JPH0121524Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current control element using barium titanate semiconductor ceramic having a positive temperature coefficient of resistance.

This type of current control element has a current control function that throttles the current by rapidly increasing its electrical resistance when the temperature reaches a certain temperature, but it is often used in various electronic devices and automobile equipment, etc. There is
When used in a DC circuit such as a 12V power supply or a 24V power supply, the positive characteristic ceramic substrate may be formed into a thin plate with a thickness of 1 mm or less in order to obtain the necessary current control characteristics.

However, the general structure of a conventional current control element, as shown in FIG. The electrodes 2 and 3 are deposited and formed.
It had a structure in which lead wires 4 and 5 were simply soldered to the top. For this reason, if the thickness t of the positive characteristic porcelain substrate 1 becomes extremely thin, 1 mm or less, the mechanical strength of the positive characteristic porcelain substrate 1 will be insufficient, and it will easily break or crack, making it difficult to handle it as a product. difficult,
It had the drawback of lack of reliability. Furthermore, there was also a drawback that the lead wires 4 and 5 were easily damaged by applying only a slight tensile force.

Furthermore, since both sides of the positive characteristic ceramic substrate 1 in the thickness direction serve as heat dissipation surfaces, it takes time to reach thermal equilibrium and exert the current control function, resulting in a problem of lack of quick response.

The present invention eliminates the above-mentioned conventional drawbacks, and ensures sufficient mechanical strength even if the positive characteristic porcelain substrate is extremely thin with a thickness of, for example, 1 mm or less, and prevents breakage.
It is an object of the present invention to provide a highly reliable current control element that can prevent cracking and is highly responsive.

In order to achieve the above object, the current control element according to the present invention is characterized in that a ceramic layer is integrally provided on at least one of both surfaces of a positive characteristic ceramic substrate in the thickness direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically described below with reference to the accompanying drawings, which are examples. FIG. 2 is a front sectional view of the current control element according to the present invention. In this example,
Electrodes 2 and 3 are formed on both sides in the thickness direction of a flat positive characteristic ceramic substrate 1, lead wires 4 and 5 are soldered and fixed to the electrodes 2 and 3, respectively, and at least one of the electrodes 2 and 3 is formed. For example, it has a structure in which a ceramic layer 6 is integrally bonded onto a surface of the electrode 2 using an adhesive 7. The ceramic layer 6 may be provided on both sides of the ceramic substrate 1.

As described above, in the structure in which the ceramic layer 6 is integrally provided on the surface of the ceramic substrate 1, the thickness t of the ceramic substrate 1 is
Even when the ceramic substrate 1 is made extremely thin, for example, 1 mm or less, the lack of mechanical strength of the ceramic substrate 1 can be compensated for by the ceramic layer 6, and damage and cracking can be prevented. Therefore, it is possible to provide a current control element that is easy to handle and has high reliability.

Moreover, by adopting a structure in which the ceramic layer 6 is integrally provided on the surface of the ceramic substrate 1, heat radiation from the side where the ceramic layer 6 is located is suppressed, and the time required to reach thermal equilibrium is shortened. Therefore, a current control element with excellent quick response can be provided.

Furthermore, since the coefficients of thermal expansion of the ceramic substrate 1 and the ceramic layer 6 are close to each other, stress due to heat generated during current control operation is reduced, and the current control element is less prone to cracking, damage, or peeling due to heat. can get.

Moreover, by adopting a structure in which the ceramic layer 6 is integrally provided on the surface of the ceramic substrate 1, it is possible to directly attach the ceramic layer 6 as the mounting side without using an insulator, and it can be used for various electronic devices and automobiles. Easy to integrate into on-board equipment.

3 and 4 show still another embodiment of the current control element according to the present invention. In these embodiments, a pair of divided electrodes 8 and 9 are provided on one surface of the ceramic substrate 1, separated from each other by a gap _g1 ,
While the lead wires 4 and 5 are soldered and fixed to the divided electrodes 8 and 9, a common electrode 10 that commonly faces the divided electrodes 8 and 9 is formed on the other surface, and on this common electrode 9. It has a structure in which the porcelain layer 6 is integrally bonded using an adhesive 7. In the case of these embodiments as well, the same effects as explained in FIG. 2 can be obtained.

As described above, the current control element according to the present invention is characterized in that a ceramic layer is integrally provided on at least one surface of both sides in the thickness direction of a positive characteristic ceramic substrate, so that it has the following effects. is obtained.

(a) Even if the thickness of the positive characteristic porcelain substrate is extremely thin, for example, 1 mm or less, it is easy to handle and highly reliable, ensuring sufficient mechanical strength and preventing damage and cracking. A current control element can be provided.

(b) By integrally providing the ceramic layer on the surface of the positive characteristic ceramic substrate, heat radiation from the side where the ceramic layer is located is suppressed, the time required to reach thermal equilibrium is short, and current control with high responsiveness is achieved. We can provide elements.

(c) Since the thermal expansion coefficients of the positive characteristic ceramic substrate and the ceramic layer are close to each other, a highly reliable current control element with low thermal stress and less likely to cause cracks, breakage, peeling, etc. due to heat can be obtained.

(d) By adopting a structure in which the ceramic layer is integrally provided on the surface of the positive characteristic ceramic substrate, it is possible to directly attach the ceramic layer as the mounting side without using an insulator, making it easy to incorporate into equipment. A simple current control element can be provided.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a conventional current control element, FIG. 2 is a front sectional view of a current control element according to the present invention,
3 and 4 are a front sectional view and a side view of another embodiment. 1... Positive characteristic ceramic substrate, 2, 3... Electrode, 6...
...porcelain layer.

Claims (1)

[Claims for Utility Model Registration] (1) A current control element characterized in that a ceramic layer is integrally provided on at least one of both sides in the thickness direction of a positive characteristic ceramic substrate. (2) The current control element according to claim 1, wherein the thickness of the positive characteristic ceramic substrate is 1 mm or less.