JP3645741B2 - Manufacturing method of thermal head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a thermal head incorporated as a printer mechanism such as a word processor or a facsimile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a thermal head incorporated as a printer mechanism such as a word processor has a glass heat storage layer deposited on the upper surface of an insulating substrate made of alumina ceramics and the like, and a number of heating resistors are formed on the heat storage layer via an etching resistant layer. And a structure in which a pair of electrodes are deposited and formed, a predetermined power is applied between the pair of electrodes, and the heating resistors are selectively joule-heated individually, and the generated heat is transferred to thermal paper. The thermal head is made to function as a thermal head by forming a predetermined print on the recording medium.
[0003]
Such a conventional thermal head is usually manufactured by the following manufacturing method.
[0004]
(1) First, an insulating substrate body larger than the insulating substrate is prepared.
[0005]
(2) Next, a glass paste is applied to a predetermined thickness on the entire upper surface of the insulating substrate body by a conventionally known screen printing or the like, and this is baked at a high temperature to form a glass heat storage layer. Next, an etching resistant layer mainly composed of Si ₃ N ₄ is deposited to a thickness of 0.1 μm to 0.5 μm by sputtering or the like that is conventionally known. This etching resistant layer is for preventing the heat storage layer from being eroded by the etching solution when patterning the heating resistor and the pair of electrodes in the step (3) described later. It is deposited so as to cover it.
[0006]
(3) Next, a large number of heating resistors and a pair of electrodes are formed on the heat storage layer by a conventionally known thin film technique.
[0007]
The large number of heating resistors and a pair of electrodes are formed by sequentially depositing a resistance layer and a conductive layer on the upper surface of the heat storage layer by sputtering, vacuum deposition, or the like, and using photolithography, etching, or the like, and processing into a predetermined pattern It is formed by doing.
[0008]
(4) Finally, an external force is applied in a direction perpendicular to the insulating substrate body, and the insulating substrate body is cut together with the heat storage layer attached to the upper surface to obtain a thermal head having a predetermined shape. . At this time, a groove called a break line is formed on the lower surface of the insulating substrate body, and the insulating substrate body is cut accurately and easily by applying an external force along the groove.
[0009]
In the conventional manufacturing method described above, a thermal head having a predetermined shape is obtained from an insulating substrate body by manufacturing a plurality of thermal heads simultaneously from one insulating substrate body. This is because the productivity is improved and the edge portion where it is difficult to control the thickness, film quality and the like is separated from the thermal head and discarded when the heat storage layer or the like is formed.
[0010]
[Problems to be solved by the invention]
By the way, in this conventional thermal head manufacturing method, the thickness of the heat storage layer that is cut together with the insulating substrate body is substantially equal between the cut portion and its periphery, and an external force is applied when cutting the insulating substrate body. At this time, the force applied to the heat storage layer is dispersed. For this reason, chipping and burrs are likely to occur at the edge of the heat storage layer when the insulating substrate body is cut, and there is a disadvantage that a part of the electrode is damaged by this chipping, or the recording medium hits the burrs when printing.
[0011]
Therefore, in order to eliminate the above disadvantages, it is conceivable to form a cutting groove on the surface of the heat storage layer with a cutter or the like, similarly to the insulating substrate body.
[0012]
However, in order to form a groove for cutting on the surface of the heat storage layer, a separate process for removing and cleaning the grooving process and fragments of the heat storage layer generated in the process is required. When machining using a cutter or the like, small chipping or burrs may occur around the groove, which cannot be a sufficient countermeasure.
