JPH01294061A - Manufacture of flat platelike heating element - Google Patents

Abstract

PURPOSE:To enable mass producing with good workability highly reliable flat platelike heating elements resistant to a thermal shock extending over a long period of time, by spray coating and accumulating ceramic on the metal shaped into a heating electrode placed on a ceramic base and by holding and fixing said metal between both ceramics. CONSTITUTION:A tungsten foil rapped into a desired shape of heating electrode 1 is temporarily fixed on an alumina single crystal base 2 by adhesive so as to be placed on said base, alumina is accumulated and stuck through plasma spray coating to form an alumina layer 3, and said tungsten foil is held and fixed between the alumina single crystal base 2 and alumina layer 3 so that a flat platelike heating element is obtained. Accordingly, the production time of said element is as short as about one minute and the number of manufacturing processes also decreases to enable the mass production of the heating element. Further, because a tungsten foil is used as the heating electrode 1 for said flat platelike heating element, the element thus manufactured is higher in denseness and less in stress than a vapor deposited film. Therefore, said element causes neither breaking of wire nor crack and can exhibit an excellent thermal shock resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial 1Q Field] The present invention relates to a method of manufacturing a flat heating element, such as a thermal head, which requires extensive production.

[Prior Art] Fig. 4 is a plan view showing a conventional flat heating element, and Fig. 5 is a cross-sectional view taken along the line ■-v in Fig.
1) is a heating electrode, and (2) is a ceramic substrate. This conventional flat heating element is produced by, for example, a vacuum evaporation method.
A metal that will become the heating electrode (1) is vapor-deposited on the entire surface of the ceramic substrate (2), and then a resist pattern is formed on the metal film to remove unnecessary material in order to make the metal film into the desired shape of the heating electrode. It was manufactured by etching away the metal film and removing the resist film.

In the conventional manufacturing method as described above, it is necessary to use an expensive film-forming apparatus, and the vacuum chamber of the film-forming apparatus generally has a
Only a limited number of ceramic substrates, about one 4-inch wafer, could be loaded.

In addition, it is necessary to heat the vacuum container for more than 1 hour to bring the vacuum level to a level suitable for film formation, and the film formation rate is generally 0.1
Since it is slow at about μs/a+in, it is necessary to form the film for more than 30 minutes to obtain a film thickness of 3μ or more required for the heating electrode, and it is necessary to cool it for more than 30 minutes to prevent impurities from being removed. For this reason, it took more than two hours to form a metal film on a ceramic substrate.

Furthermore, in order to give the formed metal film a desired shape, a resist film is applied, and a pattern is formed using a mask.
After that, it was necessary to perform etching and cleaning to remove the resist film.

[Problems to be Solved by the Invention] As described above, the conventional method for manufacturing a flat heating element has problems such as a large number of manufacturing steps, a long and complicated manufacturing process, and the inability to mass-produce the device.

In addition, the heating electrode formed by film formation has problems with the thermal shock resistance of the long upper edge, such as the adhesive force with the ceramic substrate decreasing and peeling due to repeated heating and cooling, and cracking and disconnection due to thermal stress. However, there was a problem of lack of reliability.

This invention was made to solve the above-mentioned problems, and provides a manufacturing method that allows mass production of highly reliable flat heating elements that can withstand long-term thermal shock. The purpose is to

[Means for Solving ff, d] The method for manufacturing a flat heating element of the present invention includes thermally spraying ceramic onto the ceramic substrate with metal in the shape of a heating electrode placed on the ceramic substrate. The metal is deposited, and the metal is sandwiched and fixed between ceramics.

[Function] In the flat heating element of the present invention, the 11:1 heating electrode is made of, for example, a foil-like metal, and the metal in the shape of the heating electrode is integrally formed with a ceramic coating by thermal spraying. It has higher density and less stress than the formed one.

