JP2001038915A - Production of nozzle plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle plate producing method capable of easily forming a nozzle orifice with high accuracy. SOLUTION: A nozzle orifice 13 can be easily formed by a process for forming an electroforming seed electrode 11 having an opening part 15 having a diameter larger than the nozzle diameter being the diameter of the straight part of the nozzle orifice 13 to the region to which the nozzle orifice 13 is formed on an insulating substrate 110, a process for forming a columnar resist 16 on the insulating substrate 110 within the opening part 15 so as to make the same higher than the length of the straight part of the nozzle orifice 13, a process for forming a nozzle substrate 12 on the insulating substrate 110 and the electroforming seed electrode 11 by electroforming and a process for removing the columnar resist 16 and the insulating substrate 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure generating chamber which communicates with a nozzle opening for discharging ink droplets, which is constituted by a vibrating plate. The present invention relates to a method for manufacturing a nozzle plate used in an ink jet recording head that ejects ink droplets by using a nozzle plate.

[0002]

2. Description of the Related Art In general, as an ink jet recording head constituting a part of an ink jet recording apparatus used for a printer, a facsimile, a copying machine, etc., a piezoelectric element or a heat generating element is provided in a pressure generating chamber provided on a flow path forming substrate. There is known a device in which a pressure is generated by an element and an ink droplet is ejected from a nozzle opening by the pressure.

[0003] Ink jet recording heads of this type include a bubble jet type in which a resistance wire for generating Joule heat is provided in a pressure generating chamber as a pressure generating means, and a pressure generating chamber in which a resistance wire is provided. The part is composed of a vibration plate, and the vibration plate is roughly classified into two types of a piezoelectric vibration type in which an ink droplet is ejected from a nozzle opening by deforming the vibration plate by a piezoelectric element. Further, a piezoelectric vibration type ink jet recording head uses a longitudinal vibration mode piezoelectric actuator which expands and contracts in the axial direction of the piezoelectric element, and
Two types, which use a flexural vibration mode piezoelectric actuator, have been put to practical use.

In such an ink jet recording head, a nozzle plate is used in which a plurality of nozzle openings for discharging ink droplets are formed mechanically or by a laser or the like on a substrate made of, for example, stainless steel.
The nozzle plate is joined to the flow path type substrate so that the nozzle opening communicates with the pressure generating chamber.

[0005] Since such a conventional nozzle plate is formed mechanically or by laser or the like, the shape of the nozzle opening is linear, and the ink ejection performance such as the amount and speed of ink droplet ejection is low. There was a problem. Therefore, in order to improve the ink ejection characteristics, a configuration in which the diameter of the nozzle opening on the pressure generating chamber side is gradually increased has been proposed.

However, since the size of the nozzle opening is very small, it has been difficult to obtain a desired shape. In order to solve such a problem, for example, Japanese Patent Laid-Open No. 11-1089
As disclosed in Japanese Unexamined Patent Publication No. 2 (1999) -1990, there has been proposed a method of manufacturing a nozzle plate in which a desired shape can be obtained relatively easily by forming the nozzle plate in a plurality of layers.

For example, as shown in FIG. 10A, Japanese Patent Application Laid-Open No. 8-132625 discloses that a columnar resist 122 is formed on a region of a substrate 121 where a nozzle opening is to be formed with the length of the straight portion of the nozzle opening. A method of manufacturing a nozzle plate, which is formed at substantially the same height, forms an electrode 123 for electroforming, and forms a nozzle opening 125 by forming a metal layer 124 by electroforming as shown in FIG. 10B. Has also been proposed.

[0008]

However, in the former method of manufacturing a nozzle plate, the linear portion of the nozzle opening and the other portion are formed of different members, and the linear portion and the other portion are formed in different steps. Therefore, there is a problem that the manufacturing process is complicated.

Further, in the latter manufacturing method, it is difficult to stop the deposition of the electrode layer at a predetermined position when the metal layer is formed by electroforming, and as shown in FIG. There is a possibility that the nozzle opening 125 may not be manufactured in a desired shape, since 124 is formed up to the end surface 122 a of the columnar resist 122.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing a nozzle plate that can easily and accurately form a nozzle opening.

