JP2003266689A - Liquid drop discharge head, its manufacturing method and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that bubbles are easy to stay to cause discharge failures. <P>SOLUTION: A surface roughness of a wall face 1a opposite to a diaphragm 2 of a pressure liquid chamber 6 of a channel plate 1 where the pressure liquid chamber 6 and the like are formed is made 2 μm or smaller in average roughness Ra. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet discharge head, a method of manufacturing the same, and an ink jet recording apparatus.

[0002]

2. Description of the Related Art An ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile machine, a copying machine and a plotter, has a nozzle for ejecting ink droplets and an ink flow path (ejection chamber, which communicates with this nozzle). Also referred to as a pressure chamber, a pressurized liquid chamber, a liquid chamber, etc.) and a drive unit for pressurizing the ink in the ink flow path, and an inkjet head as a droplet discharge head is mounted. As the droplet discharge head, for example, there are a droplet discharge head that discharges a liquid resist as droplets, a droplet discharge head that discharges a DNA sample as droplets, etc., but the following description will focus on the inkjet head.

In the ink jet head, as an energy generating means for generating energy for pressurizing the ink in the ink flow passage, a piezoelectric element is used to deform a vibrating plate forming a wall surface of the ink flow passage, thereby forming a volume in the ink flow passage. Of a so-called piezo type in which ink droplets are discharged by changing the temperature (see Japanese Patent Laid-Open No. 2-51734), or pressure generated by heating ink in an ink flow path using a heating resistor to generate bubbles. A so-called thermal type in which ink droplets are ejected (see Japanese Patent Application Laid-Open No. 61-59911), a diaphragm forming the wall surface of the ink flow path and an electrode are arranged so as to face each other, and are generated between the diaphragm and the electrode. An electrostatic type that changes the internal volume of the ink flow path to eject ink droplets by deforming the vibrating plate by the electrostatic force that is applied (Japanese Patent Application Laid-Open No. HEI 5 (1998)
No. -50601) and the like are known.

Among these various heads, a nozzle plate (a nozzle forming member) having a nozzle opening and a vibrating plate are adhered to both surfaces of a spacer (liquid chamber forming member) to form a pressure chamber (liquid chamber). ) Is formed and the vibration plate is deformed by the piezoelectric vibrator, the thermal energy is not used as a drive source for flying the ink droplets, so there is no deterioration of the ink due to heat, and it is particularly easy to deteriorate due to heat. There is an advantage in ejecting color ink. Moreover,
Since it is possible to freely adjust the amount of ink droplets by adjusting the amount of displacement of the piezoelectric vibrator, this head is optimal for constructing an inkjet recording device for high-quality color printing.

By the way, the ink jet head can record and print with an extremely high resolution by reducing the size of the ink droplets because the dots on the recording medium are composed of ink droplets.

However, in order to print efficiently, the number of ink openings is increased (the number of nozzles is increased).
It is necessary to increase the pressure chamber (pressurized liquid chamber) in order to use the energy of the piezoelectric vibrator efficiently in the case where the piezoelectric vibrator is used as the driving means. This is contrary to the demand for smaller heads. In order to solve such contradictory problems, the walls (partition walls) partitioning the adjacent pressure chambers are usually thinned and the shape of the pressure chambers is increased in the longitudinal direction to increase the volume.

Such a pressure chamber and a reservoir are formed by a liquid chamber forming member which is a member for keeping the distance between the vibrating plate and the nozzle plate at a predetermined value, but as described above, it is extremely small and complicated. Etching techniques are commonly used because of the need to form shaped pressure chambers. As a material for forming such a liquid chamber forming member, a photosensitive resin film is often used. However, because of its low mechanical strength, crosstalk, bending, etc. occur, and printing is attempted to obtain high resolution. There is a problem that the quality deteriorates.

Therefore, an ink jet head is constructed by applying a so-called micromachining technique, which is a component manufacturing technique using anisotropic etching of a silicon single crystal substrate capable of processing a fine shape with high precision by a relatively simple method. Processing of a member to be processed is performed. In particular, a single crystal silicon substrate having a crystal orientation (110) is used as a liquid chamber forming member to perform anisotropic etching to form a pressure chamber or a reservoir. Since the spacer using single crystal silicon has high mechanical rigidity, the deflection of the entire recording head due to the deformation of the piezoelectric vibrator can be reduced, and the etched wall surface is almost perpendicular to the surface, so the pressure chamber It has a great advantage that it can be configured uniformly.

