JPS6014483B2 - resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that heats fuel in the intake air of an automobile or other internal combustion engine to promote atomization, a device that controls the rotation speed of a blower, or a hot air generator for heating. used for, etc.
This invention relates to a resistor with positive resistance-temperature characteristics.

Conventionally, in this type of resistor, (1) a heat sink and an electrode plate are bonded together using a coil spring to a ceramic semiconductor having positive resistance-temperature characteristics, {2} a semiconductor and a heat sink are bonded together using an adhesive, The one with the electrode plate glued, or is (3
}There is one in which a heat dissipation plate and an electrode plate are soldered to a thin film electrode formed on the semiconductor surface. However, in case (1) above, there is a problem of increased contact resistance due to the coil spring, while in case (2-) above, there is a problem of increased contact resistance due to the difference in thermal expansion between the semiconductor, heat sink, and electrode plate. There is a problem that the adhesive peels off due to the generation of stress.

On the other hand, in the case of [3] above, there is a problem that the solder is likely to peel off due to thermal expansion, or the material of the thin film electrode for bonding is forced to be considered. In order to solve the above-mentioned problems, the present invention provides a graphite layer between a ceramic semiconductor having positive resistance-temperature characteristics and a metal plate, thereby improving thermal conductivity and electrical conductivity between the semiconductor and the metal plate. The object of the present invention is to provide a resistor that can effectively absorb the difference in thermal expansion between the two. The present invention will be explained below using specific examples.

The basic configuration of the present invention is as shown in FIG.
is a disk-shaped ceramic semiconductor with positive resistance-temperature characteristics, and T
It is made of a fired barium titanate material mixed with i02, mother C03, Pb0, S2, Y203, etc. This semiconductor 1 also has the characteristic that its resistance value increases rapidly at a specific temperature. Although not shown, thin film electrodes are formed on both surfaces of the semiconductor 1 by a method such as an electroless plating method or a pasting method. Reference numeral 2 denotes a disc-shaped heat sink, which is made of a metal material with good thermal conductivity, such as aluminum.

Reference numeral 3 designates a disc-shaped electrode plate, which is made of the same metal material as the heat sink plate 2.

4 is a graphite layer according to the present invention, and this graphite layer 4 is made of carbon fiber in the form of a sheet and has flexibility.

The heat dissipation plate 2 and the electrode plate 3 are mounted on the thin film electrode of the semiconductor 1 with a graphite layer 4 interposed therebetween.

FIG. 2 is a developed version of FIG. 1, and shows a structure in which the graphite layer 4, the heat dissipation plate 2, and the electrode plate 3 are in close contact with each other.

This has a coil spring 5 interposed between the electrode plate 3 and the back cover 6. Note that the heat sink 2 is formed in a box shape and is fixed to the back cover 6. In the above configuration, next, the effects of the present invention will be explained with reference to FIGS. 3 and 4.

Figure 3 shows the contact resistance between the electrode plate 3 and the semiconductor 1 in the conventional example, while Figure 4 shows the contact resistance between the electrode plate 3 and the semiconductor 1 in a conventional example, while in Figure 4 the semiconductor 1 is energized for 1 minute, then energized for 9 minutes, and repeated. This shows how contact resistance changes over time.

In the sample used in the experiment, the semiconductor 1 is made of barium titanate and has a Curie point of 15 0, a disk shape with a diameter of 5 m and a thickness of 1, and a resistance value at room temperature of 0.30.
The thin film electrode provided thereon is made of Ni, and an Ag film is formed thereon for protection. Moreover, the electrode plate 3 is
It has a disc shape with a diameter of 60 ribs and a thickness of 1.6 ribs, and the graphite layer 4 has a disc shape with a diameter of 48 ribs and a thickness of 0.4 ribs. The voltage applied to the semiconductor 1 is DC 12V. In FIG. 3 and FIG. 4, sample A shows the above-mentioned follow-up example (1) using a coil spring, and the load pressure by the coil spring 5 is 5 kg.

Sample B shows the conventional example (2) using an adhesive, and the composition of the adhesive is Ag-Si resin. Moreover, sample C shows the soldering method of the conventional example [3}. Sample D
2 shows the embodiment of the invention shown in FIG. As is clear from the comparison of FIGS. 3 and 4, it can be seen that sample D, that is, the sample of this example, is very superior.

In addition, from the results shown in FIG. 4, it is clear that the thermal conductivity to the heat sink 2 does not deteriorate in durability in sample D compared to the other samples A to C.

As described in detail above, according to the present invention, the following effects are achieved.

'1} Since the graphite layer is flexible, if there is some distortion on the surface of the metal plate, the graphite layer will deform to fit that surface, and the semiconductor and metal plate will be uniformly bonded through the graphite layer. The graphite layer has a lubricating property, so when the metal plate in contact with it expands thermally, the graphite layer The plate slides on the surface of the graphite layer, and as a result, it is possible to prevent the strain caused by the thermal tension of the metal plate from being transmitted to the semiconductor, thereby avoiding cracking of the semiconductor.

Lake: As mentioned in '21 above, thermal strain is absorbed by the metal plate not by the deformation of the graphite layer, but by the metal plate sliding on the surface of the graphite layer. Therefore, the graphite layer itself It will not deteriorate,
Therefore, the effects of '1} and (2) above can be maintained for a long period of time.

{41 The graphite layer has good heat transfer in the direction perpendicular to its thickness, so the heat on the semiconductor surface in contact with the graphite layer can be effectively transferred to the metal plate. Good heat transfer to the plate.

[5' Furthermore, the graphite layer has relatively high heat resistance, so it is safe to use a semiconductor with a high heat dissipation temperature.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are cross-sectional views showing one embodiment of the present invention;
3 and 4 are characteristic diagrams for explaining the effects of the present invention. 1... Semiconductor, 2... Heat sink, 3...
...Electrode plate, 4...Graphite layer. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A resistor characterized in that a graphite layer is attached between a ceramic semiconductor having positive resistance-temperature characteristics and a metal plate.