JP2000006454A - Insulating substrate for thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject insulating substrate preventing the separation of a formed membrane after cooling and enhanced in yield and productivity in a membrane forming process. SOLUTION: An insulating substrate is constituted of the projection 22 for a common electrode formed on the surface of an alumina substrate 21 by a thick film process, projected glaze glass layers 24a1, 24a2 having the projection 22 as apexes and the glaze glass layers 24a, 24b formed on the alumina substrate 21. In this case, if the lower part of each of the projected glaze glass layers 24a1, 24a2 having the projection 22 for the common electrode as apexes comprises a crystallized glass layer and the upper part thereof comprises a non-crystalline layer, the baking temp. of the glaze glass layer of the upper part can be set high and the surface roughness of the glaze glass layer can be reduced and this constitution is still more effective from an aspect of the elimination of separation in a film forming process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a thermal head insulating substrate used for a thermal head, which is a main component of a printing section of a color printer or the like.

[0002]

2. Description of the Related Art As prior art, the applicant of the present invention has applied for patents of related arts such as Japanese Patent Application No. 9-186021 (conventional example 1) and Japanese Patent Application No. 10-155591 (conventional example 2). Has been filed. Hereinafter, each of the conventional examples will be briefly described.

(1) Conventional Example 1 (Japanese Patent Application No. 9-186021)
No. 1) claims that Cr is 10 to 30% by weight,
A metal substrate made of an iron alloy containing 0.1 to 6% by weight of Al, a projection serving as a common electrode portion formed on the surface of the metal substrate, and an oxidation rich in aluminum oxide formed on the surface of the metal substrate A thermal head insulating substrate comprising a coating, a crystalline glass layer formed on the oxide film, and a glaze glass layer formed on the crystalline glass layer; An insulating metal substrate for a thermal head, wherein an expansion coefficient is smaller than a thermal expansion coefficient of the metal substrate.

[0004] In the second aspect, the firing temperature of the crystalline glass is set to be lower than its melting point by 10 ° C. or more,
In addition, the insulating metal substrate for a thermal head is such that the softening point of the glaze glass is lower than the softening point of the crystalline glass by 50 ° C. or more.

The use of a metal substrate as an insulating substrate having a projection serving as a common electrode portion is effective in terms of electrical conductivity, and has been used before the one shown in Conventional Example 1. However, prior to the first conventional example, there was a problem in that when processing a projection serving as a common electrode portion on the surface of a metal substrate, processing distortion was generated, and the substrate was warped by heating in a later step.

Therefore, as described in the first aspect of the prior art, by setting the thermal expansion coefficient of the glass layer to be smaller than the thermal expansion coefficient of the metal substrate, the stress remaining on the processed surface is offset, and Can be flattened.

On the other hand, in the insulating substrate before Conventional Example 1, fine defects were observed on the surface of the glass layer formed on the upper surface of the metal substrate, and the fine surface defects caused disconnection of the thin film pattern. .

Therefore, as described in claim 2 of Conventional Example 1, the first layer has a two-layer structure of crystalline glass, and the second layer has a two-layer structure of glaze glass having a softening point lower than that of the glass by 50 ° C. or more. Surface defects could be reduced without impairing heat shock resistance.

As described above, when an insulating substrate as described in Conventional Example 1 is used for a thermal head substrate,
The warpage of the substrate is eliminated, surface defects are reduced, and disconnection of the thin film pattern can be eliminated.

(2) Conventional Example 2 (Japanese Patent Application No. 10-15559)
The first aspect of the present invention relates to a metal substrate made of an iron alloy, a projection serving as a common electrode formed on the surface of the metal substrate, and an iron oxide formed on the surface of the metal substrate. In an insulating substrate for a thermal head including an oxide layer not containing and a glass layer formed on the oxide layer, the iron alloy composition was configured to be an iron alloy containing 1 to 10% by weight of Cr. This is an insulating metal substrate for a thermal head. By doing so, the specific resistance value of the thermal head insulating substrate is reduced, and power consumption during driving of the thermal head can be reduced.

