JPS5826481Y2 - Positive characteristic thermistor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a banium titanate semiconductor ceramic having a positive temperature coefficient of resistance (hereinafter referred to as a positive temperature coefficient thermistor).

A positive temperature coefficient thermistor has a current control function or self-temperature control function that can obtain any heat generation temperature by appropriately selecting the Curie temperature, and exhibits a rapid resistance increase phenomenon when the Curie temperature is exceeded to throttle the current. Recently, it has come to be widely used as a heating element incorporated into various heating devices or as a current control element.

Figure 1 shows a conventional example of a PTC thermistor, in which electrodes 2 and 3 are adhered to both sides of a plate-shaped PTC thermistor body 1, and lead terminals 4 and 5 are connected to each electrode 2 and 3 by soldering or conductive. It has a structure in which adhesive 6 is applied.

The electrodes 2 and 3 are formed as ohmic or non-ohmic electrodes by electroless nickel plating, aluminum spraying, alloy paste printing, or other methods.

However, in the above-mentioned PTC thermistor, the adhesion between the PTC thermistor body 1 made of porcelain and the electrodes 2 and 3 made of metal is inherently weak, and due to the difference in thermal expansion coefficient between the two, the heat generation operation repeatedly occurs. As a result, as shown in FIG. 2, when tensile force is applied to the lead terminals 4 and 5, separation occurs between the electrodes 2 and 3 and the positive temperature coefficient thermistor body 1. This has the disadvantage that the original performance cannot be obtained if peeling occurs.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a positive temperature coefficient thermistor in which peeling between the electrode and the positive coefficient thermistor body is extremely difficult to occur.

In order to achieve the above object, the PTC thermistor according to the present invention has a first electrode, which is the original electrode, on the electrode mounting surface of the PTC thermistor body, and a first electrode that is connected to the PTC thermistor body from the first electrode. A second electrode with high adhesion strength is formed, and a connection body to an external circuit is fixed to the second electrode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be described in detail below with reference to the accompanying drawings which are examples.

Figure 3 is a perspective view of the positive temperature coefficient thermistor according to the present invention;
The figure also shows a sectional view thereof.

In the figure, reference numeral 1 denotes a positive temperature coefficient thermistor body 2, and 3 denotes a first electrode formed by a method such as electroless nickel plating, aluminum thermal spraying, or alloy paste printing, as described above.

The center portion of the first electrode 2.3 is missing, and the missing portion 2a.

3a is a positive temperature coefficient thermistor element 1 than the first electrodes 2 and 3.
The second electrodes 7 and 8 are formed to have a high adhesion strength to the substrate.

Note that the first electrode 7 and the second electrode 8 are provided with an overlap for electrical connection.

Then, solder or conductive adhesive 6 is applied to the second electrodes 7 and 8.
Connecting bodies 4 and 5 such as lead wires are fixed together.

The second electrodes 7 and 8 are formed, for example, by printing and applying a silver paste containing a large amount of frit (lead borosilicate glass) and baking.

In this case, by selecting the material, quantity, etc. of the frit, an electrode with good adhesion strength can be obtained.

FIGS. 5A to 5C are examples of process diagrams for forming the second electrodes 7 and 8.

First, as shown in FIG. 5A, first electrodes 2 and 3 are formed on both sides of the positive temperature coefficient thermistor body 1, and then, as shown in FIG. Remove the missing part 2a,
3a, and then the missing parts 2a, 3 as shown in C.
A silver electrode with a high frit content is printed and coated on a, and is formed by baking.

As mentioned above, the problem of peeling can be solved by forming the second electrode 8, which has a stronger adhesion strength than the original electrode, on the PTC thermistor element surface of the connecting body attachment part.
If the frit content is increased, there is a concern that the conductivity and adhesive force when soldering the connecting body will decrease.

FIG. 6 shows another embodiment that solves this problem,
A conductive layer 10.11 with a small amount of frit and excellent conductivity is deposited on the surfaces of the second electrodes 7 and 8, and the conductive layer 10.1
It has a structure in which connecting bodies 4 and 5 are fixed on top of the connecting body 1.

This improves the conductivity and soldering properties of the second electrodes 7 and 8.

In the above embodiment, electrodes are provided on both sides of the positive temperature coefficient thermistor body, but the same can be applied to a structure in which electrodes are formed on only one side. The portion to be removed is not limited to the central portion, but may be the peripheral portion.

Furthermore, the present invention is not limited to pellet-like products, and can be similarly applied to honeycomb-like products.

As mentioned above, the positive temperature coefficient thermistor according to the present invention is
A first electrode, which is an original electrode, and a second electrode, which has a stronger adhesion to the PTC thermistor element than the first electrode, are formed on the electrode mounting surface of the PTC thermistor element, and a second electrode is formed on the PTC thermistor element. The feature is that the connecting body to the external circuit is fixed to the electrode, so it provides a highly reliable positive temperature coefficient thermistor that is unlikely to peel off the electrode due to tensile force applied to the connecting body such as a lead wire. can do.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional positive temperature coefficient thermistor, and FIG. 2 is a sectional view illustrating the problems of the conventional positive temperature coefficient thermistor.
FIG. 3 is a perspective view showing an embodiment of the PTC thermistor according to the present invention, FIG. 4 is a sectional view thereof, FIG. 5 is a process diagram explaining the manufacturing process of the PTC thermistor of the embodiment, and FIG. 6 FIG. 3 is a sectional view showing another embodiment of the positive temperature coefficient thermistor according to the present invention. 1... Positive temperature coefficient thermistor element, 2, 3...
... (first) electrode, 4, 5... Connection body, 6.
...Solder or adhesive, 7°8...Second electrode, 10.11...Third electrode.

Claims (3)

[Scope of utility model registration request] (1) Forming a first electrode on a positive temperature coefficient thermistor element and a second electrode having a stronger adhesion to the positive temperature coefficient thermistor element than the first electrode, and forming an external electrode with respect to the second electrode. A characteristic thermistor characterized by a fixed connection body to a circuit. (2) Above 1. Utility model registration claim 1, characterized in that the second electrode is composed of a frit-containing chain baked electrode, and the frit content of the second electrode is greater than the frit content of the first electrode. Positive characteristic thermistor described in . (3) The connecting body has higher conductivity than the second electrode, and the first. The positive temperature coefficient thermistor according to claim 1 or 2, which is fixed to the second electrode via a conductive layer integral with the second electrode.