JP2750125B2 - Substrate structure of thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Application Field> The present invention selectively heats a resistive heating element film provided on a substrate and uses a heat-sensitive paper or a heat-sensitive transfer ink ribbon. And a substrate structure of a thermal head for printing in a desired pattern on plain paper.

<Prior Art> For example, a thermal printer that prints a desired pattern on a sheet of paper by sliding a resistance heating portion of a thermal head on a sheet supported by a platen via a thermal transfer ink ribbon is known. . In the above-described thermal head, it is preferable to improve the thermal responsiveness by cooling the resistance heating portion immediately after printing in order to perform clear printing on paper at a high speed, and conventionally, an alumina ceramic substrate is used for the head. In this case, a metal heat sink for heat radiation was brought into close contact with the substrate.

However, since the thermal expansion coefficients of the alumina ceramic substrate and the metal heat sink are different from each other, when the above substrate is used for a line head or the like, the entire thermal head is deformed due to a temperature change, and the printing pressure on the paper surface becomes non-uniform, thereby causing uneven printing. Was a factor that occurred. Further, since the alumina ceramic substrate is relatively expensive and it is necessary to separately provide a heat sink, there is a problem that the number of components of the thermal head increases and the production cost tends to increase.

Therefore, it is conceivable to use an inexpensive metal substrate having good heat dissipation and workability for the substrate of the thermal head.
In this case, for example, since the melting point of aluminum used as a base layer of the metal substrate is relatively low at about 660 ° C., the glass craze layer fired on its surface has a low melting point glass having a firing temperature of about 500 ° C. to 600 ° C. Is used,
Since this low-melting glass contains a lot of relatively low heat-resistant lead oxide and the like, the glass craze layer is eroded by the etching of the acid solution performed when the resistance heating element film or the electrode film is formed on the surface of the substrate, Irregularities occur on the surface,
The lead oxide and the like eluted from the glass craze layer may adhere to the resistance heating element film and the electrode film and adversely affect the film.

<Problems to be Solved by the Invention> In view of the problems of the prior art described above, a main object of the present invention is not to impair the thermal responsiveness at the time of printing, and to print even when used in a line head or the like. An object of the present invention is to provide a substrate structure of a thermal head in which the pressure does not become non-uniform and the number of parts and production cost are further reduced.

[Constitution of the Invention] <Means for Solving the Problems> According to the present invention, there is provided a substrate structure of a thermal head having a resistor film and an electrode film formed on a surface thereof. It has a base layer made of any one of steel, a glass glaze layer made of low melting point glass provided on the surface of the base layer, and an antioxidant film formed by depositing silicon dioxide directly on the surface of the glass glaze layer. This is achieved by providing a substrate structure for a thermal head.

<Function> As described above, by providing the antioxidant film on the surface of the glass glaze layer provided on the surface of the metal base layer, the glass glaze layer is eroded by etching when forming the resistance heating element film and the electrode film. Not only that, the lead oxide and the like eluted from the glass glaze layer are suppressed from adhering to the resistance heating element film and the electrode film. Therefore, a metal substrate can be used as the substrate of the thermal head.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a substrate 1 of a thermal head to which the present invention is applied.
Is shown. The substrate 1 has a base layer 2 made of aluminum.
And a glass paste made of low-melting glass is applied to the surface of the base layer 2 by screen printing two to three times.
It has a glass glaze layer 3 fired to have a thickness of 30 μm to 50 μm, and an antioxidant film 4 made of silicon dioxide formed on the surface of the glass glaze layer 3 by sputtering to a thickness of 2 μm or more, preferably 2 μm to 3 μm. ing. Actually, after a heating resistor film made of tantalum nitride or tantalum silicon dioxide or the like and an electrode film made of gold or aluminum are formed on the surface of the antioxidant film 4 by photolithography, they are etched with an acid solution. It is formed by this.

Here, since the melting point of aluminum used for the base layer 2 is about 660 ° C., the glass craze layer 3 baked on the surface thereof has a calcination temperature of about 500 ° C. to 600 ° C. and poor corrosion resistance lead oxide. Although a low-melting glass containing a large amount of such a material is used, the surface thereof is covered with the antioxidant film 4 so that the antioxidant film 4 is not etched when the resistance heating element film and the electrode film are formed. The surface is only etched at about 500 to 600 degrees per minute, and the glass craze layer is not eroded. Further, by forming the antioxidant film 4 by sputtering, the smoothness of the surface of the substrate 1 is also improved.

[Effects of the Invention] As described above, according to the present invention, by providing an antioxidant film on the surface of the glass glaze layer provided on the surface of the metal base layer, it is possible to use an inexpensive metal substrate with good heat dissipation and workability. Can be used as a substrate. Therefore, thermal responsiveness is not impaired without providing a heat sink separately. In addition, it is possible to prevent the thermal head from being deformed due to the difference in the coefficient of thermal expansion between the substrate and the heat sink, and to further reduce the number of components. From the above, the effect of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a part of a substrate of a thermal head to which the present invention is applied. DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Base layer 3 ... Glass glaze layer, 4 ... Antioxidant film

Claims (1)

(57) [Claims] 1. A substrate structure of a thermal head having a surface on which a resistor film and an electrode film are formed, comprising: a base layer made of one of aluminum and stainless steel; and a low melting point provided on the surface of the base layer. A substrate structure for a thermal head, comprising: a glass glaze layer made of glass; and an antioxidant film formed by depositing silicon dioxide directly on the surface of the glass glaze layer.