JPH07266596A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a thermal head by which the thickness of a heat accumulation layer can be easily controlled and a small- size thermal head suited for high printing speed can be manufactured. CONSTITUTION:A thermal head is manufactured by a step to adhere a band-like reinforcing electrode 4 and a band-like glass member 5 at a specified interval and almost in parallel, along one side of a square electric insulating substrate 1, on its upper surface, step to form a heat accumulation layer 2 by filling a space between the reinforcing electrode 4 and the glass member 5 with a heat-resistant resin, and a step to bond thermal resistors 3, an individual electroconductive layer 6a connected to one end of the thermal resistor 3 and a common electroconductive layer 6b connected to the other end of the thermal resistor 3 and the reinforcing electrode 4, on the surface of the heat acumulation layer 2. Thus the thickness of a heat-resistant resin is maintained to be constant, and therefore, the heat accumulation layer 2 can be formed to a specified thickness.

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 in a printer mechanism such as a word processor and a facsimile.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 4A and 4B, a thermal head incorporated in a printer mechanism such as a word processor is provided on an upper surface of an electrically insulating substrate 11 made of alumina ceramics or the like, and is made of tantalum nitride or the like on the upper portion. The heat storage layer 12 made of a heat-resistant resin having a plurality of heating resistors 13 formed thereon and the reinforcing electrode 14 made of a metal material are attached, and the heating resistors 13 are provided on the heating resistor 13. It has a structure in which an individual conductive layer 16a connected to the driving IC 17 and a common conductive layer 16b electrically connected to the reinforcing electrode 14 are adhered to each other, and the individual conductive layer 16a and the common conductive layer 16b are formed. Predetermined electric power is applied in accordance with the driving of the driving IC 17 to selectively cause the heating resistor 13 to generate Joule heat, and the generated heat is recorded on an ink ribbon or thermal paper. Body is conducted to transfer the ink of the ink ribbon to the recording paper, or by coloring the thermal paper serves as a thermal head by forming a predetermined printing images. When an ink ribbon is used as the heat-sensitive recording medium, the ink ribbon runs on the heating resistor 13 in a state where the recording paper is superposed on the ink ribbon, and when the ink ribbon reaches the end of the electrically insulating substrate 11, Torn off.

Further, the heat storage layer 12 is for efficiently storing the heat generated by the heating resistor 13 to make the thermal response characteristics of the thermal head excellent, and has a low thermal conductivity (heat conductivity: 0. It is formed of a heat resistant resin of 1 to 0.9 W / m · k, for example, a polyimide resin or the like.

Further, the reinforcing electrode 14 includes a common conductive layer 16
It is for effectively preventing a voltage drop from occurring in the common conductive layer 16b when a large current is applied to b.
It is formed of a metal material such as silver or copper.

Such a conventional thermal head is usually manufactured by the following method.

(1) First, an electrically insulating substrate 11 made of alumina ceramics is prepared. (2) Next, a predetermined metal paste (eg, silver paste) is applied to the upper surface of the electrically insulating substrate 11 by a thick film method (eg, The reinforcing electrode 14 is formed by applying it in a strip shape along one side of the electrically insulating substrate 11 by a screen printing method and baking it at a temperature of about 600 ° C. (3) Next, the reinforcing electrode 14 is A varnish made of a polyimide resin is provided in a predetermined region on the upper surface of the formed electrically insulating substrate 11 in a predetermined thickness substantially in parallel with the reinforcing electrode 14,
The heat storage layer 12 is formed by applying it with a predetermined width and thermally curing it at a temperature of about 400 ° C.
(4) Next, the heat generating resistor 13 made of tantalum nitride and the individual conductive layers 16a and the common conductive layer 16b made of aluminum or the like are formed on the heat storage layer 12 by a thin film forming technique (for example, a sputtering method) or a photolithography technique. (5) Finally, the driving IC 17 is attached to the individual conductive layer 16a by soldering using a face-down bonding method or the like, so that the driving IC 17 is attached to the individual conductive layer 1a.
6a, which completes the thermal head.

[0007]

However, in this conventional method of manufacturing a thermal head, the heat storage layer 12 is used.
When a varnish serving as a polyimide resin is applied to the upper surface of the electrically insulating substrate 11 to form the varnish, the viscosity of the varnish decreases significantly if the temperature of the varnish rises with a change in room temperature or the like. As a result, the varnish applied on the electrically insulating substrate 11 spreads in the width direction and its thickness becomes thin, so that the heat storage layer 12 having desired heat storage characteristics and having a predetermined thickness cannot be formed. have.