For example, Japanese Laid-Open Patent Publication No. 7-178908 discloses a spacer including a nozzle plate having nozzle openings formed in rows, a spacer for forming a pressure generating chamber, an ink supply port, and a reservoir, and a cover plate. When anisotropically etching a silicon single crystal substrate having a crystal orientation (110) that forms a groove, the wall surface near the nozzle opening that defines the through hole that forms the pressure generating chamber is perpendicular to the surface of the silicon single crystal substrate. Formed with a total of six wall surfaces, four wall surfaces contacting at an obtuse angle and two wall surfaces contacting at an obtuse angle in the cross-sectional direction of the silicon single crystal substrate, to make the ink flow near the nozzle opening where ink stagnates as uniformly as possible. A head is described which is adapted to prevent the stagnation of air bubbles.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 7-125198, when anisotropically etching a silicon single crystal substrate having a crystal orientation, through holes for forming a pressure generating chamber and a reservoir are formed on the same wall surface. And the wall surface in the vicinity of the nozzle opening that defines the through hole that forms the pressure generating chamber is formed as a wall surface that is in contact with each other at an obtuse angle, thereby configuring the ink supply port and the pressure generating chamber as a smooth flow path. A head is described in which the wall surface near the nozzle opening where ink is likely to stay is made equidistant from the nozzle opening as much as possible.

[0011]

However, when the liquid chamber forming member is formed by etching silicon, it is difficult to form an ideal shape because the etching depends on the crystal orientation of the silicon. It is easy to cause stagnation and stagnation.

Therefore, a head as described in the above-mentioned publication is proposed, but since the silicon surface forming the wall surface of the liquid chamber is roughened by etching,
There is a problem in that a stable flow of ink cannot be ensured, bubbles tend to stagnate, ejection failure occurs, and stable droplet ejection cannot be performed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a droplet discharge head capable of stable droplet discharge, a method of manufacturing the same, and an ink jet recording apparatus.

[0014]

In order to solve the above problems, in a droplet discharge head according to the present invention, a liquid chamber forming member is made of silicon, and a wall surface of a liquid flow path of the liquid chamber forming member is formed. The surface roughness of the surface to be subjected to Ra does not exceed 2 μm.

In the droplet discharge head according to the present invention, the liquid chamber forming member is formed of silicon, and the surface roughness of the wall surface of the liquid flow path facing the vibration plate of the liquid chamber forming member does not exceed 2 μm in Ra. It was configured.

In the droplet discharge head according to the present invention, the liquid chamber forming member is formed of silicon, and the surface roughness of the wall surface of the nozzle communication passage of the liquid chamber forming member does not exceed Ra of 2 μm.

In each of the droplet discharge heads according to the present invention, it is preferable that an oxide film or a titanium nitride film is formed on the wall surface of the liquid chamber.

A method of manufacturing a droplet discharge head according to the present invention is a method of manufacturing a droplet discharge head according to the present invention, which uses a potassium hydroxide aqueous solution having a solution concentration of 25% or more and a treatment temperature of 80 ° C. As described above, the silicon substrate is wet-etched to form the liquid chamber forming member.

A method of manufacturing a droplet discharge head according to the present invention is a method of manufacturing a droplet discharge head according to the present invention, wherein a silicon substrate is wet-etched to form a liquid chamber forming member, and this forming step is performed. Includes a step of preventing bubbles generated during etching from adhering to the etching surface.

Here, it is preferable to rock the silicon substrate when performing wet etching, or to apply ultrasonic waves to the silicon substrate when performing wet etching.

The ink jet recording apparatus according to the present invention is
The inkjet head is a droplet discharge head according to the present invention.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. An inkjet head according to a first embodiment of a droplet discharge head of the present invention will be described with reference to FIGS. 1 to 4. 1 is an exploded perspective view of the same head, FIG. 2 is a cross-sectional view of the same head along the longitudinal direction of the liquid chamber, FIG. 3 is a cross-sectional view of main parts of the same head along the lateral direction of the liquid chamber, and FIG. FIG. 3 is an explanatory diagram of a liquid chamber forming member of the same head.

