JP2003237086A - Nozzle plate, its manufacturing method and inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle plate, its manufacturing method and an inkjet recording head which can improve the durability and water repellency of a water repellent film by preventing nozzle clogging. <P>SOLUTION: The nozzle plate 20 having a plurality of nozzle openings 21 for discharging liquid drops and joined to a channel formation substrate 10 where channels communicating with the nozzle openings 21 are formed is provided with a nozzle plate body which has the nozzle openings 21 set and is joined to the channel formation substrate 10. The water repellent film 100 formed of an inorganic compound of a lower permittivity than that of the nozzle plate body is set at least in the periphery of the nozzle openings 21 at a face opposite to the channel formation substrate 10 of the nozzle plate body. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a vibrating plate forming a part of a pressure generating chamber communicating with a nozzle opening, forming a piezoelectric element on the surface of the vibrating plate, and ejecting ink by displacement of the piezoelectric element. The present invention relates to a nozzle plate used for an inkjet recording head and the like, a method for manufacturing the same, and an inkjet recording head.

[0002]

2. Description of the Related Art A part of a pressure generating chamber that communicates with a nozzle opening for ejecting ink droplets is composed of a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize ink in the pressure generating chamber to eject it from the nozzle opening. Two types of inkjet recording heads that eject ink droplets have been put into practical use: one that uses a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of a piezoelectric element, and one that uses a flexural vibration mode piezoelectric actuator. ing.

The former allows the volume of the pressure generating chamber to be changed by bringing the end face of the piezoelectric element into contact with the vibrating plate, and a head suitable for high-density printing can be manufactured. There is a problem in that the manufacturing process is complicated because a difficult process of matching the array pitch of the openings and cutting into comb teeth or a work of positioning and fixing the cut piezoelectric element in the pressure generating chamber are required.

On the other hand, in the latter, the piezoelectric element can be formed on the vibration plate by a relatively simple process of sticking a green sheet of a piezoelectric material in conformity with the shape of the pressure generating chamber and firing it. However, due to the use of flexural vibration, a certain area is required, and there is a problem that high-density arrangement is difficult.

On the other hand, in order to eliminate the disadvantage of the latter recording head, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique as disclosed in Japanese Patent Laid-Open No. 5-286131. It has been proposed that the piezoelectric material layer is cut into a shape corresponding to the pressure generating chamber by a lithographic method and a piezoelectric element is formed so as to be independent for each pressure generating chamber.

Further, such a conventional ink jet recording head generally has a nozzle plate in which a plurality of nozzle openings for ejecting ink droplets are formed on a flow path forming substrate in which a pressure generating chamber is formed. It has a structure joined by an adhesive.

Further, a water repellent film made of a resin material is formed on the surface of the nozzle plate opposite to the flow path forming substrate. This water-repellent film prevents ink ejected from the nozzle openings from adhering to the surface of the nozzle plate.

Such a water-repellent film is formed, for example, on the surface of the nozzle plate whose nozzle openings are temporarily filled with resist.
It is formed by applying a coating liquid made of a resin material such as a fluororesin and then removing the resist.

[0009]

However, when a water-repellent film is formed on a nozzle plate in which nozzle openings are formed with high density, the inner diameter of the nozzle openings is substantially reduced, and therefore the nozzle openings are made of resist. There is a problem that the work of filling is relatively difficult.

Further, if a resin material is applied to the surface of the nozzle plate in which the nozzle openings are not surely filled with resist, the resin material enters into the nozzle openings to cause nozzle clogging.

Further, the surface of the nozzle plate is subjected to a wiping process at a predetermined timing, but at this time, the surface of the water-repellent film is damaged such as scratches, and the durability and water repellency of the water-repellent film are reduced. There is a problem of doing.

In view of such circumstances, it is an object of the present invention to provide a nozzle plate capable of preventing nozzle clogging and improving the durability and water repellency of a water repellent film, a method of manufacturing the nozzle plate, and an ink jet recording head. .

[0013]

A first aspect of the present invention for solving the above-mentioned problems is a flow having a plurality of nozzle openings for ejecting liquid droplets and forming a flow path communicating with the nozzle openings. A nozzle plate joined to a passage forming substrate, comprising a nozzle plate body provided with the nozzle opening and joined to the passage forming substrate, and a surface of the nozzle plate body opposite to the passage forming substrate. A water repellent film made of an inorganic compound having a dielectric constant lower than that of the nozzle plate body is provided at least around the nozzle opening.

