JPH106500A - Ink jet head and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the durability and heat efficiency of an ink jet head and allow vivid images to be recorded through high speed recording by providing a heat resistor on the substrate, and forming a protection layer consisting of one layer structure slant material on the heat resistor. SOLUTION: On a substrate 1 consisting of a ceramic or glass, a lower layer 11 is formed to be a thermal storage layer, and on the lower layer 11, a heat resistor layer 2 is formed to further form an electrode layer 13 on the heat resistor layer 2, and then the whole of them are covered with an all-in-one structure protection layer 14. The protection layer 14 is an all-in-one structure layer formed of a slant material, and for the salt material, the formation is done in such a manner that it consists mainly of carbon and silica and a concentration of silica is made high near the heat resistor layer 2 and is lowered stepwise or continuously toward the surface, then only carbon exists in the upper most surface. Otherwise, the formation is done in such a manner that silica and nitrogen are taken as main components, and a concentration of silica is made higher in the proximity of the heat resistor layer 2 and a ratio of silica to nitrogen comes to 3/4 as being toward the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head and a method of manufacturing the same, and more particularly, to an ink jet head having a protective layer covering a heating resistor and a method of manufacturing the same.

[0002]

2. Description of the Related Art An ink jet recording apparatus has little vibration and noise at the time of recording and is easy to colorize. Therefore, it is used not only for a printer for outputting data of a digital processing device such as a computer but also for facsimile and copying. It is supposed to be. As such an ink jet recording apparatus, for example, a thermal ink jet (heating ink) is used in which a heating resistor is used as an actuator element for pressurizing the ink, and the ink near the heating resistor is boiled to eject ink droplets by the power. A device equipped with a TIJ) head is known.

When a heating resistor is used as an actuator element of an ink-jet head, it is necessary to chemically and physically protect the heating resistor from ink, and to prevent corrosion of the heating resistor and its electrodes. There is a need. Therefore, as described in, for example, JP-A-60-236758, an inorganic material having excellent heat resistance and heat conductivity is used for the heat generating portion, and the other portions are used to prevent liquid penetration. It is known to provide a protective layer having a two-layer structure using an organic material, or to provide a protective layer having a two-layer structure by dividing an inorganic material into two or more layers and forming different thicknesses. ing.

[0004] Although not a thermal ink jet head, a two-layer structure of an inorganic material and a diamond-like carbon (DLC) film is used as a protective layer for a heat generating portion of the thermal head. A technique for preventing the body from being corroded is also known (see JP-A-7-132628).

[0005]

As described above, in a thermal ink jet head, it is required to provide a protective layer excellent in heat resistance, heat conductivity, liquid resistance, anti-penetration resistance, insulation and the like. However, in this case, it is required that the heat generating portion has excellent heat resistance and thermal conductivity, and that portions other than the heat generating portion have excellent liquid resistance and liquid permeation preventing properties.
Therefore, conventionally, a protective layer formed of an inorganic material such as a metal oxide or a metal nitride is provided on a heat generating portion, and a protective layer formed of a resin or the like is provided on a portion other than the heat generating portion. Prevents corrosion and other problems.

However, in a conventional protective layer having a two-layer structure, peeling and a decrease in insulating properties are caused in a portion in contact with a liquid (ink) due to continuous use for a long time. In addition, since it is formed into a two-layer structure by forming films with different characteristics,
The heat-generating resistor and the electrode are corroded due to a decrease in adhesion and a permeation of a liquid from a defective portion due to a pinhole, a micro crack or the like at the time of forming the protective layer.

In particular, when high-speed printing is performed, the thickness of the protective layer is increased in order to ensure the durability of the protective layer. However, the thermal conductivity deteriorates, the thermal efficiency decreases, and the image quality decreases. Is declining.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide an ink jet head which is excellent in durability and thermal efficiency and can realize clear image recording by high-speed recording, and a method of manufacturing the same.

[0009]

According to a first aspect of the present invention, there is provided an ink jet head comprising: a heating resistor provided on a substrate; and a protective layer formed on the heating resistor. The protective layer was formed of a single-layer gradient material.

According to a second aspect of the present invention, in the inkjet head of the first aspect, the inclined material contains carbon and silicon as main components, and has a high silicon concentration in the vicinity of the heating resistor, and the silicon concentration increases toward the surface. The structure was such that it decreased stepwise or continuously, and only carbon was present at the outermost surface.