[0013]
[Means for Solving the Problems]
The present invention has been devised in view of the above disadvantages, and the thermal head manufacturing method of the present invention includes a thermal head region and a thermal head region on the upper surface of an insulating substrate body having a cutting region surrounding the thermal head region. While applying a heat storage layer extending from the inside to the outside of the cutting region,
Depositing an etching resistant layer on the upper surface of the heat storage layer excluding the cutting region where a groove having a predetermined width is formed;
Sequentially depositing a resistive layer and a conductive layer on the etch-resistant layer in the thermal head region;
Etching the conductive layer and a part of the resistance layer, and the heat storage layer, processing the conductive layer and the resistance layer into a predetermined pattern and forming the groove in the heat storage layer located in the cutting region;
Cutting the insulating substrate body along the groove to obtain a thermal head.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1 is a plan view of a thermal head manufactured by a manufacturing method according to an embodiment of the present invention, FIG. 2A is a sectional view taken along line XX in FIG. 1, and FIG. 2B is a line YY in FIG. 1 is an insulating substrate, 2 is a heat storage layer, 3 is an etching resistant layer, 4 is a heating resistor, 5 and 5 are a pair of electrodes, and 6 is a protective layer.
[0015]
The insulating substrate 1 is made of an electrically insulating material such as alumina ceramics, and functions as a support base material for supporting the heat storage layer 2 and the heating resistor 4 on the upper surface thereof.
[0016]
Also on the upper surface of the insulating substrate 1, inorganic material composed mainly of SiO _2, for example, heat accumulation layer 2 made of glass or the like is deposited to a thickness of 15Myuemu～40myuemu.
[0017]
The heat storage layer 2 has a relatively low thermal conductivity of 1.8 × 10 ^{−3 to} 2.4 × 10 ⁻³ cal / cm · sec · ° C., so that the heat generated by the heating resistor 4 is adequate. Accumulation can be performed so that the temperature becomes equal, and the thermal response characteristics of the thermal head can be kept good.
[0018]
An etching resistant layer 3 mainly composed of Si ₃ N ₄ is deposited on a part of the heat storage layer 2.
[0019]
The etching resistant layer 3 effectively prevents the heat storage layer 2 located in the vicinity of the heating resistor 4 from being eroded by the etching solution when patterning the heating resistor 4 and the pair of electrodes 5 and 5 described later. For example, it is deposited and formed to a thickness of, for example, 0.1 μm to 0.5 μm over a part of the upper surface of the heat storage layer 2, specifically, the entire upper surface excluding the outer periphery of the heat storage layer 2.
[0020]
Furthermore, on the upper surface of the etching resistant layer 3, for example, a number of heating resistors 4 arranged in a straight line with a dot density of 600 dpi, for example, and a pair of electrodes 5 electrically connected to both ends of each heating resistor 4 , 5 are attached and formed.
[0021]
The heating resistor 4 is made of, for example, a TaSiO-based resistor material, a TiSiO-based resistor material, a TiCSiO-based resistor material, or the like, and has a predetermined electrical resistivity, so that it is externally connected via a pair of electrodes 5 and 5. When electric power from is applied, Joule heat is generated, and heat is generated at a temperature necessary for forming a print on the recording medium, for example, 250 ° C. to 400 ° C.
[0022]
The pair of electrodes 5 and 5 electrically connected to the heating resistor 4 is made of metal such as Al (aluminum), Cu (copper), Ag (silver), and the electrode 5 is connected to the heating resistor 4. It acts to apply a predetermined electric power necessary for causing Joule heat generation.
[0023]
A protective layer 6 made of Si ₃ N ₄ or the like is deposited on the upper surfaces of the heating resistor 4 and the pair of electrodes 5, 5, and the heating layer 4 and the pair of electrodes 5, 5 are covered by the protective layer 6. Are protected from wear due to sliding contact with the recording medium and corrosion due to contact with moisture contained in the atmosphere.
[0024]
Thus, the thermal head described above applies a predetermined power between the pair of electrodes 5 and 5 based on the image data from the outside to selectively generate Joule heat for each of the plurality of heating resistors 4 and the generated heat. Is conducted to a recording medium, and a predetermined print is formed on the recording medium, thereby functioning as a thermal head.
