JP2824088B2 - Thermal head and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head for thermal recording in which the wear resistance of a wear-resistant layer is particularly improved, and a method for manufacturing the same.

[Conventional technology]

In general, the structure of the thermal head is, as shown in FIG. 6 of a schematic longitudinal sectional configuration explanatory view, a glass layer (2) glazed on the upper surface of a ceramic substrate (hereinafter, referred to as a substrate) (1), a heating resistor, The thermal head has a structure in which a layer (3), an electrode (4), and an oxidation-resistant layer (5) are sequentially laminated, and a wear-resistant layer (6) is provided on the outermost surface on which the thermal paper is rubbed. Is required to have excellent wear resistance in addition to excellent thermal responsiveness, and since the wear resistance depends on the hardness of the wear-resistant layer, those using various ceramics as the wear-resistant layer have been proposed. .

First, JP-A-54-85734 discloses an example in which a silicon carbide film is formed on a mixture of silicon carbide and silicon oxide or a mixture of silicon carbide and silicon oxide as a wear-resistant layer. Is disclosed.

Japanese Patent Application Laid-Open No. 55-82679 discloses an example in which a film formed by mixing silicon with an oxide, carbide, or nitride is formed as a wear-resistant layer.

Japanese Patent Application Laid-Open No. _55-82679 discloses an example in which a wear-resistant layer is _formed of a ceramic film of SiO _2-2x C _x (where 0.2 ≦ x <1).

Therefore, the heating resistor is protected by the wear-resistant layer which is made of various ceramics having high hardness.

[Problems to be solved by the invention]

As described above, such a wear-resistant layer made of ceramic has extremely high hardness and is therefore useful, but from the viewpoint of its durability, it still has the following problems.

That is, since a pulse current is applied to the heating resistor of the thermal head, the wear-resistant layer is directly subjected to a thermal shock by the heat generated by the heating resistor due to the pulse current.

By the way, as is well known, a material generally has a property of becoming brittle as its hardness becomes higher. Therefore, by reducing the thickness or the thickness of the material, even if it is a brittle material, it can be bent and deformed, but the brittleness itself cannot be improved.

Therefore, the heat generated by the pulse application to the electrode is transmitted directly to the wear-resistant layer because the electrode and the wear-resistant layer are in contact with each other. In many cases, cracks were generated in the layer, and the durability of the wear-resistant layer was not always sufficiently reliable.

Accordingly, an object of the present invention is to provide a thermal head having excellent wear resistance and excellent thermal shock resistance, and a method for manufacturing the same.

[Means for solving the problem]

The present invention has been made in order to solve the above problems. Therefore, the structure of the thermal head according to the first invention of the present invention is that a glaze layer, a heating resistor layer and a wear-resistant layer are sequentially formed on a substrate. In the laminated thermal head, silicon carbide which becomes (Si _x C _y ) is used for the wear-resistant layer, and the component ratio y / x of C and Si of the silicon carbide (where x, y> 0)
Is continuously or discontinuously changed in the thickness direction of the wear-resistant layer so that the heating resistor side is minimized.

The gist of the method for manufacturing a thermal head according to the second invention of the present invention is that a substrate is set in a plasma CVD reaction chamber,
A mixed gas of a hydrocarbon gas and a hydrogen silicide gas is introduced into the reaction chamber while changing the concentration ratio of the hydrocarbon gas and the hydrogen silicide gas continuously or discontinuously, and a component ratio y / x is formed on the substrate. Is characterized in that a film of silicon carbide that becomes Si _x C _y having changed is formed.

[Action]

According to the thermal head of the present invention, the electrodes and the heating resistor layer are protected by the wear-resistant layer of silicon carbide that becomes Si _x C _y .

Then, C-rich as the Si, but the _x C _y component ratio y / x is the heating resistor layer side of C and Si of a low hardness to a Si-rich approaches the outer surface of the heating resistor layer Becomes
Since the component ratio on the outer surface can be the highest hardness in the component ratio y / x, the hardness can be increased as the heating resistor layer approaches the outer surface.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. 1 to FIG.

