JPH0640525B2 - Thermal head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal head used for thermal recording, and more particularly to improvement of a heating resistor of the thermal head.

(Prior Art) Conventional thermal heads usually consist of a heating resistor made of tantalum nitride (Ta ₂ N) and aluminum (Al), gold (Au), or copper on a substrate made of an electrically insulating material such as alumina. It has a structure in which electric conductors made of metal such as (Cu) are sequentially laminated,
A constant power is applied to the heating resistor via an electric conductor to cause Joule heat generation in the heating resistor, thereby functioning as a thermal head.

This conventional thermal head is used to prevent the heating resistor and the electric conductor from being worn due to contact with the thermal recording paper or the thermal transfer ribbon, and to prevent the oxygen in the atmosphere from contacting and oxidizing. In addition, silicon oxide (SiO ₂ ) and tantalum pentoxide (Ta ₂
A protective film of O ₅ ) is deposited.

However, in this conventional thermal head, the specific resistance of the tantalum nitride that constitutes the heating resistor is relatively small, about 250 μΩcm, and the heating resistor is inevitably required to instantly heat the heating resistor to the desired temperature. A large current had to be passed through, and a large current power supply was necessary.

In addition, since this conventional thermal head does not fit well with tantalum nitride, which is the material for the heating resistor, and aluminum, copper, etc., which are the materials for the electrical conductor, the joint strength between the heating resistor and the electrical conductor is extremely weak, and when operating When an external force is applied to the heat generating resistor, the electric conductor is easily separated from the heat generating resistor, and it becomes impossible to apply the specified power to the heat generating resistor. For this reason, this thermal head has a drawback that the heating resistor cannot generate Joule heat to a desired temperature, does not function as a thermal head, or causes printing failure.

Therefore, in order to solve the above-mentioned drawbacks of the conventional thermal head, a heating resistor is set to TixSiyOz (where x + Y + Z = 1,
X = 0.1 to 0.3, Y + Z = 0.7 to 0.9, Y ≠ 0, Z ≠ 0), and a thermal head that can obtain stable printing over a long period of time by increasing the specific resistance and the bonding strength with the electric conductor The applicant has previously proposed.

However, if this thermal head applies a large amount of power to the heating resistor and raises the temperature faster to support high-speed printing, the resistance value of the heating resistor fluctuates at high temperatures, causing printing defects. It had the drawback of

(Object of the Invention) As a result of various experiments conducted by the present inventors in view of the above-mentioned drawbacks, as a heating resistor, Tix Niq Siy Oz (20 ≦ x ≦ 30, 0.1 ≦ q ≦ 1
0, 20 ≤ y ≤ 30, 40 ≤ z ≤ 60) makes it possible to obtain a heating resistor having extremely high specific resistance and little variation in resistance value at high temperature, and aluminum which is a material of an electric conductor. It has been found that they are well compatible with gold and copper and can be firmly bonded.

Based on the above findings, the present invention has a large specific resistance as a material of a heating resistor, and has a small variation in resistance value at high temperature,
Also, by using a material that is compatible with the electric conductor, a highly reliable thermal head that can obtain stable printing for a long time without uneven printing even when high power is applied and high-speed printing is provided. The purpose is to do.

(Means for Solving the Problems) The thermal head of the present invention uses Tix Niq as a heating resistor.
Siy Oz (20 ≦ x ≦ 30, 0.1 ≦ q ≦ 10, 20 ≦ y ≦ 30, 40 ≦ z ≦ 6
It is characterized by using 0).

Titanium (Ti) used for the heat-generating resistor of the thermal head of the present invention is a component for imparting conductivity to the heat-generating resistor and having a predetermined specific resistance, and the x value which is the atomic% of Ti. Is x <
If the value is 20, the above-mentioned desired properties are not imparted, and if x> 30, the specific resistance of the heating resistor becomes small and the heating resistor cannot be heated to a desired temperature.
It is specified in the range of x ≦ 30.

Further, silicon (Si) is a component for giving a specific resistance to the heating resistor, and if the y value, which is the atomic% of Si, is y <20 or y> 30, the desired properties described above are not imparted. Since the heating resistor cannot be heated to a desired temperature, the y value is specified within the range of 20 ≦ y ≦ 30.

Furthermore, oxygen (O) is a component for improving the adhesion between the heating resistor and the electric conductor, and if the z value, which is the atomic% of O, is z <40, the desired properties described above are not provided, Z>
When the value is 60, when the electric power is applied to the heating resistor, the resistor loses heat and loses its function as a thermal head. Therefore, the z value is specified within the range of 40 ≦ z ≦ 60.

