elastically sandwiched, the spring terminals 15, 15 come into contact with Ag-Pd center electrodes 13 b, 13 b formed at the center of both main surfaces of the negative characteristic thermistor element 11. , 15 are less likely to be damaged by friction with the electrodes.

[0027]

Embodiment 2 A thermistor element according to another embodiment of the present invention is shown in FIG.
Will be described with reference to FIG. However, the same components as those described above are denoted by the same reference numerals, and detailed description is omitted. The negative characteristic thermistor element 21 is a disk-shaped negative characteristic thermistor element 12.
Formed on both main surfaces of the negative characteristic thermistor body 12
g electrodes 13a, 13a and Ag-Pd outer peripheral electrode 23
b and 23b.

The negative characteristic thermistor body 12 has a diameter of 7 m.
m, a disk shape with a thickness of 1.5 mm, and an Ag electrode 13a,
13a is formed in a circular shape with a diameter of 5 mm on both main surfaces of the negative characteristic thermistor body 12.

The Ag-Pd outer peripheral electrodes 23b, 23b
g is an annular shape having an inner diameter of 4 mm and an outer diameter of 5.5 mm, that is, a width of 0.75 mm, which extends over the outer periphery of the electrodes 13a, 13a;
On both main surfaces of the negative characteristic thermistor element 12, the negative characteristic thermistor element 12 and the Ag electrodes 13a, 13a are formed concentrically.

Further, a case type negative characteristic thermistor 24 using this negative characteristic thermistor element 21 will be described.
This will be described with reference to FIG. However, the same components as those described above are denoted by the same reference numerals, and detailed description is omitted. The negative characteristic thermistor 24 shown in FIG. 4 is one in which both main surfaces of the negative characteristic thermistor element 21 are elastically sandwiched between spring terminals 15, and the negative characteristic thermistor element 21 is further housed in an insulating case 16. .

The spring terminals 15, 15 are electrically connected to Ag electrodes 13a, 13a formed so as to substantially cover both main surfaces of the negative characteristic thermistor element 21.

Since the negative electrode thermistor element 21 and the negative characteristic thermistor 24 are formed with the Ag electrodes 13a, 13a so as to substantially cover both main surfaces of the negative characteristic thermistor element 21, the sheet resistance is small and the current capacity is small. large. Further, the ring-shaped A electrode extends over the outer peripheral edges of the Ag electrodes 13a, 13a.
Since the g-Pd outer peripheral electrodes 23b, 23b are formed, migration due to Ag during energization can be prevented.

[0033]

Embodiment 3 A thermistor element according to another embodiment of the present invention will be described with reference to a negative characteristic thermistor element 31 shown in FIG. However, the same components as those described above are denoted by the same reference numerals, and detailed description is omitted. The negative characteristic thermistor element 31 includes a disk-shaped negative characteristic thermistor element 12 and Ag electrodes 13 a, 13 a and Ag-Pd center electrode 1 formed on both main surfaces of the negative characteristic thermistor element 12.
3b, 13b and Ag-Pd outer peripheral electrodes 23b, 23b.

The negative characteristic thermistor body 12 has a diameter of 7 m.
m, a disk shape with a thickness of 1.5 mm, and an Ag electrode 13a,
13a is formed in a circular shape with a diameter of 5 mm on both main surfaces of the negative characteristic thermistor body 12.

The Ag-Pd center electrodes 13b, 13b are provided on both main surfaces of the negative temperature coefficient thermistor body 12, respectively.
13a, a circular shape having a diameter of 2 mm is formed. That is, the Ag-Pd center electrode 13b is connected to the Ag electrode 13a.
Is formed in the center of the main surface of the negative characteristic thermistor element 11 on which the negative characteristic thermistor element body 12 and the Ag electrode 13a are concentrically arranged, and 1.5 mm in the vicinity of the outer peripheral edge of the Ag electrode 13a.
It is formed leaving a width gap.

The Ag-Pd outer peripheral electrodes 23b, 23b
g is an annular shape having an inner diameter of 4 mm and an outer diameter of 5.5 mm, that is, a width of 0.75 mm, which extends over the outer periphery of the electrodes 13a, 13a;
On both main surfaces of the negative characteristic thermistor element 12, the negative characteristic thermistor element 12 and the Ag electrodes 13a, 13a are formed concentrically.