In this ink jet head, a flow path plate 1 which is a liquid chamber forming member formed of a single crystal silicon substrate, a vibration plate 2 bonded to the lower surface of the flow path plate 1, and a top surface of the flow path plate 1 are bonded. And a nozzle plate 3 for ejecting ink droplets, and a pressurizing liquid chamber 6 in which the nozzle 4 communicates via a nozzle communication passage 5, and an ink supply passage 7 serving as a fluid resistance portion in the pressurizing liquid chamber 6. A pressurized liquid chamber 6, an ink supply passage 7, a common liquid that forms a liquid flow path such as a common liquid chamber 8 through which ink is supplied and serves as a surface (wall surface of the liquid flow path) of the flow path plate 1 in contact with the ink. Room 8
A liquid-resistant thin film 10 made of an organic resin film such as an oxide film, a titanium nitride film, or a polyimide film is formed on each wall surface.

Then, a laminated piezoelectric element 12 is bonded to the outer surface side (the surface opposite to the liquid chamber 6) of the vibrating plate 2 so as to correspond to each pressurizing liquid chamber 6, and the laminated piezoelectric element 12 is formed on the base substrate 13. A spacer member 14 (not shown in FIG. 1) is bonded to the base substrate 13 around the row of the piezoelectric elements 12.

The piezoelectric element 12 has a thickness of 10 to 5, for example.
A piezoelectric layer 15 made of zirconate titanate (PZT) of 0 μn / layer and an internal electrode 16 made of silver palladium (AgPd) having a thickness of several μm / layer are alternately laminated. The electromechanical conversion element is not limited to PZT. Then, the internal electrodes 16 of the piezoelectric element are alternately taken out to the end faces to serve as end face electrodes, and the base substrate 1
3 is electrically connected to the common electrode pattern and the individual electrode pattern formed on 3, and is connected to the PCB substrate through the FPC cable connected to the common electrode pattern and the common electrode pattern to apply a driving waveform, thereby applying a driving waveform. It is designed to generate elongation displacement.

Although the ink in the pressurized liquid chamber 6 is pressurized by using the displacement of the piezoelectric element 12 in the d33 direction, the pressurized liquid chamber 6 is used by using the displacement of the piezoelectric element 12 in the d31 direction. Alternatively, the internal ink may be pressurized. Although not shown, through holes for forming ink supply ports for supplying ink to the common liquid chamber 8 from the outside are formed in the base substrate 13, the spacer member, and the diaphragm 2.

Here, the flow path plate 1 has a crystal plane orientation (11
0) single crystal silicon substrate to a potassium hydroxide aqueous solution (K
By performing anisotropic etching using an alkaline etching solution such as OH), a concave portion that becomes each pressurizing liquid chamber 6, a groove portion that becomes the ink supply path 7, and a concave portion that becomes the common liquid chamber 8 are formed, respectively, and dry etching is performed. And the nozzle communication path 5 is formed by anisotropic etching.

The diaphragm 2 is formed of a nickel metal plate and is manufactured by the electroforming method. The vibrating plate 2 has a thin portion 21 for facilitating deformation and a thick portion 22 for joining with the piezoelectric element 12 at a portion corresponding to the pressurized liquid chamber 6, and the liquid chamber spacing wall 2
The thick portion 23 is also formed in the portion corresponding to 0, and the flat surface side is adhesively bonded to the flow path plate 1. A column 24 is provided between the thick portion 23 of the diaphragm 2 corresponding to the liquid chamber spacing wall 20 and the base substrate 13. The pillar portion 24 has the same structure as the piezoelectric element 12.

The nozzle plate 3 is provided with nozzles 4 having a diameter of 10 to 30 μm corresponding to the respective pressurized liquid chambers 6 and bonded to the flow path plate 1 with an adhesive. The nozzles 4 are formed in two rows and are arranged in a staggered manner (FIG. 2 shows the same cross section for the sake of explanation). The nozzle plate 3 may be made of a metal such as stainless steel or nickel, a combination of metal and a resin such as a polyimide resin film, silicon, or a combination thereof. Further, on the nozzle surface (surface in the ejection direction: ejection surface), a water repellent film is formed by a known method such as a plating film or a water repellent agent coating in order to ensure water repellency with respect to the ink.

