JPH07137318A - Method of manufacturing thermal head - Google Patents

Abstract

PURPOSE:To produce a thermal head excellent in the heat utilizing efficiency of a heating element with high accuracy in high yield. CONSTITUTION:In a thermal head, a through-hole 11 is formed on the substrate 1 thereof and glass 2 with a low softening point holding the shape of a cavity part 3 before baking flows in the through-hole 11. A high heat-resistant film 4 holding the shape of the tunnel like cavity part 3 is formed on the substrate 1 and a glaze layer 5 composed of glass with a high softening point is formed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in a facsimile machine, an image recording apparatus, etc., and is used for printing a heat-sensitive recording medium by selectively driving a plurality of heating elements based on print data. The present invention relates to a method of manufacturing a thermal head.

[0002]

2. Description of the Related Art FIG. 15 is a partial sectional view showing an example of a conventional thermal head. In this thermal head, a glaze layer 54 having an arcuate cross-section made of glass or the like and having a thickness of 40 μm to 80 μm is formed on an electrically insulating substrate 51 made of alumina ceramic or the like, and the surfaces of the substrate 51 and the glaze layer 54 are further formed. Then, a heating resistor layer 56 made of TaSiO ₂ or the like is formed to a thickness of 0.05 μm by sputtering or the like. Further, an individual electrode 58 and a common electrode 57 made of Al or the like are formed by using a photolithography technique or the like, and a plurality of dot heating elements 56a are formed near the top of the glaze layer 54 in the direction perpendicular to the paper surface of the drawing. Furthermore, in order to prevent oxidation of the heating resistor layer 56 and abrasion due to sliding of the recording medium on these surfaces,
The protective layer 59 made of silicon nitride SiN _x has a thickness of 4 μm.
It is formed to about 8 μm. Thus, the glaze layer 54
A heat-generating region 50 is formed by a plurality of heat-generating elements 56a on the upper part of the table, and the heat-sensitive recording is performed by selectively energizing each heat-generating element 56a while the heat-sensitive recording medium is brought into contact with and conveyed to the heat-generating region 50.

In such a thermal head, since the thermal conductivity of the glaze layer 53 is relatively large, the heating element 5
Only about 10% of the amount of heat generated in 6a is used for heat-sensitive recording, and the remaining about 90% of heat is mainly dissipated from the glaze layer 54 to the substrate 51, resulting in extremely high heat utilization efficiency. There is a problem of being low.

FIG. 16 is a partial sectional view showing another example of a conventional thermal head. This thermal head is disclosed in Japanese Unexamined Patent Publication No. 56-11281, and instead of the glaze layer 54 shown in FIG. 15, a glass plate 55 having a tunnel-shaped cavity 53 along the direction perpendicular to the paper surface of the figure. Are formed on the substrate 51. Such a cavity 53
By providing the heat generating element 56a below the heat generating element 56a, it is possible to prevent the heat generated in the heat generating element 56a from being dissipated to the substrate 51 side, and it is possible to improve the heat utilization efficiency at the time of thermal recording.

[0005]

However, as shown in FIG.
When manufacturing the thermal head, the flat glass plate 5
It is difficult to accurately form the tunnel-shaped cavity 53 in FIG. 5, and there is a problem that the manufacturing cost increases.
In addition, the thickness of the glass plate 55 having such a cavity 53 does not impair the thermal response, so that the cavity 53 and the glass plate 5 have the same thickness.
5 μm when the total height including 5 is about 40 to 60 μm
Since a thickness of 10 μm is required, it is damaged immediately when an external force is applied, and it is difficult to install the substrate 51 on the substrate 51 with high accuracy, and the manufacturing yield is extremely low.

In order to solve the above-mentioned problems, an object of the present invention is to provide a method of manufacturing a thermal head which can manufacture a thermal head having excellent heat utilization efficiency of a heating element with high accuracy and a good yield. That is.

[0007]

According to the present invention, a glaze layer and a heating element are formed on an electrically insulating substrate, and a cavity is formed below the heating element between the substrate and the glaze layer. A thermal head formed, wherein (a) a step of forming a groove or a through hole in the substrate between the substrate and a glaze layer, and (b) a groove formed in the substrate on one surface of the substrate. Or a step of applying a strip-shaped first member made of a low softening point material so as to cover the opening of the through hole,
(C) depositing a second member made of a high softening point material on the surface of the belt-shaped first member so as to cover the first member, and (d) firing the first member and the second member. , The second member is a glaze layer and the first member is softened, and the softened first member is moved into a groove or a through hole formed in the substrate to form a cavity between the substrate and the glaze layer. The method for manufacturing a thermal head is characterized in that a cavity is formed by the step of forming.

