KR920005760B1 - Thermal head and production thereof - Google Patents

Abstract

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Description

[Name of invention]

Thermal head and manufacturing method thereof

[Brief Description of Drawings]

1 is a graph showing the relationship between the ruthenium content of a resistor layer containing ruthenium as a resistor component and the dispersion of resistance values of the resistor layer.

2 is a graph showing the temperature dependence of the resistance value of the resistor layer containing ruthenium.

3 and 4 are cross-sectional views showing the main parts of the thermal head according to the present invention.

Detailed description of the invention

[Technical Field]

The present invention relates to a thermal head used in a recording device such as a facsimile, a full color printer, a word processor, and more particularly, a thermal head. The present invention relates to a resistor layer which is one of the main components of and an improvement of a method of manufacturing the same.

[Background]

The thermal head is composed of at least a pair of electrodes, a substrate on which at least a surface of the resistor layer in contact with these electrodes is insulative, and supports the electrode and the resistor layer on the surface thereof, and a wear-resistant layer formed on the resistor layer. have. And there are a thin film type and a thick film type according to the manufacturing method. The thin film type is formed by sputtering or evaporation of an electrode, a resistor layer, and an abrasion resistant layer in a vacuum. Further, the thick film type may include, for example, a paste of a thermally decomposable organic compound of gold, a paste containing RuO ₂ (ruthenium oxide) and glass frit, and a paste of borosilicate glass frit. By printing and firing, respectively, a gold electrode, a resistive layer made of a glass layer in which RuO ₂ is dispersed, and a wear resistant layer made of glass can be obtained, and a high performance thermal head can be obtained at a lower cost than a thin film type.

The thermal head generates heat in a specific region of the resistor layer in contact with both electrodes by passing a current between a pair of electrodes, thereby heating a specific region of the recording member, for example, a thermal recording paper, and a dot portion. ) Is given. Therefore, the important characteristics required for the thermal head are that the heat generation of the resistor layer should be efficiently transferred to the recording sheet, and that the heat generation of the resistor layer between the individual electrode pairs arranged in a regular line form should be uniform. If the resistance of these resistor layers is uneven, the amount of heat generated is not uniform. Therefore, the density of the individual recording dots recorded on the recording paper becomes uneven, resulting in dark or thin lines in the recording, resulting in poor recording quality. In particular, such a characteristic is important as a thermal head for a full color printer in which gradation records are required. As a cause of such an imbalance in the recording density, dispersion of resistance values of individual resistor dots is considered. In order to reduce the dispersion of the resistance values of the individual resistor dots, a trimming process is employed in the thick film method. In this step, an overload pulse is applied to each dot of the resistor layer, whereby the resistance value can be within ± 0.5% of the target. On the other hand, in the case of a thin film type, the resistance value of each resistor dot can be made within +/- 2.5% by adjusting conditions of the intermediate | middle adhesion and sputtering for obtaining a resistor. However, it is difficult to further improve the current dispersion value in the thin film type head, and there is a problem in the current type as described below in the thick film type head. The resistor layer of the current thick-film thermal head is formed by screen printing a paste formed of RuO ₂ , a glass frit, and an organic binder of the resistor component and firing the paste. By the way, since the starting paste is a mixture of RuO ₂ powder and glass powder, the resulting resistor layer also becomes a mixture of both.

Further, even when a small particle size is used as the RuO ₂ powder, the particles are agglomerated or poorly dispersed in the glass matrix, and the particle size is considerably large in the resistor layer obtained. As a result, current flows through the RuO ₂ powders in contact with each other. Therefore, in order to obtain a resistor having a uniform resistance value, a considerable amount of RuO ₂ powder is required. On the other hand, even if the dot resistance value is constant by trimming, a preferential change of the resistance value occurs in one of the resistive dots, particularly in a part which is easily trimmed. Heat generation is concentrated on a part of the dot, so that a normal dot shape cannot be obtained. The deviation of the passage of current in this one resistor dot is due to the nonuniform distribution of the resistance value, that is, the nonuniform distribution of the conductive element such as RuO ₂ in the resistor layer.