In the ink jet head constructed as described above, 20 to 50 is selectively applied to the piezoelectric element 12.
By applying the drive pulse voltage of V, the piezoelectric element 12 to which the pulse voltage is applied is laminated in the stacking direction (in the case of FIG. 3).
Is displaced to deform the vibrating plate 2 in the direction of the nozzle 5, and the ink in the pressurized liquid chamber 6 is pressurized by the volume / volume change of the pressurized liquid chamber 6, and ink droplets are ejected (jetted) from the nozzle 4. It

Then, the liquid pressure in the pressurized liquid chamber 6 decreases as the ink droplets are discharged, and a slight negative pressure is generated in the pressurized liquid chamber 6 due to the inertia of the ink flow at this time. In this state, by turning off the voltage application to the piezoelectric element 12, the diaphragm 2 returns to its original position and the pressurized liquid chamber 6 returns to its original shape, so that a negative pressure is further generated. To do. At this time, ink is filled in the pressurized liquid chamber 6 from the ink supply port through the common liquid chamber 8 and the ink supply path 7 which is a fluid resistance portion. Therefore, after the vibration of the ink meniscus surface of the nozzle 4 is attenuated and stabilized, a pulse voltage is applied to the piezoelectric element 12 to eject the ink droplet in order to eject the next ink droplet.

Here, referring to FIG. 4, the flow path plate 1 which is the liquid chamber forming member of the ink jet head, the wall surface 1a of the concave portion which forms the pressurized liquid chamber 6 facing the vibrating plate 3 and the nozzle communication path. The wall surface 1b of No. 5 is formed to have a surface roughness Ra of 2 μm or less. Although the pressurized liquid chamber 6 is not formed only by the flow path plate 1, for convenience of description, the concave portion that forms the pressurized liquid chamber 6 of the flow path plate 1 is referred to as “the addition of the flow path plate 1”. Pressure chamber 6 ".

This point will be described with reference to FIGS. Here, FIG. 5 is a plan view of the nozzle plate joint surface of the flow channel plate 1 according to the embodiment of the present invention and an enlarged plan explanatory view of the nozzle communication passage, and FIG. 6 is a plan view of the vibration plate joint surface of the flow channel plate 1. And FIG. 7 is an enlarged plan view of the pressurized liquid chamber, FIG.
It is an expanded sectional explanatory view which follows a line.

FIG. 8 is a plan view of a nozzle plate joint surface of a flow channel plate 1'according to a comparative example and an enlarged plan explanatory view of a nozzle communication path. FIG. 9 is a vibration plate joint surface of the flow channel plate 1 '. A plan view and an enlarged plan explanatory view of the pressurized liquid chamber, and FIG. 10 is an enlarged sectional explanatory view taken along the line BB of FIG. 9.

In this case, an adhesive escape concave portion (thinning portion) 31 is formed on the nozzle plate joint surface of the flow path plates 1 and 1 '.
Recessed portion (removed portion) 32 for releasing the adhesive on the diaphragm bonding surface
Are formed respectively.

As can be seen from these figures, the surface roughness of the wall surface 1a of the flow path plate 1 according to the embodiment of the present invention which faces the vibrating plate of the pressurized liquid chamber 6 is Ra which does not exceed 2 μm. Is forming. This is obtained by taking measures to prevent hydrogen generated during etching of silicon for forming the flow path plate 1 from adhering to the wall surface. This can be performed, for example, by rocking the silicon substrate during etching or by applying ultrasonic waves.

On the other hand, the surface roughness Ra of the wall surface 1a 'of the flow passage plate 1'according to the vibrating plate of the pressurized liquid chamber 6'according to the comparative example exceeds 2 .mu.m. This is because hydrogen (air bubbles) generated at the time of etching silicon for forming the flow path plate 1 ′ adheres to the wall surface to roughen the wall surface 1a ′, and the surface roughness Ra cannot be set to 2 μm or less. .