The present invention also provides a thermal head in which a glaze layer and a heating element are formed on an electrically insulating substrate, and a cavity is formed between the substrate and the glaze layer below the heating element. Between the substrate and the glaze layer; (a) depositing a strip-shaped first member made of an etchable material on the substrate; and (b) a surface of the strip-shaped first member. And a step of covering the glaze layer made of an etching resistant material so that a part of the first member is exposed, and (c) etching and removing the first member from the exposed portion of the first member to form a substrate and a glaze layer. A method of manufacturing a thermal head, characterized in that the cavity is formed by a step of forming a cavity between the two.

[0009]

According to the present invention, the first member made of the low softening point material is applied in a strip shape so as to cover the opening of the groove or the through hole formed in the substrate, and the second member made of the high softening point material is further applied. After depositing the member, the second member is hardened by baking the entire substrate, while the first member is softened and moved to the groove or the through hole. In this way, it is possible to easily and accurately form the cavity between the substrate and the glaze layer.

According to the invention, a first member made of an etchable material such as metal is formed in a strip shape on a substrate, and a glaze layer made of an etching resistant material such as glass is further formed on the first member. The first member is removed by etching after the first member is formed so that a part of it is exposed. In this way, it is possible to easily and accurately form the cavity between the substrate and the glaze layer.

[0011]

【Example】

(First Embodiment) FIG. 1 is a partial sectional view of a thermal head obtained by using the method of manufacturing a thermal head according to the first embodiment of the present invention. This thermal head has a through hole 1 formed in an electrically insulating substrate 1 made of alumina ceramic or the like.
1 is formed, and the cavity 3 is formed in the through hole 11 before firing.
The low softening point glass 2 such as a glass containing lead, which has been kept in the shape, flows in. Further, on the substrate 1, the shape of the tunnel-shaped cavity portion 3 along the direction perpendicular to the plane of the drawing is kept S
A high heat resistant film 4 made of iN _x , SiC or the like is formed, and a glaze layer 5 made of high softening point glass such as borosilicate glass is formed thereon so as to cover the cavity 3.

Thereafter, as in the conventional thermal head, a heating resistor layer 6 made of TaSiO ₂ or the like is formed to a thickness of 0.05 μm on the surfaces of the high heat resistant film 4 and the glaze layer 5 by sputtering or the like. Further, an individual electrode 8 and a common electrode 7 made of Al or the like are formed by using a photolithography technique, and a plurality of dot heating elements 6a are formed near the top of the glaze layer 5 in the direction perpendicular to the paper surface of the figure.
Further, a protective layer 9 made of SiN _x or the like is formed on these surfaces.
Is formed to have a thickness of about 4 μm to 8 μm. In this way, the heat-generating region 10 is formed by the plurality of heat-generating elements 6a on the glaze layer 5, and the heat-sensitive recording is performed by bringing the heat-sensitive recording paper into contact with the heat-generating region 10 and selectively energizing each heat-generating element 6a. Is done.

Next, a method of manufacturing the thermal head according to the first embodiment of the present invention will be described. First, as shown in the plan view of FIG. 2, in the electrically insulating substrate 1, a diameter of, for example, 200 is provided in a region where a tunnel-shaped cavity is to be formed.
The through holes 11 of about μm are linearly formed with a pitch of 1 mm to 5 mm. As a method of forming the through holes 11, a method of preliminarily forming holes in a green sheet before firing of an alumina ceramic substrate by using a large number of pins or the like, or a method of performing mechanical processing such as laser processing on the substrate after firing There are ways.

Next, the plan view of FIG. 3A and FIG.
As shown in the cross-sectional view taken along line X1-X1 of (b), a low softening point glass paste having a thickness of 5 μm to 20 μm and a width of 200 μ is used to cover the opening of the through hole 11 by using a screen printing method or the like.
It is applied in a band shape with an arc cross section of about m to 500 μm and left in an atmosphere at a temperature of 200 ° C. for about 30 minutes to evaporate the solvent in the paste and dry it to form the first member 13.