Furthermore, nickel (Ni) is a component for suppressing the variation in the resistance value of the heating resistor at high temperature, and the desired value is not provided when the q value, which is the atomic% of Ni, is q <0.1, Further, when q> 10, the specific resistance of the heating resistor becomes small, the heating resistor cannot be heated to a desired temperature, and variations in the specific resistance of the heating resistor at high temperature cannot be suppressed. Is specified in the range of 0.1 ≦ q ≦ 10.

(Example) Next, the present invention will be described in detail based on an example shown in the accompanying drawings.

FIG. 1 shows an embodiment of the thermal head of the present invention.
Is a substrate made of an electrically insulating material such as alumina.

A heating resistor 2 is attached on the insulating substrate 1,
An electric conductor 3 is attached on the heating resistor 2.

The heating resistor 2 is Tix Niq Siy Oz (20 ≦ x ≦ 30, 0.1 ≦
q ≦ 10, 20 ≦ y ≦ 30, 40 ≦ z ≦ 60), and the heating resistor 2 is made of titanium (Ti) and nickel (Ni) with respect to silicon (Si).
By changing the atomic% of oxygen and oxygen (O), the specific resistance of the heating resistor 2 can be set to 500 to 3000 μΩcm.

When a constant electric power is applied to the heating resistor 2 so as to have a predetermined electric resistance, Joule heat is generated,
It generates heat at a temperature required for printing, for example, a temperature of 300 to 500 ° C.

The specific resistance of the heating resistor 2 is x of Tix Niq Siy Oz.
Since the value can be adjusted to any value by changing the value, y value, z value, and q value, the heat generation temperature of the heat generating resistor 2 can be adjusted to a desired value, and the applicable range of the thermal head can be widened. Becomes

Further, the heating resistor 2 is a Tix which constitutes the resistor 2.
Niq Siy Oz (20 ≦ x ≦ 30, 0.1 ≦ q ≦ 10, 20 ≦ y ≦ 30, 40 ≦
Since the specific resistance of z ≦ 60) is as large as 500 to 3000 μΩcm, it is possible to heat the heating resistor to a desired temperature without requiring a large current power source. Further, it is not necessary to increase the resistance value of the resistors 2 by reducing the film thickness, and the film thickness of all the heating resistors 2 can be made substantially uniform. As a result, the resistance values of all the heating resistors 2 become substantially the same, and it is possible to make the Joule heat generation amount of each resistor 2 uniform and to achieve excellent printing quality.

Particularly, if the film thickness of the heating resistors 2 is set to 200 to 1000Å, the Joule calorific values generated by all the heating resistors 2 can be made substantially the same, so the film thickness is 200 to 1000
It is preferably in the range of Å.

The electric conductor 3 on the heating resistor 2 is aluminum (Al),
The electric conductor 3 is made of copper (Cu) or the like, and applies electric power for causing Joule heat generation to the heating resistor 2.

The material of the heating resistor 2 is Tix Niq Siy Oz (20 ≦ x
≤30, 0.1 ≤ q ≤ 10, 20 ≤ y ≤ 30, 40 ≤ z ≤ 60) are very familiar to the materials of the electric conductor 3, such as aluminum (Al) and copper (Cu), and both are firmly joined. Therefore, even if an external force is applied at the time of operation or the like, peeling does not occur between the heating resistor 2 and the electric conductor.

The heating resistor 2 made of Tix Niq Siy Oz
When 23 to 26, q value is 3 to 7, y value is 23 to 26, and z value is 46 to 54, the Joule heat generation temperature of the heating resistor 2 is about 400 ° C, and the printing quality is extremely good and the electrical conductor is Since the connection strength with 3 is also extremely high, the x value is 23 to 26,
It is preferable that the q value is 3 to 7, the y value is 23 to 26, and the z value is 46 to 54.

Further, tantalum pentoxide (Ta ₂ O ₅ ) having excellent wear resistance is provided on the heating resistor 2 and the electric conductor 3 in order to prevent the heating resistor 2 and the like from being worn due to contact with thermal paper. A protective film 4 made of, for example, is formed.

The heating resistor 2 is formed by, for example, a sputtering method described later, and the electric conductor 3 and the protective film 4 are formed by a conventionally known vacuum deposition method or sputtering method.

When the heating resistor 2 is formed by the sputtering method, first, a low-pressure container having a vacuum degree of 1 × 10 ^{−3 to} 5 × 10 ⁻³ Torr is prepared, and argon and oxygen are injected into the container to remove argon. Create a mixed atmosphere of oxygen. Next, a target made of titanium silicide (TiSi) doped with an appropriate amount of nickel (Ni) is placed in the container, and titanium silicide (TiSi) doped with nickel (Ni) is scattered and a part of the target is placed in an atmosphere. Tix Niq Siy Oz is created by reacting with oxygen (O).
Finally, the Tix Niq Siy Oz is applied to the surface of the substrate such as alumina to form a heating resistor on the substrate.