[0011]

According to a first aspect of the present invention, there is provided an electroforming seed electrode having an opening having a diameter larger than the nozzle diameter, which is the diameter of the straight portion of the nozzle opening. Forming a column resist on the insulating substrate in the opening on the insulating substrate in the opening, the column resist being higher than the length of the straight portion of the nozzle opening; A method for manufacturing a nozzle plate, comprising: a step of forming a nozzle base on a substrate and the electroforming seed electrode by electroforming; and a step of removing the columnar resist and the insulating substrate.

In the first aspect, by forming the nozzle base by electroforming, the nozzle opening having a desired shape can be formed in one step, and the manufacturing process is simplified and the cost is reduced. .

A second aspect of the present invention is the method for manufacturing a nozzle plate according to the first aspect, wherein the insulating substrate is obtained by forming an insulating film on a conductive substrate.

[0014] In the second aspect, the range of materials can be widened by forming the insulating substrate with the conductive substrate and the insulating film.

According to a third aspect of the present invention, in the first or second aspect, a substantially tapered large diameter in which the diameter of the columnar resist is gradually increased toward the insulating substrate toward the insulating substrate. Forming a portion of the nozzle plate.

In the third aspect, by providing the columnar resist with a large diameter portion, the nozzle diameter at one end side of the nozzle opening is gradually increased to form a tapered shape.

According to a fourth aspect of the present invention, in any one of the first to third aspects, before the step of forming the electroforming seed electrode, the insulating substrate is formed in a region where the opening is formed. Forming a convex portion having a larger diameter than the nozzle diameter and a smaller diameter than the opening portion, and a step of removing the convex portion together with the insulating substrate. In the manufacturing method.

In the fourth aspect, a crater portion having a diameter larger than the nozzle diameter can be easily formed around the nozzle opening on one side of the nozzle plate.

According to a fifth aspect of the present invention, in the fourth aspect, the convex portion is formed by patterning an insulating film provided on an uppermost layer of the insulating substrate. Manufacturing method.

In the fifth aspect, the use of a specific material for the insulating substrate facilitates patterning of the surface of the insulating substrate.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the method further comprises a step of forming a water-repellent film at least around the nozzle opening on the ink droplet ejection side surface. Nozzle plate manufacturing method.

In the sixth aspect, a water-repellent film can be formed relatively easily around the nozzle opening.

A seventh aspect of the present invention is the method for manufacturing a nozzle plate according to any one of the first to sixth aspects, wherein the columnar resist has a substantially cylindrical shape.

In the seventh aspect, a nozzle opening having a substantially circular cross section can be formed relatively easily.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

(Embodiment 1) FIG. 1 is a perspective view and a sectional view of a nozzle plate manufactured by a manufacturing method according to Embodiment 1 of the present invention.

As shown in FIG. 1, the nozzle plate 10 of the present invention is provided with an electroforming seed electrode 11, which will be described in detail later.
A nozzle base 12 is formed on the electroforming seed electrode 11 by electroforming, and a plurality of nozzle openings 13 are provided at predetermined positions. The nozzle openings 13 are basically formed substantially linearly, but are formed so that the diameter gradually increases near the end on the ink introduction side. That is, the nozzle opening 13 of the present embodiment includes a substantially linear straight portion 13a and a curved portion 13b having a tapered shape with a gradually increasing diameter.

Here, a manufacturing method of this embodiment for manufacturing such a nozzle plate 10 will be described. FIG. 2 is a cross-sectional view illustrating a manufacturing process of the nozzle plate according to the present embodiment.

In this embodiment, first, as shown in FIG. 2A, an electroformed electrode layer 14 serving as an electrode for electroforming described later is formed on the surface of the insulating substrate 110, and then each nozzle is patterned. An opening portion 15 having a diameter larger than the nozzle diameter of the nozzle opening 13 and exposing the insulating substrate 110 is formed in a region where the opening 13 is formed, and is used as an electroforming seed electrode 11.