On the other hand, as shown in FIGS. 5 (a) and 5 (b),
Reinforcing electrode 24 on the upper surface of electrically insulating substrate 21 and driving IC 2
A frame member 28 made of glass is attached between the
The heat storage layer 22 is formed by filling the frame material 28 with a polyimide resin.
According to such a manufacturing method, since the frame material 28 restricts the varnish, which is a polyimide resin, from trying to spread in the width direction, the heat storage layer 22 has a thickness immediately after the application of the varnish. And a predetermined thickness approximately equal to.

However, a frame member 28 made of glass is adhered between the reinforcing electrode 24 on the upper surface of the electrically insulating substrate 21 and the driving IC 27, and the frame member 28 is filled with a polyimide resin to form the heat storage layer 22. In the case of forming a large area, a large area for arranging a large frame member 28 in which the heat storage layer 22 having a width of about 2 mm is formed is provided between the reinforcing electrode 24 on the upper surface of the electrically insulating substrate 21 and the driving IC 27. Must be,
Therefore, there is a drawback that the thermal head becomes large.

Further, the reinforcing electrode 2 on the upper surface of the electrically insulating substrate 21.
When the frame member 28 is adhered between the driving IC 27 and the driving IC 27 and the heat storage layer 22 is formed in the frame member 28, the heat generating resistor 2 that conducts heat to the ink ribbon on which the recording papers are stacked.
3 and the end portion of the electrically insulating substrate 21 that peels the recording paper from the ink ribbon, the distance R1 becomes long, so that the recording paper and the ink ribbon are removed from the heating resistor 23 on the electrically insulating substrate 21. The ink that has once been transferred to the recording paper due to the heat generated by the heating resistor 23 cannot be peeled off quickly by conveying it to the end portion in a short time and the high speed printing can be performed on the ink ribbon again. A reverse transfer phenomenon occurs in which the image is transferred, which causes a defect that print quality is deteriorated.

[0011]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to easily control the thickness of a heat storage layer, and
It is an object of the present invention to provide a method of manufacturing a thermal head capable of manufacturing a small thermal head for high speed printing.

[0012]

According to the method of manufacturing a thermal head of the present invention, a strip-shaped reinforcing electrode and a strip-shaped glass member are provided along one side of the substrate on the upper surface of a square-shaped electrically insulating substrate. A step of applying the heat-resistant resin between the reinforcing electrode and the glass member to form a heat storage layer, and a step of applying a plurality of heat generations on the heat storage layer. A step of depositing a resistor, an individual conductive layer connected to one end of the heating resistor, and a common conductive layer connected to both the other end of the heating resistor and the reinforcing electrode. And

[0013]

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

FIG. 1A is a perspective view of a thermal head manufactured by the manufacturing method of the present invention, and FIG. 1B is FIG.
It is the XX sectional view of (a), 1 is an electrically insulating substrate,
2 is a heat storage layer, 3 is a heating resistor, 4 is a reinforcing electrode, 5 is a glass member, 6a is an individual conductive layer, 6b is a common conductive layer, 7 is a driving IC, and 8 is a protective film.

The electrically insulating substrate 1 has a rectangular shape and is made of an electrically insulating material such as alumina ceramics, and has an upper surface for supporting the heating resistor 3 and the like.

On the upper surface of the electrically insulating substrate 1,
A reinforcing electrode 4 made of a metal material such as gold, silver or copper is deposited to a thickness of 30 μm, for example.

The reinforcing electrode 4 is arranged along one side of the electrically insulating substrate 1 and is led out from both ends in a direction orthogonal to the one side of the substrate 1 and electrically connected to a common conductive layer 6b described later. By being connected, the common conductive layer 6b
This effectively prevents a voltage drop from occurring in the common conductive layer 6b when a large current is applied to the common conductive layer 6b.

The upper surface of the electrically insulating substrate 1 is substantially parallel to one side of the electrically insulating substrate 1 and the reinforcing electrode 4 is provided.
A glass member 5 having a slanted outer surface 5a is attached in a strip shape with a thickness of 30 μm, which is substantially equal to that of the reinforcing electrode 4, at a position separated by a predetermined distance (for example, 2 mm).

Further, both ends of the glass member 5 are in contact with the reinforcing electrode 4, and between the reinforcing electrode 4 and the glass member 5, that is, inside the frame member composed of the reinforcing electrode 4 and the glass member 5. The heat storage layer 2 having a width of 2 mm is filled with a thickness of 30 μm, which is substantially equal to the reinforcing electrode 4 and the glass member 5.