As described above, in the conventional method of forming a resistor layer from a mixture of RuO ₂ and glass powder, it is difficult to obtain a resistor layer having a uniform resistance value.

[Initiation of invention]

An object of the present invention is to provide a thermal head which solves the above conventional inconveniences, has a resistor layer with a uniform resistance value, and exhibits excellent recording quality. An object of the present invention is also to provide a method of manufacturing a thermal head which exhibits a record of excellent quality.

In a thermal head having at least a pair of electrodes, a resistor layer in contact with the aforementioned electrodes, and a substrate having at least a surface insulating and supporting the electrode and the resistor layer on the surface thereof, the thermal head of the present invention is glass. It has a resistor layer composed of a metal and / or an oxide of a resistor component element embedded in a gap between the matrix and the atomic bond of the matrix. In addition, such a thermal head usually has a wear-resistant layer surrounding the resistor layer.

Here, a preferred method for obtaining the resistor layer of the thermal head is printing and spin coating a film of a paste containing a thermally decomposable organic compound of a resistor component element and a thermally decomposable organic compound of an element forming a glass matrix. a step of forming by a coating method, a painting method, or the like, and thermally decomposing the organic compound in the paste by heat treatment to form a glass matrix and a resistive layer made of a metal and / or oxide, which is a component of the resistor dispersed in the matrix. It is a process to produce.

It is preferable that said paste consists of said organic compound, the solvent which melt | dissolves in these organic compounds, and the organic binder which melt | dissolves in this solvent. In such a paste, an organic compound of a resistive component element and an organic compound of an element forming a glass matrix are mixed at a molecular level, and the oxide of an element forming a glass matrix by thermal decomposition thereof and a metal which is a resistive component element and // Or an oxide is formed and the latter metal and / or oxide is incorporated into the glass matrix resulting from the fusion of the oxides to form an antibody layer. In the resistor layer thus produced, the metal and / or oxide of the resistor component element is in a state of being embedded in the gap of the atomic bond of the glass matrix at the atomic or molecular level. Therefore, the resistor layer has a very uniform composition, and the amount of the resistor component element is much smaller than in the prior art.

×100의 값을 표시하였다.

은 저항값의 평균값, σ는 표준편차값이다.FIG. 1 shows the relationship between the ruthenium element content of the resistor layer of the glass matrix and the oxide layer mainly composed of ruthenium oxide dispersed in the matrix, and the dispersion of the resistance value of the resistor layer. In addition, the vertical axis associated with the resistance value has σ /

The value of x100 was shown.

Is the average value of the resistance values, and σ is the standard deviation value.

In Fig. 1, A represents the properties of the resistor layer obtained by the method of the present invention, and B represents the properties of the resistor layer by the conventional method. In the case of A, the particle size of the ruthenium oxide is 1 m or less, and in the case of B, the particle size is 5 m or more.

In the case of B, the Ru element content is less than 10 wt.% And the dispersion of the resistance value rapidly increases. On the other hand, in the case of A, the dispersion of the resistance value is extremely low even if the Ru element content is small.

As another method for obtaining the resistor layer, there is a method of using a paste containing a thermally decomposable organic compound of a resistor component element and glass frit instead of the paste described above. Even in this case, the paste preferably contains a solvent which dissolves the above-mentioned organic compound and an organic binder which dissolves in such a solvent. When such a paste is used, the dispersibility of the metal and / or oxide of the resistive component element in the resulting resistive layer is inferior to the above-described method, but much better than the conventional method. That is, the above-mentioned organic compound is in contact with the glass frit particles in the form of a solution in the paste, so that metals and / or oxides produced by thermal decomposition are dispersed on the surface of the glass frit particles at the molecular level, and in this state, the glass frit is fused to the glass frit particles. It is embedded into the glass matrix formed by this.