According to a third aspect of the present invention, in the ink jet head of the first aspect, the inclined material contains silicon and nitrogen as main components, the silicon concentration is high in the vicinity of the heating resistor, and the silicon / nitrogen goes to the surface. The configuration is such that the ratio approaches 3/4.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an ink-jet head for manufacturing an ink-jet head according to any one of the first to third aspects, wherein the gas phase is produced while continuously changing the mixing ratio of the raw material gas. In this configuration, a protective layer having a single-layer structure made of the grown gradient material is formed.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of an inkjet head to which the present invention is applied, and FIG. 2 is a schematic sectional view of a main part of the head.

In this ink jet head, a wall member 3 is provided by using a photoresist on a substrate 1 having a heating resistor layer 2 for generating thermal energy, and a covering member 4 made of glass or the like is adhered on the wall member 3. Then, the ink flow path 5,
The liquid chamber 6 and the orifice 7 are formed, and a state change accompanied by a steep volume increase is caused in the ink by the action of the thermal energy of the heating resistor layer 2, and the ink droplet is ejected from the orifice 7 by the action force based on the state change. Let it.

In this ink jet head, as shown in FIG. 2, a lower layer 11 serving as a heat storage layer is formed on a substrate 1 made of a ceramic substrate or a glass substrate. A body layer 2 is formed, an electrode layer 13 is formed on the heating resistor layer 12, and the whole is covered with a protective layer 14 having a single-layer structure.

The lower layer 11 can be formed of an inorganic oxide material such as silicon oxide (SiO ₂ ), silicon, zirconium oxide, tantalum oxide, magnesium oxide or aluminum oxide by a method such as sputtering. _Two
Is used. The lower layer 11 is configured such that the heat generated in the heating resistor layer 2 at the time of liquid ejection is transmitted to the substrate 1 rather than to the substrate 1 side.
The rate of transmission to the ink side becomes as large as possible, and after the liquid is discharged, that is, after the power supply to the heating resistor layer 2 is turned off,
Heat provided in the heating resistor layer 2 is quickly released to the substrate 1 side, and the ink and generated bubbles on the heating resistor layer 2 are rapidly cooled.

As a specific material of the heating resistor layer 2, any material can be used as long as it generates heat when energized. For example, metals such as tantalum, tungsten, molybdenum, niobium, and chromium, alloys such as nichrome and silver-palladium, metal nitrides such as tantalum nitride, zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and boride A metal boride such as niobium is mentioned as a preferable material, and here, a TaSiO ₂ film is used. The electrode layer 13 is formed by evaporating aluminum.

The protective layer 14 has a single-layer structure made of a gradient material. As the graded material, carbon and silicon are the main components, and the silicon concentration is increased near the heating resistor layer 2,
A structure in which the silicon concentration is reduced stepwise or continuously toward the surface, and only carbon is provided at the outermost surface,
Alternatively, a configuration in which silicon and nitrogen are main components, the silicon concentration is high in the vicinity of the heating resistor layer 2, and the silicon / nitrogen ratio approaches 3/4 toward the surface can be used.

Here, a general description of the protective layer will be given with reference to FIG. 2. In the heat generating portion 15, the protective layer is in direct contact with the ink in the ink flow path and the heat generating resistor layer 2 is formed.
In order to transfer the heat generated in the above to the ink, it is necessary to use a material having excellent heat resistance and heat conductivity. In this case, as the protective layer of the heat generating portion 15 is thicker, the conduction of thermal energy in the layer becomes worse and the loss increases, and the amount of heat generated in the heat generating resistor layer 2 must be increased. The deterioration of the body layer 2 becomes faster. In addition, the time required for heating and cooling in the heat generating unit 15 is lengthened, the ejection responsiveness is reduced, and the recording speed is reduced. Therefore, it is not preferable to increase the thickness of the protective layer in the heat generating portion 15.

On the other hand, when the thickness of the protective layer is reduced, it becomes difficult to completely cover the step generated by the electrode layer 13 or the like, and ink is removed from defective portions of the protective layer where the coating is incomplete. There is a possibility that the heat generating resistor layer 2 and the electrode layer 13 are corroded by permeation, so that the thickness cannot be reduced too much.