The heat storage layer 2 has a low heat conductivity (heat conductivity:
It is made of a heat-resistant resin having 0.1 to 0.9 W / m · k), for example, a polyimide resin, and has the function of accumulating the heat generated by the heating resistor 3 to keep the thermal response characteristics of the thermal head good. Do

A plurality of heating resistors 3 made of tantalum nitride or the like are deposited and arranged on the upper surface of the heat storage layer 2. One end of each heating resistor 3 drives the heating resistor 3. The individual conductive layers 4 connected to the ICs 7 are individually connected, and the other end of each heating resistor 3 is commonly connected to the common conductive layer 5 connected to the reinforcing electrode 4.

Since the heating resistor 3 is made of, for example, tantalum nitride or the like and has a predetermined electric resistivity, a predetermined electric power is applied through the individual conductive layer 4 and the common conductive layer 5. Then, Joule heat is generated, and heat is generated at a predetermined temperature necessary for forming a printed image, for example, a temperature of 200 ° C to 350 ° C.

The individual conductive layer 4 and the common conductive layer 5 connected to both ends of the heating resistor 3 are made of metal such as aluminum, and the individual conductive layer 4 and the common conductive layer 5 are connected to the heating resistor 3. It has a function of applying a predetermined electric power necessary for causing Joule heat generation.

Further, a driving IC 7 is formed on the individual conductive layer 6a.
Are connected via a brazing material such as solder by a face-down bonding method.
Is a heating resistor 3 based on a print signal input from the outside.
To selectively control heat generation.

Further, the heating resistor 3 and the like are covered with a protective film 8 made of silicon nitride, sialon or the like, and the protective film 8 is oxidized and corroded by contact of moisture contained in the atmosphere or a heat-sensitive recording medium. The heating resistor 3 is protected from abrasion caused by sliding contact with the heating resistor 3.

Thus, in the above-mentioned thermal head, a predetermined electric power is applied between the individual conductive layer 6a and the common conductive layer 6b as the driving IC 7 is driven, and the heating resistor 3 is selectively heated by Joule heat. The heat generated is conducted to the thermal recording medium, the ink of the ink ribbon is transferred to the recording paper, or the thermal paper is colored to form a predetermined print image, thereby functioning as a thermal head.

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

(1) First, a square electric insulating substrate 1 made of alumina ceramics or the like is prepared.

The electrically insulating substrate 1 is formed into a sludge form by adding and mixing an appropriate organic solvent or solvent to a ceramic raw material powder such as alumina, silica, magnesia, etc., and the same is formed by a conventionally known doctor blade method or calender roll method. Etc. are used to form a ceramic green sheet, and thereafter, the ceramic green sheet is punched into a predetermined rectangular shape and is fired at a high temperature.

(2) Next, as shown in FIG. 2A, on the upper surface of the electrically insulating substrate 1, from one side of the substrate 1, for example,
Outside surface 5a at a position separated by 3.0 mm and substantially parallel to the one side.
The glass member 5 in which is inclined is adhered and formed in a strip shape.

The glass member 5 is prepared by adding an organic solvent suitable for glass powder, and a predetermined glass paste obtained by adding and mixing a solvent, from one side of the upper surface of the electrically insulating substrate 1 by a thick film method such as screen printing. A predetermined thickness (for example, 30 μm) and a predetermined width (for example, 1.5 mm) at positions 0 mm apart
And is baked at a temperature of about 800 ° C. to be deposited on the upper surface of the electrically insulating substrate 1.

The viscosity of the glass paste does not change so much even if the temperature rises by about 10 ° C. due to a change in room temperature or the like. Therefore, when the glass member 5 is adhered and formed on the electrically insulating substrate 1. The thickness of the glass paste rarely becomes thin due to the decrease in the viscosity of the glass paste, and the glass member 5 can be formed to have a predetermined thickness and a predetermined width.

(3) Next, the reinforcing electrode 4 is provided on the upper surface of the electrically insulating substrate 1 along one side of the substrate 1 and is led out from both ends in a direction orthogonal to the one side.
Is formed so that the lead-out portion is in contact with both ends of the glass member 5.

The reinforcing electrode 4 is formed by screen-printing a metal paste obtained by adding and mixing an appropriate organic solvent and an organic solvent to a metal powder of gold, silver, copper or the like in a predetermined region on the upper surface of the electrically insulating substrate 1. It is applied to the upper surface of the electrically insulating substrate 1 by applying a thick film technique such as the above to a thickness of about 30 μm and baking it at a temperature of about 600 ° C.

