JPH0592596A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a thermal head wherein reliability of the thermal head to be manufactured can be improved and the manufacturing process can be simplified at the same time. CONSTITUTION:On insulating substrates 22, a glazed layer 23 is formed. On the glazed layer 23, a plurality of heat generating resistors 37, a common electrode 25 for pinching a heat generating resistor 27, and a plurality of individual electrodes 26 are formed. At this time, at forming the glazed layer, a plurality of protrusions 28 are formed in clearances 38 between the individual electrodes 26 in parallel with the arranging direction of the heat generating resistors 37. On the glazed layer 23, the heat generating resistors 37, the common electrode 25, and the individual electrodes 26 are formed. Next, the insulating substrates 22 are layered in a state that the glazed layer is disposed in the same direction and an area including a forming area of the glazed layer 23 is exposed, so as to form a protective film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thermal head with improved mass productivity.

[0002]

2. Description of the Related Art In recent years, thermal heads have been widely used as printing apparatuses such as word processors and facsimile machines. FIG. 7 shows a perspective view of a typical conventional thermal head 1. The thermal head 1 has a heating element array 3 including a large number of heating elements formed on an insulating substrate 2, and a common electrode and an individual electrode (not shown) are connected to each heating element. The individual electrodes are connected to the drive circuit element 4 and selectively heat-driven.

On the other hand, a protective film covering the vicinity of the heating element array 3 and made of silicon nitride Si ₃ N ₄ or the like is provided as a protective film forming region 5.
Are formed by using a vacuum film forming apparatus such as sputtering. In order to improve the mass productivity in this protective film forming step, as shown in FIG. 8, a plurality of head substrates 6 each having a heating element array 3, a drive circuit element 4 and a protective film formed on the insulating substrate 2 are provided. They are stacked on the support base 7 while being displaced from each other. This positional deviation is determined so that the upper head substrate 6 covers the lower head substrate 6 except for the protective film formation region 5. The head substrates 6 thus stacked are fixed by a pressing tool 8 and sputtering is performed.

At this time, as described above, the individual electrodes and the like are formed on the main surface of the insulating substrate 2, and when the substrates are stacked, these individual electrodes and the like are on the upper head substrate 6.
May be cut by sliding on the edge of the. In order to prevent such a problem, (1) As shown in FIG. 9, the organic sheet 9 is sandwiched between the head substrates 6 stacked on the support 7 to protect the lower head substrate 6.

(2) As shown in FIG. 10, an organic substance is linearly applied on the head substrate 6 to form the protective ridges 10 to prevent the wiring pattern from being damaged.

Techniques such as the above have been proposed.

[0007]

The protective film is formed by a vacuum film forming technique such as sputtering. In order to make the protective film highly hard, it is necessary to form the protective film at a substrate temperature of about 400.degree. It is known to be good. However, when such a high temperature treatment is performed, since the organic substances are used in the above-mentioned two conventional examples, the organic sheet 9 and the protective ridges 10 are decomposed, gas is generated, Causes a problem such as seizure on the insulating substrate 2, resulting in a problem that high temperature processing is impossible.

When the organic sheet 9 is used, the high temperature causes the organic sheet 9 to be stretched to be in a so-called wavy state, a large gap is generated between the head substrates 6 stacked, and a component of the protective film is generated. This causes a problem that another head substrate should go around to the surface of the substrate to be covered. When the protective film component wraps around the surface of the substrate, in the connecting step of the drive circuit element 4 mounted on the insulating substrate 2 after the formation of the protective film, a connection terminal portion for the drive circuit element 4 such as an individual electrode on the insulating substrate 2 is formed. It is covered with the above-mentioned protective film component, which causes a problem that electrical conduction becomes impossible.

As a manufacturing process of the thermal head 1,
The step of sandwiching the organic sheet 9 between the head substrates 6 or the step of forming the protective ridges 10 is required, resulting in a problem that the manufacturing process becomes complicated. Further, when the organic sheet 9 is used, the number of parts and cost increase.

