JPH0584948A - Production of thermal head - Google Patents

Abstract

PURPOSE:To prevent the corrosion of a heating resistor layer and a pair of conductive layers due to the contact of moisture in the atmosphere with said layers. CONSTITUTION:In a thermal head wherein a heating resistor layer 3 and a pair of conductive layers 4a, 4b are formed to the upper surface of an electric insulating substrate 1 and covered with a protective layer 5, an alkoxide glass solution with a viscosity of 3cps or less and surface tension of 25 dyn.s/cm<2> or less is applied to the surface of the protective layer 5 and subjected to polycondensation under heating to deposit a glass layer 6. The alkoxide glass solution well penetrates in the film fault 5a of the protective layer 5 by a capillary phenomenon and the glass layer 6 is formed to the upper surface of the protective layer 5 in such a state that part thereof is received in the film fault 5a.

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 incorporated as a printer mechanism such as a word processor or a facsimile.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a thermal head incorporated as a printer mechanism for a word processor, a facsimile or the like has a heat storage layer 12 made of glass or the like on a substrate 11 made of an electrically insulating material such as alumina.
A heating resistor layer 13 made of tantalum nitride or the like and a pair of conductive layers 14a, 14b made of aluminum or the like, and the heating resistor layer 13 and the pair of conductive layers 1 are attached.
It has a structure in which the surface of 4a, 14b is covered with a protective layer 15 made of silicon nitride or the like, a predetermined electric power is applied between the pair of conductive layers 14a and 14b, and the heating resistor layer 13 is printed as an image. The Joule heat is generated to a temperature required to form the heat transfer sheet, and the generated heat is conducted to the thermal paper 17 or the like to form a print image on the thermal paper 17 or the like, thereby functioning as a thermal head.

It is to be noted that the heating resistor layer 13 and the pair of conductive layers 14a and 14b are prevented from being abraded by sliding of thermal paper or the like, or moisture in the atmosphere or chlorine ions or sodium contained in the thermal paper or the like. This is for preventing ions and the like from coming into contact with the heating resistor layer 13 and the like and causing corrosion in the heating resistor layer 13 and the like.

However, in this conventional thermal head, the protective layer 15 is usually deposited by a thin film forming technique such as sputtering, and at this time, the protective layer 15 has pinholes, cracks and the like. The large number of film-forming defects 15a are not formed so as to completely cover the surfaces of the heating resistor layer 13 and the pair of conductive layers 14a and 14b. Therefore, moisture in the atmosphere and chlorine ions, sodium ions, etc., contained in the thermal paper, etc., may cause the film-forming defects 15 to occur.
via the heating resistor layer 13 and the pair of conductive layers 14a, 1
4b to cause corrosion in the heating resistor layer 13 or the like to cause disconnection in the heating resistor layer 13 or the pair of conductive layers 14a and 14b, or to cause variations in these conductive resistances. Therefore, the function as a thermal head is lost.

In order to solve the above-mentioned drawbacks, therefore, as shown in FIG. 3, an overcoat layer 16 made of resin, glass or the like is deposited on the upper surface of the protective layer 15 to form a film-forming defect 15a formed in the protective layer 15. It is conceivable to cover the upper part of the with an overcoat layer 16.

However, since this thermal head only covers the upper portion of the film-forming defect 15a formed in the protective layer 15 with the overcoat layer 16, it is initially contained in the atmospheric moisture or thermal paper. Chloride ion,
Although the sodium ion or the like does not contact the heating resistor layer 13 or the pair of conductive layers 14a and 14b, the thermal head can be normally operated, but the thermal head is repeatedly operated to form a printed image on thermal paper or the like. In this case, the overcoat layer 16 is abraded by the sliding of the thermal paper 17 or the like, and as a result, the film forming defect 15a formed on the protective layer 15 is opened in a short period of time, and the above-mentioned defects reoccur. I had.