In the first aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film.

A second aspect of the present invention is the nozzle plate according to the first aspect, characterized in that the dielectric constant ε of the inorganic compound is ε <10.

In the second aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved.

A third aspect of the present invention is the nozzle plate according to the first or second aspect, characterized in that the inorganic compound is magnesium oxide or silicon oxide.

In the third aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film.

A fourth aspect of the present invention is the nozzle plate according to the third aspect, wherein the inorganic compound is one in which a hydroxy group present in the molecule is replaced with fluorine.

In the fourth aspect, the hydroxy group having hydrophilicity is replaced with fluorine to further improve the water repellency.

A fifth aspect of the present invention is the nozzle plate according to the first or second aspect, characterized in that the inorganic compound is silicon nitride.

In the fifth aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the water repellent film has a thickness of 0.05 to 10 μm.
m in the nozzle plate.

In the sixth aspect, the strength of the water repellent film can be secured.

A seventh aspect of the present invention is the nozzle plate according to any one of the first to sixth aspects, characterized in that the nozzle plate body is made of silicon or stainless steel.

In the seventh aspect, the strength of the nozzle plate body can be ensured.

According to an eighth aspect of the present invention, a nozzle plate provided with a nozzle opening, a flow path forming substrate in which a pressure generating chamber communicating with the nozzle opening is formed, and one surface side of the flow path forming substrate An inkjet recording head provided with a piezoelectric element for generating a pressure change in the pressure generating chamber, the nozzle being provided on at least the nozzle of a surface of the nozzle plate opposite to the flow path forming substrate. In the ink jet recording head, a water repellent film made of an inorganic compound having a dielectric constant lower than that of the nozzle plate is provided around the opening.

In the eighth aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film.

A ninth aspect of the present invention is the ink jet recording head according to the eighth aspect, characterized in that the dielectric constant ε of the inorganic compound is ε <10.

In the ninth aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved.

A tenth aspect of the present invention is the ink jet recording head according to the eighth or ninth aspect, characterized in that the inorganic compound is magnesium oxide or silicon oxide.

In the tenth aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film.

An eleventh aspect of the present invention is the ink jet recording head according to the tenth aspect, wherein the inorganic compound is one in which a hydroxy group present in the molecule is replaced with fluorine.

In the eleventh aspect, the hydroxy group having hydrophilicity is substituted with fluorine to further improve the water repellency.

A twelfth aspect of the present invention is the ink jet recording head according to the eighth or ninth aspect, characterized in that the inorganic compound is silicon nitride.

In the twelfth aspect, the electrical interaction between the droplet and the water repellent film can be suppressed to a low level, and the water repellency of the water repellent film can be improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film.

A thirteenth aspect of the present invention is any one of the eighth to twelfth aspects, wherein the water repellent film has a thickness of 0.05 to 1.
The inkjet recording head is characterized by having a thickness of 0 μm.

In the thirteenth aspect, the strength of the water repellent film can be secured.

A fourteenth aspect of the present invention is the ink jet recording head according to any one of the eighth to thirteenth aspects, characterized in that the nozzle plate is made of silicon or stainless steel.

In the fourteenth aspect, the strength of the nozzle plate body can be ensured.

A fifteenth aspect of the present invention is a method of manufacturing a nozzle plate, which has a plurality of nozzle openings for ejecting droplets and is joined to a flow path forming substrate having a flow path communicating with the nozzle openings. In the method, a step of forming an oxide film on a surface of the nozzle plate main body provided with the nozzle openings, the surface being opposite to the bonding surface with the flow path forming substrate, and the hydroxy group existing on the surface of the oxide film being fluorine-containing. Forming a water repellent film having a dielectric constant lower than that of the nozzle plate body on the surface of the nozzle plate body.

In the fifteenth aspect, the electrical interaction between the droplet and the water repellent film is suppressed to a low level, and the water repellency of the water repellent film is improved. Moreover, durability is improved by increasing the rigidity of the water-repellent film. Further, the water-repellent film can be formed without filling the nozzle openings with the resist, and the nozzle clogging can be prevented.