The material of the insulating substrate 110 is not particularly limited, and may be any material having an insulating property, such as a glass substrate. The insulating substrate 110 is not limited to a single layer made of a material having an insulating property. For example, the insulating property may be set on a substrate made of a conductive material such as a single crystal silicon substrate with a thermal oxide film. It may be provided with an insulating layer made of a material having the same. In any case, it may be formed of a material that can be etched mechanically or by gas, liquid, or the like.

The material of the electroforming seed electrode 11, that is, the material of the electroforming electrode layer 14 is not particularly limited. For example, it has a two-layer structure, and the insulating substrate 110
It is preferable to use titanium (Ti) or chromium (Cr) or the like having high adhesion to nickel, and use nickel (Ni) or the like for the surface layer. In the present embodiment, titanium (Ti) and nickel (Ni) are sequentially laminated on the insulating substrate 110 to form the electroformed electrode layer 14.

Next, as shown in FIG. 2B, a substantially central portion of a region of the insulating substrate 110 facing each opening 15 is
The columnar resist 16 is formed to be higher than the length of the linear portion 13a of the nozzle opening 13. For example, in this embodiment, the photoresist film 17 is formed on the insulating substrate 1 by spin coating.
After being formed over the entire surface of the seed electrode 10 and the seed electrode 11 for electroforming, a columnar resist 16 was formed by patterning. This columnar resist 16 is finally removed, and the removed portion becomes the nozzle opening 13. Therefore, the columnar resist 16
Is the nozzle diameter of the nozzle opening 13, that is, the linear portion 13
It is patterned into a columnar shape having the same diameter as the diameter a.

The photoresist film 17 is not limited to the formation by the spin coating method, and may be, for example, a film-like photoresist film (dry film photoresist).

Next, as shown in FIG. 2C, the nozzle base 12 is formed by nickel electroforming. For example, in the present embodiment, the nozzle base 12 is formed by electroforming using a nickel sulfamate electroforming solution. In addition, although the material of the nozzle base 12 is not particularly limited,
For example, it is preferable to use copper, nickel, a nickel-cobalt alloy, a nickel-phosphorus alloy, a nickel-boric acid alloy, or the like.

When the nozzle base 12 is formed by electroforming, the nozzle base 12 is formed from the surface of the electroforming seed electrode 11 at substantially the same speed in each direction.
The opening edge 12a of the nozzle base 12 at a portion corresponding to the opening edge 11a of the electroforming seed electrode 11, which is the peripheral edge of the electrode, is formed in a substantially round shape.

The thickness of the nozzle base 12 can be adjusted by controlling the magnitude of the current applied to the electrodes or the application time. Opening edge 1
The radius of 2a is equal to the size of the electroforming seed electrode 11 forming the opening 15.
Can be adjusted by the distance between the end face of the substrate and the columnar resist 16.

Thereafter, as shown in FIG. 2D, the insulating substrate 110 and the columnar resist 16 are removed to form the nozzle plate 10 having the nozzle openings 13 including the linear portions 13a and the curved portions 13b.

By forming the nozzle plate 10 by the manufacturing process of the present embodiment, the straight portion 13a and the curved portion 13b of the nozzle opening 13 can be formed in one process, and the manufacturing process can be simplified. Can be. Further, by simplifying the manufacturing process, the yield can be improved, and the manufacturing cost can be significantly improved. Further, since the columnar resist 16 is formed to be longer than the length of the linear portion 13a of the nozzle opening 13, the nozzle opening 1 is formed when the nozzle base 12 is formed by electroforming.
The boundary between the straight portion 13a and the curved portion 13b of No. 3 can always be formed smoothly.

Further, a water-repellent film 90 may be provided on the surface of the nozzle plate 10 thus formed, that is, at least around the nozzle openings 13 of the nozzle plate 10 as shown in FIG. 3, for example. Good. Thereby, the adhesion of the ink around the nozzle openings 13 is suppressed, and failures such as clogging of the nozzle openings 13 can be suppressed.

The material of the water-repellent film 90 is not particularly limited. For example, a fluorine-based resin, for example, polytetrafluoroethylene, polyperfluoroalkoxybutadiene, polyfluorovinylidene, polyfluorovinyl, polydiperfluoroalkyl fumarate Or eutectoid plating of nickel with any of them, or a silicon resin.