Here, the resistive component elements to be applied to the present invention include ruthenium, gold, silver, nickel, chromium, tantalum, and the like, and ruthenium is preferable. Ruthenium exists mainly as an oxide in a resistor layer. In the resistor layer using ruthenium, the temperature dependence of the resistance value is very large as shown in a of FIG. To improve this, it is better to use rhodium together. In combination with rhodium, the temperature dependence of the resistance value is improved as in b of FIG. In addition, the film forming property of the resistor layer is also improved by the addition of rhodium. When using ruthenium and rhodium together, 0 <(Rh / Ru) <5 is suitable for a weight ratio.

Next, examples of the element forming the matrix of the glass include boron constituting the borosilicate glass, lead constituting silicon and other borosilicate lead glass, lanthanum constituting the lanthanum glass, and other bismuth.

In addition to the above, zirconium, titanium, vanadium, aluminum, tantalum, zinc and the like may be added as necessary.

Examples of the thermally decomposable organic compounds of the above-described elements include alcoholates such as ethyl alkoxide and isopropoxide, fatty acid esters represented by hexanoic acid ester, polycyclic organic compounds such as menthol alcoholate and ester, and abiet. Rosin compounds such as acid salts, siloxanes, and boric acid organic compounds.

The temperature at which the paste containing these organic compounds is heated to produce a desired metal or oxide is different depending on the compound used, but is usually 500 to 800 ° C., and an atmosphere containing oxygen is preferable.

In the above-mentioned compounds, pyrolytic organic compounds are used, but compounds which decompose by ultraviolet irradiation to produce metals and / or oxides, for example, ruthenium salts of naphthoquinonediazo compounds having carboxyl groups and novolac phenolic resin compounds And a compound with lead, silicon or bismuth.

When using these compounds, ultraviolet rays are decomposed by irradiating the coating film of the paste.

According to the present invention, a resistor layer having a uniform film thickness of 0.3-3 µm can be obtained. Since the resistor layer is thin and there are few defects such as bubbles, the thermal efficiency at the time of recording is also good.

In the conventional thin film resistor layer, it is difficult to obtain a film having a uniform composition with a film thickness of 0.3 µm or more. On the other hand, in the thick film type, it is easy to obtain a stable film having a thickness of 3 µm or more, but it is difficult to form a homogeneous film below this value. As described above, it is difficult to obtain a stable film having a thickness in the range of 0.3 µm to 3.0 µm as a conventional technique.

The present invention can provide a thermal head having a resistive layer of a uniform and excellent film having a film thickness of 0.3 to 3 µm, which was not possible in the related art. According to the present invention, excellent thermal heads, such as recording quality and thermal efficiency, are obtained.

Best Mode for Carrying Out the Invention

3 is a longitudinal sectional view of a main portion showing a configuration example of a thermal head according to the present invention.

(1) is a board | substrate whose surface is insulating at least. A steel plate coated with porcelain enamel and an alumina substrate having a glaze layer on the surface are used. (2) is a resistor layer formed on the surface thereof. (3) and (4) are electrodes formed on the resistor layer 2. Usually, one electrode is a common electrode and the other is an individual electrode, and a plurality of such electrode pairs are arranged in a line form. (5) is a wear-resistant layer covering the surfaces of these electrodes (3), (4) and resistor layer (2), in contact with the recording paper to transfer heat generation of the resistor layer to it, and at the same time the electrode or resistor layer wears out. To prevent them.

4 shows another configuration example of the thermal head. Reference numeral 11 denotes a substrate, on which electrodes 13 and 14 are formed, and then a resistor layer 12 and a wear resistant layer 15 are formed.

Hereinafter, specific embodiments of the present invention will be described.

Example 1

A pair of gold electrode layers is formed on an alumina substrate having a glaze layer of 50 µm thick. The resistor paste is screen printed and baked in contact with both electrodes between the electrode layers to form a 350 탆 wide resistor layer. The resistor paste used was a resin having a viscosity of 50,000 cp, which was made of hexalate, Ru, Rh, Si, B, and Pb, respectively, cellulose, and terpineol. After paste printing, it was prevented, dried and calcined at 800 ° C. to obtain a resistor layer. A paste of borosilicate glass frit was printed on the resistor layer and fired to form a wear resistant layer. In addition, the mixing ratio of the hexanoate in the resistor paste was 10: 4: 14: 4: 68 by the weight ratio of Ru: Rh: Si: B: Pb.