As a method for forming the protective layer, a film having a desired shape and excellent adhesion to the substrate 1 on which the heating resistor layer 2 and the electrode layer 13 are provided can be formed with good film forming properties. A deposition method such as a CVD method, a sputtering method, and an evaporation method is used. As a material for forming the protective layer, an inorganic material mainly having heat resistance and heat conductivity, and having excellent liquid resistance and insulation properties, for example, a carbide, an inorganic oxide such as SiO ₂ , and an inorganic material such as Si ₃ N ₄ . Materials that can form a high-resistance thin film, such as inorganic nitride, titanium oxide, tantalum oxide, chromium oxide, silicon nitride, and aluminum nitride are used. Table 1 shows the thermal conductivity of the main materials.

[0022]

[Table 1]

It is generally known that carbon (C), particularly diamond, is the material having the highest thermal conductivity, high hardness, and excellent denseness. Thus, an attempt was made to form a protective layer made of only diamond (C), but no result was obtained that satisfied the requirements.

Therefore, in the present invention, referring to FIG. 3, as a material for forming the protective layer 14, carbon (C) and silicon (Si) are used as main components, and the heat generating resistor layer 2 and the electrode layer 13 side are formed. In the vicinity (the lowermost layer) 14a, the Si concentration is increased in order to increase the toughness in consideration of the denseness, and in the outermost surface 14c, the diamond (C) is considered in consideration of the heat conduction.
As the material, a gradient material having an intermediate concentration of Si and C was used in the intermediate portion 14b.

The protection layer 14 is formed by plasma CVD.
Using the method, hydrocarbon compounds (CH ₄ , C ₂ H ₆ , C
_Using a mixed gas of ₂ H ₂ ) and hydride (SiH ₄ ) as a source gas, a film was formed by vapor phase growth on the substrate 1. In depositing the film, the film was formed by changing the mixture ratio of the above-mentioned source gases stepwise (or continuously). As for the mixing ratio, FIG.
As shown in the figure, the Si concentration was maximized in the vicinity of the lowermost layer portion (interface) 14c of the protective layer 14, the Si concentration was decreased in the intermediate portion 14b, and the diamond (C) concentration was rich in the outermost surface portion 14c.

The thickness of the protective layer 14 may be within a range in which a layer having high toughness, no breakage, and excellent in heat resistance and thermal conductivity can be obtained, and is about 0.3 to 3.0 μm. However, it is more preferably 0.4 to 2.0 μm.

Next, the material of the protective layer 14 is mainly composed of silicon (Si) and nitrogen (N).
In order to increase the toughness in consideration of the denseness, it is necessary to increase the Si concentration, and to use a gradient material that becomes a theoretical Si ₃ N ₄ film having a Si / nitrogen ratio of 3/4 toward the outermost surface portion 14c. Can also. Even with such a protective layer, a layer having high toughness, no breakage, and excellent heat resistance and thermal conductivity can be obtained.

The protective layer 14 is formed in the vicinity of the lowermost layer portion (interface) 14c of the protective layer 14 by using a mixed gas of SiH ₄ / NH ₃ as a raw material gas by the plasma CVD method as described above. Then, the flow rate of SiH ₄ is increased so as to be Si-rich, and then the flow rate of SiH ₄ is reduced in the intermediate portion 14b so that the Si / N ratio becomes 3/4 in the outermost surface portion 14c so that the Si3N4 becomes stable. It is formed to be a film. Although the inclination can be changed by changing the substrate temperature, the process time becomes longer.

Therefore, a specific embodiment will be described. <Embodiment 1> Using a mixed gas of SiH ₄ / CH ₄ ,
₄ / CH ₄ mixed gas at a total flow rate of 50SCCM to form a lowermost layer portion 14a, then the middle portion 14b is formed in a mixed gas with a reduced flow rate of SiH _4, to further reduce the flow rate of SiH _4, CH ₄ concentration 2%, the outermost surface portion 14
The protective layer 14 in which c became a C-rich diamond-like carbon film was provided. The total time of the deposit was 60 minutes, and the total film thickness was 2 μm.

Example 2 Example 2 was the same as Example 1 except that the CH ₄ concentration when forming the outermost surface portion 14c was 3%.

<Embodiment 3> This embodiment is the same as Embodiment 1 except that the CH ₄ concentration at the time of forming the outermost surface portion 14c is 3.5%.

