JPS6013283B2 - thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head having a shelved vanadium thin film and a method for manufacturing the same.

The thermal head used for thermal print recording is, for example, ``a plurality of heating resistors on a substrate with electrical insulation and a smooth surface, such as glass, and an electric conductor for supplying power to the heating resistors. "Recording is performed by making contact with the recording medium by passing a current through the corresponding heating resistor through an electric conductor to generate heat in order to obtain the necessary thermal pattern according to the information to be recorded." .

Heat generating resistors used therein include conventional thin film heat generating resistors such as tantalum nitride and nichrome, thick heat generating resistors using silver-palladium, etc., and semiconductor heat generating resistors using silicon semiconductor. Among these, thermal heads using thin-film heating resistors have better thermal response than thick-film heating resistors, semiconductor heating resistors, etc., and have good heat resistance and thermal shock resistance.
It has features such as long life and high reliability. Conventionally, tantalum nitride has been used as a thin film heating resistor because it has relatively excellent heat resistance, high reliability, and has a specific resistance value of 250~250.
It is particularly widely used because it has a relatively high value of 300 French Q, and has good manufacturing controllability. However, tantalum nitride rapidly oxidizes when exposed to high temperatures of about 300 pm or more, resulting in a rapid increase in its resistance value, which has the disadvantage of deteriorating print density when printing on recording paper.

Generally, silicon oxide (Sj02
) is provided with an oxidation-resistant protective layer of tantalum oxide (T
A205) is equipped with a wear-resistant layer and used as a thermal head, but ``the resistance change when the thermal head is operated for a long time is not small, and it is still not fully satisfactory.Especially in recent years, the demand for high-speed thermal heads has been met. As the current is increasing, it is necessary to shorten the energizing pulse of the head in order to color the thermal paper, which means that the electric power will be higher than before, and the heating resistor will become even hotter, so its life will be shorter. Therefore, there is a need for a heating resistor with even higher heat resistance.The present invention improves the above points and provides a thermal head having a thin film heating resistor that is resistant to oxidation and has a stable resistance value. The purpose of this invention is to provide a thermal head using shelved vanadium as a thin film heating resistor in combination with a protective film covering the heating element, and a method for manufacturing the thin film heating resistor.
A detailed description will be given below with reference to the drawings. Figure 1 shows “
FIG. 2 is a sectional view of a main part of an example of the shape of a thermal head applied to the present invention. In the figure, 1 is a substrate made of an electrically insulating material such as ceramic glass or grade ceramics. 2 is a thin film heating resistor made of shelved vanadium.

Reference numeral 3 denotes an electrical conductor for supplying power to the thin film heating resistor, which is made of a good electrical conductor such as aluminum to gold.

In addition, protective layers for 4G thin-film heating resistors and electrical conductors include silicon oxide made by electron beam deposition, sputtering, etc., magnesium oxide, aluminum oxide, tantalum oxide, etc., or multilayer structures made of a combination of these. This makes it possible to further extend the life of the thermal head. A thin film heat generating resistor made of shelved vanadium can be manufactured by either electron beam evaporation or sputtering.For production by electron beam evaporation, tablets can be obtained by pressing shelved vanadium powder at a pressure of about 100 x 9 or more. can be prepared and deposited on a substrate that has been kept at a constant temperature in a high vacuum of 1 x 10-4 Tom or higher.

On the other hand, when manufacturing by sputtering, there are two methods: one uses shelved vanadium as a target, the other uses shelved vanadium and metal vanadium as targets at the same time, and the active sputtering uses only metal vanadium as a target. For example, it is possible to use shelved vanadium as a target by placing it in a powder or pressed state on a quartz dish, etc. It is easier to control sputtering when using a sputtering method.Also, when targeting shelf elements and metal vanadium at the same time, it is possible to mix the shelf elements and metal vanadium, or to embed one in the other or place it on a part of the surface. In both cases, lxlo-precipitation orr~5×io-ITo
It is best to carry out in an argon atmosphere of rr, preferably lx
lo-Nom to 1×10-ITom is preferable. In addition, when performing active sputtering, a single metal such as a metal vanadium plate is used as a target, and it is performed in a mixed gas atmosphere of argon and diborane, and the gas pressure at that time is the total gas pressure of argon and diborane of 1 × 10-orr~5 ×10-IT
orr, preferably 1×10-orr to 5×10-
At 2 tons, diborane accounts for 1 to 10% of the total pressure, preferably 2 to 6%.

