JP2667540B2 - Manufacturing method of thermal head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal head used in a thermal printer, and more particularly to improvement of a manufacturing method thereof.

[Conventional technology]

In general, a thermal head is provided with a glaze layer having a heat storage function on an insulating substrate in front or in part, and a plurality of heating resistors and heating resistors constituting heating dots on the glaze layer are energized. The electrodes are formed in an array and covered with a protective layer above them.

In such a thermal head, the heating resistor is selectively heated in accordance with the print information, and the heating resistor to which the thermal head is pressed is partially heated, or the thermal head is pressed. The printing can be performed by partially melting the ink of the present ink ribbon and transferring it to paper.

Conventionally, in the formation of a heating resistor and an electrode in a thermal head, usually, a heating resistor layer is formed by sputtering, a high-temperature vacuum heat treatment is applied, and a photoresist is formed thereon by patterning. Is used as a mask to form a plurality of heating resistors by pattern etching, then an electrode layer is formed by sputtering, a photoresist is formed on this electrode layer by patterning, and the photoresist is used as a mask to form an electrode. Either pattern etching of the layer to form a plurality of electrodes, or, after vacuum heat treatment of the heating resistor layer, forming an electrode layer on the heating resistor layer by sputtering, and applying a photoresist on the electrode layer Formed by patterning, using this photoresist as a mask, the electrode layer and heating resistor The etched had methods are taken of forming a plurality of heating resistors and electrodes.

[Problems to be solved by the invention]

In the above-described conventional method, the temperature in the vacuum heat treatment step for stabilizing the heating resistor is as high as 500 to 700 ° C., and the heat capacity of the vacuum heat treatment apparatus is very large, so that the cooling time becomes long. Also, since a vacuum chamber is used, the processing capacity is small and the production efficiency is extremely poor.

Also, in these heat treatments, since the heating resistor layer is naked,
If foreign matter adheres to the heating resistor layer, defects such as diffusion occur, so that it is necessary to work in a high-level clean room.

Further, in recent years, a heat-resistant resistor having high heat resistance has been desired in view of a market need for high-speed printing in a thermal printer. Therefore, high-temperature heat treatment of the heat-resistant resistor layer has become indispensable. That is, the heating resistor that does not perform this heat treatment, when the heating temperature of the heating dot becomes high,
There is a strong tendency that recrystallization or the like of the resistor structure occurs and the resistance value sharply decreases. However, since the thermal head is driven at a constant voltage, excessive power is supplied to the heating resistor, which leads to accelerated destruction. The fact that the temperature coefficient of the heating resistor is generally negative also causes the accelerated destruction of the heating resistor.

According to high-speed printing of the market needs for a thermal printer in recent years as described above, the high heat resistance of the heating resistor is essential, Ta ₂ that has been used conventionally N or Ta-Si-based heating resistor ratio Since the resistance is as small as 200 to 250 .mu..OMEGA.cm, in order to obtain high resistance, the thickness must be extremely thin, for example, 100.degree., And there are problems such as poor oxidation resistance and unstable film quality. For this reason, in recent years, a cermet-based heating resistor has been used in place of the above-described tantalum-based heating resistor, and a high specific resistance of 1 mΩ · cm · several tens of mΩ · cm has been achieved. Although the oxidation resistance is improved by securing 1000 mm or more, there is a manufacturing problem that it is difficult to use a material suitable for high heat resistance arbitrarily due to limitations on etching properties. I have.

An object of the present invention is to provide a method of manufacturing a thermal head capable of overcoming the above-described problems of the related art and providing a thermal head that satisfies high-speed printing even with a heating resistor having poor etching properties. Aim.