An object of the present invention is to solve the above-mentioned technical problems, improve the reliability of the manufactured thermal head, and at the same time simplify the manufacturing process. It is to provide a manufacturing method.

[0011]

According to the present invention, a glaze layer is formed on an insulating substrate, and a plurality of heating elements, a common electrode sandwiching the heating elements, and a plurality of individual electrodes are formed on the glaze layer. In the method, when forming the glaze layer, a step of forming a plurality of protrusions in a space between the individual electrodes in parallel with the arrangement direction of the heating elements, and forming a plurality of heating elements, a common electrode and an individual electrode on the glaze layer And a step of stacking a plurality of insulating substrates in a state where the glaze layer faces in the same direction and the glaze layer is exposed to form a protective film.

[0012]

In the method of manufacturing the thermal head according to the present invention,
A glaze layer is formed on an insulating substrate, and a plurality of heating elements, a common electrode sandwiching the heating elements, and a plurality of individual electrodes are formed on the glaze layer. At this time, at the time of forming the glaze layer, a plurality of protrusions are formed in the space between the individual electrodes in parallel with the arrangement direction of the heating elements, and the plurality of heating elements, the common electrode and the individual electrodes are formed on the glaze layer. Next, a stacked protective film is formed on the plurality of insulating substrates so that the glaze layer faces in the same direction and the region including the region where the glaze layer is formed is exposed.

Thus, in the step of forming the protective film, the protrusion can be used as a means for holding the insulating substrates in a state of being separated from each other. The protrusions are made of the same material as the glaze layer and have resistance to relatively high temperatures. Therefore, in order to make the protective film have high hardness, it can be formed at a substrate temperature of about 400 ° C. Moreover, the high temperature decomposes the protrusions and generates gas,
Furthermore, it is possible to prevent problems such as seizing on the insulating substrate. With these, the reliability of the thermal head can be significantly improved.

Further, since the protrusions are prevented from wavy due to high temperature, it is possible to solve the problem that the protective film material wraps around the surface of the substrate to be originally covered, and to prevent the problem that electrical conduction becomes impossible or defective. To do. Further, since the protrusion is formed in the same step as the step of forming the glaze layer,
The manufacturing process is simplified.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a thermal head 2 according to an embodiment of the present invention.
2 is a sectional view of the thermal head 21. FIG. The thermal head 21 includes a heat-resistant substrate 22 formed in the shape of a rectangular plate from a ceramic such as aluminum oxide Al ₂ O _3, and a glaze layer 23 made of, for example, glass is formed in the shape of a strip on the heat-resistant substrate 22.
As will be described later, a plurality of protrusions 28 are formed, for example, at a height h1 (10 to 20 μm as an example). A resistor layer 24 made of, for example, tantalum nitride Ta ₂ N is formed on the heat-resistant substrate 22 over almost the entire surface by a thin film technique such as sputtering or etching, for example, 500 Å
With a layer thickness t1.

On the end portion side of the heat resistant substrate 22 on the resistor layer 24, for example, a metal layer is formed by a vacuum film forming technique such as sputtering to a film thickness t2 (1 μm as an example) and then patterned. The common electrode 25 is formed in parallel with the glaze layer 23, and the plurality of individual electrodes 26 are formed.
Are arranged in a straight line. The common electrode 25 is the heat resistant substrate 22.
Along the peripheral edge of the connection terminal 27, and the vicinity of the end thereof is configured as a connection terminal 27. Such common electrode 25 and individual electrode 2
6 is a range including the formation region of the heating resistor 37, and is covered with a protective film 29 such as SiN.