A sixteenth aspect of the present invention is the method for manufacturing a nozzle plate according to the fifteenth aspect, characterized in that the oxide film is formed by a sputtering method.

In the sixteenth aspect, the water repellent film can be formed without filling the nozzle opening with the resist, and the nozzle clogging can be prevented.

The seventeenth aspect of the present invention is the fifteenth or first aspect.
In a sixth aspect, there is provided a method for manufacturing a nozzle plate, wherein the oxide film is formed by thermally oxidizing the periphery of the nozzle opening.

In the seventeenth aspect, the water repellent film can be formed without filling the nozzle opening with the resist, and the working process is simplified. In addition, the manufacturing cost can be kept low.

The present invention is characterized in that a water repellent film made of an inorganic compound having a dielectric constant lower than that of the nozzle plate body is provided. By forming the water repellent film with such an inorganic compound, it is possible to suppress the electrical interaction between the droplets of ink or the like and the water repellent film.

The inorganic compound is not particularly limited as long as it has a dielectric constant ε lower than that of the nozzle plate body. For example, the inorganic compound is an inorganic compound having a dielectric constant ε smaller than 10, specifically, silicon oxide, Examples thereof include oxides such as magnesium oxide and nitrides such as silicon nitride.

The water-repellent film of the present invention may be made of an inorganic compound layer deposited on the surface of the nozzle plate by using, for example, a sputtering method, or the surface of the nozzle plate may be thermally oxidized. It may be made of an oxide film formed as described above.

When the water-repellent film is formed of an oxide, the hydroxyl group of the molecule is present on the surface and exhibits hydrophilicity. For this reason, it is desirable to substitute such a hydroxy group with fluorine for water repellency treatment. Thereby, the water repellency can be further improved.

In addition, for example, when a water repellent film made of an inorganic compound such as metal oxide or silicon nitride is formed on the surface of the nozzle plate, there is no risk of the inorganic compound adhering to the inside of the nozzle opening. There is no need to fill in with etc. Therefore, there is an effect that the manufacturing cost can be kept low.

[0052]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments.

(Embodiment 1) FIG. 1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a sectional view of FIG.

As shown in the figure, the flow path forming substrate 10 is a silicon single crystal substrate having a plane orientation (110) in this embodiment. The flow path forming substrate 10 is usually 100 to 3
A thin film having a thickness of about 00 μm is preferably used in order to increase the array density while maintaining the rigidity of the partition walls between the adjacent pressure generating chambers.

One surface of the flow path forming substrate 10 is an opening surface, and the other surface is formed with an elastic film 50 of 1 to 2 μm in thickness made of silicon dioxide formed by thermal oxidation in advance.

On the other hand, the opening surface of the flow path forming substrate 10 is anisotropically etched to form a silicon single crystal substrate.
Pressure generating chambers 12 partitioned by a plurality of partition walls 11 are arranged side by side in the width direction, and on the outer side in the longitudinal direction, the pressure generating chambers 12 communicate with a reservoir portion of a reservoir forming substrate, which will be described later, and a common ink chamber of each pressure generating chamber 12. A communication portion 13 that forms a part of the reservoir is formed, and is connected to one end portion in the longitudinal direction of each pressure generating chamber 12 via an ink supply passage 14.

Here, the anisotropic etching is performed by utilizing the difference in the etching rate of the silicon single crystal substrate. For example, in this embodiment, the silicon single crystal substrate is set to K.
When it is dipped in an alkaline solution such as OH, it is gradually eroded and the first (111) plane perpendicular to the (110) plane and the first (111) plane
Forms an angle of about 70 degrees with the (111) plane of
A second (111) plane that makes an angle of about 35 degrees with the (0) plane appears, and the etching rate of the (111) plane is about 1/180 of the etching rate of the (110) plane. Is done using. By such anisotropic etching, it is possible to perform precision machining based on the depth machining of the parallelogram shape formed by the two first (111) planes and the two diagonal second (111) planes. The pressure generating chambers 12 can be arranged in high density.