Therefore, it prevents the heating electrode from cracking or breaking due to thermal stress. Long-term 18H resistance against II blows is improved. Since the ceramic is integrally molded by thermal spraying, it is easy to work, easy to use, and can be manufactured in large quantities.

[Example] The present invention will be explained below with reference to the drawings. FIG. 1 shows a flat heating element obtained by an embodiment of the present invention.
Figure 2 is a cross-sectional view taken along the ■-n line in Figure 1;
Figure Is3 is a partially cutaway perspective view of the flat heating element in Figure 1. In Figure 0, (1) is a heating electrode, in this case a tungsten foil with a thickness of 10 μm; (2)
is a ceramic substrate, in this case an alumina single crystal substrate with a thickness of 0.3-1, and (3) is a ceramic coating layer, in this case an alumina coating layer deposited on an alumina single crystal substrate (2) by plasma spraying. layer, thickness 100
The tungsten foil of the μ-1 heating electrode (1) is sandwiched and fixed between the alumina single crystal substrate (2).

Next, a method for manufacturing this flat heating element will be explained.

First, cut out the tungsten foil into the desired heating electrode (1) shape, and then cut out the tungsten foil in the shape of the heating electrode (+).
Alumina is deposited and adhered by plasma spraying on the alumina single crystal substrate (2), which has been made with 0-order tungsten foil. Form layer (3) and tungsten foil
A flat heating element was obtained by sandwiching and fixing the alumina single crystal substrate (2) and the alumina layer (3). First, tungsten foil, which had been previously formed into a desired shape, was integrally molded by alumina plasma spraying. Therefore, the production time is as short as about 1 minute, the number of manufacturing steps is small, and full production is possible.

Moreover, it can be manufactured using inexpensive equipment without using expensive equipment such as a vapor deposition equipment.

Furthermore, the obtained flat heating element uses tungsten foil for the heating electrode, and has higher m-density and less stress than a vapor-deposited film. m5I 1 minute, cooling 3 minutes 100
Although it could not withstand the thermal shock of 0 o'clock leap or more, this heating element exhibited excellent heat resistance without peeling of the heating electrode, disconnection, or cracking. It was highly reliable and could be used as a heating element for electronic components such as thermal heads.

In the above example, the same ceramic as the ceramic substrate was thermally sprayed, but it does not necessarily have to have the same composition, and although the entire surface is thermally sprayed, it is necessary to thermally spray only the necessary areas. Furthermore, thermal spraying is not limited to plasma spraying, and explosive thermal spraying, gas combustion thermal spraying, etc. can also be applied.

Furthermore, in the above embodiment, a case was described in which a tungsten foil, which had been previously cut and formed into the shape of a heating electrode, was placed on a ceramic substrate and ceramic was thermally sprayed. It is also possible to form a heating electrode shape using laser trimming or the like, and then thermally spray ceramic.

The metal used in this invention is molybdenum in addition to tungsten, and the thickness is required to be 3 μm or more in order to function as a heating electrode, and in practice it is 10 μm thick.
μ- or more is desirable.

[Effects of the Invention] As described above, according to the present invention, the ceramic is deposited on the ceramic substrate by thermal spraying with a heating electrode-shaped metal placed on the ceramic substrate,
By sandwiching and fixing the metal between ceramics, it is possible to easily mass-produce a highly reliable flat heating element that can withstand long-term thermal shock with good workability.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a flat heating element according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a part of the flat heating element shown in Fig. 1. FIG. 4 is a plan view showing a conventional flat heating element, and FIG.
The figure is a sectional view taken along the line V-V in FIG. 4. In the figure, (1) is a heating electrode, (2) is a ceramic substrate, and (3) is a ceramic coating layer. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A method for manufacturing a flat heating element, in which a heating electrode-shaped metal is placed on a ceramic substrate, the ceramic is deposited on the ceramic substrate by thermal spraying, and the metal is sandwiched and fixed between the ceramics.