A drive circuit element 30 is provided on the head substrate 22.
Will be installed. Such driving circuit elements 30 are arranged in parallel with the arrangement direction of the heating resistors 37 for each of the plurality of heating resistors 37 as shown in FIG. Further, on the heat-resistant substrate 22, the same material as the common electrode 25 is formed, and in the same step, a signal line 31 for externally inputting print data, control signals and the like input to the drive circuit element 30 is formed. An external wiring board 32 is connected to the signal line 31.

FIG. 3 is a process drawing showing the manufacturing process of this embodiment, and FIG. 4 is a perspective view showing this manufacturing process. Process a
In No. 1, as shown in FIG. 4A, the glaze layer 23 and the plurality of protrusions 28 are formed on the heat resistant substrate 22 by a screen printing device described later. As shown in FIG. 1, the protrusion 28 is formed at a position which becomes a void 38 between the individual electrode 26 and the signal line 31 which are formed in the subsequent manufacturing process.

FIG. 5 is a system diagram of the screen printing device 33 used in this embodiment. In order to perform printing, the screen 34 on which the printing pattern is formed is arranged at a position separated from the heat-resistant substrate 22 below by a distance d1. The glass paste 35 applied to the heat-resistant substrate 22 is provided on the screen 34, and the squeegee 36 is lowered in the arrow A2 direction to make contact with the screen 34 and then further pressed to bend the heat-resistant substrate 22. Contact. After that, the squeegee 36 is moved in the arrow A1 direction and printing is performed.

In step a2, the heat resistant substrate 22 is entirely covered,
The resistor layer 24 is formed by a thin film technique such as sputtering. In step a3, a metal layer such as aluminum is formed on the resistor layer 24 by sputtering or the like, and the common electrode 25 and the individual electrode 26 are formed as shown in FIG.
And patterning so that the signal line 31 is formed. In step a4, the plurality of heat resistant substrates 22 at this manufacturing stage are stacked on the support base 39 as shown in FIG.

The respective heat-resistant substrates 22 are mutually main-scanned so that the upper heat-resistant substrate 22 covers the remaining region of the lower heat-resistant substrate 22 other than the protective film forming region 40 shown in FIG. 4B. They are arranged in a staggered manner. Heat resistant substrate 22 in this state
Are held by the protrusions 28 at a distance of about the height h1 of the protrusions 28. In this state, the substrate is heated at a high temperature of about 400 ° C., and the protective film 29 is simultaneously formed on the protective film forming region 40 for each heat resistant substrate 22. Process a5
Then, the heat resistant substrates 22 after the formation of the protective film are separated, and the drive circuit elements 30 are connected to the individual electrodes 26 and the connection terminals of the signal lines 31 for each heat resistant substrate 22. In this way, the thermal head 21 is formed.

As described above, in this embodiment, when the protective film 29 is formed, the heat-resistant substrates 22 stacked on the support 39 are separated from each other by using the protrusions 28 made of the same material as the glaze layer 23. It was designed to separate h1. Therefore, even if the backside end of the upper heat-resistant substrate 22 is sharp due to fluff or the like, it is possible to prevent the individual electrodes 26 and the like of the lower heat-resistant substrate 22 from being damaged by the fluff. As a result, the reliability and yield of the manufactured thermal head 21 can be significantly improved.

The protrusions 28 are made of the same material as the glaze layer 23, that is, silicate glass or the like.
2 has a sufficient resistance to a surface temperature of 400 ° C. Therefore, it is possible to realize the protective film 29 having a hardness higher than that of the conventional one, and cracks are generated during use, and foreign matter is caught between the platen roller (not shown) and the protective film 29 during the printing operation. It is possible to prevent the occurrence of cracks, improve the reliability of the thermal head 21, and extend the life of the thermal head 21.