[0025]
Next, the manufacturing method of the thermal head mentioned above is demonstrated using Fig.3 (a)-(e). In the present embodiment, a case where one thermal head is obtained from one insulating substrate body 1A will be described as an example.
[0026]
(1) First, an insulating substrate body 1A that is slightly larger than the insulating substrate 1 described above is prepared.
[0027]
The insulating substrate body 1A is made of an electrically insulating material such as alumina ceramic. For example, an appropriate organic solvent or solvent is added to and mixed with a ceramic raw material powder such as alumina, silica, or magnesia to form a slurry. A ceramic green sheet is obtained by adopting a conventionally known doctor blade method, calendar roll method, etc., and then manufactured by punching the ceramic green sheet into a predetermined shape and firing it at a high temperature (about 1600 ° C.). Is done.
[0028]
A plurality of grooves 1a are formed near the outer periphery of the lower surface of the insulating substrate body 1A, and a section surrounded by these grooves 1a is a thermal head region T. The groove 1a is for facilitating cutting when the insulating substrate body 1A is cut into a predetermined shape of the insulating substrate 1 by bending in the step (7) described later, and becomes the insulating substrate body 1A. It is formed by cutting a ceramic green sheet with a cutter knife in advance. At this time, the depth of the groove 1a is preferably set to one-fourth to one-third of the thickness of the insulating substrate body 1A, and the insulating substrate body 1A is set within this range. It is possible to effectively prevent cracking due to vibration during conveyance before reaching the cutting step (7).
[0029]
(2) Next, the heat storage layer 2 is deposited on the upper surface of the insulating substrate body 1A so as to extend from the thermal head region T to the outside of the region T 1. In this embodiment, the heat storage layer 2 is formed over the entire top surface of the insulating substrate body 1A.
[0030]
The heat storage layer 2 is applied to an inorganic material mainly composed of SiO ₂ , for example, glass to a thickness of 15 μm to 40 μm, and a predetermined glass obtained by adding and mixing an appropriate organic solvent and solvent to the glass powder. The paste is formed by printing and applying the paste over the entire upper surface of the insulating substrate body 1A by a known thick film technique such as screen printing, and baking it at a temperature of about 1300 ° C.
[0031]
The heat storage layer 2 formed by such a process has a shape in which the outer peripheral part swells due to the surface tension of the glass paste, etc., but this swelled part exists in the cut and removed part, and the subsequent process (7) Is separated from the thermal head.
[0032]
(3) Next, as shown in FIG. 3 (a), the etching resistant layer 3 is deposited on the upper surface of a part of the heat storage layer 2, specifically, the entire upper surface of the heat storage layer 2 excluding the outer periphery of the thermal head region T. .
[0033]
The etching resistant layer 3 is deposited to a thickness of 0.1 μm to 0.5 μm with an inorganic material mainly composed of Si ₃ N ₄ and is formed by employing a conventionally known thin film method such as sputtering.
[0034]
In addition, since the patterning of the etching resistant layer 3 does not require very high accuracy, the etching resistant layer 3 can be stored by simply covering a part of the surface of the thermal storage layer 2 with a metal mask or the like during the above-described sputtering. It can be formed only in a predetermined region on the upper surface of the layer.
[0035]
(4) Next, as shown in FIG. 3B, a resistance layer 4A and a conductive layer 5A are sequentially deposited on the etching resistant layer 3.
[0036]
The resistance layer 4A is 0.01 μm to 0.10 μm with a resistance material such as TaSiO, TiSiO, TiCSiO, and the conductive layer 5A is 0.5 μm to 2.0 μm with a metal such as Al, Cu, or Ag. 3 is applied and formed on both the upper surface of the heat storage layer and the upper surface of the heat storage layer in the region where the surface is exposed.
[0037]
The resistance layer 4A and the conductive layer 5A are sequentially deposited and formed on the upper surface of the etching resistant layer 3 and the like by a well-known thin film technique such as sputtering or vacuum deposition.
