JPS6349357B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a positive temperature coefficient thermistor heating element which generates a large amount of heat, is lightweight, has high moisture resistance and corrosion resistance, and a method for manufacturing the same at a low cost.

A positive temperature coefficient thermistor has a characteristic that its resistance value increases rapidly at a certain temperature (Curie temperature). Therefore, it has a self-temperature control effect in that when it is energized, the temperature it generates remains almost constant regardless of fluctuations in ambient temperature or voltage.
Various heating elements have been proposed utilizing this property. In addition, in order to increase the heat generation amount of this heating element and obtain a large output, it is effective to increase its heat dissipation coefficient, and for this purpose, heat dissipation fins with a large surface area and high thermal conductivity are used with positive characteristics. The method of fixing it to a thermistor is well known. The heat dissipation fins are preferably made of aluminum in consideration of cost, weight, thermal conductivity, ease of processing, etc. Further, in order to apply a voltage to the positive temperature coefficient thermistor, if the heat dissipation fin is also used as an electrode terminal, the structure is simplified and a new electrode terminal component is not required.

At this time, the aluminum heat dissipation fins become conductive paths and must be brought into contact with external connection terminals and lead wires. When the conductive part used externally is made of a metal other than aluminum such as copper or copper alloy, aluminum must come into contact with a metal other than aluminum such as copper or copper alloy at some point. Must be. However, since aluminum is a very base metal, if the parts that come into contact with other metals are exposed to a high humidity atmosphere or condensation occurs, a local battery will form there, corrode the aluminum, and cause holes to form. There was a risk that the connection portion as a conductive path would become disconnected, and the device would not be able to withstand long-term use.

The present invention has been made in view of the above points, and embodiments thereof will be described below with reference to the drawings.

First, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Electrodes 2, 2' made of sprayed aluminum are provided on the opposing largest surfaces of the thin plate-like positive temperature coefficient thermistor 1, and heat dissipation fins 3, 3' made of aluminum are attached to the surfaces with conductive adhesive (not shown). ) is fixed. Lugs 3a, 3a' are formed at the ends of the heat radiation fins 3, 3',
Copper wires 4, 4' serving as external connection terminals are connected thereto by solders 5, 5'(5' is not shown). The entire connecting portion is covered with epoxy resin 6, 6' to form an airtight structure.

By making the connection between aluminum and other metals airtight in this way, the formation of local batteries there is eliminated, making it possible to use the product for long periods of time in environments with high humidity or dew condensation.

3 and 4 show other embodiments of the invention. This embodiment relates to a structure in which a hermetic connection can be easily and completely obtained. That is, the heat radiation fins 3, 3' have ears 3a, 3a' as shown in the first embodiment, and these ears 3a, 3a' are covered with an insulating protective case 7 made of unsaturated polyester resin or the like. Recess provided 7
a, 7a'. The ears 3a, 3a' of the heat dissipating fins 3, 3' and the copper 4,
4' are connected by welding, soldering, etc.
Further, the recesses 7a, 7a' are filled with epoxy resins 8, 8'.

According to this embodiment, in order to make the connection between the aluminum heat dissipation fin and the copper wire airtight, it is only necessary to fill the recess of the insulating protection case with resin, which eliminates sagging of the resin and exposure of the connection. The amount of resin can be easily controlled and completely airtight connections can be easily obtained.

Still another embodiment of the present invention is shown in FIGS. 5 and 6, and this relates to a manufacturing method for easily obtaining an airtight structure at the connection portion between the aluminum heat dissipation fin and the external connection terminal.

In this embodiment, aluminum heat dissipation fins 3,
Copper wires 4, 4' are connected to a part of 3' by welding, soldering, etc. After that, cover the entire area with unsaturated polyester resin, etc., covering the area around this connection part.
An insulating protective case 9 that also serves as a protective case for the heat radiation fins 3, 3' is integrally formed.

In this embodiment, as mentioned above, the connection part is made airtight at the same time as the protective case is molded, so there is no need for resin filling in the post-process, and the positive temperature coefficient thermistor heating element of the connection part is made durable. can be obtained at low cost.

The present invention is configured as described above, and since aluminum is used as the metal heat radiator, the structure can generate a large amount of heat and is lightweight. In addition, by creating an airtight structure at the connection between the metal heat sink made of aluminum and the external connection terminal made of metal other than aluminum, it is possible to obtain a positive temperature coefficient thermistor heating element with high moisture resistance and corrosion resistance. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a PTC thermistor heating element according to the present invention, and FIG.
3 is a perspective view of a PTC thermistor heating element showing another embodiment of the present invention, FIG. 4 is a sectional view taken along line B-B' in FIG. The figure is a perspective view of a PTC thermistor heating element obtained by yet another manufacturing method of the present invention, and FIG.
- It is a sectional view taken along the line C'. 1... Positive characteristic thermistor, 2, 2'... Electrode, 3,
3'...Metal heat sink (aluminum heat sink),
4, 4'... External connection terminal (copper wire), 7, 9... Insulation protection case, 7a, 7a'... Recess, 8... Resin (epoxy resin).

Claims (1)

[Scope of Claims] 1. In a PTC thermistor heating element in which an electrode is provided on the largest surface of the PTC thermistor, a metal heat radiator is fixed to the surface, and the metal heat radiator also serves as an electrode, the above-mentioned metal A positive temperature coefficient thermistor heating element characterized in that aluminum is used as a heat radiator, a metal other than aluminum is used for an external connection terminal connected to the heat radiator, and the connection part has an airtight structure. 2. The connection part between the metal heat radiator and the external connection terminal is housed in a recess of an insulating protective case, and the recess is made airtight by injecting resin, and the insulating protective case also serves as a protective case for the metal heat radiator. A positive temperature coefficient thermistor heating element according to claim 1, characterized in that: 3. In a method for manufacturing a positive temperature coefficient thermistor, in which an electrode is provided on the largest surface of the positive temperature coefficient thermistor, a metal heat sink is fixed to the surface, and the metal heat sink also serves as an electrode, aluminum is used as the metal heat sink. A metal other than aluminum is used for the external connection terminals used and connected to the external connection terminals, and an insulating protective case is integrally molded to cover the entire area including the periphery of the connection between the metal heat sink and the external connecting terminals. A method for manufacturing a positive temperature coefficient thermistor heating element, characterized in that the metal heat radiating element also serves as a protective case and the connecting portion has an airtight structure.