<Embodiment 4> Using a mixed gas of SiH ₄ / NH ₃ , a total flow rate of a mixed gas of SiH ₄ / NH _{4 of} 300 was used.
The lowermost layer portion 14a is formed by SCCM, and then SiH ₄
Forming an intermediate portion 14b with a mixed gas having a reduced flow rate of
Furthermore, the flow rate of SiH ₄ is reduced, and Si
A protective layer 14 of a silicon nitride film with an / N ratio of 1.2 was provided. The total film thickness was 2 μm.

Example 5 Example 4 is the same as Example 4 except that the Si / N ratio used when forming the outermost surface portion 14c was 1.0.

Example 6 Example 4 is the same as Example 4 except that the Si / N ratio when forming the outermost surface portion 14c was 0.8.

Examples 1 to 3 and 6 thus obtained
The durability of the inkjet head was evaluated as the life. This was performed by measuring the printing distance at which a predetermined printing density was obtained using plain paper. Table 2 shows the results. The same evaluation was performed using a conventional protective film having a two-layer structure as a comparative example, and the life of the examples 1, 4 and the comparative example is represented by a relative value in FIG. .

[0036]

[Table 2]

As can be seen from these results, the ink jet head using the inclined material according to the present invention is significantly improved in durability compared to the comparative example. In addition, excellent properties were obtained as a result of the experiment in terms of thermal efficiency.

[0038]

As described above, according to the ink jet head of the first aspect, the heating resistor is provided on the substrate,
In the inkjet head in which the protective layer is formed on the heating resistor, the protective layer is formed of a one-layered gradient material, so that the inkjet head has excellent durability and thermal efficiency, and can realize clear image recording by high-speed recording. Is obtained.

According to the ink jet head of the second aspect, in the ink jet head of the first aspect, the inclined material contains carbon and silicon as main components, and has a high silicon concentration in the vicinity of the heating resistor and a silicon concentration near the surface. Decreased stepwise or continuously, the outermost surface is made of only carbon, so the adhesion with the base is improved, the durability is improved by the hardest material on the outermost surface, and the thermal conductivity is reduced by the thin layer An ink jet head capable of realizing recording of a clear image by high-speed recording can be obtained by improving the thermal efficiency by the improvement.

According to a third aspect of the present invention, in the ink jet head of the first aspect, the inclined material contains silicon and nitrogen as main components, and has a high silicon concentration in the vicinity of the heat generating resistor. / Nitrogen ratio is close to 3/4, so the adhesion to the base is improved, the durability of the outermost hard material is improved, and the thermal conductivity of the thin layer is improved to improve the thermal efficiency. An ink jet head capable of realizing clear image recording by high-speed recording is obtained.

According to a fourth aspect of the present invention, in the method of manufacturing an inkjet head according to any one of the first to third aspects, the mixing ratio of the raw material gas is changed stepwise or continuously. Since the protection film made of the gradient material formed by the vapor phase growth is formed while changing, it is possible to manufacture the ink jet head which can realize the recording of the clear image by the high-speed recording in a simple process.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an inkjet head to which the present invention has been applied.

FIG. 2 is a schematic sectional view of a main part of the head.

FIG. 3 is an explanatory diagram for explaining a gradient density of a protective layer of the inkjet head.

FIG. 4 is an explanatory diagram provided for explaining the durability of the inkjet head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Heating resistor layer, 3 ... Wall member, 4 ... Covering member, 5 ... Ink channel, 6 ... Liquid chamber, 7 ... Orifice, 11
... lower layer, 13 ... electrode layer, 14 ... protective layer, 15 ... heating part.

Claims (4)

[Claims] 1. An ink jet head comprising: a heating resistor provided on a substrate; and a protection layer formed on the heating resistor, wherein the protection layer is formed of a one-layer inclined material. 2. The ink jet head according to claim 1, wherein the inclined material contains carbon and silicon as main components, and has a high silicon concentration in the vicinity of the heating resistor, and has a stepwise or continuous silicon concentration toward the surface. The ink jet head is characterized in that the outermost surface portion contains only carbon. 3. The ink jet head according to claim 1, wherein the inclined material contains silicon and nitrogen as main components, and has a high silicon concentration near the heating resistor and a silicon / nitrogen ratio of 3/4 toward the surface. An inkjet head characterized by being close to. 4. A method for manufacturing an ink jet head for manufacturing an ink jet head according to claim 1, wherein the gradient material is vapor-phase grown while changing the mixing ratio of the raw material gas stepwise or continuously. Forming a protective layer having a single-layer structure comprising: