JP2002326379A - Thermal head and its fabricating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power saving thermal head of low thermal capacity exhibiting high thermal response and ensuring high speed printing and high print quality, and its fabricating method, by forming a heat insulation layer having a thermal conductivity lower than that of a conventional glaze heat insulation layer and exhibiting excellent adhesion properties by vapor deposition and forming a thin protective layer using the same material as that of the heat insulation layer. SOLUTION: The thermal head comprises a heat insulation layer 13 formed on the upper surface of a heat radiating substrate 11, a plurality of heating elements 15a formed of a plurality of heating resistors 15 and power supply bodies 16 and 17 on the upper surface of the heat insulation layer 13, and a protective layer 18 covering at least the surface of the heating resistors 15 and power supply bodies 16 and 17 wherein the protective layer 18 and the heat insulation layer 13 are formed of a homogenous ceramic film having a low thermal conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head mounted on a thermal printer, and more particularly to a thermal head capable of saving power in a thermal transfer printer using an ink ribbon and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a conventional thermal head, as shown in FIG. 4, a glaze heat insulating layer 2 made of glass is formed to a thickness of about 80 .mu.m on the entire surface or a part of the surface of a heat dissipating substrate 1 made of alumina or the like. Have been. On the surface of the glaze heat insulating layer 2, a ridge 2a is formed at a height of 2 to 10 μm. On the upper surface of the glaze insulating layer 2, TaS
A plurality of heating resistors 3 made of iO2 are stacked by sputtering or the like, and then a plurality of heating resistors 3 are arranged by photolithography according to the number of dots.

Further, a common power supply 4 and an individual power supply 5 for supplying power energy to the heating resistor 3 are formed on the upper surface of the heating resistor 3 by sputtering and photolithography, respectively. The heating element 3 has a heating element 3a formed in a dot shape while being sandwiched between the power feeders 4 and 5.

[0004] In addition, on the upper surface of each of the power supply bodies 4 and 5 and the heat generating resistor 3, oxidization and wear may occur at positions other than connection terminals of external circuits and pad portions (not shown) for mounting driver ICs. In order to prevent this, a protective layer 6 having a thickness of 5 to 7 μm and made of a material having excellent oxidation resistance and abrasion resistance, such as sialon, is coated by sputtering or the like. Then, after a post-process such as terminal plating, the heat-radiating substrate 1 is divided by dicing, and a driver IC is mounted on a block (chip) -shaped thermal head substrate to manufacture a conventional thermal head. .

In a thermal printer using such a conventional thermal head, for example, first, a plurality of heating elements 5a generate Joule heat by energizing each heating resistor 5 based on print information. . Then, by heating a thermal paper or a thermal transfer ink ribbon (not shown) in close contact with the surface of the protective layer 6, coloring of the thermal paper or ink transfer to recording paper is performed, and desired characters or Images and the like can be printed.

In recent years, there has been a growing demand for such a thermal printer which is of a battery-driven type, easily portable, and portable. In order to make a thermal printer portable, the battery life had to be extended.However, a thermal head having a large number of heating elements consumes the most power, and there is a demand for power saving for thermal heads. I was getting stronger.

[0007]

However, in the conventional thermal head as described above, as a method of saving power, the thickness of the glaze heat insulating layer 2 is conventionally made sufficiently large and the heat dissipation substrate 1 However, since the heat storage of the glaze heat insulating layer 2 is significantly increased and the thermal response of the heating element 5a is inferior, the difference in the heat generation temperature between the pulse and the continuous pulse conduction is merely increased. This is so large that heat control becomes difficult and print density unevenness occurs. Further, in high-speed printing, there is a possibility that a defect such as tailing occurs in the printing and the printing quality is degraded.

The glaze insulating layer 2 has a thermal conductivity of 3
At 0 ° C., approximately 1.0 W / m. k is relatively small,
For example, at a high temperature of 600 ° C., approximately 1.6 W / m. In the range of 300 to 600 ° C., which is the operating heat generation temperature of the heat generating resistor 3, the heat conductivity increases and the heat flow flowing to the heat radiation substrate 1 increases. There is a limit to power saving only by increasing the thickness of the heat insulating layer 2. The present invention has been made in view of the above-described problems, and has a smaller thermal conductivity than the conventional glaze heat insulating layer, and forms a heat insulating layer having excellent adhesion by a vapor deposition method. An object of the present invention is to provide a power-saving thermal head having a thin protective layer formed of the same material and having a small heat capacity and good thermal responsiveness, high-speed printing and good printing quality, and a method of manufacturing the same.