[0007]

According to the method of manufacturing a thermal head of the present invention, a heating resistor layer and a pair of conductive layers are deposited on the upper surface of an electrically insulating substrate, and the heating resistor layer and the pair of conductive layers are formed. Which is coated with a protective layer on the surface of the protective layer, the alkoxide glass solution having a viscosity of 3 cps or less and a surface tension of 25 dyn · s / cm ² or less is applied and the glass layer is heated and polycondensed. Is characterized by being attached.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a thermal head of the present invention, in which 1 is a substrate, 2 is a heat storage layer, 3a, 3
b is a pair of conductive layers, 4 is a heating resistor layer, 5 is a protective layer, 6
Is a glass layer.

The substrate 1 is made of an electrically insulating material having excellent heat resistance such as alumina ceramics, and a heat storage layer 2 is attached to the upper surface thereof.

The heat storage layer 2 is made of glass, polyimide resin or the like, and stores and dissipates the heat generated by the heating resistor layer 3 to keep the thermal response characteristics of the thermal head good.

A heating resistor layer 3 is deposited on the upper surface of the heat storage layer 2, and a pair of conductive layers 4a and 4b are deposited on the upper surface of the heating resistor layer 3 with a constant gap therebetween. Has been done.

The heating resistor layer 3 is made of, for example, tantalum nitride or the like, and has a predetermined electric resistance by itself. Therefore, when a predetermined electric power is applied through the pair of conductive layers 4a and 4b, the joule is formed. Heat is generated, and the temperature is required to form a printed image, for example, 300 to 450 ° C.

The pair of conductive layers 4a and 4b deposited on the heating resistor layer 3 are made of a metal such as aluminum, and the power required to cause Joule heating in the heating resistor layer 3 is generated. It acts to apply.

The heating resistor layer 3 and the pair of conductive layers 4
A protective layer 5 made of a material having excellent wear resistance, such as silicon nitride, is deposited on the upper surfaces of a and 4b, whereby the heating resistor layer 3 and the pair of conductive layers 4a and 4b are formed on the thermal paper. It protects against abrasion due to sliding with other materials, corrosion from moisture in the atmosphere, and contaminants such as chlorine ions and sodium ions contained in thermal paper.

The protective layer 5 is formed of a heating resistor layer 3 and a pair of conductive layers 4 by a conventionally known sputtering method or the like.
It is deposited on a and 4b, and at this time, a large number of film formation defects 5a such as pinholes and cracks are formed on the protective layer 5.

Further, a glass layer 6 is deposited on the upper surface of the protective layer 5 on which the film formation defect 5a is formed, with a part of the glass layer 6 being filled in the film formation defect 5a.

The glass layer 6 has a function of preventing corrosion of the heating resistor layer 3 and the like due to contaminants by closing the film formation defect 5a formed in the protective layer 5, and the glass layer 6
Is partially deposited on the upper surface of the protective layer 5 in a state of being filled in the film forming defect 5a, and therefore, the film is formed even if the glass layer 6 is worn by sliding of thermal paper during printing. The glass layer 6 filled in the defect 5a does not wear, and it is possible to always close the film formation defect 5a. As a result, the contaminants can generate contaminants through the film formation defect 5a and the heating resistor layer 3 and a pair of layers. Almost no occurrence of corrosion due to contact with the conductive layers 4a and 4b.

When the glass layer 6 is filled into the film-forming defect 5a of the protective layer 5 to a depth of 0.5 μm or more from the top surface, contaminants penetrate the glass layer 6 and the heating resistor layer 3 and a pair of layers. Corrosion of the conductive layers 4a and 4b is effectively prevented. Therefore, in order to prevent the heat generating resistor layer 3 and the pair of conductive layers 4a and 4b from being corroded more effectively by the contaminants and to make the thermal head function stably and satisfactorily for a long period of time, a part of the glass layer 6 is protected. It is preferable to fill the film forming defects 5a formed in the layer 5 from the top surface to a depth of 0.5 μm or more.

Thus, in the above-described thermal head, electric power is applied between the pair of conductive layers 4a and 4b in response to an external electric signal to cause the heating resistor layer 3 to have a Joule heating resistor layer at a predetermined temperature, and It functions as a thermal head by transmitting the generated heat to thermal paper or the like and forming a printed image on the thermal paper or the like.

Next, a method of manufacturing the above-mentioned thermal head will be described.

(1) First, a substrate 1 made of an electrically insulating material such as alumina ceramics is prepared.