In this embodiment, the long side of each pressure generating chamber 12 is formed by the first (111) plane, and the short side is formed by the second (111) plane. The pressure generating chamber 12 is provided in the flow path forming substrate 1
It is formed by etching through almost 0 to reach the elastic film 50. Here, the elastic film 50 is
The amount of the alkaline solution that etches the silicon single crystal substrate is extremely small. Each ink supply passage 14 communicating with one end of each pressure generation chamber 12 is formed shallower than the pressure generation chamber 12, and keeps the flow resistance of the pigment ink flowing into the pressure generation chamber 12 constant. That is, the ink supply path 14 is formed by etching the silicon single crystal substrate halfway in the thickness direction (half etching). The half etching is performed by adjusting the etching time.

On the opening surface side of the flow path forming substrate 10,
A nozzle plate 20 having a nozzle opening 21 that communicates with the pressure generating chamber 12 on the side opposite to the ink supply path 14 is fixed via an adhesive or a heat-welding film.

In the present embodiment, the nozzle plate 20 has a thickness of, for example, 0.1 to 1 mm and a linear expansion coefficient of 300 ° C. or less, for example, 2.5 to 4.5 [× 10 ^-6 /
C.], a metal material such as stainless steel (SUS), silicon (Si), glass ceramics, and rust-free steel.

The nozzle plate 20 as described above may be formed of a material having a thermal expansion coefficient substantially the same as that of the flow path forming substrate 10. In this case, since the flow path forming substrate 10 and the nozzle plate 20 are deformed substantially by heat,
It can be easily joined using a thermosetting adhesive or the like. In this embodiment, silicon is used as the material of the nozzle plate.

Further, the nozzle plate 20 entirely covers one surface of the flow path forming substrate 10 with one surface, and also serves as a reinforcing plate for protecting the silicon single crystal substrate from impact and external force.

A water repellent film 100 made of an inorganic compound having a dielectric constant lower than that of the nozzle plate 20 is provided on the surface of the nozzle plate 20 opposite to the flow path forming substrate 10. The water-repellent film 100 has a thickness of 0.05 to 1
It is about 0 μm.

The lower the dielectric constant ε of this water repellent film is, the more preferable it is. Specifically, it is desirable that the dielectric constant ε is ε <10.

Examples of the inorganic compound forming the water repellent film 100 include oxides such as silicon oxide and magnesium oxide, and nitrides such as silicon nitride. Here, the dielectric constant ε of silicon oxide or magnesium oxide is 3 to 4, and the dielectric constant ε of silicon nitride is 8.

For example, in this embodiment, the water repellent film 100 made of silicon oxide is formed by thermally oxidizing the surface of the nozzle plate 20.

Such an inorganic compound has a dielectric constant ε of ε <
Since it is 10, the electrical interaction with the ink droplet can be suppressed low.

When the inorganic compound is an oxide as in this embodiment, a hydroxy group, which is a hydrophilic group, exists in the molecule. Therefore, when forming a water-repellent film with such an oxide, it is desirable to replace the hydrophilic group with fluorine. Thereby, the water repellency can be further improved. If the water repellent film made of an inorganic compound having a low dielectric constant ε exhibits desired water repellency, it is not necessary to replace the hydrophilic group with fluorine.

As described above, the water-repellent film 100 of the present embodiment.
Is formed of an inorganic compound having a dielectric constant ε lower than that of the nozzle plate, so that electrical interaction with ink droplets can be suppressed to a low level. Therefore, the water repellency can be improved.

Further, since the water repellent film 100 is formed of an inorganic compound, it is possible to improve the durability as compared with a water repellent film formed of an organic compound such as a resin material. That is, since the water-repellent film 100 made of an inorganic compound has higher rigidity than that made of a resin material, the pigment particles contained in the ink come into contact with each other when wiping,
Damage such as scratches generated on the surface of the water-repellent film 100 can be reduced, and the durability of the water-repellent film 100 is improved.

On the other hand, a thickness of, for example, about 0.2 μm is formed on the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10.
The lower electrode film 60, the piezoelectric layer 70 having a thickness of, for example, about 1 μm, and the upper electrode film 80 having a thickness of, for example, about 0.1 μm are laminated in a process described below to form the piezoelectric element 30.
Configures 0. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. Generally, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. Further, here, a portion which is composed of one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the lower electrode film 60 is the common electrode of the piezoelectric element 300, and the upper electrode film 80 is the individual electrode of the piezoelectric element 300.
There is no problem in reversing this due to the driving circuit and wiring.
In any case, the piezoelectric active portion is formed for each pressure generating chamber 12. Further, here, the piezoelectric element 300 and the vibration plate that is displaced by the driving of the piezoelectric element 300 are collectively referred to as a piezoelectric actuator.