The nozzle plate 10 of the present embodiment as described above is used in, for example, an ink jet recording head, and ink is ejected from the nozzle openings 13 by driving a piezoelectric element.

Hereinafter, an example of an ink jet recording head having the nozzle plate 10 manufactured by the manufacturing method of the present embodiment will be described. In addition, FIG.
FIG. 5 is an exploded perspective view showing an example of the ink jet recording head, and FIG. 5 is a sectional view thereof.

As shown in the figure, the flow path forming substrate 20 to which the nozzle plate 10 is bonded has, for example, a plane orientation (11
0) A silicon single crystal substrate. Flow path forming substrate 20
The thickness is usually about 150 to 300 μm, preferably about 180 to 280 μm, and more preferably about 220 μm. This maintains the rigidity of the partition between adjacent pressure generating chambers,
This is because the array density can be increased.

One surface of the flow path forming substrate 20 is an opening surface, and the other surface is formed with an elastic film 50 having a thickness of 1 to 2 μm and made of silicon dioxide previously formed by thermal oxidation.

On the other hand, a silicon single crystal substrate is anisotropically etched on the opening surface of the flow path forming substrate 20 to form an opening.
Pressure generating chambers 22 defined by a plurality of partition walls 21 are arranged in the width direction, and one end of each pressure generating chamber 22 in the longitudinal direction communicates with a reservoir section of a reservoir forming substrate described later. Reservoir 1 serving as 22 common ink chambers
In addition, a communication portion 23 that forms a part of the pressure supply chamber 24 is formed, and one end in the longitudinal direction of each pressure generation chamber 22 and the ink supply path 24 are formed.
Are communicated through.

The nozzle plate 10 in which the nozzle openings 13 communicating with the respective pressure generating chambers 22 on the side opposite to the ink supply passages 24 are formed on the opening side of the flow path forming substrate 20 with an adhesive or the like. It is fixed via a heat welding film or the like.

Here, the size of the pressure generating chamber 22 for applying the ejection pressure of the ink droplet to the ink and the size of the nozzle opening 13 for ejecting the ink droplet depend on the amount of the ejected ink droplet, the ejection speed, and the ejection frequency. Optimized. For example, in the present embodiment, the nozzle openings 13 are formed with a diameter of about several tens μm with high accuracy.

It should be noted that such a nozzle plate 10 is
One surface entirely covers one surface of the flow path forming substrate 20, and also serves as a reinforcing plate for protecting the silicon single crystal substrate from impact and external force.

The thickness of the elastic film 50 on the opposite side of the flow path forming substrate 20 from the nozzle plate 10 is, for example,
The lower electrode film 60 having a thickness of about 0.2 μm
m, and an upper electrode film 80 having a thickness of, for example, about 0.1 μm, are laminated by a process described later,
The piezoelectric element 300 is constituted. Here, the piezoelectric element 30
0 indicates a portion including the lower electrode film 60, the piezoelectric film 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 film 7 are used as a common electrode.
0 is patterned for each pressure generating chamber 22.
Here, a portion which is constituted by one of the patterned electrodes, the piezoelectric film 70 and the other electrode and in which a piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 320. In the present embodiment, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300, and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. However, there is no problem even if the upper electrode film 80 is reversed for convenience of a drive circuit and wiring. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Further, here, the piezoelectric element 300 and a diaphragm whose displacement is generated by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In the example described above, the elastic film 50 and the lower electrode film 60 function as a diaphragm, but the lower electrode film may also serve as the elastic film.

Further, the piezoelectric element 30 of the flow path forming substrate 20
On the 0 side, a reservoir forming substrate 30 having a reservoir portion 31 constituting at least a part of the reservoir 100 is joined. The reservoir portion 31 is basically formed in the width direction of the pressure generating chamber 22 so as to penetrate the reservoir forming substrate 30 in the thickness direction, and as described above, the communication portion of the flow path forming substrate 20. The reservoir 100 communicates with the pressure generating chamber 23 and serves as a common ink chamber for each of the pressure generating chambers 22.