When the heating resistor is formed on the surface of the substrate by the sputter rig method, heating the substrate to a temperature of 200 to 500 ° C. improves the adhesion between the substrate and the heating resistor. It becomes possible to heat the substrate to 200 to 500 ° C. In addition, the film forming speed of the heating resistor is usually about 100Å / mm.

(Experimental Example) Next, various experimental results of the example product of the present invention and the conventional example product will be described.

First, in the thermal head having the cross section shown in FIG. 1, a heating resistor sample having a width of 100 μm, a length of 200 μm and a resistance value of 1000 Ω was prepared by using the resistors having the compositions shown in Table 1 below.

Pulse width 1.0 ms, pulse period 10 ms for each of these samples
So that the surface temperature of the heating resistor reaches 500 ° C, 1.0 [W / do
The electric power of [t] was applied and the actual printing life test on the thermal paper was performed. The results are shown in FIG. From this result, the conventional product that uses tantalum nitride (Ta ₂ N) as a heating resistor has a thermal paper of about 70 km.
When the sheet is continuously striking and fed, peeling occurs between the heating resistor and the electric conductor and the function as a thermal head is lost, whereas Tix Niq Siy Oz within the composition range of the present invention is used as the heating resistor. What was used (Samples A to G) and Ti
x Siy Oz (however, x + Y + Z = 1, X = 0.1-0.3, Y +
Z = 0.7 to 0.9, Y ≠ 0, Z ≠ 0) was used as the heating resistor (Sample I), and the thermal paper was peeled between the heating resistor and the electric conductor even when continuously fed for 150 km or more. The resistance change rate is within 4%, and extremely stable printing is possible.

For each of the above samples, pulse width 1.0 ms, pulse period 10 m
I also did a step stress test with s.

The results are shown in FIG. From these results, it is found that the conventional product using tantalum nitride (Ta ₂ N) as a heating resistor is 1.
With applied power of 4 [W / dot], Tix Siy Oz (however, x +
Y + Z = 1, X = 0.1 to 0.3, Y + Z = 0.7 to 0.9, Y ≠
0, Z ≠ 0) used as a heating resistor is 1.5 [W
/ dot] causes a large variation in the resistance value by the applied power, and the print quality is deteriorated.
With Tix Niq Siy Oz, the resistance value does not change significantly up to an applied power of 1.8 [W / dot], and it can be seen that the printing quality can be high.

(Effect of the Invention) Thus, according to the thermal head of the present invention, Tix Niq Siy Oz (20 ≦ x ≦ 30, which has a high specific resistance as a material of the heating resistor,
0.1 ≤ q ≤ 10, 20 ≤ y ≤ 30, 40 ≤ z ≤ 60) makes it possible to heat the heating resistor to a desired temperature without the need for a large current power source, and the resistance of the heating resistor. The value can be made large without thinning the film thickness or narrowing the film width, making the film thickness uniform and making the resistance values of all the heating resistors substantially the same, and It is possible to obtain a thermal head with extremely high print quality without variations.

Further, according to the thermal head of the present invention, the Tix Niq Siy Oz (20
≦ x ≦ 30, 0.1 ≦ q ≦ 10, 20 ≦ y ≦ 30, 40 ≦ z ≦ 60), so that the heating resistor and the electric conductor can be firmly joined.

Therefore, even if an external force is applied during operation, the electric conductor does not peel off from the heating resistor at all, and it is possible to constantly apply the specified power to the heating resistor to generate Joule heat at a desired temperature.

Furthermore, since there is little variation in the resistance value of the heating resistor at high temperature, it can be suitably used for a thermal head for high-speed printing in which high power is applied to the heating resistor to reach high temperature, and its printing quality is also extremely high. You can

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a thermal head of the present invention, FIG. 2 is a characteristic diagram showing the actual print life test results of the product of the present invention and a conventional product, and FIG. 3 is the product of the present invention and the conventional product. It is a characteristic view which shows the result of the step stress test of an example product. 1 ... Insulating substrate, 2 ... Heating resistor 3 ... Electric conductor

Claims (1)

[Claims] 1. A Tix Niq Siy Oz (20 ≦ x
≦ 30, 0.1 ≦ q ≦ 10, 20 ≦ y ≦ 30, 40 ≦ z ≦ 60).