Further, the piezoelectric element 300 of the flow path forming substrate 10
On the side, a reservoir portion 31 that constitutes at least a part of a reservoir 110 that serves as a common ink chamber for each pressure generation chamber 12
The reservoir forming substrate 30 having the is bonded. In the present embodiment, the reservoir portion 31 is formed to penetrate the reservoir forming substrate 30 in the thickness direction and extend in the width direction of the pressure generating chamber 12, and as described above, the communicating portion of the flow passage forming substrate 10. A reservoir 110 that communicates with the pressure generating chamber 12 and serves as a common ink chamber for the pressure generating chambers 12 is configured.

As the reservoir forming substrate 30, it is preferable to use a material having substantially the same coefficient of thermal expansion as that of the passage forming substrate 10, for example, glass or a ceramic material. It was formed using a silicon single crystal substrate of the same material.

In addition, the piezoelectric element 3 of the reservoir forming substrate 30
In a region facing 00, a piezoelectric element holding portion 32 that can seal the space is provided in a state where a space that does not hinder the movement of the piezoelectric element 300 is secured, and the piezoelectric element 300 includes the piezoelectric element holding portion 32. It is sealed inside.

Here, the lower electrode film 60, which is a common electrode that constitutes each piezoelectric element 300 and is common to the plurality of piezoelectric elements 300, is extended to the region where the reservoir forming substrate 30 is bonded. For example, in the present embodiment, the lower electrode film 60 is formed from the region facing the pressure generating chamber 12 to the reservoir 1
It is extended to the peripheral wall on the opposite side to 10. And
A part of the reservoir forming substrate 30 is joined to the flow path forming substrate 10 in a region facing the lower electrode film 60.

The reservoir forming substrate 30 includes a compliance substrate 4 including a sealing film 41 and a fixing plate 42.
0 is joined. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm),
One surface of the reservoir section 31 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm).
Etc.). The area of the fixing plate 42 facing the reservoir 110 is the opening 4 completely removed in the thickness direction.
Therefore, the one surface of the reservoir 110 is sealed only by the sealing film 41 having flexibility, and is a flexible portion 33 that can be deformed by a change in internal pressure.

An ink inlet 35 for supplying ink to the reservoir 110 is formed on the compliance substrate 40 outside the central portion in the longitudinal direction of the reservoir 110. Further, the reservoir forming substrate 30 is provided with an ink introducing passage 36 that connects the ink introducing port 35 and the side wall of the reservoir 110.

The ink jet recording head of the present embodiment as described above takes in ink from the ink introduction port 35 connected to an external ink supply means (not shown) and fills the interior from the reservoir 110 to the nozzle opening 21 with ink. Then, according to a recording signal from a driving circuit (not shown), a voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12 via the external wiring, and the elastic film 50, By flexurally deforming the electrode film 60 and the piezoelectric layer 70, the pressure in each pressure generating chamber 12 is increased and an ink droplet is ejected from the nozzle opening 21.

Here, a method for manufacturing the ink jet recording head of this embodiment will be described with reference to FIGS. 3 to 5 show the pressure generating chamber 1
It is sectional drawing which shows a part of 2 longitudinal direction.

First, as shown in FIG. 3A, about 110 wafers of silicon single crystal substrates to be the flow path forming substrate 10 are prepared.
An elastic film 50 made of silicon dioxide is formed by thermal oxidation in a 0 ° C. diffusion furnace.

Next, as shown in FIG. 3B, the lower electrode film 60 is formed on the entire surface of the elastic film 50 by sputtering, and then the lower electrode film 60 is patterned to form an overall pattern. Platinum (Pt) or the like is suitable as a material for the lower electrode film 60. This is because the piezoelectric layer 70 described later, which is formed by the sputtering method or the sol-gel method, needs to be crystallized by baking at a temperature of about 600 to 1000 ° C. in the air atmosphere or the oxygen atmosphere after the film formation. Because. That is, the material of the lower electrode film 60 must be able to maintain the conductivity under such a high temperature and oxidizing atmosphere, and especially when lead zirconate titanate (PZT) is used as the piezoelectric layer 70. It is desirable that the change in conductivity due to the diffusion of lead oxide is small, and platinum is preferable for these reasons.