In this case, the reinforcing electrode 4 is replaced by the glass member 5
If the heat storage layer 2 is formed substantially at the same height as that of the heat storage layer 2, the surface of the heat storage layer 2 formed between the reinforcing electrode 4 and the glass member 5 becomes flat. 3 can be closely attached to the thermal recording medium, and the thermal efficiency of the thermal head can be increased. Therefore, it is preferable to form the reinforcing electrode 4 at substantially the same height as the glass member 5.

Further, in this case, since the lead-out portion of the reinforcing electrode 4 is formed so as to be in contact with both ends of the glass member 5, the frame member composed of the reinforcing electrode 4 and the glass member 5 is formed on the upper surface of the electrically insulating substrate 1. Therefore, when the heat storage layer 2 is formed between the reinforcing electrode 4 and the glass member 5, the heat storage layer 2 is formed only by filling the frame material with the necessary minimum heat resistant resin. You will be able to. Therefore, it becomes possible to reduce the amount of heat-resistant resin used and to make the thermal head as a product inexpensive.

(4) Next, a polyimide resin is filled between the reinforcing electrode 4 attached to the upper surface of the electrically insulating substrate 1 and the glass member 5 so that the reinforcing electrode 4 and the glass member 5 have substantially the same thickness. The heat storage layer 2 is formed.

The heat storage layer 2 has a thickness of the varnish made of polyimide resin between the reinforcing electrode 4 and the glass member 5 on the upper surface of the electrically insulating substrate 1 until the thickness becomes substantially equal to the height of the reinforcing electrode 4 and the glass member 5. It is formed by filling it with a dispenser or the like, and then thermosetting the filled varnish at a temperature of about 400 ° C. to form a polyimide resin.

In this case, since the heat storage layer 2 is formed by filling the varnish between the reinforcing electrode 4 and the glass member 5, the temperature of the varnish applied on the electrically insulating substrate 1 is room temperature or the like. Even if the viscosity of the varnish rises due to the change and the viscosity of the varnish decreases significantly, the reinforcing electrode 4 and the glass member 5 prevent the applied varnish from spreading in the width direction. As a result, the thickness of the varnish is kept constant, and the heat storage layer 2 can be formed to have a predetermined thickness.

Since the heat storage layer 2 is formed by filling a polyimide resin between the reinforcing electrode 4 and the glass member 5, a large frame material for forming the heat storage layer 2 having a width of about 2 mm is not required. It becomes unnecessary at all, and the heat storage layer 2 can be arranged in contact with the reinforcing electrode 4. Therefore, the thermal head can be downsized.

Further, since the heat storage layer 2 is arranged in contact with the reinforcing electrode 4, the distance R2 between the heating resistor 3 and the end of the electrically insulating substrate 1 can be shortened. As a result, the recording paper and the ink ribbon can be conveyed from above the heat generating resistor 3 to the end of the electrically insulating substrate 1 in a short time and both of them can be quickly peeled off. Also, it is possible to form a high-quality printed image without the reverse transfer phenomenon in which the ink once transferred to the recording paper is again transferred to the ink ribbon by the heat generated by the heating resistor 3.

(5) Next, the heating resistor 3 made of tantalum nitride or the like, the individual conductive layer 4 and the common conductive layer 5 made of aluminum or the like, and the protective layer 7 made of silicon nitride, sialon or the like are formed on the heat storage layer 2. And are deposited.

For the heating resistor 3, the individual conductive layers 4 and the common conductive layer 5, first, tantalum nitride having a thickness of 0.01 μm to 0.5 μm and aluminum having a thickness of 0.5 μm to 2.0 μm are formed by a thin film forming technique (for example, sputtering). Method), and the tantalum nitride and aluminum are partially etched away by a photolithography technique to form a heating resistor 3 and an individual conductive layer 4.
And the common conductive layer 5 is processed into a predetermined pattern.

In this case, the individual conductive layer 4 has the outer surface 5a of the glass member 5 inclined from the upper surface of the heat storage layer 2.
Since it is deposited on the upper surface of the electrically insulative substrate 1 through the above, even if the individual conductive layer 4 is formed by the thin film forming technique such as the sputtering method as described above, the individual conductive layer 4 is electrically connected to the upper surface of the heat storage layer 2. There is no disconnection or increase in the conductive resistance due to the step between the upper surface of the insulating substrate 1.