[0038]
(5) Next, the conductive layer 5A and the resistance layer 4A in the thermal head region T are processed into a predetermined pattern, and a groove 2a along the outer peripheral portion of the thermal head region T is formed in the heat storage layer 2.
[0039]
The patterning of the conductive layer 5A and the resistance layer 4A and the formation of the groove 2a are performed by employing conventionally known photolithography and etching. Specifically, first, as shown in FIG. 3C, an ultraviolet curable resin varnish is applied to the surface of the conductive layer 5A by a conventionally known spin coating method or the like, and ultraviolet light having a predetermined wavelength is applied to the varnish. Irradiate a predetermined pattern corresponding to 5 to partially cure the ultraviolet curable resin, then remove the uncured ultraviolet curable resin, and then apply the ultraviolet curable resin r to the predetermined pattern. The insulating substrate element 1A is immersed in an etching solution containing hydrofluoric acid for a predetermined time, and the conductive layer 5A and the resistance layer 4A in the region where the ultraviolet curable resin r does not exist and the region where the etching resistant layer 3 does not exist. By continuously eroding the heat storage layer 2, the patterning of the heating resistor 4 and the pair of electrodes 5, 5 and the formation of the groove 2 a are simultaneously performed as shown in FIG.
[0040]
At this time, the etching-resistant layer 3 containing Si ₃ N ₄ as a main component is less likely to be eroded by the etching solution containing hydrofluoric acid than the heat storage layer 2 containing SiO ₂ as a main component. Even in this case, the etching resistant layer 3 is hardly eroded, while the heat storage layer 2 in a region where the etching resistant layer 3 does not exist is greatly eroded, thereby forming the groove 2a.
[0041]
In this case, since the groove 2a of the heat storage layer 2 is formed in the same process as the patterning of the electrodes 5, 5 and the heating resistor 4, there is no additional process for forming the groove 2a. It is possible to effectively prevent the manufacturing process from becoming complicated.
[0042]
The patterning of the heating resistor 4 is performed by removing a part of the conductive layer 5A and exposing a part of the underlying resistance layer 4A by well-known photolithography and etching. The resistance layer 4A functions as the heating resistor 4.
[0043]
(6) Next, a protective layer 6 is deposited on the surface of the heating resistor 4, the pair of electrodes 5, 5 and the heat storage layer 2.
[0044]
The protective layer 6 is deposited and formed to a thickness of 0.1 μm to 0.5 μm by Si ₃ N ₄ or the like, which is the same as the etching resistant layer 3, and a heating resistor is formed by employing a conventionally known thin film method such as sputtering. 4. It is formed so as to cover the pair of electrodes 5, 5 and the heat storage layer 2 and the like.
[0045]
(7) Finally, as shown in FIG. 3 (e), the insulating substrate body 1A and the heat storage layer 2 are cut along the grooves 1a and 2a to obtain a thermal head having a predetermined shape.
[0046]
This cutting is performed by placing jigs having predetermined protrusions on both upper and lower sides of the insulating substrate body 1A, pressing predetermined portions of the insulating substrate body 1A with the protrusions of these jigs, and applying a bending stress. Done.
[0047]
Since the edge portion of the heat storage layer 2 raised due to the surface tension of the glass paste is located in this cut and removed portion, there is no large rise in the heat storage layer 2 of the thermal head obtained after cutting and removing. First, when printing is performed using such a thermal head, the recording medium can be brought into sliding contact with all the heating resistors 4 uniformly and satisfactorily.
[0048]
At this time, since the groove 2a is formed at the cut portion of the heat storage layer 2 cut together with the insulating substrate body 1A, the bending stress applied to the heat storage layer 2 at the time of cutting is applied to the formation portion of the groove 2a. It will be applied intensively. Therefore, chipping and burrs are rarely generated in the heat storage layer 2 of the obtained thermal head, and damage to the electrode 5 can be effectively prevented, and the productivity of the thermal head can be dramatically improved. When printing using the recording medium, it is possible to effectively prevent the recording medium from being damaged by sliding contact with the thermal head.