Further, a case type negative characteristic thermistor 34 using the negative characteristic thermistor element 31 will be described.
This will be described with reference to FIG. However, the same components as those described above are denoted by the same reference numerals, and detailed description is omitted. The negative characteristic thermistor 34 shown in FIG. 6 is one in which both main surfaces of the negative characteristic thermistor element 31 are elastically held between the spring terminals 15, 15, and the negative characteristic thermistor element 31 is housed in the insulating case 16. .

The spring terminals 15, 15 are electrically connected to Ag-Pd center electrodes 13b, 13b formed at the center of both main surfaces of the negative characteristic thermistor element 31.

Since the negative electrode thermistor element 31 and the negative characteristic thermistor 34 are formed with the Ag electrodes 13a, 13a so as to substantially cover both main surfaces of the negative characteristic thermistor element 31, the sheet resistance is small and the current capacity is small. large. Further, an annular A is formed over the outer peripheral edge of the Ag electrodes 13a, 13a.
Since the g-Pd outer peripheral electrodes 23b, 23b are formed, migration due to Ag during energization can be prevented. Furthermore, the Ag-Pd formed at the center of both main surfaces of the negative characteristic thermistor element 11 has spring terminals 15 and 15.
Since the contact is made with the center electrodes 13b, 13b, the spring terminals 1
Electrode damage due to friction with 5 and 15 is unlikely to occur.

In each of the above embodiments, the negative characteristic thermistor for suppressing the inrush current has been described as an example. However, the present invention is not limited to this, and is applied to a positive characteristic thermistor for a large current, and the like. be able to.

[0041]

As described above, in the thermistor element according to the present invention, since the Ag electrode having a low specific resistance is formed so as to substantially cover both main surfaces of the thermistor element, a large current capacity is realized. it can.

Further, since the Ag-Pd center electrode is formed at the center of the main surface of the thermistor element corresponding to the contact portion of the spring terminal, the electrode is hardly damaged by friction even when sandwiched by the spring terminal.

Furthermore, since the annular Ag-Pd outer peripheral electrode is formed over the outer peripheral edge of the Ag electrode, migration due to Ag can be prevented.

From the above, the current capacity characteristics are good,
In addition, a thermistor element and a thermistor that are resistant to contact with the spring terminal and have an electrode structure that prevents migration during energization and have excellent breakdown resistance when a large current is applied can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a negative temperature coefficient thermistor according to one embodiment of the present invention.

FIG. 3 is a plan view showing a negative temperature coefficient thermistor element according to another embodiment of the present invention.

FIG. 4 is a sectional view of a negative temperature coefficient thermistor according to another embodiment of the present invention.

FIG. 5 is a plan view showing a negative characteristic thermistor element according to another embodiment of the present invention.

FIG. 6 is a sectional view of a negative temperature coefficient thermistor according to another embodiment of the present invention.

FIG. 7 is a plan view of a conventional negative characteristic thermistor element.

FIG. 8 is a sectional view of a conventional negative characteristic thermistor.

[Explanation of symbols]

 11, 21, 31 Negative characteristic thermistor element 12 Negative characteristic thermistor element 13a Ag electrode 13b Ag-Pd center electrode 23b Ag-Pd outer peripheral electrode 14, 24, 34 Negative characteristic thermistor 15 Spring terminal 16 Insulation case

Claims (5)

[Claims] 1. A plate-like thermistor body, an Ag electrode formed to cover substantially both main surfaces of the thermistor body, and a central part of both the main surfaces of the thermistor body on the Ag electrode. And a formed Ag-Pd center electrode. 2. A plate-shaped thermistor body, an Ag electrode formed to cover substantially both main surfaces of the thermistor body, and an A-shaped ring formed over an outer peripheral edge of the Ag electrode.
and a g-Pd outer peripheral electrode. 3. A plate-shaped thermistor element, an Ag electrode formed to cover substantially both main surfaces of the thermistor element, and a central part of both the main surfaces of the thermistor element on the Ag electrode. A thermistor element comprising: a formed Ag-Pd center electrode; and an Ag-Pd outer peripheral electrode formed annularly over the outer peripheral edge of the Ag electrode. 4. The thermistor element according to claim 1 or 3, a pair of spring terminals electrically connected to Ag-Pd center electrodes formed on both main surfaces of the thermistor element, and the thermistor. A thermistor, comprising: an insulating case for housing the element. 5. The thermistor element according to claim 2, a pair of spring terminals electrically connected to respective Ag electrodes formed on both main surfaces of the thermistor element, and an insulation for housing the thermistor element. A thermistor, comprising: a case;