Next, the plan view of FIG. 4A and FIG.
As shown in the X2-X2 sectional view of (b), the first member 13
A high heat resistant film 4 made of a heat resistant material such as SiN _x or SiC is formed to a thickness of about 1 μm to 10 μm by sputtering or the like in a shaded region shown by a two-dot chain line in the figure so as to cover the above.

Next, the plan view of FIG. 5A and FIG.
As shown in the X3-X3 sectional view of (b), the first member 13
And a high softening point glass paste with a height of 40 μm from the substrate 1 to the top in a region narrower than the high heat resistant film 4 described above.
m to 60 μm, width 0.8 mm to 1.2 mm, is applied by a screen printing method or the like, and is left in an atmosphere at a temperature of 200 ° C. for about 30 minutes to evaporate the solvent in the paste to dry it. , The second member 5a is formed. In this example, the low softening point glass paste has a softening point of 490 ° C and the high softening point glass paste has a softening point of 860 ° C.

Next, when it is put into a firing furnace in the state shown in FIG. 5 and fired at a temperature of 1000 ° C. to 1200 ° C., the viscosity of the first member 13 made of low softening point glass is lowered and liquefied, and When it penetrates into the through hole 11 under the influence of surface tension and gravity, the space occupied by the first member 13 until now is shown in FIG.
The cavity 3 is formed as shown in FIG. On the other hand, the second member 5
The a is baked while maintaining its shape to form the glaze layer 5 as shown in FIG. At this time, since the high heat-resistant film 4 is made of a heat-resistant material, it exhibits sufficient strength even at the above-mentioned firing temperature, and prevents the cavity 3 from being broken during firing. In this way, the cavity 3 can be formed between the substrate 1 and the glaze layer 5.

Hereinafter, a method of forming a plurality of heating elements will be described.
It is the same as the conventional one and will be described with reference to FIG.
After the heating resistor layer 6 made of TaSiO ₂ or the like is formed to a thickness of 0.05 μm on the surfaces of the glaze layer 5 and the high heat resistant film 4, the individual electrode 8 and the common electrode 7 made of Al or the like are formed by using a photolithography technique or the like. Then, a plurality of dot heating elements 6a are formed in the vicinity of the top of the glaze layer 5 in the direction perpendicular to the plane of the drawing. Further, a protective layer 9 made of silicon nitride SiN _x or the like is formed with a thickness of about 4 μm to 8 μm on these surfaces in order to prevent oxidation of the heating resistor layer 6 and abrasion due to sliding of the recording medium. In this way, it is possible to obtain the thermal head of FIG. 1 in which the heat generating region 10 formed by the plurality of heat generating elements 6 a is formed on the glaze layer 5 having the cavity 3 between the heat generating element 6 a and the substrate 1.

(Second Embodiment) FIG. 6 is a partial sectional view of a thermal head obtained by using a method of manufacturing a thermal head according to a second embodiment of the present invention. The overall structure of the thermal head of FIG. 6 is the same as that shown in FIG. 1, except that a groove 21 is formed instead of the through hole 11 of FIG. The groove 21 is provided for withdrawing the low softening point glass 2 that has retained the shape of the cavity 3 before firing.

Next, a method of manufacturing the thermal head according to the second embodiment of the present invention will be described. First, as shown in the plan view of FIG. 7, in the electrically insulating substrate 1, for example, a groove 21 having a concave cross section with a width of about 200 μm and a depth of 10 μm to 50 μm is formed linearly. As a method of forming the groove 21, there are a method of pre-grooving the green sheet before firing the alumina ceramic substrate, a method of subjecting the substrate after firing to mechanical processing such as laser processing, and the like. The former is preferred in terms of.

Next, the plan view of FIG. 8A and FIG.
As shown in the cross-sectional view taken along the line X4-X4 in (b), a low softening point glass paste having a thickness of 5 μm to 20 μm and a width of 200 μm is formed so as to cover the opening of the groove 21 by using a screen printing method or the like.
It is applied in a band shape with an arc cross section of about 500 μm. At this time, the viscosity of the glass paste is adjusted so that the groove 21 is not filled.

Then, the first member 23 is formed by leaving it in an atmosphere at a temperature of 200 ° C. for about 30 minutes to evaporate the solvent in the paste and dry it.

Next, FIG. 9A is a plan view and FIG.
As shown in the cross-sectional view taken along the line X5-X5 in (b), a high heat-resistant film made of a heat-resistant material such as SiN _x or SiC by using sputtering or the like in a hatched area indicated by a two-dot chain line in the figure so as to cover the convex portion 23. 4 is formed to a thickness of about 1 μm to 10 μm.