[Means for solving the problem]

In order to achieve the above-mentioned object, a method of manufacturing a thermal head according to claim 1 includes providing a glaze layer on an insulating substrate, forming a plurality of heating resistors and electrodes on the glaze layer in an aligned manner, In a thermal head in which each heating resistor, electrode and glaze layer are covered with a protective layer, a conductive oxide layer is laminated on the heating resistor layer laminated on the glaze layer, and the conductive oxide layer Is etched by photolithography to form a mask pattern. The exposed heating resistor layer and conductive oxide layer are thermally oxidized, and an electrode layer is laminated on the heating resistor layer and conductive oxide layer. Then, an electrode pattern is formed by a photolithography technique, and the glaze layer, the heating resistor layer and the electrode are covered with a protective layer.

Further, the method for manufacturing a thermal head according to claim 2 comprises:
The heat generating resistor and the conductive oxide layer exposed in the first aspect are thermally oxidized, and then the conductive oxide layer is removed, and then the electrode layer is laminated.

The method of manufacturing a thermal head according to claim 3, further comprising: providing a glaze layer on the insulating substrate; forming a plurality of heating resistors and electrodes on the glaze layer in an aligned manner; A thermal head in which an electrode and a glaze layer are covered with a protective layer, an insulating oxide layer is laminated on the heating resistor layer laminated on the glaze layer, and the insulating oxide layer is formed by photolithography. A mask pattern is formed by etching, the exposed heating resistor layer is thermally oxidized, the insulating oxide layer is removed, an electrode layer is laminated on the heating resistor layer, and the electrode pattern is formed by photolithography. Is formed, and the glaze layer, the heating resistor and the electrodes are covered with a protective layer.

(Operation)

According to the present invention described above, since the conductive oxide layer or the insulating oxide layer is provided on the heating resistor layer, a vacuum heat treatment apparatus is not required, and a large-capacity heat treatment apparatus in an air atmosphere can be easily applied. can do. Also, by simultaneously forcibly oxidizing the heating resistor layer using the conductive oxide layer or the insulating oxide layer as a mask, a plurality of heating resistors can be patterned, and the heating resistor can be patterned without using conventional etching. Since the body can be formed, the heating resistor layer, which was conventionally difficult to etch, can be easily made practical by the method of the present invention, so that a wide range of heating resistor materials suitable for higher heat resistance can be selected. Become like Further, the heating resistor layer is not etched, and since the oxide layer is interposed, the step coverage of the protective layer is increased, and the oxidation resistance of the resistor is improved.

〔Example〕

1 and 2 show an embodiment of a method for manufacturing a thermal head according to the present invention. In FIG. 1, a flat plate made of alumina or the like is used. A glaze layer 2 made of glass or the like having an upper surface formed in an arc-shaped cross section on the insulating substrate 1 of FIG.
Are piled up for heat storage.

Then, on the upper surfaces of the insulating substrate 1 and the glaze layer 2, a heating resistor layer 30 made of Ta-Si-C or the like for forming the plurality of heating resistors 3A is formed to a thickness of about 0.2 μm. Is formed by sputtering. A conductive oxide (eg, In ₂ O ₃ , Nb ₂ O ₅ , Ti) is formed on the heating resistor layer 3.
_Ox, etc.) 4 is formed by sputtering so as to have a thickness of about 0.1 μm, and a mask pattern (not shown) is formed on the conductive oxide layer 4 using a photoresist. The oxide layer 4 is etched with a suitable etchant (for example, hydrofluoric nitric acid water) to form a mask at the portion corresponding to each heating resistor 3A (FIG. 2). Then, a thermal head in an intermediate stage of this production is placed in an electric furnace in an air atmosphere, a heat treatment at about 700 ° C. for 3 hours is simultaneously performed with air oxidation, and then gradually cooled. This heat treatment oxidizes and insulates the heating resistor layer 3 at a portion not covered by the conductive oxide layer 4. As a result, a plurality of unoxidized heating resistors are provided below the conductive oxide layer 4. The bodies 3A will be formed in an array.