Example 2

Ethyl alcohols of ruthenium octanate, ethyl alkoxide of ruthenium, Pb, Si, and B are mixed in a weight ratio of Ru: Pb: Si: B to 8: 70: 15: 7, and ethyl cellulose and ter The paste to which pinene was added was printed and fired to obtain a resistor layer. Others are the same as in Example 1.

Example 3

A resistor layer as in Example 1 was formed, and a silicon carbide film having a thickness of 3 µm was formed on the resistor layer by sputtering to form a wear resistant layer.

Example 4

Terpineol was added to the paste of Example 1 and the viscosity was set to 1000 cps. This paste was applied using a spinner on a steel sheet having an enamel coating layer having a thickness of 100 µm. The spin speed of the spinner was 2000 rpm. After drying, baking was carried out at 800 ° C., and then a resistor was formed in a predetermined pattern by a photo plate etching method. Here, the liquid mixture of sulfuric acid and ammonium fluoride was used for the etching liquid. Next, a paste of gold ethyl mercaptide was printed on the above-mentioned resistor layer and baked to form a gold layer, and then a gold electrode layer was formed in a predetermined pattern by a photo plate etching method. On this, a paste consisting of hexalate salts of Si, B, and Pb, ethyl cellulose, and terpineol was printed and fired to form a wear resistant layer.

Example 5

The same resist paste paste film as in Example 4 was formed on a steel sheet having an enamel coating layer and baked at 800 ° C. to obtain a resistor layer. A chromium-copper layer was formed on this resistor layer by sputtering, and then the resistor layer and the electrode layer were formed in a predetermined pattern by photolithography etching of the chromium-copper layer and photolithography etching of the resistor layer. Thereafter, a wear resistant layer was formed in the same manner as in Example 3.

Example 6

A large number of individual electrodes were formed in a line state on the alumina substrate having the glaze layer on the surface, and the common electrodes were formed by opposing the individual electrodes. A resistive paste was discharged using a painting pen having a slit having a size of 350 μm × 10 μm between these electrodes to form a film in contact with both electrodes. The resistor paste used here is the same as in Example 1. The paste film was dried and then fired at 800 ° C. to obtain a resistor layer. The paste of borosilicate glass frit was printed and baked on the resistor layer to form a wear resistant layer.

Example 7

The same procedure as in Example 1 was carried out except that ethyl cellulose and terpineol were added to a mixture of ruthenium hexanate and borosilicate glass frit with a weight ratio of 1:10.

Example 8

It is the same as Example 1 except the paste which consists of ethyl mercaptide of gold, diphenylsiloxane, the menthol compound of boron, ethyl cellulose, and terpineol as a paste for resistors. However, the mixing ratio of the organic compound in the paste was 0.15: 1 by weight ratio of gold: (Si + B).

Comparative Example 1

A thick film-type thermal head in which a paste is printed and baked on an alumina substrate having a glaze layer on its surface to form a gold electrode, a resistor layer, and a wear-resistant layer made of glass. Here, the paste used for forming the resistor is an average particle diameter of 0.1 mu m, and ethyl cellulose and terpineol are added to a mixture of 40 wt.% Ruthenium oxide powder and 60 wt.% Borosilicate glass frit having a maximum particle diameter of 0.8 mu m. The printed paste film was baked at 800 ° C.

Comparative Example 2

A thin film-type thermal head in which a resistor layer made of Ta-Si, an electrode layer made of Cr-Cu, and a wear resistant layer made of silicon carbide are formed on an alumina substrate having a glaze layer on its surface.

Various characteristics of the thermal head of each of the above Examples and Comparative Examples are shown in the following table.