Furthermore, heating the substrate to 20 to 500 oo during sputtering or electron beam evaporation improves the adhesion of the shelved vanadium to the substrate, and is also effective in improving the stability of the film. Furthermore, after sputtering or electron beam evaporation, the resistance value can be controlled to the required value by heat treatment at a temperature of 200 to 650 qo in vacuum, air, or an atmosphere such as argon gas, and moreover, it can be used as a thermal head. It also increases stability during use, which has an effect on longevity. When the heat treatment temperature is below 200oC, the change in resistance value is very small, so a long heat treatment time is required.On the other hand, when the heat treatment temperature is above 650oC, the change in resistance value occurs suddenly, and it becomes impossible to use it with substrates such as glass. Due to the above restrictions or the difficulty of control, the heat treatment temperature is preferably 200 to 650°C. The shelved vanadium thermal head obtained in this way is stable and resistant to oxidation, and the power usage limit of conventional thermal heads using tantalum nitride is 17 to 18%.
Although it was originally a power supply of 20 to 22.5W, it can be used to supply power of up to 20 to 22.5W. This is a thermal head for high-speed printing that applies a large amount of power to the heating resistor to create a high temperature! This is also suitable. Furthermore, the specific resistance value of this shelved vanadium thin film resistor is 100F to 5×
Since you can choose from a wide range of 1pi #Q skin, if you set it to a high resistance value, you will need less current to generate heat, and the electrodes can be made thinner, which simplifies the manufacturing process and reduces unevenness. This makes it more resistant to wear. Further, the amount of heat generated by the thin film heating resistor due to the influence of the resistance of the electrode portion can be ignored. Next, it will be explained based on an example.

Example 1 Shelf vanadium V hot-pressed at 1300 qo onto a glazed ceramic substrate that has been thoroughly cleaned in advance
& [manufactured by U.S. Research, 99% purity] using high-frequency bipolar sputtering with a total pressure of 5 argon.
A heating element with a thickness of 1000 A was manufactured under the conditions of ×10-2 Torr and a substrate heating temperature of 300 pm.

This specific resistance value was about 180 degrees Fahrenheit, and the area resistance at this time was about 180 degrees Fahrenheit. On top of this, 10A of titanium and 1.5A of aluminum were deposited using an electron beam, and then selective etching was performed on the thermal head A with 4 pieces/skin disassembly.
．． was formed. Then the thermal heads A, . Thermal head A, 2 has tantalum oxide deposited to a thickness of 6 mm by electron beam evaporation as a protective layer, Thermal head A, 3 has aluminum oxide deposited to a thickness of 8 mm, and magnesium oxide is deposited to a thickness of 5 r. Thermal heads A, 4 and thermal heads A, 5 were prepared in which silicon oxide was deposited in a two-layer structure with a thickness of 1.5 am followed by tantalum oxide with a thickness of 6 am. For comparison, tantalum was targeted by high-frequency bipolar reactive sputtering, and the total pressure of argon and nitrogen was 8 × 10-2 Ton, and the partial pressure of nitrogen was 1 × 10
Thermal head B, . of tantalum nitride heating resistor with a thickness of 1000A under the condition of -4 Tom. was created.

When this thin film was analyzed by X-ray diffraction, it was found to be Ta2N. Further, since the specific resistance value was 240〃○, the sheet resistance value at this time was 24Q'□. Then the thermal head B,
．． A protective layer with a two-layer structure in which a tantalum oxide protective layer with a thickness of 6 mm is provided by sputtering B2 and a silicon oxide film of 1.5 mm is provided on top of which a tantalum oxide film with a thickness of 6 mm is provided. I prepared B3. For these thermal heads, the pulse width was 6ms 5
The rate of change in resistance, etc., when a thigh test was performed by repeatedly applying a voltage of 0 Hz and increasing the supplied power by IWatt' every 30 minutes.

. (%) measurement results are shown in Figure 2. Here, R is the resistance value before the test, and ΔR is the change in resistance value. sputter
Shelved vanadium thin film heating resistors A, . is about 1.4 to 1.5 mm per unit area compared to tantalum nitride thin film heating resistor B. It can supply the power of Kalaon. In addition, by providing a protective layer, the power that can be supplied per unit area is greatly improved, but the shelved vanadium thin film heating resistor is made of tantalum oxide (A, 2
), aluminum oxide (A, 3), and magnesium oxide (A, 4). Comparable results were obtained and were far superior to thermal heads B and 2, which were made of a tantalum nitride thin film heating resistor with a single protective layer. Thermal heads A and 5 provided with the protective layer have further improved significantly.This increase in the maximum power supply means that in the case of constant power drive, deterioration of the heating resistor due to heat generation phenomenon is reduced. Normally, the power supplied when transmitting thermal energy to thermal recording paper varies depending on the contact pressure, but is approximately 11 to 14 W.
In the case of a tantalum nitride thin film heating resistor, a two-layer protective layer such as a combination of silicon oxide and tantalum oxide is required, whereas in the case of a shelved vanadium thin film heating resistor, It can be seen that printing is sufficient with only one protective layer such as tantalum oxide, aluminum oxide, magnesium oxide, etc., and that the life span is further extended when two protective layers are provided.