Next, as shown in FIG. 3C, the piezoelectric layer 70 is formed. The piezoelectric layer 70 preferably has crystals oriented. For example, in the present embodiment, a so-called sol-gel method is used in which a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied, dried, gelled, and fired at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. To form a piezoelectric layer 70 in which crystals are oriented. As a material for the piezoelectric layer 70, a lead zirconate titanate-based material is suitable for use in an inkjet recording head. The method for forming the piezoelectric layer 70 is not particularly limited, and may be formed by, for example, a sputtering method.

Further, after forming a lead zirconate titanate precursor film by a sol-gel method or a sputtering method,
A method of growing crystals at a low temperature by a high-pressure treatment method in an alkaline aqueous solution may be used.

In any case, in the piezoelectric body layer 70 thus formed, the crystals are preferentially oriented unlike the bulk piezoelectric body, and in the present embodiment, the piezoelectric body layer 70 has the crystals. It has a columnar shape. Note that the preferential orientation means that the crystal orientation direction is not disordered, and a specific crystal plane is oriented in a substantially constant direction. Further, a thin film having a columnar crystal means a state in which crystals having a substantially columnar body are aggregated in a plane direction with the central axes substantially aligned with the thickness direction to form a thin film. Of course, it may be a thin film formed of preferentially oriented granular crystals. The thickness of the piezoelectric layer manufactured in the thin film process is generally 0.2 to 5 μm.

Next, as shown in FIG. 4A, the upper electrode film 80 is formed. The upper electrode film 80 may be made of a material having high conductivity, and for example, many metals such as aluminum, gold, nickel and platinum, and a conductive oxide can be used. In this embodiment, platinum is deposited by sputtering.

Next, as shown in FIG. 4B, only the piezoelectric layer 70 and the upper electrode film 80 are etched to pattern the piezoelectric element 300.

In this embodiment, the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80 are left on a part of the peripheral portion of the region where the reservoir 110 is formed, so that the peripheral portion of the reservoir 110 is formed. Improves rigidity.

The above is the film forming process. After the film formation is performed in this manner, anisotropic etching of the silicon single crystal substrate with the above-mentioned alkaline solution is performed, and the result of FIG.
As shown in (c), the pressure generating chamber 12, the communication portion 13, the ink supply path 14 and the like are formed.

Next, as shown in FIG. 5A, the reservoir forming substrate 30 is provided on the piezoelectric element 300 side of the flow path forming substrate 10.
Are bonded via an adhesive or the like.

Next, as shown in FIG. 5B, on the surface of the flow path forming substrate 10 opposite to the reservoir forming substrate 30,
The nozzle plate 20 having the water repellent film 100 formed around the nozzle opening is bonded.

A method of forming the water repellent film 100 on the surface of the nozzle plate 20 will be described with reference to FIG. 6 is a cross-sectional view of the main parts of the nozzle plate according to the first embodiment of the present invention.

First, as shown in FIG. 6A, an oxide film 101 is formed by thermally oxidizing the surface of a nozzle plate 20 provided with a plurality of nozzle openings 21. In addition,
In this embodiment, since silicon is used as the material of the nozzle plate 20, the oxide film 101 is silicon oxide.

Next, as shown in FIG. 6B, the oxide film 1
The fluorine compound 102 is attached to the surface of 01 to replace the hydroxy group existing on the surface of the oxide film 101 with fluorine. Specifically, after immersing the surface of the oxide film 101 in a solution containing concentrated sulfuric acid and potassium dichromate, lithium fluoride (LiF) which is a fluorine compound 102 is attached to the surface of the oxide film 101. Thereby, the oxide film 101
The hydroxy groups present on the surface of can be replaced with fluorine.

As the fluorine compound, in addition to lithium fluoride (LiF), for example, sodium fluoride (N
aF), magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), or the like may be used.

As described above, in this embodiment, since the oxide film is formed by thermally oxidizing the surface of the nozzle plate 20, the water repellent film 100 is reliably formed even if the inner diameter of the nozzle opening 21 is relatively small. can do. Further, since it is not necessary to fill the nozzle opening 21 having such a small inner diameter with a resist or the like, the working process can be simplified. Therefore, the manufacturing cost can be kept low.