The piezoelectric element 3 of the reservoir forming substrate 30
In a region opposed to the piezoelectric element 300, a piezoelectric element holding portion 34 capable of sealing the space is provided while securing a space that does not hinder the movement of the piezoelectric element 300. At least the piezoelectric active portion 320 of the piezoelectric element 300 is provided. Are sealed in the piezoelectric element holding portion 34.

Further, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded to such a reservoir forming substrate 30. 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), and one surface of the reservoir portion 31 is sealed by the sealing film 41. I have. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SU) having a thickness of 30 μm.
S) etc.). The reservoir 3 of the fixing plate 42
1 is an opening 43 completely removed in the thickness direction, so that one surface of the reservoir 100 is sealed only with the sealing film 41 having flexibility, and the internal pressure changes. It can be deformed by.

Further, an ink inlet 35 for supplying ink from an ink supply means such as an ink cartridge is formed on the compliance substrate 40 substantially outside the central portion in the longitudinal direction of the reservoir portion 31. The substrate 30 is provided with an ink introduction path 36 that communicates the ink introduction port 35 with the side wall of the reservoir 31. Then, ink is supplied to the reservoir section 31 from the ink supply means via the ink introduction port 35 and the ink introduction path 36.

(Embodiment 2) FIG. 6 is a cross-sectional view of a main part of a nozzle plate manufactured by a manufacturing method according to Embodiment 2, and FIG. 7 is a cross-sectional view showing the manufacturing process.

As shown in FIG. 6, the nozzle plate 10 manufactured by the manufacturing method of this embodiment is provided with a crater 18 at least at the peripheral portion of the nozzle opening 13 on the ink droplet ejection surface side. The second embodiment is the same as the first embodiment except that a water-repellent film 90 is provided on the surface of the nozzle plate 10 including the nozzle plate 18.

By the way, in the ink jet recording head, printing is performed with a short distance between the nozzle plate and the recording paper such that they are almost in contact with each other. There is a possibility that the water-repellent film provided around may be worn away.

Therefore, in this embodiment, the nozzle opening 1
A crater portion 18 is provided on the periphery of No. 3 to prevent the recording paper from contacting the water-repellent film 90 provided on the periphery of the nozzle opening 13 during printing.

Hereinafter, a method for manufacturing the nozzle plate according to the second embodiment will be described.

The insulating substrate 110 of this embodiment includes, for example, a conductive substrate 111 made of a silicon single crystal substrate,
An insulating layer 112 made of, for example, silicon oxide formed by oxidizing a silicon single crystal substrate on both surfaces thereof,
First, as shown in FIG. 7A, the insulating layer 112 on one surface side of the conductive substrate 111 is patterned, and the area where the nozzle opening 13 is to be formed is determined by the nozzle diameter of the nozzle opening 13. Are larger in diameter and smaller in diameter than the opening 15 of the electroforming seed electrode 11 formed in the following steps.
12a is formed.

After that, as in the first embodiment, as shown in FIG. 7B, after the electroformed electrode layer 14 is formed, a pattern having a larger diameter than the diameter is formed in a region corresponding to the projection 112a by patterning. Of the electroforming seed electrode 11
And Next, as shown in FIG.
After the columnar resist 16 is formed substantially at the center of FIG.
As shown in FIG. 5, the nozzle base 12 is formed by nickel electroforming. Thereafter, as shown in FIG. 7E, the nozzle plate 10 having the nozzle openings 13 having a desired shape is formed by removing the silicon crystal substrate 111, the insulating films 112 and 113, and the columnar resist 16. Then, the water-repellent film 90 may be formed on the surface of the nozzle plate 10 formed as described above.

As described above, according to the manufacturing method of this embodiment,
Patterning a part of the insulating substrate 110 to form the convex 112
Only by forming a, the crater portion 18 can be easily formed around the nozzle opening 13. That is, the manufacturing process is simplified and the cost can be reduced. In addition, by using the nozzle plate 10 having such a structure, the water-repellent film on the periphery of the nozzle opening 13 can be protected, and an ink jet recording head with improved durability and reliability can be relatively easily manufactured. .

In the present embodiment, the crater section 18
Is provided for each nozzle opening 13, but is not limited to this, and it goes without saying that the crater portion may be provided continuously over a plurality of nozzle openings 13.

