JPH06320774A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To provide the manufacturing method of a thermal head, which is capable of forming a thicker porous layer and eliminating troubles such as oxidization and the like due to the existence of pores on the surface thereof. CONSTITUTION:Coating solution (wet gel) 108 is formed on a heat resistant resin film 110, constituting a transfer supporting member 99 consisting of a material having comparatively low bonding strength against dry porous gel, and the solution is dried to obtain a dry porous gel layer 111. Then, a supporting substrate 101, on which glass paste 107 is applied, is bonded to a transfer supporting member 99, on which the dry porous gel layer 111 is formed, so that the coating surface of the glass paste 107 is opposed to the formed surface of the dry porous gel layer 111. Next, the transfer supporting member 99 is peeled from the dry porous gel layer 111 and the dry porous gel layer 111 is baked to form a porous layer 102.

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 used in a recording section of a facsimile machine, a printer machine, a copying machine or the like.

[0002]

2. Description of the Related Art FIG. 3 is a vertical sectional view showing a conventional thermal head. In the figure, 201 is a support substrate formed of alumina having a relatively high thermal conductivity, and a heat insulating layer 202 made of glass having a relatively low thermal conductivity is formed on the support substrate 201. .

The heating resistor 2 is formed on the heat insulation layer 202.
03 and a pair of electrodes 2 connected to the heating resistor 203.
04a and 204b are formed. A protective layer 20 is provided on the heat generating resistor 203 and the electrodes 204a and 204b to prevent the heat generating resistor 203 from being oxidized and to prevent abrasion due to contact with a thermal paper or an ink sheet.
5,206 is coated.

The heating resistor 203 is formed in a line in the direction perpendicular to the plane of the drawing, and the pair of electrodes 204a, 204a,
A plurality of 204b are arranged at a predetermined interval in the direction perpendicular to the plane of the drawing, and thereby a heating resistor line is formed.

When recording is performed using a thermal paper or an ink sheet with the thermal head having the above-mentioned configuration, the above-mentioned electrode is brought into contact with the surface of the heating resistor 203 on which the thermal paper or the ink sheet is pressed by a platen roller or the like. 204
The portion of the heating resistor 203 to be heated is energized via a and 204b. As a result, the heat-generating resistor 203 in the energized portion generates heat, and the heat-sensitive paper causes the heat-sensitive paper to develop color, or the ink of the ink sheet adheres to the recording paper to perform recording.

By the way, in a thermal recording apparatus using such a thermal head, there is a demand for high-speed printing and low power consumption. To meet this demand, the heat generation efficiency and thermal response of the thermal head are required. Both need to be improved.

In order to improve the heat generation efficiency, it is necessary that the heat of the heat generating resistor 203 is efficiently conducted to the side of the thermal paper or the ink sheet and the heat is not so much conducted to the opposite side. is there.

On the other hand, in order to improve the thermal responsiveness, it is necessary to increase the thermal efficiency and increase the temperature rising rate, and to reduce the amount of heat stored near the heating resistor to shorten the cooling time. It is necessary to reduce the heat capacity of the layer.

Here, if the above-mentioned heat retaining layer is thickened, the heat escape is reduced, but the heat storage amount is increased. Therefore, it is desirable to use a material having a small thermal conductivity and a small heat capacity for the heat retaining layer. For this reason, for example,
As disclosed in Japanese Patent Publication No. 18834 and Japanese Patent Publication No. 4-60025, a method of using a thin layer of a resin such as polyimide having small heat conductivity and heat resistance as a heat insulating layer, or containing air inside Therefore, there has been proposed a method using porous glass that can significantly reduce the apparent thermal conductivity and heat capacity.

[0010]

However, the above polyimide resin is not sufficient in heat resistance, and the porous glass has the one using the phase separation method, the one obtained by sintering particles, and the hollow filler. It is known to use a foaming agent, a foaming agent, a spraying agent, or a sol-gel method, but each has the following drawbacks.