[0011]

Incidentally, in the manufacturing process of the insulating substrate shown in the above-mentioned prior art examples 1 and 2, spattering and chemical vapor deposition (CVD) are performed.
Since the insulating substrate is exposed to a high temperature during the film formation by (ion), the substrate is thermally deformed, and there is a problem that the formed thin film is separated after cooling.

[0012] In addition, since chocolate breakage is difficult with a metal substrate, it is difficult to take a large number of pieces, and there is a problem that productivity is low. An object of the present invention is to provide an insulating substrate for a thermal head which solves the above problems (problems), prevents peeling of a formed thin film after cooling, and improves the yield and productivity in a film forming process. Aim.

[0013]

According to the present invention, there is provided an insulating substrate for a thermal head for solving the above problems.
The common electrode projections formed on the surface of the ceramic substrate by a thick film process, a convex glaze glass layer having the projections as vertices, and a glaze glass layer formed on the ceramic substrate. A configuration was provided. In this way, by using a ceramic substrate as the base material of the insulating substrate and forming the projections for the common electrode on the surface of the substrate using a thick film technique, the thermal deformation of the substrate due to the high temperature generated during film formation such as sputtering or CVD is suppressed. In addition, peeling of the film formation pattern can be prevented. Further, since the base material of the insulating substrate is made of ceramic, chocolate break is easy and a large number of pieces can be obtained, thereby improving the productivity of the thermal head insulating substrate.

In the insulating substrate for a thermal head according to the present invention, in the convex glaze glass layer having the projection for the common electrode as an apex, a lower portion is a crystallized glass layer and an upper portion is an amorphous glass layer. It was configured as follows. As described above, if the lower portion is made of a crystalline glass layer, the softening point for turning into a ceramic after firing increases. This makes it possible to set the firing temperature of the upper glaze glass layer high,
The surface roughness of the glaze glass layer can be reduced,
This is more effective in eliminating separation in a later film forming step.

According to a third aspect of the present invention, in the thermal head insulating substrate, the step of forming the common electrode projection includes a thick film printing step, a drying step, a baking step, a photolithography step,
The etching step and the resist removing step were performed in this order. By configuring the manufacturing process as described above, first, a resist is applied to the surface on the side on which the protrusions are to be formed after firing the ceramic substrate by using a spin coater. Alternatively, a film-like dry resist film can be used. Then, patterning is performed to a desired width by photolithography. Next, after processing the common electrode into a desired projection shape by wet etching or dry etching, the resist layer is peeled off. Through the above steps, the insulating substrate for a thermal head of the present invention can be actually formed.

According to a fourth aspect of the present invention, in the thermal head insulating substrate, the step of forming the common electrode projection includes a thick film printing step, a drying step, a baking step, a photolithography step,
The shot blast process and the resist removal process were performed in this order. By configuring the manufacturing process in this manner, a resist is applied to the surface on the side on which the projections are to be formed after firing the ceramic substrate by a spin coater. Alternatively, a film-like dry resist film can be used. Then, patterning is performed to a desired width by photolithography. Next, after removing excess metal parts by shot blasting and processing the common electrode into a desired projection shape,
By peeling off the resist layer, the insulating substrate for a thermal head of the present invention can be formed.

According to a fifth aspect of the present invention, the insulating substrate for a thermal head is configured such that the step of forming the projection for the common electrode is performed in the order of a thick film printing step, a drying step, a firing step, and a cutting step. By structuring the manufacturing process in this way, after firing the ceramic substrate, an extra metal portion is removed by a disk-shaped outer peripheral blade coated with diamond truss, and the common electrode is processed into a desired projection shape. The thermal head insulating substrate of the invention can be formed.

According to a sixth aspect of the present invention, in the thermal head insulating substrate, the common electrode protrusion has a height of 5 to 150 mm.
μm and a width of 10 to 100 μm. By setting the height of the common electrode protrusion to 5 μm or more, the bulge of the common electrode protrusion is reduced, the contact area with the platen roller is increased, and the suppression pressure of the thermal head is too large, and the printing speed is reduced. Can be prevented. Also, the height of the common electrode projection is set to 1
By setting the thickness to 50 μm or less, it is difficult to form a resist required in a subsequent film forming step, and it is possible to prevent a situation in which breakage during etching increases. Further, the width of the common electrode protrusion is also in the above-mentioned practical range.

According to a seventh aspect of the present invention, there is provided an insulating substrate for a thermal head, wherein a groove is provided on an upper surface of the common electrode projection. This groove blocks heat conduction just above the common electrode protrusion in preheat thermal heads, double line thermal heads, and dot shift thermal heads that use the protrusion formed on the substrate surface as a common electrode, thereby improving energy efficiency. A thermal head in which a drop is prevented can be obtained.

In the thermal head insulating substrate according to the present invention, the main component of the common electrode protrusion is preferably Au, Ag, or N.
i is configured to be at least one selected from i. By using these metal fine powders, oxidation of the common electrode is suppressed and electric conductivity is improved.

According to a ninth aspect of the present invention, in the thermal head insulating substrate, the thick film baking step is performed under reduced pressure in the step of forming the common electrode projection. In this case, the metal fine powder shrinks at the firing temperature, and its true density becomes 10%.
When the value approaches 0%, the etching characteristics and mechanical characteristics of the projection for the common electrode are improved, and it is easy to finish to a desired shape.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an insulating substrate for a thermal head according to the present invention will be described with reference to FIGS. FIG. 1 is a partially cutaway perspective view showing an external configuration of a double heat line thermal head using the thermal head insulating substrate of the present embodiment. FIG. 2 is a vertical sectional side view showing the insulating substrate for a thermal head of the present invention. FIG. 3 is a vertical sectional side view showing one process of manufacturing the insulating substrate for a thermal head of the present invention. FIG. 4 is a plan view in which a part of a thermal head using the thermal head insulating substrate of the present invention is cut away.

In the thermal head 20 shown in FIG.
Reference numeral 21 denotes an alumina substrate as a ceramic substrate having a thickness of, for example, 0.8 mm. On the surface of the alumina substrate 21, a long common electrode projection 22 is formed so as to protrude. The height of the common electrode projection 22 is 50 μm.

24a is a common electrode projection 22 shown in FIG.
The first glaze glass formed on the left surface of the alumina substrate 21 on the left side of FIG.
A bulge is formed in the vicinity, and is a bulge 24a1. Reference numeral 24b denotes a second glaze glass formed on the right surface of the alumina substrate 21 on the right side of the drawing with respect to the common electrode protrusion 22, and a portion near the common electrode protrusion 22 is formed with a swell. The portion 24a2 is provided.

A heating resistor 25 is formed on each surface extending from the first glaze glass 24a to the second glaze glass 24b via the common electrode projection 22. The heating resistors 25 are provided corresponding to one dot, and a plurality of the heating resistors 25 are provided at regular intervals. In the heating resistor 25, the common electrode protrusion 22
The portion that contacts the surface 22a is electrically connected to the surface 22a.

Reference numeral 26a denotes a first individual electrode formed on the surface of the first glaze glass 24a, one end of which is electrically connected to one end of the heating resistor 25a.
The other end of the first individual electrode 26a is connected to a terminal of the first control IC 12a shown in FIG. Here, the correspondence between the configurations shown in FIGS. 2 and 4 will be supplementarily described. 8a and 8b in FIG. 4 correspond to 9a and 9b in the first and second heating resistors 25a and 25b in FIG. Is also the first
And the second individual electrodes 26a and 26b,
Is a common electrode 27 shown in FIG.