As described above, since the surface roughness of the wall surface 1a of the flow path plate 1 facing the vibrating plate does not exceed 2 μm in Ra, the flow of ink in the pressurized liquid chamber 6 becomes smooth, and As shown in FIG. 7, it is possible to prevent the bubbles Ba from being caught by the fine irregularities of the wall surface 1a and staying therein, to prevent defective ejection, and to perform stable droplet ejection.

On the other hand, when the surface roughness of the wall surface 1a 'facing the vibrating plate exceeds Ra of 2 μm like the flow path plate 1', the flow of the ink flowing through the pressurized liquid chamber 6'is smooth. In addition, as shown in FIG. 10, the bubbles Ba easily catch on the irregularities of the wall surface 1a ′ and easily stay, so that ejection failure occurs and stable droplet ejection cannot be performed.

The flow channel plate 1 according to the first embodiment
Is such that the surface roughness of each wall surface forming the nozzle communication passage 5, the pressurized liquid chamber 6, the fluid resistance portion 7 and the common liquid chamber 8 does not exceed 2 μm in Ra. It is preferable that the surface roughness Ra of the wall surface 1a of No. 6 or the wall surface 1b of the nozzle communication passage 5 does not exceed 2 μm in Ra.

Next, the ink jet head according to the second embodiment will be described with reference to FIG. It should be noted that this figure is a cross-sectional explanatory view showing a flow path plate which is a liquid chamber forming member of the same head. In this head, a nozzle surface side flow path 42 and a diaphragm side flow path 43 are formed in the flow path plate 41 as liquid flow paths for ink to flow into the nozzles 4 of the nozzle plate 3. That is, the flow path plate 1 of the head of the first embodiment is a single-sided flow path system having only the diaphragm-side flow path, whereas the flow path plate 41 of the head of the second embodiment is a double-sided flow path method. .

When this flow path plate 41 is used, the vibration plate side flow path 43 serves as a pressurized liquid chamber (pressurized flow path) in which the piezoelectric element or the like pressurizes the ink by the pressure generating means. The nozzle surface side flow passage 42 and the vibration plate side flow passage 43 communicate with the communication passages 44, 4
5 are in communication with each other.

As described above, since the nozzle 4 of the nozzle plate 3 has the nozzle surface side flow channel 42 and the vibration plate side flow channel 43, pressure is applied in the vibration plate side flow channel 43 which is a pressure flow channel. Since the ink reaches the nozzle 4 via the communication passage 44 and the nozzle surface side flow passage 42 and reaches the nozzle 4 via the communication passage 45, sufficient refilling of the ink can be ensured even when driven at a high frequency. it can.

Next, as a first embodiment of the method of manufacturing a droplet discharge head of the present invention, a process of manufacturing the flow path plate 1 of the head of the first embodiment will be described with reference to FIGS. 12 and 13. To do. First, as shown in FIG. 12A, a silicon substrate (using a silicon wafer) 61 having a thickness of 400 μm and a plane orientation (110) is prepared, and silicon having a thickness of 1.0 μm is formed on both surfaces of the silicon substrate 61. An oxide film 62 and a nitride film 63 having a thickness of 0.2 μm were formed. The nitride film 63 was formed by LP-CVD.

Next, as shown in FIG. 3B, when the nozzle plate 3 is joined to the opening for forming the nozzle communication passage 5 on the surface of the nitride film 63 on the nozzle plate joining surface side of the silicon substrate 61. A resist pattern 64 having an opening for forming a thinned portion 31 for allowing an excess adhesive to flow is formed, and then dry etching is performed to form an opening 65 and a nozzle for forming the nozzle communication path 5 in the nitride film 63. The opening 66 for forming the lightening portion 31 into which the surplus adhesive is caused to flow at the time of joining with the plate 3 is patterned. At this time, the opening 65 of the nozzle communication path forming pattern has a shape formed by six sides that are in contact with each other at an obtuse angle. Although the resist is solidly formed on the side not to be etched, the illustration is omitted.

Next, as shown in FIG. 7C, the nitride film 6 is formed.
The opening 66 of No. 3 is buried, and a resist pattern 67 having an opening corresponding to the opening 65 of the nitride film 63 and corresponding to the shape of the nozzle communication path 5 is formed.
Is used as a mask to perform dry etching to pattern an opening 68 corresponding to the shape of the nozzle communication path 5 in the silicon oxide film 62.