In the nozzle plate 20 manufactured in this manner, the nozzle openings 21 are filled with resist or the like, or a resin material is applied to form no water-repellent film, so that nozzle clogging may occur. There is no. Therefore, the ink can be surely ejected from the nozzle opening 21.

In this embodiment, the water repellent film 100 is
Although it is formed on the entire surface of the nozzle plate 20, the invention is not limited to this and may be formed only around the nozzle opening 21. In this case, the portion other than the region where the water repellent film is formed may be formed, for example, in a state of being covered with a resist or the like.

Further, although the water repellent film 100 is formed on the nozzle plate 20 having the nozzle openings 21, the present invention is not limited to this, and the nozzle openings may be formed after forming the oxide film, The nozzle openings may be formed after forming the water-repellent film, and then the reservoir forming substrate 3
By bonding the compliance substrate 40 on the surface of the ink jet recording head, the ink jet recording head of this embodiment is formed (see FIG. 5B).

In practice, a large number of chips are simultaneously formed on one wafer by the above-described series of film formation and anisotropic etching, and after the process is completed, one chip size as shown in FIG. The flow path forming substrate 10 is divided. Then, the ink jet recording head is formed by sequentially adhering the reservoir forming substrate 30 and the compliance substrate 40 to the divided flow path forming substrate 10 and integrating them.

Here, the nozzle plates of the following Examples and Comparative Examples were prepared and a test for comparing water repellency was conducted. The result will be described.

(Example) A nozzle plate body made of silicon is prepared, and an oxide film is formed by thermally oxidizing the surface of the nozzle plate body. Then, a solution of potassium dichromate dissolved in concentrated sulfuric acid is heated to 70 ° C., and the surface of the oxide film of the nozzle plate body is dipped in the solution.

Then, after cooling the nozzle plate body, the surface of the oxide film is coated with a slight amount of LiF. In this way, the nozzle plate of the example having the water repellent film formed of the inorganic compound was formed.

(Comparative Example) The same nozzle plate body as in the example was prepared, and after coating the surface of the nozzle plate body with a polyfluorinated ethylene resin material, the resin material was cured to form a water repellent film. Formed. The nozzle plate body having the water repellent film formed of the organic compound in this manner was used as a nozzle plate of a comparative example.

(Test Example) On the surface of the water-repellent film of the nozzle plates of the above-mentioned Examples and Comparative Examples, 10 identical ink droplets were applied.
Each mg was adhered, and as shown in FIG. 7, the contact angle (θ ₁ ) between the ink droplet and the water-repellent film and the sliding angle (θ ₂ ) representing the angle of inclination at which the ink droplet moves were measured. The results are shown in Table 1.
Shown in.

[0105]

[Table 1]

As shown in Table 1 above, the nozzle plate of the example has a contact angle between the ink droplet and the water-repellent film which is about the same as that of the nozzle plate of the comparative example, and the falling angle of the ink droplet is very small. It is clear that the nozzle plates of the examples, which are small, have excellent water repellency as compared to the comparative examples.

(Other Embodiments) Although the embodiments of the present invention have been described above, the basic structure of the ink jet recording head is not limited to the above.

For example, in the above-described first embodiment, the water repellent film 100 is formed by thermally oxidizing the surface of the nozzle plate 20, but the present invention is not limited to this, and the sputtering method is used to form the water repellent film. A water repellent film made of an inorganic compound may be formed on the surface.

By forming the water repellent film by using such a sputtering method, the same effect as that of the above-described first embodiment can be obtained, and the water repellent film can be formed of an inorganic material such as silicon nitride. .

As described above, when the water repellent film is formed by the sputtering method, there is no possibility that the inorganic compound will adhere to the inside of the nozzle opening. Therefore, similarly to the first embodiment described above, it is possible to simplify the work process and reduce the manufacturing cost.

Further, in the above-described first embodiment, the thin film type ink jet recording head manufactured by applying the film formation and the lithographic process is taken as an example, but the present invention is not limited to this, for example, green. The present invention can also be applied to a thick film type ink jet recording head formed by a method such as attaching a sheet.

[0112]

As described above, according to the present invention, an inorganic compound having a dielectric constant lower than that of the nozzle plate is formed on at least the periphery of the nozzle opening on the surface of the nozzle plate opposite to the surface where the flow path forming substrate is joined. Since the water repellent film is provided, there is an effect that the durability and water repellency of the water repellent film can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an ink jet recording head according to a first embodiment of the invention.