In FIG. 2, reference numeral 26b denotes a second individual electrode formed on the surface of the second glaze glass 24b, one end of which is electrically connected to one end of the heating resistor 25b. The other end of the second individual electrode 26b is connected to a terminal of the second control IC 12b shown in FIG.

Numeral 27 designates a common electrode arranged along the common electrode projection 22 shown in FIG. 1. The back surface of the common electrode is electrically connected to the surface of the heating resistor 25 shown in FIG. I have. That is, in the heating resistor 25 shown in FIG. 2, a portion that is not joined to the first individual electrode 26a and the common electrode 27 actually acts as a heating resistor.
This portion is referred to as a first heating resistor 25a.

In the heating resistor 25, a portion not joined to the second individual electrode 26b and the common electrode 27 actually acts as a heating resistor. Hereinafter, this portion is referred to as a second heating resistor. 25b. That is, the thermal head 20 shown in FIG. 1 has a plurality of first heating resistors 25a.
.. 25a and a plurality of second heating resistors 25b
・ It has 25b. Reference numeral 28 shown in FIG. 2 is a protective layer covering the entire surface of the first individual electrode 26a and the like. In FIG. 1, illustration of the protective layer 28 is omitted.

Next, a method of manufacturing the insulating substrate having the common electrode projections 22 according to the present embodiment will be described with reference to FIG. First, the alumina substrate 21 shown in FIG.
Is an organic solvent such as n-propyl bromide,
After being degreased and washed, it is washed with a scrubber. As a result, dust and the like adhering to the front and back surfaces of the alumina substrate 21 are removed.

Next, the alumina substrate 21 is ultrasonically cleaned after being immersed in a cleaning solution of methyl bromide. As a result, dust adsorbed on the minute uneven portions on the front and back surfaces of the alumina substrate 21 is removed.

Thereafter, using a metal mask or a screen mask having a desired opening width, a printing paste obtained by kneading a metal fine powder and an organic substance is printed on the surface of the alumina substrate 21 to form a projection for a common electrode. . Au, A which is hard to be oxidized and has good electric conductivity as metal fine powder.
An alloy containing g and Ni as main components, or a single metal thereof is desirable. After printing, leveling is performed for about 10 minutes to flatten the surface of the alumina substrate 21, and then
Air drying is performed at 50 ° C. for 20 minutes.

Next, the organic matter in the printing paste is burned out by heating at 300 ° C. in the atmosphere in an incinerator. Subsequently, the metal fine powder is sintered and fired at a temperature for increasing the density (about 600 ° C. in the atmosphere). As the atmosphere environment of this firing step, a hydrogen atmosphere, or even a reduced pressure atmosphere may be used.
By doing so, it is expected that the common electrode projections will be further densified.

Next, a glaze glass paste 24b1 is screen-printed to a thickness of 20 μm on the left surface of the alumina substrate 21 on the left side of the figure from the common electrode projection 22 shown in FIG. Similarly, the common electrode protrusion 2
2, the right side of the alumina substrate 21 on the right side of FIG.
Glaze glass paste 24b2 is screen-printed to a thickness of 20 μm. Here, the above-mentioned first glaze glass paste 24b1 and second glaze glass paste 24b2 refer to a mixture of a solvent and amorphous glass powder. Then, the above-mentioned first glaze glass paste 24b1 and second glaze glass paste 24b2
When the screen printing is completed, these surfaces are flattened by leveling.

Next, the printed board flattened by the leveling is left in a vacuum container at a degree of vacuum of 1 Pa or less for 15 minutes or more, so that the air contained in the paste is released from the screen printing surface. Next, a pre-baking process of heating the glaze glass pastes 24b1 and 24b2 to a relatively low temperature of 140 ° C. in a furnace is performed. The reason why the prebaking is performed at 140 ° C. is to evaporate the solvent contained in the glass paste gradually without bumping.