[0049]
In addition, this invention is not limited to the above-mentioned form, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.
[0050]
For example, in the above-described embodiment, the method of obtaining only one thermal head from the insulating substrate body 1A has been described. However, a so-called "so-called" that obtains a plurality of thermal heads simultaneously from one insulating substrate body having a plurality of thermal head regions. The present invention can also be applied to the case of “multiple picking”.
[0051]
In the above embodiment, the case where a thermal head in which the heat storage layer 2 is attached to the entire upper surface of the insulating substrate 1 has been described as an example. Instead, the heat storage layer 2 has an arcuate cross section. The present invention can also be applied when manufacturing a partially formed thermal head. In this case, the etching resistant layer only needs to be applied to the entire top surface of the heat storage layer except the outer periphery of the thermal head region. It does not necessarily have to be deposited.
[0052]
Further, in the above-described embodiment, a plurality of dummy patterns d formed of the same material as the heating resistor 4 and the electrode 5 are arranged in the groove 2a of the heat storage layer 2 as shown in FIG. May be arranged in parallel. In this case, since the dummy pattern d functions as an adhesive layer between the heat storage layer 2 and the protective layer 6 at the edge of the thermal head, the adhesion strength of the protective layer 6 to the underlayer is increased, and the reliability of the thermal head is improved. There are also advantages to doing.
[0053]
【The invention's effect】
According to the present invention, since the groove is formed at a predetermined location of the heat storage layer that is cut together with the insulating substrate body, the bending stress applied to the heat storage layer at the time of the cutting is concentrated on the groove formation location. Applied. Therefore, chipping and burrs are unlikely to occur in the heat storage layer of the obtained thermal head, and it is possible to effectively prevent breakage of a predetermined pattern and dramatically improve the productivity of the thermal head, and use such a thermal head. Thus, it is possible to effectively prevent the recording medium from being damaged by sliding contact with the thermal head when printing.
[0054]
Further, according to the present invention, since the groove of the heat storage layer is formed in the same process as the patterning of the electrode and the heating resistor, there is no additional process for forming the groove in the heat storage layer. It is possible to effectively prevent the manufacturing process from becoming complicated.
[Brief description of the drawings]
FIG. 1 is a plan view of a thermal head manufactured by a manufacturing method according to an embodiment of the present invention.
2A is a cross-sectional view taken along line XX in FIG. 1, and FIG. 2B is a cross-sectional view taken along line YY in FIG.
FIGS. 3A to 3E are cross-sectional views for each step for explaining a method of manufacturing the thermal head of FIG.
FIG. 4 is an enlarged cross-sectional view of a main part for explaining a modification of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulating substrate, 1A ... Insulating substrate body, 2 ... Thermal storage layer, 2a ... Groove, 3 ... Etching-resistant layer, 4 ... Heat generating resistor, 4a ... Resistance Layer, 5,5 ... pair of electrodes, 5a ... conductive layer, 6 ... protective layer

Claims (1)

A thermal storage layer extending from the inside of the thermal head region to the outside of the cutting region is attached to the upper surface of the insulating substrate body having a thermal head region and a cutting region surrounding the thermal head region,
Depositing an etching resistant layer on the upper surface of the heat storage layer excluding the cutting region where a groove having a predetermined width is formed ;
A step of the resistive layer and the conductive layer are sequentially deposited on the etch-resistant layer of the thermal head region,
Some of the conductive layer and the resistive layer, and by etching the heat storage layer, and forming the groove in the heat storage layer positioned on the cutting area while processing the conductive layer and the resistive layer in a predetermined pattern,
Cutting the insulating substrate body along the groove to obtain a thermal head.

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