First Embodiment This first embodiment is described by referring to FIG. 1 of a schematic longitudinal sectional configuration diagram of a thermal head, FIG. 2 of a schematic configuration diagram of a flat plate type plasma CVD apparatus, and the component ratio of carbon and silicon. Based on FIG. 3 illustrating the relationship between y / x and hardness change, the same components as those in the conventional example will be described with the same reference numerals.

That is, reference numeral (1) shown in FIG.
A glass layer (2), a heating resistor layer (3), and an electrode (4) that are glazed on the upper surface of the substrate (1) are sequentially laminated, and a heat-resistant paper is rubbed on the electrode (4). The layer (6) was laminated.

The above wear-resistant layer (6) was formed using a flat plate type plasma CVD apparatus described below.

That is, the symbol (10) shown in FIG. 2 is the gas inlet (10a).
And a gas exhaust port (10b). An electrode (11) is provided in an upper part inside the decompression chamber (10), and a matching circuit (11a) is provided in the electrode (11). A voltage is applied by a high-frequency power supply (11b) via the.

On the other hand, a ground electrode (12) is located inside the lower part of the decompression chamber (10).
Are arranged. Then, the substrate (1) is placed on the earth electrode (12), and a mixed gas of C ₂ H ₄ as a hydrocarbon gas and SiH ₄ as a hydrogen silicide gas is introduced through a gas inlet (10a). While introducing into the decompression chamber (10) while changing the mixing ratio, and applying a predetermined voltage to the electrode (11),
The carbon C and silicon Si in the hydrocarbon gas and the hydrogen silicide gas excited by the applied voltage adhere to the substrate (1) in accordance with the mixed component ratio y / x of the hydrocarbon gas and the hydrogen silicide gas. ), A wear-resistant layer (6) of Si _x C _y is formed.

The film forming conditions for forming Si _x C _y are shown below.
0.1 (torr), load power = 300 W, substrate temperature = 200 ° C., and standard supply flow rates of the reaction gas were as shown in Table 1.

And in this embodiment, the component ratio y / of C and Si
x was in the range of 0.6 to 2.8.

More specifically, the component ratio on the side of the heating resistor (3) described above
y / x = 0.6, and the y / x value was gradually increased in the thickness direction of the wear-resistant layer (6), and y / x = 2.8 on the surface.

FIG. 3 shows the change in Mohs hardness with respect to the change in the component ratio y / x value.

That is, the hardness of the wear-resistant layer (6) was about 4 on the heating resistor (3) side, but gradually increased to about 8 on the surface.

Therefore, even if the heat-resistant resistor (3) side of the wear-resistant layer (6) has a low hardness, the toughness is high and even if there is a thermal shock, no crack is generated in the wear-resistant layer (6). The surface of (6) has high hardness, so that excellent wear resistance is imparted, and the heat generated by the heating resistor (3) is alleviated during transmission through the wear-resistant layer (6). Cracks did not occur on the surface of the layer (6).

Second Embodiment The second embodiment will be described below with reference to FIG. 4 which is a schematic longitudinal sectional configuration diagram of a thermal head and FIG. 5 which is a diagram of a resistance change rate with respect to an applied voltage. Reference numeral (1) indicates a substrate. A glazed glass layer (2), a heating resistor layer (3), and an electrode (4) are sequentially laminated on the upper surface of the substrate (1). And a wear-resistant layer (6) on which thermal paper is rubbed.

The details of the wear-resistant layer (6) described above include a first layer (6a) having a component ratio y / x = 0.8 in order from the electrode (4) side, and a component ratio y / x
= 1.5, a second layer (6b) with a component ratio y / x = 2.2, and a fourth layer (6d) with a component ratio y / x = 2.8. The thickness of each layer was 0.5 μm, and the thickness of each layer was 2 μm.

Next, in order to indirectly confirm the effect of the wear-resistant layer (6), the thickness of 2 μm of tantalum oxide (Ta ₂ O ₅ ), which is currently frequently used as a protective film for the electrode (4), is used.
A thermal head having a m-wear layer (6) formed thereon was prepared, and the thermal shock resistance of both of them was evaluated by a step stress test.

The conditions of this step stress test are as follows: the pulse period of the applied voltage = 1.5 ms, the pulse width of the applied voltage = 0.3 ms, and the number of pulses of the applied voltage in one step = 1 × 10 ⁵ .