Next, an electrode layer 5 made of Al or the like is provided on the conductive oxide layer 4 and the exposed heating resistor layer 3 in an amount of about 1 to 2 μm.
m by sputtering, a mask pattern (not shown) is formed on the electrode layer 5 using a photoresist, and etching is performed so as to conform to the conductive oxide layer 4. The electrode 5A is formed at the position where the process is to be performed. This electrode 5A is composed of a common electrode and an individual electrode extending on both sides of the heating dot of each heating resistor 3A. Then, a thermal head can be manufactured by forming a protective layer 6 on the electrode layer 5, the exposed heating resistor layer 3, and the conductive oxide layer 4 by sputtering.

According to the present embodiment as described above, the heating resistor layer 3 is partially covered with the conductive oxide layer 4 and is heat-treated, so that a portion of the heating resistor layer not covered with the conductive oxide layer 4 is heated. 3 is oxidized and insulated, whereby the heating resistor 3A is formed below the conductive oxide layer 4, so that the heating resistor 3A can be formed without etching. As a result, even if the material has excellent heat resistance that can cope with high-speed printing, even a material having poor etching properties can be used as a material of the heating resistor 3A, and the heating resistor 3A can be used.
Can be selected in a wide range.

After the conductive oxide layer 4 on the heating resistor layer 3 is etched and heat-treated, the electrode layer 5 is formed after removing the conductive oxide layer 4 on the heating resistor 3A by etching. It may be.

Further, a portion corresponding to each heat-dissipating resistor 3A is covered with an insulating oxide layer such as SiO ₂ instead of the above-described conductive oxide layer 4, and the heat treatment described above is performed to form the heat-generating resistor 3A. You may make it. In this case, it is necessary to remove the insulating oxide layer by etching with hydrofluoric-nitric acid solution before forming the electrode layer 5.

Furthermore, the present invention can be modified in various ways.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a thermal head that satisfies high-speed printing even when using a heating resistor having poor etching properties. can do.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a thermal head showing an embodiment of a method of manufacturing a thermal head according to the present invention, and FIG. 2 is a plan view of a main part of the thermal head at an intermediate stage of manufacturing. DESCRIPTION OF SYMBOLS 1 ... Insulating substrate, 2 ... Glaze layer, 3 ... Heating resistor layer, 3A ... Heating resistor, 4 ... Conductive oxide layer, 5 ...
... electrode layer, 6 ... protective layer.

Claims (3)

(57) [Claims] A glaze layer is provided on an insulating substrate, a plurality of heating resistors and electrodes are formed in an array on the glaze layer, and each of the heating resistors, electrodes and glaze layer is covered with a protective layer. In the thermal head, a conductive oxide layer is stacked on the heating resistor layer stacked on the glaze layer, and a mask pattern is formed by etching the conductive oxide layer by a photolithography technique. The exposed heating resistor layer and the conductive oxide layer are thermally oxidized, an electrode layer is laminated on the heating resistor layer and the conductive oxide layer, and an electrode pattern is formed by a photolithography technique. A method for manufacturing a thermal head, wherein a protective layer covers a layer, a heating resistor layer, and an electrode. 2. The method according to claim 1, wherein after the exposed heating resistor and the conductive oxide layer are thermally oxidized, the conductive oxide layer is removed and the electrode layer is laminated. The manufacturing method of the thermal head described in the above. 3. A glaze layer is provided on an insulating substrate, a plurality of heating resistors and electrodes are formed on the glaze layer in an array, and a protective layer is formed on each of the heating resistors, electrodes and glaze layer. In a coated thermal head,
An insulating oxide layer is laminated on the heating resistor layer laminated on the glaze layer, a mask pattern is formed by etching the insulating oxide layer by photolithography technology, and the exposed heating resistor layer is removed. Thermal oxidation, removing the insulating oxide layer, laminating an electrode layer on the heating resistor layer, forming an electrode pattern by photolithography technology, and protecting these glaze layer, heating resistor and the electrode with a protective layer A method of manufacturing a thermal head, wherein the thermal head is coated with.