The protective film 8 is formed so as to cover the heating resistor 3 and the like by depositing silicon nitride on the upper surface of the heating resistor 3 and the like by a sputtering method or the like.

(6) Next, a driving I is formed on the individual conductive layer 6a.
Connect C7.

The driving IC 7 is mounted on the electrically insulating substrate 1 so that the solder bumps provided on the lower surface of the driving IC 7 come into contact with the individual conductive layers 6a.
It is connected to the individual conductive layer 6a by heating at a temperature of 0 ° C. to melt the solder, thereby completing the thermal head.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in forming a heat storage layer, a reinforcing electrode and a glass member are used. When a varnish which is a heat-resistant resin is filled in the frame material constituted by, if the amount of the varnish to be filled is made a little larger, the varnish becomes arcuate in cross section due to the surface tension, as shown in FIG. As described above, the top portion of the heat storage layer 2 can be formed so as to project upward. In this case, in addition to the effects similar to those of the above-described embodiment, the heating resistor 3 on the heat storage layer 2 can be brought into good contact with the thermal recording medium during printing, and the heat generated by the heating resistor 3 is generated. Can be satisfactorily conducted to the thermal recording medium.

Further, as described above, after a little more varnish which is a heat resistant resin is filled in the frame material composed of the reinforcing electrode and the glass member, the varnish is tilted at a predetermined angle to the electrically insulating substrate. 3B is dried, the top portion of the heat storage layer 2 protruding upward can be formed so as to be inclined toward the end portion side of the electrically insulating substrate 1, as shown in FIG. 3B. In this case, in addition to the effect similar to that of the above-described embodiment, the distance R3 between the end of the electrically insulating substrate 1 and the heating resistor 3 is further shortened, so that the ink ribbon and the recording paper can be printed. And will be able to be peeled off more quickly.

[0050]

According to the method of manufacturing a thermal head of the present invention, since the heat storage layer is formed by filling the heat-resistant resin between the reinforcing electrode and the glass member, the heat storage layer is formed on the electrically insulating substrate. Even if the temperature of the applied heat-resistant resin rises due to changes in room temperature and the like, and the viscosity of the heat-resistant resin decreases significantly, the applied heat-resistant resin will try to spread in the width direction. Regulated. Thereby, the thickness of the heat resistant resin is maintained constant, and the heat storage layer can be formed to have a predetermined thickness.

Further, according to the method of manufacturing the thermal head of the present invention, the heat storage layer is formed by filling the polyimide resin between the reinforcing electrode and the glass member, so that the heat storage layer having a predetermined width is formed. A large frame material for the purpose is not necessary at all, and the heat storage layer can be arranged in contact with the reinforcing electrode, which enables downsizing of the thermal head.

Further, according to the method of manufacturing a thermal head of the present invention, the heat storage layer can be disposed in contact with the reinforcing electrode, so that the distance between the heating resistor and the end of the electrically insulating substrate is shortened. be able to. This makes it possible to convey the recording paper and the ink ribbon from the heating resistor to the end of the electrically insulating substrate in a short time and quickly peel them off, and even when performing high-speed printing, It is possible to form a high-quality printed image by eliminating the reverse transfer phenomenon of ink.

[Brief description of drawings]

FIG. 1A is a perspective view of a thermal head manufactured by an embodiment of the manufacturing method of the present invention, and FIG.
It is an X-ray sectional view.

2A to 2C are perspective views showing a manufacturing process according to the present invention.

3A and 3B are cross-sectional views of a thermal head manufactured according to another embodiment of the manufacturing method of the present invention.

FIG. 4A is a perspective view of a conventional thermal head,
(B) is a YY line sectional view of (a).

FIG. 5A is a perspective view of a conventional thermal head,
(B) is a ZZ line sectional view of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrically insulating substrate 2 ... Heat storage layer 3 ... Heating resistor 4 ... Reinforcing electrode 5 ... Glass member 6a ... Individual conductive layer 6b ... Common conductive layer 7 ...・ Drive IC 8 ・ ・ ・ Protective film

Claims (1)

[Claims] 1. An upper surface of an electrically insulating substrate having a rectangular shape,
A step of depositing a strip-shaped reinforcing electrode and a strip-shaped glass member along one side of the substrate in a substantially parallel manner with a predetermined gap therebetween, and filling a heat-resistant resin between the reinforcing electrode and the glass member. Forming a heat storage layer on the heat storage layer, a plurality of heating resistors, an individual conductive layer connected to one end of the heating resistor, the other end of the heating resistor and a reinforcing electrode A step of depositing a common conductive layer connected to the thermal head.