Next, FIG. 10A is a plan view and FIG.
As shown in the X6-X6 sectional view of (b), the first member 23
And a high softening point glass paste with a height of 40 μm from the substrate 1 to the top in a region narrower than the high heat resistant film 4 described above.
m-60 μm, width 0.8 mm-1.2 mm, and leave this in an atmosphere at a temperature of 200 ° C. for about 30 minutes to evaporate the solvent in the paste and dry it.
a is formed. In this example, the low softening point glass paste has a softening point of 490 ° C and the high softening point glass paste has a softening point of 860 ° C.

Next, when it is put into a firing furnace in the state shown in FIG. 10 and fired at a temperature of 1000 ° C. to 1200 ° C., the viscosity of the first member 23 made of low softening point glass is lowered and liquefied. A cavity 3 as shown in FIG. 6 is formed in the space occupied by the first member 23 up to now by entering the groove 21 under the influence of surface tension and gravity. On the other hand, the second member 5a
Is baked while maintaining its shape to form a glaze layer 5 as shown in FIG. At this time, since the high heat-resistant film 4 is formed of a heat-resistant material, it exhibits sufficient strength even at the above-mentioned firing temperature, and prevents the cavity 3 from being broken during firing. In this way, the cavity 3 can be formed between the substrate 1 and the glaze layer 5. Hereinafter, the method of forming the plurality of heating elements is the same as that of the first embodiment, and the duplicated description will be omitted.

(Third Embodiment) FIG. 11 is a partial sectional view of a thermal head obtained by using a method of manufacturing a thermal head according to a third embodiment of the present invention. The overall structure of the thermal head shown in FIG. 11 is similar to that shown in FIGS. 1 and 6, except that the through hole 11 of FIG. 1 and the groove 21 of FIG. 6 are not formed in the substrate 1. .

Next, a method of manufacturing the thermal head according to the third embodiment of the present invention will be described. First, FIG.
As shown in the plan view of (a) and the X7-X7 sectional view of FIG. 12 (b), for example, Cu is formed on the electrically insulating substrate 1.
A metal paste containing, as a main component, a thickness of 5 μm to 20 μm and a width of 200 μ to 500 μ by a screen printing method or the like.
After being applied in a strip shape with a circular arc cross section of m, it is left in an atmosphere at a temperature of 200 ° C. for about 30 minutes to evaporate and dry the solvent in the paste, and then baked at a temperature of 600 ° C. to 700 ° C. First, the first member 30 made of a baked metal is formed.

Next, FIG. 13A is a plan view and FIG.
As shown in the X8-X8 sectional view of (b), the first member 30
Of the SiN is exposed to the exposed portion by using sputtering or the like in the hatched area indicated by the two-dot chain line in the figure.
_A high heat resistant film 4 made of a heat resistant material such as _x or SiC is formed to a thickness of about 1 μm to 10 μm.

Next, FIG. 14A is a plan view and FIG.
As shown in the X9-X9 sectional view of (b), the first member 30
And a high softening point glass paste with a height of 40 μm from the substrate 1 to the top in a region narrower than the high heat resistant film 4 described above.
The second member 5a is formed by applying a coating having a thickness of m to 60 μm and a width of 0.8 mm to 1.2 mm. In this embodiment, a high softening point glass paste having a softening point of 860 ° C. is used.

Next, when it is put into a firing furnace in the state shown in FIG. 14 and fired at a temperature of 1000.degree.
The glaze layer 5 as shown in 1 is formed. At this time,
Since the high heat-resistant film 4 is made of a heat-resistant material, the metal component of the first member 30 is diffused toward the glaze layer 5 during firing and the composition of the glaze layer 5 is largely changed. The strength deterioration of No. 5 is prevented.

Next, of the first member 30 shown in FIG. 14A, the exposed portion 30a which is not covered with the high heat resistant film 4 is immersed in an etching solution such as hydrochloric acid or sodium hydroxide to form the first member. By removing all 30 by etching, it is possible to form the cavity 3 having an arcuate cross section as shown in FIG. In this way, the tunnel-shaped cavity 3 can be formed between the substrate 1 and the glaze layer 5. Hereinafter, the method of forming the plurality of heating elements is the same as that of the first embodiment, and the duplicated description will be omitted.