In this embodiment, the insulating substrate 110
The crater portion 18 is formed by patterning a part of the ridge portion 112a to form the ridge portion 112a. However, the crater portion 18 is not limited to this method. Needless to say, the ridge portion is separately formed on the insulating substrate 110. You may.

For example, as shown in FIG.
Instead of providing the convex portion 112a, when the columnar resist 16 is formed, the end of the columnar resist 16 on the side of the insulating substrate 110 is made to have a gradually increasing diameter, thereby forming a tapered large diameter portion 16a. You may do so. Then, FIG.
As shown in FIG. 9B, the nozzle base 12 is formed and the insulating substrate 110 and the like are removed in the same manner as in the above-described manufacturing process. A curved portion 13c whose diameter is gradually increased is formed in the portion, similarly to the opposite end portion. Even with such a structure, the curved portion 13c of the nozzle opening 13 functions substantially similarly to the crater portion 18 described above, and the recording paper comes into contact with the water-repellent film 90 provided on the peripheral portion of the nozzle opening 13. Can be prevented.

The large-diameter portion 16a of the columnar resist 16
Can be formed by using a low-sensitivity photoresist film or the like.

[0066]

As described above, according to the present invention, the linear portions of the nozzle openings formed in the nozzle plate and other portions can be formed in one step. Therefore,
The manufacturing process can be simplified, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view of a nozzle plate manufactured by a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a manufacturing process of the nozzle plate according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating another example of a nozzle plate manufactured by the manufacturing method according to the first embodiment of the present invention.

FIG. 4 is a perspective view illustrating an example of an ink jet recording head including a nozzle plate manufactured by the manufacturing method according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of an ink jet recording head including a nozzle plate manufactured by the manufacturing method according to the first embodiment of the present invention.

FIG. 6 is a sectional view of a nozzle plate manufactured by a manufacturing method according to a second embodiment of the present invention.

FIG. 7 is a sectional view illustrating a manufacturing process of the nozzle plate according to the second embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating another manufacturing process of the nozzle plate according to the second embodiment of the present invention.

FIG. 9 is a sectional view showing another example of the nozzle plate according to the second embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a method for manufacturing a nozzle plate according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Nozzle plate 11 Electroforming seed electrode 12 Nozzle base 13 Nozzle opening 13a Straight part 13b Curved part 20 Flow path forming substrate 22 Pressure generating chamber 50 Elastic film 60 Lower electrode film 70 Piezoelectric film 80 Upper electrode film 300 Piezoelectric element 320 Piezoelectric Active part

Claims (7)

[Claims] A step of forming an electroforming seed electrode having an opening having a diameter larger than the nozzle diameter, which is a diameter of a straight portion of the nozzle opening, in a region of the insulating substrate where the nozzle opening is formed; Forming a columnar resist on the insulating substrate in the opening higher than the length of the straight portion of the nozzle opening; and forming a nozzle base by electroforming on the insulating substrate and the electroforming seed electrode. A method for manufacturing a nozzle plate, comprising: a step of removing the columnar resist and the insulating substrate. 2. The method according to claim 1, wherein the insulating substrate is obtained by forming an insulating film on a conductive substrate. 3. The tapered large-diameter portion according to claim 1, wherein a diameter of the columnar resist on the insulating substrate side is gradually increased toward the insulating substrate. Nozzle plate manufacturing method. 4. The method according to claim 1, wherein, prior to the step of forming the electroforming seed electrode, a diameter of the opening is formed on the insulating substrate in a region larger than the nozzle diameter. Forming a convex part having a diameter and a diameter smaller than the opening part;
Removing the protrusions together with the insulating substrate. 5. The method according to claim 4, wherein the protrusion is formed by patterning an insulating film provided on an uppermost layer of the insulating substrate. 6. The method for manufacturing a nozzle plate according to claim 1, further comprising a step of forming a water-repellent film on at least the periphery of the nozzle opening on the ink droplet ejection side surface. 7. The method for manufacturing a nozzle plate according to claim 1, wherein the columnar resist has a substantially columnar shape.