When the pre-baking process is completed, the alumina substrate 21 is taken out of the furnace and naturally cooled from 140 ° C. to room temperature. Next, the alumina substrate 21
After baking at 0 ° C. for 10 minutes, it is naturally cooled to room temperature. Next, the first glaze glass paste 24c1 and the second glaze glass paste 24 are applied to both sides of the common electrode protrusion 22 and both surfaces of the common electrode protrusion 22 shown in FIG.
The surface of c2 is prepared. The present glaze glass has a melting point lower by about 100 ° C. than the above glaze glass layer.

Next, the glaze glass paste 24c1,
24c2 etc. are prebaked at 140 ° C. in the same manner as above,
The solvent contained in 1, 24c2 and the like is gradually evaporated. After this pre-baking process, the alumina substrate 21
A baking treatment is performed for 10 minutes in a furnace at a temperature of. Thereby, the glaze glass paste 24c1
And the glaze glass underneath are integrated, and as a result,
A first glaze glass 24a having a raised portion 24a1 shown in FIG. 4 is formed.

At the same time, the glaze glass paste 24c2 and the glaze glass thereunder are integrated, and as a result, a second glaze glass 24b having a raised portion 24a2 shown in FIG. 4 is formed. Here, the surface H including the common electrode projections 22 shown in FIG. 3 is polished as necessary. Thereby, the extra glaze glass and the surface oxide film of the common electrode protrusion 22 are removed.

According to the above-described embodiment, the base material of the insulating substrate is an alumina substrate, which is a ceramic substrate, and the projections for the common electrode are formed on the substrate surface by the thick film technique, so that sputtering, CVD or the like can be performed. Thermal deformation of the substrate at a high temperature generated in the film can be suppressed, and peeling of the film formation pattern can be prevented. Further, since the base material of the insulating substrate is made of ceramic, chocolate break is easy and a large number of pieces can be obtained, thereby improving the productivity of the thermal head insulating substrate.
Further, the first layer of the glass insulating layer is made of glaze glass, the second layer is made of glaze glass having a melting point lower than that of the first layer by 50 ° C. or more. By lowering the melting temperature by several tens of degrees Celsius, surface defects can be eliminated without lowering the peel strength and the etching resistance.

In addition, 1 to 1
When a groove of about 2 μm is provided, this groove can be used for a preheat thermal head, a double-line thermal head, and a dot shift thermal head that use the protrusion formed on the substrate surface as a common electrode. A thermal head can be obtained in which conduction is cut off, thereby preventing a decrease in energy efficiency.

[0041]

The insulating substrate for a thermal head of the present invention comprises:
The configuration as described above has the following excellent effects. (1) As described in claim 1, the substrate of the insulating substrate is made of a ceramic substrate, and the common electrode protrusion is formed on the substrate surface by a thick film technique, which is generated during film formation such as sputtering or CVD. Thermal deformation of the substrate due to high temperature can be suppressed, and peeling of a film formation pattern can be prevented. (2) In addition, since the base material of the insulating substrate is made of ceramic, chocolate breaks are easy and a large number of pieces can be obtained, thereby improving the productivity of the thermal head insulating substrate.

(3) As described in the second aspect, if the lower portion is made of a crystalline glass layer, the softening point for making a ceramic after firing increases. As a result, the firing temperature of the upper glaze glass layer can be set higher, and the surface roughness of the glaze glass layer can be reduced, which is more effective in eliminating peeling in a later film forming process. It is a target.

(4) With the structure as described in claim 3, first, a resist is applied to the surface on the side on which the projections are to be formed after firing the ceramic substrate by a spin coater. Alternatively, a film-like dry resist film can be used. Then, patterning is performed to a desired width by photolithography. Next, after processing the common electrode into a desired projection shape by wet etching or dry etching, the resist layer is peeled off. Through the above steps, the insulating substrate for a thermal head of the present invention can be actually formed.

(5) According to the structure of the fourth aspect, a resist is applied by a spin coater to the surface on which the projections are to be formed after firing the ceramic substrate. Alternatively, a film-like dry resist film can be used. Then, patterning is performed to a desired width by photolithography. Next, after removing excess metal parts by shot blasting and processing the common electrode into a desired projection shape,
By peeling off the resist layer, the insulating substrate for a thermal head of the present invention can be formed.