Thereafter, as shown in FIG. 3D, when the diaphragm 2 is bonded to the diaphragm 2 on the surface of the silicon substrate 61 on the diaphragm bonding surface side, the opening for forming the pressurized liquid chamber 6 is bonded. A resist pattern 69 having an opening for forming the thinned-out portion 32 for allowing the excess adhesive to flow, and then dry etching is performed on the nitride film 63 to pressurize the liquid chamber 6.
The openings 70 for forming the holes and the openings 71 for forming the thinned portions 32 into which the surplus adhesive at the time of joining the diaphragm 2 are patterned.

Then, as shown in FIG. 7E, a resist pattern 72 having an opening 71 formed in the nitride film 63 and having an opening corresponding to the opening 70 of the nitride film 63 and corresponding to the shape of the nozzle communication path 5 is formed. Form this resist pattern 7
2 is used as a mask to perform dry etching, and an opening 73 corresponding to the shape of the nozzle communication path 5 is formed in the silicon oxide film 62.
Pattern.

Next, as shown in FIG. 13A, the ICP
Using a dry etcher, the silicon substrate 61 was patterned from the diaphragm bonding surface side to form the dug 74 to be the nozzle communication path 5. At this time, the film thickness of the resist 72 is 8
μm. The digging 74 by dry etching using an ICP etcher was performed to a depth of 300 μm.

After that, as shown in FIG. 7B, the resist 72 is removed, and anisotropic etching of silicon is performed by using an aqueous solution of potassium hydroxide to penetrate the silicon substrate 61 to form the nozzle communication passage 5. The hole 75 was formed. In the step (penetration step) of forming the through hole 75 that becomes the nozzle communication path 5 of the silicon substrate 61 with this potassium hydroxide aqueous solution, etching was performed from both the nozzle plate joint surface side and the diaphragm plate joint surface side. Immediately after the penetration of the through hole 75, an inclined portion is generated by anisotropic etching, but in the present embodiment, the inclined portion is set back in the penetrating step to etch the entire inclined portion.

Then, as shown in FIG. 7C, the oxide film 62 is wet-etched with dilute hydrofluoric acid using the nitride film 63 as a mask, and the silicon oxide film 62 is pressurized in the pressurized liquid chamber 6.
The openings 76 for forming the holes and the openings 77, 78 for forming the thinned portions 31, 32 are patterned.

Then, as shown in FIG. 6D, the silicon substrate 61 is anisotropically etched again with an aqueous solution of potassium hydroxide, and the pressurized liquid chamber 6 is placed in the silicon substrate 61.
The concave portion 80 that becomes the lightening portion 31 and 32
1, 82 were formed.

Here, the anisotropic etching of silicon at the time of forming the pressurized liquid chamber portion was performed at a treatment temperature of 85 ° C. using a potassium hydroxide aqueous solution having a solution concentration of 30%. Further, the silicon substrate 61 (silicon wafer) was mechanically rocked. Due to the swinging of the silicon substrate 61 during this etching, hydrogen generated by etching is prevented from adhering to the wall surface, and the surface roughness of the bottom surface (wall surface facing the vibrating plate) of the recess 80 that becomes the pressurized liquid chamber 6 is prevented. Ra is 2 μm
It can be kept below.

Then, as shown in FIG. 7E, the nitride film 63 and the silicon oxide film 62 are removed, and thereafter, although not shown, a silicon oxide film having a thickness of 1 μm is used as an ink-resistant liquid contact film (liquid resistant thin film) 10. To obtain an ink jet flow path plate 1.

Since the surface roughness of the surface of the pressurized liquid chamber 6 facing the vibrating plate is controlled to be Ra of 2 μm or less in this way, the ink flow is smooth and there is no bubble retention. It was possible to obtain a reliable inkjet.

Now, anisotropic etching of silicon will be described with reference to FIG. This figure shows the relationship between the concentration of potassium hydroxide and the temperature and surface property during anisotropic etching of silicon.