The phase separation method is a method in which the phase is separated into an acid-insoluble phase and a soluble phase, and then the latter is eluted with an acid to obtain a porous material. This phase separation method requires a high temperature for phase separation, and the residue of acid may erode the resistor and the electrode.

The method of sintering particles, using a hollow filler, a foaming agent, and spraying has a drawback in that the surface of the heat retaining layer is hard to be smooth, which deteriorates the printing quality.

According to the sol-gel method, several Å to several 100 Å
Such fine holes can be obtained, and if they are evenly distributed, the heat distribution will be uniform and the print quality will not deteriorate. Furthermore, there is an advantage that it can be manufactured at a lower temperature than the conventional melting method. It has the drawback that it is not easy to manufacture.

That is, the sol-gel method is a method of producing a glass oxide by subjecting a gel obtained by hydrolyzing a metal alkoxide to heat dehydration condensation, but it is cracked due to a large volume change due to drying of the gel. There is a drawback that peeling from the substrate or the substrate easily occurs. Peeling is likely to occur when the generated gel has a weak adhesion to the substrate, and cracking is likely to occur when the gel has a strong adhesion to the substrate. In order for the porous layer to function as a heat retaining layer, it is desirable that the film thickness be 1 μm or more, but the thicker the film, the more likely cracks and peeling will occur.

On the other hand, in order to obtain a thick porous body layer, a method of stacking a number of thin porous body layers is conceivable, but this causes a problem that manufacturing takes time.

Further, since the porous body obtained by the sol-gel method has pores which are minute but open on the surface, when the heating resistor or the electrode is directly formed on the surface, the air existing in the pores is formed. There is also a drawback that the heating resistor and the electrode are oxidized by this to cause a change in the resistance value and the printing quality is deteriorated.

In view of the above circumstances, the present invention makes it possible to form a thicker porous layer and eliminate problems such as oxidation due to the presence of pores on its surface. It is an object of the present invention to provide a method of manufacturing a thermal head that can be used.

[0018]

In order to solve the above-mentioned problems, the method of manufacturing a thermal head of the present invention comprises a wet gel on a transfer support member made of a material having a relatively low adhesive strength with a dry porous gel. Forming a layer and drying the layer, a step of peeling the dry porous gel layer obtained by this drying from the transfer support member, a step of fixing the dry porous gel layer to a support substrate, and the dry porous layer And a step of forming a porous body layer by firing the porous gel layer.

[0019]

According to the above-described manufacturing method, the transfer support member on which the dry porous gel layer is formed is made of a material having a relatively low adhesion strength to the dry porous gel, so that the wet gel layer is a dry porous gel. Even if volume contraction occurs when forming a layer, the contraction is accompanied by peeling from the transfer supporting member. As a result, even if an attempt is made to obtain a thick dry porous gel layer, the cracks do not occur, and a thick porous body layer is obtained to further improve both heat generation efficiency and thermal responsiveness. be able to.

Also, when the dry porous gel layer is peeled off from the transfer supporting member, this can be easily performed. Then, after the transfer support member is peeled off, the dry porous gel layer is fixed to the support substrate, or after the dry porous gel layer is fixed to the support substrate, the transfer support member is peeled off, so that the support substrate A dry porous gel layer is formed on the substrate, and a porous body layer is formed by firing. Since the volumetric shrinkage of the dried porous gel layer due to this firing is small, cracking does not occur.

Here, the fine pores of the dry porous gel are generated by the escape of water generated during the dehydration condensation to the outside. Therefore, the micropores are opened on the surface of the dry porous gel layer that is not in contact with the transfer supporting member, and the micropores are closed on the surface of the dry porous gel layer that is in contact with the transfer supporting member. ing. Therefore, if the surface on the side where the micropores are opened is fixed to the support substrate, the smooth surface on the side where the micropores are closed in the porous body layer is located on the surface. It is possible to form the heating resistor and the electrode on the top. Since the electrodes and heating resistors formed on the surface do not touch the air in the fine holes, oxidation does not occur, and since they are formed on a smooth surface, print quality is also improved. Become.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments. In the following examples, an example in which the porous body layer is manufactured by the sol-gel method is shown.