2A and 2B are a plan view and a sectional view of the ink jet recording head according to the first embodiment of the invention.

FIG. 3 is a cross-sectional view showing the manufacturing process of the ink jet recording head according to the first embodiment of the invention.

FIG. 4 is a cross-sectional view showing the manufacturing process of the inkjet recording head according to the first embodiment of the invention.

FIG. 5 is a cross-sectional view showing the manufacturing process of the ink jet recording head according to the first embodiment of the invention.

FIG. 6 is a schematic cross-sectional view illustrating the method of manufacturing the nozzle plate according to the first embodiment of the invention.

FIG. 7 is a diagram showing a contact angle (θ ₁ ) and a falling angle (θ ₂ ).

[Explanation of symbols]

10 Flow path forming substrate 12 Pressure generation chamber 20 nozzle plate 21 nozzle opening 30 Reservoir forming substrate 40 compliance board 60 Lower electrode film 70 Piezoelectric layer 80 Upper electrode film 100 water repellent film 101 oxide film 102 Fluorine compound 110 reservoir 300 Piezoelectric element

Claims (17)

[Claims] 1. A nozzle plate, which has a plurality of nozzle openings for discharging droplets and is joined to a flow path forming substrate having a flow path communicating with the nozzle openings, wherein the nozzle openings are provided. A nozzle plate main body joined to the flow path forming substrate, and having a dielectric constant lower than that of the nozzle plate main body at least around the nozzle opening on a surface of the nozzle plate main body opposite to the flow path forming substrate. A nozzle plate provided with a water-repellent film made of an inorganic compound. 2. The nozzle plate according to claim 1, wherein the dielectric constant ε of the inorganic compound is ε <10. 3. The nozzle plate according to claim 1, wherein the inorganic compound is magnesium oxide or silicon oxide. 4. The nozzle plate according to claim 3, wherein the inorganic compound is one in which a hydroxy group existing in the molecule is replaced with fluorine. 5. The nozzle plate according to claim 1, wherein the inorganic compound is silicon nitride. 6. The nozzle plate according to claim 1, wherein the water repellent film has a thickness of 0.05 to 10 μm. 7. The nozzle plate according to claim 1, wherein the nozzle plate body is made of silicon or stainless steel. 8. A nozzle plate having a nozzle opening, a flow path forming substrate in which a pressure generating chamber communicating with the nozzle opening is formed, and provided on one surface side of the flow path forming substrate via a vibration plate. An ink jet recording head comprising a piezoelectric element for generating a pressure change in the pressure generating chamber, wherein the nozzle is provided on at least a surface of the nozzle plate opposite to the flow path forming substrate, at least around the nozzle opening. An ink jet recording head having a water repellent film made of an inorganic compound having a lower dielectric constant than that of a plate. 9. The ink jet recording head according to claim 8, wherein the dielectric constant ε of the inorganic compound is ε <10. 10. The ink jet recording head according to claim 8 or 9, wherein the inorganic compound is magnesium oxide or silicon oxide. 11. The ink jet recording head according to claim 10, wherein the inorganic compound is one in which a hydroxy group present in the molecule is replaced with fluorine. 12. The ink jet recording head according to claim 8, wherein the inorganic compound is silicon nitride. 13. The ink jet recording head according to claim 8, wherein the water repellent film has a thickness of 0.05 to 10 μm. 14. The ink jet recording head according to claim 8, wherein the nozzle plate is made of silicon or stainless steel. 15. A method of manufacturing a nozzle plate, comprising: a plurality of nozzle openings for ejecting droplets, wherein the nozzle plate is joined to a flow path forming substrate having a flow path communicating with the nozzle openings. A step of forming an oxide film on the surface of the provided nozzle plate body opposite to the surface to be joined to the flow path forming substrate; and the nozzle by substituting fluorine for a hydroxy group existing on the surface of the oxide film. And a step of forming a water repellent film having a dielectric constant lower than that of the nozzle plate body on the surface of the plate body. 16. The method for manufacturing a nozzle plate according to claim 15, wherein the oxide film is formed by a sputtering method. 17. The method of manufacturing a nozzle plate according to claim 15, wherein the oxide film is formed by thermally oxidizing the periphery of the nozzle opening.