[0009]

According to a first aspect of the present invention, there is provided a thermal head including a heat insulating layer formed on an upper surface of a heat radiating substrate, and a plurality of heat generating layers formed on the upper surface of the heat insulating layer. A plurality of heating elements formed by a resistor and a power supply, and a protection layer covering at least the surfaces of the heating resistor and the power supply, and the heat insulation layer and the protection layer are made of the same low thermal conductivity ceramic. The structure was made of a material.

As a second means for solving the above problems, the heat insulation layer and the protection layer mainly contain silicon, a transition metal, oxygen or nitrogen, and have a thermal conductivity of 0.8 to 0.8. 1.0 W / m. k low thermal conductivity ceramic film.

As a third means for solving the above problem, the protective layer is formed to have a thickness of 1 to 3 μm.

According to a fourth aspect of the present invention, there is provided a manufacturing method according to the present invention, wherein a heat insulating layer is formed on an upper surface of a heat radiating substrate, and a plurality of heating resistors and a power supply are formed on the upper surface of the heat insulating layer. Forming a heating element with the body, having a protective layer covering the upper surface thereof, the heat insulating layer and the protective layer,
TaSi2, WSi2, CrSi2, TiSi2, Zr
Si2, NbSi2, MoSi2, HfSi2, VSi
2, Ar + O2 or Ar + N2, using a sintered target of at least two or more kinds of silicides selected from NiSi2 and FeSi2, or a sputtering target formed of a sintered body of a plurality of silicides and silicon.
Alternatively, a manufacturing method was employed in which a homogeneous low thermal conductivity ceramic film was formed by reactive sputter deposition of any of Ar + O2 + N2.

According to a fifth aspect of the present invention, the heat insulating layer and the protective layer have a thermal conductivity of 0.8 to 1.0 W / m. k, a low thermal conductivity ceramic film of the same quality was formed by vapor deposition.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermal head according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of the present invention, FIG. 2 is a manufacturing flowchart according to the present invention, and FIG. 3 is a thermal response characteristic diagram of the thermal head of the present invention.

First, as shown in FIG. 1, a thermal head according to the present invention is provided on the surface of a heat dissipating substrate 11 made of alumina or the like, over the entire area or along the edge of the heat dissipating substrate 11.
Glaze heat insulating layer 12 made of glass with a thickness of ~ 80 µm
Are formed. The glazing heat insulating layer 12 is formed with a protruding ridge 12a having a substantially trapezoidal cross section at a height of 2 to 10 μm by a photolithographic etching technique.

The entire surface of the heat-radiating substrate 11 and the glaze insulating layer 12 including the ridges 12a is reactively sputter-deposited with oxygen or nitrogen by using a sputtering target material mainly composed of silicon and transition metal silicide. Thus, the heat retaining layer 13 is formed. The heat insulating layer 13 has a thermal conductivity of 0.8 to 1.0 W / m. k and a thickness of 10 to 30 μm.

On the upper surface of the heat insulating layer 13, an anti-etchant layer 14 made of alumina or the like is formed with a thickness of about 0.2 μm. In addition, a plurality of heating resistors 15 made of a high-melting-point metal cermet such as Ta-SiO2 are formed in a pattern on the heat-retaining layer 13 via the anti-etchant layer 14. The upper surface of the heating resistor 15
A common feeder 16 and an individual feeder 17 each having a thickness of about 2 μm and made of a metal such as Al, Cu, or Au are laminated on both skirt portions of the ridges 12 a of the glaze insulating layer 12, respectively. Electrode configuration. Then, the ridge 12 between the common power supply 16 and the individual power supply 17 is provided.
The heating element 15a is formed in a dot shape on a.

With respect to the above-mentioned electrode configuration,
17, above or below, further thinly made of Al, Cu, etc.
An auxiliary power feeder (not shown) having a thickness of about 0.1 μm is formed to extend and be laminated, and a two-layer power feeder (not shown) in which the heating element 15a is formed only on the top of the ridge may be used. is there.

Further, the heating resistor 15 and each power supply 1
On each of the upper surfaces of the heat insulating layers 6 and 17, a protective layer 18 made of a low thermal conductive ceramic of the same quality as the heat insulating layer 13 is formed by using the same sputtering target as the heat insulating layer 13 and under substantially the same reactive sputtering conditions. Coated.

The heat insulating layer 13 and the protective layer 18 have, in addition to low thermal conductivity,
By forming a semi-insulating ceramic aggregate that contains active unreacted metal in the film appropriately by adjusting the reactivity of oxygen and nitrogen, it has crack resistance, peeling resistance and resistance to cracking. It is rich in static electricity. Therefore, even if the protective layer 18 is formed as thin as 1 to 3 μm,
In a thermal transfer printer using an ink ribbon with low abrasion, the printing life can be sufficiently satisfied.

Further, in the embodiment of the present invention, the heat-radiating substrate 11 is made of alumina or the like. However, as another embodiment of the present invention, a single-crystal S
i, or a heat dissipating substrate (not shown) is formed of a metal plate,
The thing which does not form the glaze insulation layer 12 may be sufficient. By forming a heat dissipating substrate (not shown) from such a single crystal Si or a metal plate, a ridge (not shown) is directly formed on the heat dissipating substrate 11 by photolithography, polishing, or pressing. ) Can be formed. for that reason,
A thermal head that can be easily manufactured and that can reduce the manufacturing time can be provided.

Next, a method for manufacturing a thermal head according to the present invention will be described with reference to a manufacturing flowchart shown in FIG. First, a heat dissipating substrate 11 made of alumina or the like
A glaze insulating layer 12 made of glass or the like is formed to a thickness of approximately 60 μm along the entire upper surface of the substrate or along the edge of the heat radiation substrate 11, and the surface of the glaze insulating layer 12 is formed to a thickness of 2 to 10 μm by a photolithographic etching technique. Is formed. When the heat-radiating substrate 11 is made of metal or silicon, the ridges are formed directly on the heat-radiating substrate 11, and the glaze heat insulating layer 12 is not formed. (Step 1)

Next, on the upper surface of the heat dissipating substrate 11 including the glaze heat insulating layer 12, a heat insulating layer 13 of a low thermal conductive ceramic comprising silicon, transition metal, oxygen and nitrogen is formed to a thickness of about 10 to 30 μm by sputtering. I do. Then, alumina or the like having excellent chemical resistance, which becomes the etchant resistant layer 14, is formed on the heat retaining layer 13 to a thickness of about 0.2 μm. (Step 2)

Next, on the upper surface of the anti-etchant layer 14, T
The heating resistor 15 made of a-SiO2 or the like is approximately 0.3 μm.
The pattern of the heating resistor 15 is formed by laminating to a thickness of m. (Step 3) The common electrode 16 and the individual electrode 17 made of Al, Cu, etc., which extend outward from both skirt portions on the upper surface of the heating resistor 15 with the ridge 12a therebetween, are substantially Laminate to a thickness of 2 μm. Then, the heating element 15a is formed in a portion sandwiched between the common electrode 16 and the individual electrode 17 on the ridge 12a. (Step 4)

Next, on the upper surfaces of the heating resistor 15, the common electrode 16 and the individual electrodes 17, in order to prevent abrasion and oxidation, the same material as that of the heat insulating layer 13 including silicon, transition metal, oxygen and nitrogen as main components is used. Low thermal conductivity ceramic
The protective layer 18 is formed by laminating and coating to a thickness of about 3 μm by sputtering. (Step 5) Then, after predetermined plating is applied to external connection terminals and mounting pads (not shown) of the driver IC, the heat radiation substrate 11 is divided by dicing, and then the driver IC is mounted to save power. A thermal head can be manufactured.

The thermal response characteristics of the thermal head according to the present invention will be described with reference to FIG. The graph shown in FIG.
The thermal response characteristics of the conventional thermal head and the thermal head of the present invention are compared. Graph A shows the conventional thermal head, and graph B shows the thermal head of the present invention. Then, the conventional thermal head shown in the graph A has the heating resistor 5 shown in FIG.
When the heating element 5a generates heat by applying a pulse current to the protective layer 6 having a large thermal conductivity, the heat is diffused in the plane direction of the film. Therefore, the conventional thermal head is
It shows a characteristic in which the heat generation temperature rises slowly and saturates quickly.

On the other hand, in the thermal head of the present invention shown in the graph B, the thermal conductivity of the heat retaining layer 13 and the protective layer 18 is the smallest as an inorganic film, and the thickness of the protective layer 18 is small. Is reduced to 1 to 3 μm, the heat diffusion in the surface direction of the film is reduced, the heat generation temperature rises sharply, and a high temperature can be obtained even with power supply of the same value as in the past.

For that purpose, the thermal head of the present invention
Even if the power energy supplied to the heating resistor 15 is reduced, high quality printing can be performed, and power saving such as a portable thermal transfer printer equipped with the thermal head of the present invention becomes possible. Battery life can be extended.