FIGS. 1A to 1D are vertical sectional views showing a method of manufacturing a thermal head according to the present invention in the order of steps.

In FIG. 1A, reference numeral 99 is a transfer supporting member, and the transfer supporting member 99 is composed of a supporting plate 109 and a heat-resistant resin film 110 fixed on the supporting plate 109. Reference numeral 108 denotes a coating solution (wet gel) applied on the heat resistant resin film 110 of the transfer supporting member 99. The coating solution 108 is a silicon methoxide [Si (OC
H ₃ ) ₄ ] is diluted with methanol, water is added and the mixture is stirred to promote hydrolysis. That is, Si (OH) _x (OCH ₃ ) _4-x produced by this hydrolysis
Each other repeats the dehydration condensation reaction to develop a chain-like or three-dimensional siloxane bond (Si-O-Si) and become a polymer solution.

After coating the coating solution 108, the coating solution 108 is dried in an atmosphere at a temperature lower than the heat resistant temperature of the heat resistant resin film 110, and the dehydration condensation reaction is further proceeded, as shown in FIG. Thus, a dry porous gel layer 111 having a large number of fine pores of about several tens of liters and relatively uniformly distributed is obtained. At this time, the heat-resistant resin film 110 of the transfer supporting member 99 is made of a material having a relatively low adhesion strength to the dry porous gel layer 111, and the coating solution 108 is used as the dry porous gel layer 1.
Even if the volume shrinkage occurs when it becomes 11, since the shrinkage is accompanied by peeling from the heat-resistant resin film 110, cracking does not occur even when the thick dry porous gel layer 111 is formed. That is, the dry porous gel layer 111 having a large film thickness can be obtained.

Next, as shown in FIG. 3C, glass (ceramic) is formed on the support substrate 101 made of alumina or the like.
The paste 107 is applied. Then, the support substrate 101 coated with the glass paste 107 and the transfer support member 99 on which the dry porous gel layer 111 is formed,
The surface on which the glass paste 107 is applied and the surface on which the dry porous gel layer 111 is formed face each other and are bonded together.

Next, the transfer support member 99 is peeled off from the dry porous gel layer 111. Since the adhesion strength between the dry porous gel layer 111 and the support substrate 101 is relatively low, it can be easily peeled off. Here, the fine pores of the dry porous gel layer 111 are open on the surface not in contact with the transfer supporting member 99 and conversely closed on the surface in contact with the transfer supporting member 99. Therefore, by performing the bonding as described above, the smooth surface on the side where the fine holes are closed faces the surface (the surface on the printing side).

Then, the dry porous gel layer 111 and the glass paste 107 are fired in an atmosphere of 500 to 600 ° C.

As a result, as shown in FIG. 3D, the porous body layer 1 functioning as a heat retaining layer on the support substrate 101.
02 is formed. Since the volumetric shrinkage of the dry porous gel layer 111 at the time of this firing is small, cracking does not occur. If the firing temperature is too high, the fine pores of the porous body layer 102 disappear due to sintering,
The temperature should be controlled so that the required porosity is obtained.

Thereafter, a cooling process is performed. At this time, the support substrate 101, the porous body layer 102, and the glass paste 1 are used.
The temperature is slowly lowered so that there is no difference in the contraction speed between No. 07 and No. 07. Further, it is important to select these materials so that the thermal expansion coefficients of the support substrate 101, the porous body layer 102 and the glass paste 107 are as equal as possible.

After that, the heating resistor 1 is formed by a known method.
03, the electrodes 104a and 104b, the oxidation protection layer 105, and the abrasion resistant layer 106 are formed by a method such as sputtering or vapor deposition.

FIG. 2 is a vertical cross-sectional view of the thermal head manufactured by the above manufacturing method. As shown in the figure, the heating resistor 103 and the electrodes 104a and 104b are
Is formed on the smooth surface of the porous body layer 102 on the side where the fine pores are closed, and does not come into contact with the air in the fine pores.
3 generates heat, the heating resistor 103 and the electrode 104
Oxidation of a and 104b will not occur.