[Industry availability]

The resistive layer of the thermal head according to the present invention has a uniform distribution of the composition of the material, and because the heat capacity is small in the thin film, the thermal efficiency at the time of recording is excellent, and the recording of excellent quality is given. Therefore, the present invention can be applied to a high gradation full-color printer, a facsimile or a word processor.

Claims (13)

In a thermal head composed of at least one pair of electrodes, a resistor layer in contact with these electrodes, and a substrate having at least a surface insulating and supporting the electrode and the resistor layer thereon, the resistor layer is formed of glass. A thermal head comprising a matrix and ruthenium and rhodium and / or oxides thereof embedded in a gap between the matrix and the atomic bond. The thermal head according to claim 1, wherein ruthenium contained in the resistor layer is less than 10 wt.%. The thermal head according to claim 1, wherein the glass constituting the resistor layer is borosilicate glass or lead borosilicate glass. The thermal head according to claim 1, wherein the glass forming the resistor layer is lanthanum-based glass. In a thermal head comprising at least a pair of electrodes, a resistor layer in contact with these electrodes, and a substrate having at least a surface insulating and supporting the electrode and the resistor layer thereon, the resistor layer is formed of glass. A thermal head comprising a matrix and elements selected from the group consisting of gold, silver, nickel, chromium and tantalum dispersed mainly at the molecular level in the matrix. The thermal head according to claim 5, wherein the matrix is borosilicate glass or lead borosilicate glass. In the method of manufacturing a thermal head comprising at least a pair of electrodes, a resistor layer in contact with these electrodes, and a substrate on which at least the surface is insulating and supports the electrode and the resistor layer on the surface, the resistor layer described above. The process for forming a metal contains a pyrolytic organic compound of an element selected from the group consisting of ruthenium and rhodium and / or gold, silver, nickel, chromium and tantalum and an element forming a matrix of glass. Forming a film of the paste on the substrate before or after forming the electrode; heat-treating the organic compound in the paste by heat treatment; and a metal of the resistive component element dispersed in the matrix and And / or a process for producing a resistive layer of oxide, wherein the thermal head is produced. . 8. The method of manufacturing a thermal head according to claim 7, wherein the paste comprises the organic compound, a solvent in which the organic compound is dissolved, and an organic binder soluble in the solvent. In the method of manufacturing a thermal head comprising at least a pair of electrodes, a resistor layer in contact with these electrodes, and a substrate on which at least the surface is insulating and supports the electrode and the resistor layer on the surface thereof, the above-described resistor layer The process of forming a film is a film of a paste containing a thermally decomposable organic compound and glass frit of an element selected from the group consisting of ruthenium and rhodium and / or gold, silver, nickel, chromium and tantalum to form the electrode described above. A step of thermally decomposing the organic compound in the paste by a step of forming on a substrate before or after formation and by heat treatment to produce a resistor layer of a metal matrix and / or oxide of a glass matrix and a resistor component element dispersed in the matrix. Method of manufacturing a thermal head, characterized in that the. 10. The method of manufacturing a thermal head according to claim 9, wherein the paste is composed of the organic compound, a solvent in which the organic compound is dissolved, and an organic binder which can be dissolved in the solvent. In the method of manufacturing a thermal head comprising at least a pair of electrodes, a resistor layer in contact with these electrodes, and a substrate on which at least the surface is insulating and supports the electrode and the resistor layer on the surface thereof, the above-described resistor layer Forming a film of a paste containing an ultraviolet-decomposable organic compound of a resistive element and an ultraviolet-decomposable organic compound of an element forming a matrix of glass on a substrate before or after forming the electrode. And decomposing the organic compound in the paste by ultraviolet irradiation to produce a resistive layer of a glass matrix and a metal and / or oxide of a resistive component element dispersed in the matrix. Method of manufacturing the head. 12. The method of manufacturing a thermal head according to claim 11, wherein the paste is composed of the organic compound, a solvent in which the organic compound is dissolved, and an organic binder which can be dissolved in the solvent. The thermal head according to claim 1, wherein 0 <(Rh / Ru) <5.

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