The substrate is made into a slurry by adding a suitable organic solvent or solvent to a ceramic material powder such as alumina, silica, magnesia, etc. to form a slurry, and by adopting a conventionally known doctor blade method, a ceramic green sheet. Is formed, and then the ceramic green sheet is punched into a predetermined shape and fired at a high temperature (about 1600 ° C.).

(2) Next, the heat storage layer 2 made of glass or the like is deposited on the substrate 1.

The heat storage layer 2 is formed by printing and applying a glass paste obtained by adding and mixing a suitable organic solvent or solvent to glass powder on the substrate 1 by employing a conventionally known screen printing method or the like. It is then deposited on the substrate 1 by baking it at high temperature.

(3) Next, the heating resistor layer 3 made of tantalum nitride or the like and the pair of conductive layers 4a, 4b made of aluminum or the like are sequentially deposited on the heat storage layer 2.

The heating resistor layer 3 and the pair of conductive layers 4
A and 4b are sequentially deposited on the heat storage layer 2 by adopting a conventionally known sputtering method or the like.

(4) Next, a protective layer 5 made of silicon nitride or the like is formed on the upper surfaces of the heating resistor layer 3 and the pair of conductive layers 4a and 4b.
Put on.

The protective layer 5 is formed by depositing silicon nitride or the like on the upper surfaces of the heating resistor layer 3 and the pair of conductive layers 4a and 4b by using a conventionally known sputtering method or the like.

(5) Finally, the glass layer 6 is deposited on the upper surface of the protective layer 5 to complete the thermal head.

The glass layer 6 is made of an alkoxide glass (for example, a silicon compound: R _n Si (OH) _4-n , n is a positive number, R is an organic functional group), and an appropriate organic solvent or solvent ( For example, by adding and mixing (for example, methanol), the viscosity is 3 cps or less and the surface tension is 25 dyn · s / cm.
An alkoxide glass solution having a ratio of ² or less is prepared, and then the alkoxide glass solution is applied to the upper surface of the protective layer 5 by using a conventionally known dipping method or the like and left for about 2 minutes. The alkoxide glass solution is heated at a high temperature for about 1 hour using an oven, for example, at a temperature of 500 ° C. to heat-condensate the alkoxide glass, and water dissociated by the heat-condensation polymerization or an organic solvent or solvent in the alkoxide glass solution. Etc. are evaporated to form a glass layer 6 and deposited on the upper surface of the protective layer 5.
In this case, the alkoxide glass solution applied on the protective layer 5 has a viscosity of 3 cps or less and a surface tension of 25 dyn · s /
Since it is cm ² or less, when the alkoxide glass solution is applied to the upper surface of the protective layer 5, a part of the alkoxide glass solution satisfactorily penetrates into the film formation defect 5a of the protective layer 5 due to the capillary phenomenon, and as a result, The glass layer 6 obtained by heating the alkoxide glass solution at a high temperature is deposited on the protective layer 5 so that a part of the glass layer 6 covers the film formation defect 5a.

The alkoxide glass solution has a viscosity of more than 3 cps and a surface tension of 25 dyn · s /
When it exceeds cm ² , when the alkoxide glass solution is applied to the surface of the protective layer 5, the alkoxide glass solution cannot sufficiently penetrate into the film formation defects 5a formed in the protective layer 5. Therefore, in order to deposit the glass layer 6 on the surface of the protective layer 5 while partially filling the film forming defects 5a formed in the protective layer 5, the alkoxide glass solution has a viscosity of 3 cps or less, Tension is 25 dyn · s / cm
² Must be specified below.

Next, the function and effect of the present invention will be described based on the two experimental examples described below.

Experimental Example 1 First, as an experimental sample, as shown in FIG. 1, a plurality of heating resistor layers and a pair of conductive layers were applied to the upper surface of a substrate, and the heating resistor layers were covered with a protective layer. In the thermal head formed by, the surface of the protective layer has a viscosity of 1 cps and a surface tension of 22 dyn · s / cm ^2.
After applying the alkoxide glass solution made of
By heating this at a high temperature, a glass layer is deposited to a depth of 40% from the upper surface of the surface of the protective layer and the film-forming defects (diameter: 0.1 μm, depth: 3 μm) formed in the protective layer. A filled product of the present invention and a conventional product in which a glass layer is not attached to the surface of the protective layer are prepared.