In the present embodiment, the process of peeling the transfer support member 99 from the dry porous gel layer 111 is performed after the above-mentioned bonding, but it may be performed before this bonding. is there.

Further, the above-mentioned dry porous gel layer 111 is fixed to the support substrate 101 with the surface on the side where the fine pores are closed facing the surface. When the surface on the side where the holes are opened is disposed as the surface (the surface on which the heating resistor or the like is formed), it is not possible to prevent oxidation of the heating resistor or the like, but the porous layer 102 having a large thickness is used. It is possible to obtain the effect of being obtained.

The above-mentioned pasting was performed using the glass paste 107. However, if the dry porous gel 111 and the support substrate 101 can be sintered and bonded even without the glass paste 107, the glass paste 107 is used. Can be eliminated.

[0036]

As described above, according to the present invention, it is possible to form a porous layer having a large film thickness without causing cracking or peeling. Further, the dry porous gel layer can also be fixed with the surface on the side where the fine pores are closed facing the surface, whereby oxidation of the heating resistor layer and the like can be prevented. As a result, it is possible to improve the thermal efficiency and the thermal response of the thermal head while maintaining the printing quality, thereby achieving lower power consumption and higher printing speed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing, in the order of steps, steps up to forming a dry porous gel layer on a support substrate in a method of manufacturing a thermal head according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a thermal head manufactured by the above method.

FIG. 3 is a vertical sectional view showing a thermal head manufactured by a conventional method.

[Explanation of symbols]

 101 Support Substrate 102 Porous Body Layer 103 Heating Resistor 105 Antioxidant Layer 106 Abrasion Resistant Layer

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

A plurality of the heating resistors 203 and the pair of electrodes 204a and 204b are arranged at a predetermined interval in the direction perpendicular to the plane of the drawing, whereby a heating resistor line is formed.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

However, the above polyimide resin is not sufficient in heat resistance, and the porous glass has the one using the phase separation method, the one obtained by sintering particles, and the hollow filler. It is known to use a foaming agent or a sol-gel method, but they have the following drawbacks.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The method of sintering particles or using a hollow filler or a foaming agent has a drawback that the surface of the heat retaining layer is hard to be smooth, which deteriorates the printing quality.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

That is, the sol-gel method is a method for producing glass by hydrolyzing and condensing a gel obtained by hydrolyzing a metal alkoxide, but cracks and cracks are caused due to a large volume change accompanying drying of the gel. There is a drawback that peeling from the substrate is likely to occur. Peeling is likely to occur when the generated gel has a weak adhesion to the substrate, and cracking is likely to occur when the gel has a strong adhesion to the substrate. In order for the porous body layer to function as a heat retaining layer, it is desirable that the film thickness be 1 μm or more. However, the thicker the film thickness is,
It tends to crack and peel.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

On the other hand, in order to obtain a thick porous body layer, a method of stacking a number of thin porous body layers can be considered, but this causes a problem that it takes time to manufacture.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Next, the transfer support member 99 is peeled off from the dry porous gel layer 111. Since the adhesion strength between the dry porous gel layer 111 and the heat resistant resin film 110 is relatively low, it can be easily peeled off. Here, the fine pores of the dry porous gel layer 111 are open on the surface not in contact with the transfer supporting member 99 and conversely closed on the surface in contact. Therefore, by performing the bonding as described above, the smooth surface on the side where the fine holes are closed faces the surface (the surface on the printing side).

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

After that, a heating resistor, an electrode, an oxidation protection layer, and an abrasion resistant layer (not shown) are formed by a known method by a method such as sputtering or vapor deposition.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Kuwahara 2-18, Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A step of forming a wet gel layer on a transfer support member made of a material having a relatively low adhesive strength with a dry porous gel and drying the wet gel layer, and a dry porous gel layer obtained by this drying. Characterized by including a step of peeling from the transfer support member, a step of fixing the dry porous gel layer to a support substrate, and a step of firing the dry porous gel layer to form a porous body layer. Method of manufacturing thermal head.