JPS6412074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing method suitable for mass production of a constant temperature heating element which is a combination of a ceramic constant temperature heating element having positive thermistor characteristics and a metal heat sink.

Various types of heaters are known that use ceramic fixed-temperature heating elements with positive thermistor characteristics, but these are usually composed of semiconductor ceramics containing barium titanate as a main component, and their resistance suddenly decreases when the temperature exceeds a predetermined temperature. It has the property of rising. Therefore, it is possible to provide a safe heater without overheating above a certain temperature. Moreover, if the heat dissipation is increased, the input power per unit number increases, and a heater with a large amount of heat generation can be provided. One example of this is the structure shown in Figures 1 and 2, in which a metal heat radiator is fixed to one or both sides of the ceramic constant-temperature heating element to increase the heat radiation effect, in order to reduce the number of constant-temperature heating elements used. There is. Figure 1 shows a heat dissipation fin 1 made by cutting or extruding a block of aluminum or the like, and Figure 2 shows a heat dissipation fin 1 made by bending a flat aluminum plate into a corrugated shape suitable for small parts. Both devices use a heat dissipation body 2 that is integrated with a ceramic heat generating element 3, and electrodes 4, 4' are placed on both sides of a ceramic constant temperature heating element 3.
It was installed through the

When obtaining such a structure, the constant temperature heating element 3, which is the main part, is a ceramic element made mainly of BaTio ₃ with necessary additives and sintered at 1200 to 1300°C, and its material composition The required characteristics such as switching temperature and resistance value are adjusted according to manufacturing conditions. Since it is a ceramic sintered body, there are restrictions on the size at which a homogeneous one can be obtained.In particular, in order to obtain a sintered body that does not warp, it is necessary to avoid large objects due to its thickness, vertical and horizontal ratio, etc. The tendency for it to become more difficult to obtain is inevitable. Specifically, when the thickness is about 1 to 2.5 mm, the vertical and horizontal ratio is 2.
In the case of 3 to 3, a size of about 2 x 6 cm is appropriate; the larger the vertical/width ratio and dimensions, the lower the yield, so for practical purposes, economical dimensions are specified. On the other hand, in the case of metal heat sinks, large ones can be easily obtained, and small ones can be easily obtained by cutting or extruding aluminum as shown in Figure 1, or by bending aluminum plates as shown in Figure 2. It is more efficient for manufacturing to be larger than .

The present invention provides an efficient manufacturing method that complements the merits and demerits of both manufacturing techniques. After the heat generating elements are arranged side by side and both are fixed, they are cut and divided including the metal heat radiator at positions corresponding to the required number of ceramic constant temperature heat generating elements. The combination of the ceramic fixed-temperature heating element and the metal heat radiator can be stacked in as many stages as necessary and fixed using aluminum brazing, heat-resistant adhesive, heat-transfer conductive adhesive, or the like. In addition, when cutting and dividing, it is necessary to select a cutting method and conditions so that cutting dust from a metal heat sink such as aluminum does not remain on the cut surface of the ceramic sintered body and impair its electrical characteristics.

As one method to avoid setting such complicated cutting conditions, when fixing ceramic constant temperature heating elements, it is effective to leave a gap at the cutting position by a dimension corresponding to the cutting allowance. By taking this measure, there is no possibility that metal powder will get mixed into the cross section of the ceramic constant temperature heating element, and it can greatly contribute to improving the reliability of the product.

The invention will now be described in detail with reference to the illustrated embodiments. Figure 3 shows an example of a hot air heater constructed by combining three fixed-temperature ceramic heating elements each having a unit shape and attaching radiation fins to both sides of the heater. However, a large number of ceramic constant temperature heating elements 11 are arranged vertically and horizontally as shown in the figure on the flat plate surface of an aluminum heat dissipation fin 10 whose depth corresponds to several tens of pieces, and another heat dissipation fin 10' is placed on top of this, and between the two It is also pressure bonded through a thin layer of heat-resistant silicone adhesive. Next, by cutting this at once at the position of the dotted line in the figure according to the product dimensions of the constant temperature heating element, multiple finished product units with dimensions l x t as shown in Fig. 4 can be obtained at once. . Ceramic constant temperature heating element 1 in this case
FIG. 5 shows how the heat generating elements 1 are arranged, in which a large number of ceramic constant temperature heating elements 11 are arranged vertically and horizontally with no gaps between them.

In FIG. 6, ceramic constant temperature heating elements 11 are arranged in groups according to the required quantity according to the product dimensions, and a gap 12 corresponding to the cutting allowance is provided around the periphery.
This figure shows an example of a case where cutting is performed at once at 12 intervals as shown by the arrow.

Although FIGS. 3 and 4 show an example of an aluminum heat sink as the metal heat sink, the same applies to an aluminum heat sink as shown in FIG.

In addition, if the basic features of the present invention are exhibited, the difference in detail is that the electrode structure of the ceramic constant temperature heating element 11 is on both the upper and lower surfaces as in the present invention, and it is directly electrically and thermally connected to the metal heat sink. Also, when the electrodes are connected to the ceramic constant temperature heating element 11,
Any similar structure, such as a structure formed on the side surface of a metal heat sink and having an insulating plate such as an alumina thin plate on both the upper and lower surfaces to avoid short circuit with the metal heat sink, is the basic principle of the present invention. If the purpose and effect are the same, they are considered to be the same, and are not limited to these examples, but can be effectively used in similar technical fields, reducing costs and stabilizing quality by reducing man-hours in mass production. The effects are great.

As described above, according to the method for manufacturing a constant temperature heating element of the present invention, the necessary product dimensions can be obtained simply by manufacturing a unit-shaped ceramic constant temperature heating element, and therefore products of various sizes can be manufactured. Even if necessary, only one type of ceramic constant-temperature heating element, which requires complicated processes, needs to be produced, and it can be easily handled at low cost by simply processing metal, which is easy to process.
Furthermore, since the metal heat radiator is fixed, the input power to the ceramic fixed temperature heating element is increased, and a heating element with a large amount of heat generated per unit number can be provided.

[Brief explanation of drawings]

Figures 1 and 2 are perspective views showing conventional examples;
FIG. 4 is a perspective view showing an embodiment of the present invention,
FIGS. 5 and 6 are explanatory diagrams showing the arrangement of ceramic constant temperature heating elements. 10, 10' are aluminum heat dissipation fins, 11
12 is a ceramic constant temperature heating element, and 12 is a spacing.

Claims (1)

[Claims] 1. When manufacturing a constant temperature heating element made by combining a ceramic constant temperature heating element with positive thermistor characteristics and a metal heat radiator, a unit-shaped ceramic constant temperature heating element whose size is equivalent to one constant temperature heating element in several pieces is used. After arranging the required number of heat sinks in parallel and fixing a metal heat radiator of a size equivalent to multiple constant temperature heating elements on one or both sides of the metal heat radiating elements, and integrating the required number of stages, the product dimensions of the constant temperature heating elements are adjusted. A method for manufacturing a constant temperature heating element, characterized in that a plurality of pieces are obtained at once by cutting them at once according to the requirements.