The surface roughness can be reduced by increasing the concentration of the aqueous potassium hydroxide solution. However, if the concentration is too high, Si (1
It is known that a protrusion surrounded by the 11) plane is generated. In the figure, the area A is an area where no micropyramid occurs. Further, in the area C, the surface roughness of the etching surface is R.
It is a region where a is 2 μm or less. In area B, micropyramids do not occur, and the surface roughness of the etched surface is R.
It is a region where a is 2 μm or less. Therefore, as the anisotropic etching conditions for silicon, it is preferable to prevent bubbles from adhering and to perform the processing under the conditions corresponding to the region B.

When the anisotropic etching of silicon is performed with an aqueous solution of potassium hydroxide, the etching rate of silicon reaches its maximum value when the concentration of the aqueous solution of potassium hydroxide is 20 to 25%. In order to bring the state of the silicon etching surface to the region B at this concentration, the treatment temperature is preferably 80 ° C. or higher. By suppressing the processing conditions (concentration, temperature) at the time of etching and the progress of etching due to the adhesion of air bubbles, a more reliable inkjet head can be formed.

Next, as a second embodiment of the method of manufacturing a droplet discharge head of the present invention, a process of manufacturing the flow path plate 41 of the head of the second embodiment will be described with reference to FIGS. 15 and 16. To do. First, as shown in FIG.
A silicon substrate (using a silicon wafer) 91 having a thickness of 400 μm and a plane orientation (110) is prepared, and a silicon oxide film 92 having a thickness of 1.0 μm is formed on both surfaces of the silicon substrate 91.
And a nitride film 93 having a thickness of 0.2 μm was formed. The nitride film 93 was formed by LP-CVD.

Next, as shown in FIG. 9B, the nozzle plate 3 is bonded to the opening for forming the nozzle surface side flow path 42 on the surface of the nitride film 93 on the nozzle plate bonding surface side of the silicon substrate 91. A resist pattern 94 having an opening for forming the lightening portion 31 into which the excess adhesive at the time is to be formed, and then dry etching is performed to form the nozzle surface side channel 42 in the nitride film 93. The lightening portion 3 into which the surplus adhesive flows when the opening 95 and the nozzle plate 3 are joined.
1 and the opening 96 for forming 1 are patterned. At this time, the opening 95 of the nozzle surface side flow path pattern has a shape formed by four sides that are in contact with each other at an obtuse angle. Although the resist is solidly formed on the side not to be etched, the illustration is omitted.

Next, as shown in FIG. 7C, the nitride film 9 is formed.
The opening 96 of No. 3 is filled in to form a resist pattern 97 having openings corresponding to the shapes of the communication passages 44 and 45 that connect the nozzle surface side flow passage 42 and the diaphragm side flow passage 43. The resist pattern 97 is used as a mask. As a result, dry etching is performed to pattern openings 98, 98 in the silicon oxide film 92 corresponding to the shapes of the communication paths 44, 45.

Thereafter, as shown in FIG. 6D, the opening for forming the diaphragm side flow channel 43 and the diaphragm 2 are bonded to the surface of the nitride film 93 on the diaphragm bonding surface side of the silicon substrate 91. Forming a resist pattern 99 having an opening for forming the thinned portion 32 for allowing the excess adhesive at the time to flow in,
After that, dry etching is performed to form the opening 100 for forming the diaphragm-side channel 43 in the nitride film 93 and the opening 101 for forming the thinned-out portion 32 into which the surplus adhesive at the time of joining the diaphragm 2 flows. And pattern.

Then, as shown in FIG. 7E, the opening 101 of the nitride film 93 is embedded to correspond to the shapes of the communication passages 44 and 45 which connect the nozzle surface side flow passage 42 and the diaphragm side flow passage 43. A resist pattern 102 having an opening is formed, and dry etching is performed using the resist pattern 102 as a mask to connect the silicon oxide film 92 to the communication path 4.
The openings 103, 103 corresponding to the shapes of 4, 45 are patterned.

Next, as shown in FIG. 16A, the ICP
Using a dry etcher, the silicon substrate 91 is dug 104 which forms the communication passages 44 and 45 from the diaphragm bonding surface side.
Was patterned. At this time, the film thickness of the resist 102 was 8 μm.

After that, as shown in FIG. 6B, the resist 102 is removed, and anisotropic etching of silicon is performed with an aqueous solution of potassium hydroxide to penetrate the silicon substrate 91 to form the nozzle surface side channel 42. Through holes 105, 105 are formed to form communication passages 44, 45 communicating with the diaphragm side flow passage 43.