The protrusions 28 do not become wavy even when the temperature is high, as in the case of using the organic sheet 9 in the prior art, so that a situation in which an excessive gap is formed between the heat resistant substrates 22 is prevented. You can According to the measurement by the inventor of the present invention, the heat-resistant substrate 22 of this embodiment is used to form the protective film 29.
It was confirmed that the wraparound of the protective film material from the protective film formation region 40 toward the signal line 31 side when the film was formed by sputtering could be suppressed to about 2 to 3 mm.
As a result, when the drive circuit element 30 is mounted on the heat-resistant substrate 22 on which the protective film 29 has been formed, the protective film material side wraps around to the connection parts of the individual electrodes 26 and the signal lines 31, which makes electrical conduction difficult. In this respect, the reliability of the thermal head 21 can be improved.

The protrusions 28 are simultaneously formed of the same material in the same process as the manufacturing process of the glaze layer 23. That is, the screen 3 of the screen printing device 33 shown in FIG.
This can be realized by only slightly changing the pattern of No. 4, and the need for a special device or process for forming the protrusion 28 is eliminated, and the manufacturing process can be simplified.

[0026]

As described above, in the method of manufacturing the thermal head according to the present invention, the glaze layer is formed on the insulating substrate,
A plurality of heating elements, a common electrode sandwiching the heating elements, and a plurality of individual electrodes are formed thereon. At this time, at the time of forming the glaze layer, a plurality of protrusions are formed in the space between the individual electrodes in parallel with the arrangement direction of the heating elements, and the plurality of heating elements, the common electrode and the individual electrodes are formed on the glaze layer. Next, a stacked protective film is formed on the plurality of insulating substrates so that the glaze layer faces in the same direction and the region including the region where the glaze layer is formed is exposed.

Thus, in the step of forming the protective film, the protrusion can be used as a means for holding each insulating substrate in a state of being separated from each other. The protrusions are made of the same material as the glaze layer and have resistance to relatively high temperatures. Therefore, since the protective film has high hardness, it can be formed at a substrate temperature of about 400 ° C. Moreover, it is possible to prevent problems such as the decomposition of the protrusions and the generation of gas due to the high temperature, and the seizure of these on the insulating substrate. With these, the reliability of the thermal head can be significantly improved.

Further, since it is possible to prevent the protrusions from becoming wavy due to high temperature, it is possible to solve the problem that the protective film material wraps around the surface of the substrate to be originally covered, and to prevent the problem that electrical conduction becomes impossible or defective. To do. Further, since the protrusion is formed in the same step as the step of forming the glaze layer,
The manufacturing process is simplified.

[Brief description of drawings]

FIG. 1 is a perspective view of a thermal head 21 according to an embodiment of the present invention.

FIG. 2 is a sectional view of a thermal head 21.

FIG. 3 is a process drawing showing the manufacturing process of the thermal head 21.

FIG. 4 is a perspective view showing this manufacturing process.

FIG. 5 is a cross-sectional view showing the manufacturing process of the present embodiment.

FIG. 6 is a system diagram of a screen printing apparatus used in this embodiment.

FIG. 7 is a perspective view of a conventional thermal head 1.

FIG. 8 is a cross-sectional view showing a manufacturing process of a conventional example.

FIG. 9 is a cross-sectional view showing a manufacturing process of a conventional example.

FIG. 10 is a cross-sectional view showing a manufacturing process of a conventional example.

[Explanation of symbols]

 21 Thermal Head 22 Heat Resistant Substrate 23 Glaze Layer 28 Protrusion 33 Screen Printing Device 35 Glass Paste 38 Void 39 Supporting Stand 40 Protective Film Forming Area

Claims (1)

[Claims] 1. A method of manufacturing a thermal head, wherein a glaze layer is formed on an insulating substrate, and a plurality of heating elements, a common electrode sandwiching the heating elements, and a plurality of individual electrodes are formed on the glaze layer. A step of forming a plurality of protrusions in the gap between the individual electrodes in parallel with the arrangement direction of the heating elements, a step of forming a plurality of heating elements, a common electrode and an individual electrode on the glaze layer, and a plurality of insulating substrates And a step of stacking the glaze layers in the same direction and exposing the glaze layers to form a protective film.