Example 2 The same thermal heads A, . Thermal head 2 has tantalum oxide sputtered to a thickness of 6 mm as a protective layer, Thermal head 8 has aluminum oxide sputtered to a thickness of 8 mm, and Thermal head 8 has sputtered magnesium oxide to a thickness of 5 mm. Thermal head A teeth were prepared by sputtering a two-layer protective layer having a thickness of 1.5 mm and 1.5 mm of silicon oxide, and 6 mm thick of tantalum oxide.

These thermal heads were subjected to the same test as in Example 1, and the resistance change G rate was measured. As a result, the power limit values per unit area at which the rate of resistance change rapidly increases are 19.0 W/Iso for A-2, 19.0 W/fence for A-2, and 19.0 W/fence for A-2.
In case 4, it was 19.5 W/mound, and in case 5, it was 22.5 W/fence, which showed very good results. Better results were obtained when the protective layer was prepared by sputtering than by electron beam evaporation. Example 3 Shelved vanadium VB2 [manufactured by American Research, purity 99%]
A tablet is made by pressing the powder at a pressure of 100 k9 or more, and the tablet is placed on a glazed ceramic substrate that has been thoroughly cleaned in advance at a temperature of 300°C and a vacuum of 5xlo-6.
It was deposited by electron beam to a thickness of 1000A.

This specific resistance value is about 750 mountains, and this area resistance is about 7
It was 50/mouth. Next, titanium (10△) and aluminum (1.5 μm) were evaporated on top of this using an electron beam, and then a pattern with a resolution of 4 lines/rib was formed by selective etching to form thermal heads C, . And so. These thermal heads C, . Thermal head C8 has tantalum oxide deposited as a protective film by electron beam evaporation to a thickness of 6 mounds,
Thermal head C. with aluminum oxide deposited to a thickness of 8r. 3. A thermal head C, 4 in which magnesium oxide was skin-deposited to a thickness of 5 mm, and a thermal head C, 5 in which a two-layer structure of silicon oxide, 1.5 mm, and then tantalum oxide, 6 mm thick, were prepared. The same test as 1 was conducted. As a result, the limit values of power per unit area at which the resistance change G rate increases rapidly are C, . Then 11.0W/fence,
C, 2: 16.0W/no, C, 3: 165W/pine,
At C, 4, it was 16.5 W/Kyo, and at C, 5, it was 19.0 W/Iso.

The shelved vanadium heating resistor produced by electron beam evaporation in this example was also much better than the tantalum nitride heating resistor. Example 4 Thermal heads C, . A protective layer was formed by sputtering on the thermal head C22 with 6 µm of tantalum oxide, the thermal head C23 with 8R of aluminum oxide, the foundation of thermal head C with 5 µm of magnesium oxide, and then oxidation of 1.5 µm of silicon oxide. A thermal head C25 with a two-layer structure of tantalum 6 Buddha skin was prepared.

These thermal heads were subjected to the same test as in Example 1 to measure the rate of change in resistance.

As a result, the power limit values per unit area at which the resistance change G rate rapidly increases are 17.0 W' for C2 and 17.0 W' for C2, respectively.
23: 18.0W'fence, C24: 18.0W/masu,
In C25, it was 20.5W/fence. Example 5 A 6 inch diameter metal vanadium plate was used as a target.

A thoroughly cleaned glazed ceramic plate is heated to 400°C.
The substrate was heated and active sputtering was performed in an argon and diporane mixed gas atmosphere. The pressure of argon ten diborane is 3.5 × 10-Tom, and the partial pressure of diborane is 1.5
A film thickness of 800A was formed by high-frequency bipolar sputtering at ×10-4Ton. Since this specific resistance value was 1040 mm, the area resistance at this time was 1300'. After evaporating titanium at 150 Δ and gold at 1 μm using an electron beam, selective etching was performed to form a thermal head pattern having four holes per side. Next, aluminum oxide was applied as a protective film. (AI203) loAm was seeded by sputtering. When this thermal head was subjected to the same acceleration test as in Example 1, the resistance change rate was ±± up to 17.5W.
It was within 2%. This example also gave much better results than the thermal head using tantalum nitride in the comparative example. Example 6 A target was used in which a large number of 1'4 inch diameter boron plates were placed on a 6 inch diameter metal vanadium slope so that the surface area ratio of metal vanadium to column element was approximately 1:2. .