The test results are as shown in FIG. 5, in which the vertical axis represents the resistance change rate (%) and the horizontal axis represents the applied voltage level.
Note that when the wear layer (6) of this example Si _x C _y in solid lines, in which the wear-resistant layer (6) is shown respectively by the chain line in the case of Ta ₂ O _5.

As can be clearly understood from this figure, it can be seen that the wear-resistant layer (6), which becomes Si _x C _y , alleviates the thermal shock. Thus, the abrasion-resistant layer (6) according to this embodiment no longer causes cracks as in the first embodiment.

Therefore, the operation and effect of this embodiment are substantially the same as those of the first embodiment.

In the above-described embodiments, the case where ethane (C ₂ H ₄ ) and monosilane (SiH ₄ ) are used as the reaction gas has been described as an example, but other gases include methane as a hydrocarbon. (CH ₄ ), acetylene (C ₂ H ₂ ), or the like, or disilane (Si ₂ H ₆ ), trisilane (Si ₃ H ₈ ), or the like, may be mixed and supplied in appropriate amounts.

It should be noted that each of the above-described embodiments is merely a specific example of the present invention, and therefore, the scope of the technical idea of the present invention is not limited by this embodiment, and within the scope not departing from the technical idea. The design can be changed freely.

〔The invention's effect〕

According to the thermal head according to the present invention, the electrode and the heating resistor layer is protected by a wear-resistant layer of silicon carbide comprising the Si _x C _y, the component ratio of the Si _x C _y C and Si y / x is Si-rich and low hardness on the heating resistor layer side, becomes C-rich as approaching the outer surface of the heating resistor layer, and becomes the highest hardness at the component ratio y / x on the outer surface. Since the hardness can be increased as the outer surface of the heating resistor layer approaches, the vicinity of the heating resistor layer is resistant to thermal shock, and the outermost surface side of the wear-resistant layer is Although hard and brittle, thermal shock was reduced by passing through the wear-resistant layer, and cracks did not occur at this portion.

Therefore, according to the present invention, a thermal head excellent in abrasion resistance and excellent in thermal shock and a method for manufacturing the same can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional configuration view of a thermal head according to a first embodiment, FIG. 2 is a schematic configuration diagram of a flat-plate type plasma CVD apparatus, and FIG. 3 is a component ratio y / x of carbon and silicon. , FIG. 4 is a schematic longitudinal sectional configuration diagram of a thermal head according to a second embodiment, FIG. 5 is a diagram illustrating a resistance change rate with respect to an applied voltage, and FIG. 6 is a diagram of a conventional thermal head. FIG. 2 is a schematic longitudinal sectional configuration explanatory view. (1) ... substrate, (2) ... glass layer, (3) ... heating resistor layer, (4) ... electrode, (6) ... wear-resistant layer, (1)
0) ... decompression chamber, (10a) ... gas inlet, (10b) ...
Outlet, (11) ... electrode, (11a) ... matching circuit, (11b) ... high-frequency power supply, (12) ... earth electrode.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Joji Ogura 100 Takegahana-cho, Ise-shi, Mie Prefecture Inside Ise Works, Shinko Electric Machinery Co., Ltd. (72) Inventor Hiroyuki Tachibana 2- 4-6 Chimori-cho, Suma-ku, Kobe-shi, Hyogo (72) Inventor Yoshihiko Onishi 7-3-4-424 Takamaru, Tarumi-ku, Kobe-shi, Hyogo (56) References 62-286761 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B41J 2/335

Claims (2)

(57) [Claims] 1. A thermal head in which a glaze layer, a heating resistor layer and a wear-resistant layer are sequentially laminated on a substrate, wherein the wear-resistant layer is made of silicon carbide (Si _x C _y ),
The component ratio y / x of C and Si of the silicon carbide (where x, y
> 0) is changed continuously or discontinuously in the thickness direction of the wear-resistant layer so that the heating resistor side is minimized. 2. A substrate is placed in a plasma CVD reaction chamber, and the reaction is carried out while changing the concentration ratio of the hydrocarbon gas and the hydrogen silicide gas continuously or discontinuously. A method of manufacturing a thermal head, comprising: introducing a silicon carbide film having a composition ratio y / x changed to Si _x C _y into a chamber on the substrate.