In the description of the embodiment of the present invention, the heat radiation substrate 11 is made of alumina or the like.
As another embodiment of the present invention, the heat dissipating substrate (not shown) may be formed of single-crystal Si or a metal plate having high heat dissipating property, and the glaze heat insulating layer 12 may not be formed.
By forming such a heat dissipating substrate (not shown) from single crystal Si or a metal plate, a ridge (not shown) is directly formed on the heat dissipating substrate 11 by a photolithography technique, a polishing technique, a pressing technique, or the like. ) Can be formed. Therefore, it is possible to provide a thermal head that can be easily manufactured and that can reduce the manufacturing time.

[0030]

According to the thermal head of the present invention, the protective layer and the heat insulating layer are formed of the same low thermal conductive ceramic film, so that the heat loss due to the heat diffusion in the plane direction of each film can be reduced. For this reason, even if the power energy supplied to the heating element is smaller than in the past, the heating element can be appropriately heated to the printable range. Therefore, power can be saved, and the battery life of a portable thermal transfer printer or the like can be extended.

The heat insulating layer and the protective layer mainly contain silicon, a transition metal, and oxygen or nitrogen, and have a thermal conductivity of 0.8 to 1.0 W / m. k, the thermal conductivity of the heat insulation layer and the protective layer can be minimized as an inorganic film, the heat capacity of the heat insulation layer and the protective layer can be reduced, Can provide head.

Further, since the protective layer is formed to be thin to a thickness of 1 to 3 μm, the thermal conductivity in the plane direction of the film can be remarkably reduced, and the heat generation peak temperature of the heating element can be increased. . Therefore, it is possible to provide a power-saving thermal head that has high thermal conductivity to the print medium, does not deteriorate print quality, and has high print thermal efficiency.

Further, in the method of manufacturing a thermal head according to the present invention, the thermal insulation layer and the protective layer are appropriately depleted of oxygen and nitrogen depending on the sputtering conditions, and the unreacted metal is contained in the film to improve the chemical activity. Highly-adhesive and semi-insulating multi-element oxides or multi-element nitrides provide excellent adhesion and crack resistance and peeling resistance even on uneven surfaces of electrodes with poor step coverage. The protective layer has no problem, and there is no fear of corrosion or oxidation of the heating resistor or the like due to sudden cracking or peeling of the protective layer, and the printing durability can be extended.

The heat insulating layer and the protective layer have a thermal conductivity of 0.8 to 1.0 W / m. Since it was formed by vapor deposition with a low thermal conductivity ceramic film of the same quality as k, the film-forming equipment can be shared,
A highly productive manufacturing process can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a thermal head according to the present invention.

FIG. 2 is a view showing a manufacturing flowchart of a thermal head according to the present invention.

FIG. 3 is a graph illustrating the thermal insulation characteristics of a thermal head according to the present invention.

FIG. 4 is a sectional view of a main part of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Heat dissipation board 12 Glaze heat insulation layer 13 Heat insulation layer 14 Anti-etchant layer 15 Heating resistor 15a Heating element 16 Common power supply 17 Individual power supply 18 Protection layer

Claims (5)

[Claims] A heat insulating layer formed on an upper surface of the heat dissipating substrate;
On the upper surface of the heat insulating layer, there are provided a plurality of heating elements formed by a plurality of heat generating resistors and a power supply, and a protective layer covering at least the surfaces of the heat generating resistor and the power supply. A thermal head characterized in that the layers and the layers are formed of the same low thermal conductivity ceramic material. 2. The heat insulating layer and the protective layer contain silicon, a transition metal, oxygen or nitrogen as main components, and have a thermal conductivity of 0.8 to 1.0 W / m. 2. The thermal head according to claim 1, wherein the thermal head is made of a low thermal conductive ceramic film. 3. The thermal head according to claim 1, wherein said protective layer is formed to a thickness of 1 to 3 μm. 4. A heat-insulating layer is formed on an upper surface of a heat-dissipating substrate, and a heating element is formed on the upper surface of the heat-insulating layer by a plurality of heat-generating resistors and a power feeder, and a protective layer covering these upper surfaces is provided. , The heat insulating layer and the protective layer are made of TaSi2, WS
i2, CrSi2, TiSi2, ZrSi2, NbSi
2, MoSi2, HfSi2, VSi2, NiSi2,
Ar + O2 or Ar + N2 or Ar + O2 by using a sintered body of at least two or more kinds of silicides selected from FeSi2 or a sputtering target formed of a sintered body of a plurality of silicides and silicon.
A method of manufacturing a thermal head, wherein a homogeneous low thermal conductivity ceramic film is formed by reactive sputtering deposition of any one of + N2. 5. The thermal insulation layer and the protective layer have a thermal conductivity of 0.8 to 1.0 W / m. 5. The method for manufacturing a thermal head according to claim 4, wherein said thermal head is formed by vapor deposition on a low thermal conductive ceramic film of the same quality as k.