[0032]

As described above in detail, according to the present invention, since the cavity can be formed between the substrate and the glaze layer easily and with high accuracy, the thermal efficiency of the heat generating element is excellent. The head can be manufactured with high yield and at low cost.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a thermal head obtained by using a method of manufacturing a thermal head according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a manufacturing process of the first embodiment of the present invention.

3 (a) is a plan view showing a manufacturing process of the first embodiment of the present invention, and FIG. 3 (b) is a sectional view taken along line X1-- in FIG. 3 (a).
It is sectional drawing which followed the X1 line.

4 (a) is a plan view showing a manufacturing process of the first embodiment of the present invention, and FIG. 4 (b) is a sectional view taken along line X2-- in FIG. 4 (a).
It is sectional drawing which followed the X2 line.

5 (a) is a plan view showing a manufacturing process of the first embodiment of the present invention, and FIG. 5 (b) is a sectional view taken along line X3-- in FIG. 5 (a).
It is sectional drawing which followed the X3 line.

FIG. 6 is a partial cross-sectional view of a thermal head obtained by using the method of manufacturing a thermal head according to the second embodiment of the present invention.

FIG. 7 is a plan view showing the manufacturing process of the second embodiment of the present invention.

8 (a) is a plan view showing a manufacturing process of the second embodiment of the present invention, and FIG. 8 (b) is a sectional view taken along line X4-- in FIG. 8 (a).
It is sectional drawing which followed the X4 line.

9 (a) is a plan view showing a manufacturing process of the second embodiment of the present invention, and FIG. 9 (b) is a sectional view taken along line X5-- in FIG. 9 (a).
It is sectional drawing which followed the X5 line.

10A is a plan view showing a manufacturing process of the second embodiment of the present invention, and FIG. 10B is a sectional view taken along line X6-X6 in FIG. 10A. is there.

FIG. 11 is a partial cross-sectional view of a thermal head obtained by using the method of manufacturing a thermal head according to the third embodiment of the present invention.

12 (a) is a plan view showing a manufacturing process of the third embodiment of the present invention, and FIG. 12 (b) is a sectional view taken along line X7-X7 in FIG. 12 (a). is there.

13 (a) is a plan view showing a manufacturing process of the third embodiment of the present invention, and FIG. 13 (b) is a sectional view taken along line X8-X8 in FIG. 13 (a). is there.

14 (a) is a plan view showing a manufacturing process of the third embodiment of the present invention, and FIG. 14 (b) is a sectional view taken along line X9-X9 in FIG. 14 (a). is there.

FIG. 15 is a partial cross-sectional view showing an example of a conventional thermal head.

FIG. 16 is a partial cross-sectional view showing another example of a conventional thermal head.

[Explanation of symbols]

 1 Substrate 2 Low Softening Point Glass 3 Cavity 4 High Heat-Resistant Film 5 Glaze Layer 5a Second Member 6 Heating Resistor Layer 6a Heating Element 7 Common Electrode 8 Individual Electrode 9 Protective Layer 10 Heating Area 11 Through Hole 13, 23, 30th One member 21 Groove 30a Exposed part

Claims (2)

[Claims] 1. A thermal head in which a glaze layer and a heating element are formed on an electrically insulating substrate, and a cavity is formed below the heating element and between the substrate and the glaze layer. A method of manufacturing a thermal head, characterized in that a cavity is formed between the substrate and the glaze layer by the following steps (a) to (d). (A) a step of forming a groove or a through hole in the substrate,
(B) depositing a strip-shaped first member made of a low softening point material on one surface of the substrate so as to cover an opening of a groove or a through hole formed in the substrate; and (c) the strip-shaped first member. A step of depositing a second member made of a high softening point material on the surface of one member so as to cover the first member; and (d) firing the first member and the second member to form a glaze layer on the second member. And a step of softening the first member and moving the softened first member into a groove or a through hole formed in the substrate to form a cavity between the substrate and the glaze layer. 2. A thermal head in which a glaze layer and a heating element are formed on an electrically insulating substrate, and a cavity is formed below the heating element between the substrate and the glaze layer. A method of manufacturing a thermal head, characterized in that a cavity is formed between the substrate and the glaze layer by the following steps (a) to (c). (A) depositing a strip-shaped first member made of an etchable material on the substrate, and (b) forming a glaze layer made of an etching resistant material on the surface of the strip-shaped first member,
Covering with exposing a part of the first member,
(C) A step of etching and removing the first member from the exposed portion of the first member to form a cavity between the substrate and the glaze layer.