(6) With the configuration as described in claim 5, after firing the ceramic substrate, an extra metal portion is removed by a disk-shaped outer peripheral blade coated with diamond truss, and a common electrode is formed as desired. After processing into the projection shape, the insulating substrate for a thermal head of the present invention can be formed.

(7) As described in claim 6, by setting the height of the common electrode projection to 5 μm or more, the swelling of the common electrode projection is reduced, and the contact area with the platen roller is increased. It is possible to prevent a situation in which the printing pressure is reduced due to too large a pressure for suppressing the thermal head. (8) Further, by setting the height of the common electrode projection to 150 μm or less, it is difficult to form a resist required in a subsequent film forming step, and it is possible to prevent a situation in which breakage during etching increases.

(9) When the groove is provided on the upper surface of the common electrode projection as described in claim 7, the groove blocks heat conduction immediately above the common electrode projection, thereby providing energy. A thermal head in which a decrease in efficiency is prevented can be obtained.

(10) When the main component of the common electrode projection is at least one selected from Au, Ag, and Ni, the oxidation of the common electrode is prevented. Suppress and the electric conductivity is improved.

(11) As described in the ninth aspect, in the step of forming the projection for the common electrode, if the firing step of the thick film is performed under reduced pressure, the metal fine powder shrinks at the firing temperature, and the true As the density approaches 100%, the etching properties and mechanical properties of the common electrode projections are improved, and it is easy to finish the projection into a desired shape.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a thermal head using an insulating substrate for a thermal head of the present invention.

FIG. 2 is a vertical sectional side view showing an insulating substrate for a thermal head according to the present invention.

FIG. 3 is a vertical sectional side view showing one process of manufacturing the insulating substrate for a thermal head of the present invention.

FIG. 4 is a partially cutaway plan view showing a thermal head using the thermal head insulating substrate of the present invention.

[Explanation of symbols]

 20: thermal head 21: alumina substrate (ceramic substrate) 22: projection for common electrode 24a, 24b: glaze glass

Claims (9)

[Claims] 1. A projection for a common electrode formed on a surface of a ceramic substrate by a thick film process, a convex glaze glass layer having the projection as an apex, and a glaze glass layer formed on the ceramic substrate. An insulating substrate for a thermal head. 2. The convex glaze glass layer having the projections for the common electrode as vertices, wherein a lower part is a crystallized glass layer and an upper part is an amorphous glass layer. Insulating substrate for thermal head. 3. The method according to claim 1, wherein the step of forming the common electrode projection comprises a thick film printing step, a drying step, a baking step, a photolithography step, an etching step, and a resist removing step. Item 3. The thermal head insulating substrate according to item 1 or 2. 4. The method according to claim 1, wherein the step of forming the projection for the common electrode is performed in the order of a thick film printing step, a drying step, a baking step, a photolithography step, a shot blast step, and a resist removing step. The insulating substrate for a thermal head according to claim 1. 5. The thermal device according to claim 1, wherein the step of forming the common electrode projection is performed in the order of a thick film printing step, a drying step, a baking step, and a cutting step. Insulating substrate for head. 6. A shape of the common electrode projection having a height of 5
The insulating substrate for a thermal head according to any one of claims 1 to 5, wherein the insulating substrate is formed to have a width of 10 to 150 m and a width of 10 to 100 m. 7. The insulating substrate for a thermal head according to claim 1, wherein a groove is provided on an upper surface of said common electrode projection. 8. The main component of the common electrode projection is Au,
8. The insulating substrate for a thermal head according to claim 1, wherein the insulating substrate is at least one selected from Ag and Ni. 9. The thermal head insulating substrate according to claim 1, wherein in the step of forming the common electrode projection, the thick film baking step is performed under reduced pressure.