Next, for each of the above samples, the temperature was 35
In a predetermined print standby state (a state in which a thermal paper is brought into contact with the protective layer of the thermal head and a voltage of 24 V is applied between the pair of conductive layers to heat the heating resistor layer) in an environment of ℃ and humidity of 85% The time until the number of set and corroded heating resistor layers reached 0.1% of the entire heating resistor layers (this is defined as the initial breakdown time) was examined.

According to such an experiment, in the conventional product, the initial breakdown time was about 20 hours, whereas in the product of the present invention, it was about 100 hours, which was five times as long as that of the conventional product, and the reliability of the thermal head was improved. It can be seen that is improved.

Experimental Example 2 As an experimental sample, as shown in FIG. 1, a plurality of heating resistor layers and a pair of conductive layers were applied to the upper surface of a substrate, and the heating resistor layers were covered with a protective layer. In the thermal head consisting of the above, an alkoxide glass solution having a viscosity of 1 cps and a surface tension of 22 dyn · s / cm ² is applied to the surface of the protective layer, which is then heated at a high temperature and the surface of the protective layer and The product of the present invention in which a glass layer was adhered and filled to a depth of 40% from the upper surface in the film formation defect (diameter: 0.1 μm, depth: 3 μm) formed in the protective layer, and the viscosity on the surface of the protective layer. 10 cps, surface tension 3
An alkoxide glass solution of 0 dyn · s / cm ² is applied, and then heated at a high temperature to prepare a conventional product in which a glass layer is adhered only to the surface of the protective layer.

Next, with respect to each of the above-mentioned samples, a predetermined electric power (electric power:
0.2 W / dot, application period: 10.0 msec, application time: 2.0 msec) and a high ion content (sodium ion: 2) in the protective layer of the thermal head.
000 ppm or more) of the thermal paper was slid to examine the sliding distance of the thermal paper when corrosion was first generated in the heating resistor layer.

According to the results of this experiment, in the conventional product, the first corrosion occurred when the thermal paper was slid about 10 km, while in the product of the present invention, it was about 30 km, which is about three times as long as that of the conventional product. It can be seen that the reliability of the thermal head has been improved.

The present invention is not limited to the above embodiments, and various modifications and improvements may be made without departing from the scope of the present invention.

[0041]

According to the method of manufacturing a thermal head of the present invention, the viscosity is 3 cps or less and the surface tension is 25 dyn · s.
/ Cm ² or less is applied to the protective layer and the glass layer is formed by heat polycondensation of the alkoxide glass solution. Therefore, the alkoxide glass solution printed and applied on the protective layer is a film formation defect of the protective layer. A glass layer is deposited on the upper surface of the protective layer, which is well penetrated into the inside by a capillary phenomenon and in which a film-forming defect is formed, so as to close the film-forming defect in a state where the glass layer is partially filled.

Therefore, in this thermal head, the film-forming defects formed in the protective layer are not opened by sliding of the thermal paper or the like, and the film-forming defects can always be closed by the glass layer, resulting in heat generation. Contamination of the resistor layer or the pair of conductive layers with a contaminant causes minimal corrosion, and the thermal head can function well for a long period of time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a thermal head manufactured by a manufacturing method of the present invention.

FIG. 2 is a sectional view of a thermal head showing a conventional example.

FIG. 3 is a sectional view of a thermal head showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrically insulating substrate 3 ... Heating resistor layer 4a, 4b ... A pair of conductive layers 5 ... Protective layer 5a ... Deposition defect 6 ... Glass layer

Claims (1)

[Claims] 1. A thermal head comprising a heating resistor layer and a pair of conductive layers deposited on the upper surface of an electrically insulating substrate, and the heating resistor layer and the pair of conductive layers being covered with a protective layer. The surface of the protective layer has a viscosity of 3 cps or less and a surface tension of 2
A method for manufacturing a thermal head, characterized in that a glass layer is deposited by applying an alkoxide glass solution of 5 dyn · s / cm ² or less and subjecting this to heat condensation polymerization.