500 thoroughly cleaned glazed ceramic substrates
The substrate was heated to ℃ and the argon pressure was 3×10-2 Tom.
R. F. Sputtering was performed using two electrodes. Sputtering rate is 100A/
When sputtered for 10 minutes, a thin film heating resistor with a film thickness of 1000 A, a specific resistance value of 850 arcs, and a sheet resistance of 850/hole was obtained. 30A titanium on top of this
After aluminum was deposited using an IAw electron beam, a thermal head pattern with a four-line/side resolution was formed by selective etching. Next, tantalum oxide (Ta) was used as a protective film.
205) 10A was laminated by sputtering. When this thermal head was subjected to the same acceleration test as in Example 1, the resistance change rate was within ±2% up to 17.0 W/K.
Much better results were obtained than thermal heads using tantalum nitride. EXAMPLE A 75-inch diameter quartz plate was placed with shelved vanadium powder as a target.

The thoroughly cleaned glazed ceramic substrate was subjected to high frequency bipolar sputtering under a substrate heating condition of 20 psi and an argon partial pressure of 5.times.10@-2 Ton. When sputtering was carried out for 10 minutes at a sputtering rate of 100 A/side, a shelved vanadium thin film heating resistor with a specific resistance of 400 square arcs and a sheet resistance of 400/hole was obtained. After evaporating titanium at 100A and gold at 100A using an electron beam, a thermal head pattern having 4 ribs/ribs was formed by selective etching.
Next, when heat treated in air at 550° C. for 10 minutes, the resistance value of the heating resistor increased from 400/port to 1200/port. Magnesium oxide (
M phantom) to the thickness of 8th desk and thermal head D
,2 was obtained. For comparison, thermal heads D, . We also prepared The results of measuring the resistance change rate when a rectangular wave of 14 Wao/square was continuously applied to these thermal heads for 6 ms at 50 Hz are shown in the third table.
As shown in the figure.

The number of applied pulses is D, . The resistance change rate is about 11
%, whereas D,2 was about 7.5%, and the resistance change was reduced and stabilized by heat treatment.

Example 8 When the heat treatment in Example 7 was changed to 65,000 yen in Ar for 2 hours, the resistance changed from 400' to 350'.

Here, 8rm of magnesium oxide (Mg0) was used as a protective film.
Thermal head D, 3 was obtained by sputtering.

Here, the same durability test as in Example 7 was conducted.

The results are shown in Fig. 3, and the results were better than those of Example 7, and the resistance change rate was about 5% even when the pulse was applied 0 times (1×1 times). Ta.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an example of the shape of a thermal head according to the present invention. FIGS. 2 and 3 are characteristic diagrams showing the effects of the present invention. 1...
·substrate. 2... Thin film heating resistor. 3... Electric conductor. 4...Protective layer. younger brother! Figure 2 Hiroo diagram

Claims (1)

[Scope of Claims] 1. A thermal head having a substrate, a heating resistor formed on the substrate, and an electric conductor for supplying power to the heating resistor, wherein the heating resistor is made of vanadium boride. A thermal head featuring: 2. The thermal head according to claim 1, wherein the heating resistor is covered with a silicon oxide thin film. 3 Claim 1 having a tantalum oxide protective film
The thermal head according to item 1 or 2. 4. The thermal head according to claim 1 or 2, which has a protective film of aluminum oxide. 5. The thermal head according to claim 1 or 2, which has a protective film of magnesium oxide. 6. A method for manufacturing a thermal head, comprising manufacturing a boride thin film on a substrate by electron beam evaporation. 7. The manufacturing method according to claim 6, wherein electron beam evaporation is performed while heating the substrate at 200°C to 500°C. 8. The manufacturing method according to claim 6 or 7, wherein heat treatment is performed at 200°C to 650°C after electron beam evaporation. 9. A method for manufacturing a thermal head, which comprises manufacturing a heating resistor of a vanadium boride thin film on a substrate by sputtering. 10. The manufacturing method according to claim 9, wherein the sputtering target is hot-pressed vanadium boride. 11. The manufacturing method according to claim 9, wherein active sputtering is carried out using metal vanadium as a target in a mixed gas atmosphere of argon and diborane. 12. The manufacturing method according to claim 9, wherein metal vanadium and boron are arranged so as to be targets at the same time. 13 1×10^-^3Torr~5×10^-^1T
13. The manufacturing method according to claim 9, 10, or 12, wherein sputtering is performed in an argon atmosphere. 14. The manufacturing method according to claims 9 to 13, wherein sputtering is performed while heating the substrate at 200°C to 500°C. 15. The manufacturing method according to claims 9 to 14, wherein heat treatment is performed at 200°C to 650°C after sputtering.