Then, as shown in FIG. 6C, the oxide film 92 is wet-etched with dilute hydrofluoric acid using the nitride film 93 as a mask, and the silicon oxide film 62 is subjected to the nozzle surface side flow passage 42 and the diaphragm side flow. Aperture 10 for forming the passage 43
6 and 107 and openings 108 and 109 for forming the thinned portions 31 and 32 are patterned.

Then, as shown in FIG. 6D, the silicon substrate 91 is anisotropically etched again with an aqueous solution of potassium hydroxide to form recesses 110 and the recesses 110 to be the nozzle surface side flow passages 42 in the silicon substrate 91. Recessed portion 111 that becomes diaphragm side flow path 43 and recessed portion 10 that becomes thinned portions 31 and 32
2, 103 was formed.

Here, the anisotropic etching of silicon is performed as follows.
The treatment was carried out at a treatment temperature of 85 ° C. using a potassium hydroxide aqueous solution having a solution concentration of 30%. Further, the silicon substrate 91 (silicon wafer) was mechanically rocked. The swing of the silicon substrate 91 during the etching prevents hydrogen generated by the etching from adhering to the wall surface, and the surface roughness of the bottom surface (wall surface facing the vibrating plate) of the recess 111 serving as the pressurized liquid chamber. Of Ra is suppressed to 2 μm or less.

Then, as shown in (e) of the figure, the nitride film 93 and the silicon oxide film 92 are removed, and thereafter, although not shown, a silicon oxide film having a thickness of 1 μm is used as an ink-resistant liquid-contact film (liquid-resistant thin film) 10. To obtain an ink jet flow channel plate 41.

As described above, since the surface roughness of the surface of the vibrating plate side flow path 43, which is the pressurized liquid chamber, facing the vibrating plate is controlled to be 2 μm or less in Ra, the ink flow is smooth. It was possible to obtain a highly reliable ink jet in which no bubbles remained. The flow channel plate 41 also has a nozzle surface side flow channel 42 that supplies ink to the nozzles on the nozzle surface side.
Was formed, it was possible to secure sufficient refilling of ink during high frequency driving, and high-speed printing was possible.

FIG. 17 shows the result of jetting evaluation made by manufacturing the ink jet head according to the first embodiment. In this jet evaluation, the head according to the embodiment of the present invention having a liquid chamber forming member whose surface roughness Ra of the liquid chamber surface (the surface facing the vibrating plate) is 2 μm as Ra and a potassium hydroxide aqueous solution. Surface roughness (Ra) of 3μm, 4μ by changing the concentration, temperature and bubble adhesion prevention conditions.
m and a head according to a comparative example having a liquid chamber forming member changed to 5 μm as a component.

As a result, as shown in the figure, the surface roughness of the upper surface of the pressurized liquid chamber (wall surface facing the vibrating plate) was 2 μm in Ra.
It has been confirmed that in a head using a liquid chamber forming member exceeding the range, an ejection down bit occurs, and the defect rate increases as the surface roughness (Ra) increases. On the other hand, it was confirmed that the jet down bit did not occur in the head according to the present invention in which the surface roughness (Ra) of the upper surface of the pressurized liquid chamber was 2 μm or less.

Next, an ink cartridge in which an ink jet head as a droplet discharge head according to the present invention is integrated with an ink tank will be described with reference to FIG.
The ink cartridge 200 is one in which the inkjet head 202 of any of the above-described embodiments having a nozzle hole 201 and the like and an ink tank 203 for supplying ink to the inkjet head 202 are integrated.

As described above, in the case of the head integrated with the ink tank, the reliability of the head immediately leads to the reliability of the entire ink cartridge. Therefore, as described above, the head and the ink tank which have a low defect rate and can perform stable droplet ejection. By integrating and, the yield of ink cartridges,
Improves reliability.

Next, an example of an ink jet recording apparatus equipped with an ink jet head (including an ink cartridge integrated head) according to the present invention will be described with reference to FIGS. 19 and 2.
This will be described with reference to 0. 19 is a perspective explanatory view of the recording apparatus, and FIG. 20 is a side view of a mechanical portion of the recording apparatus.

This ink jet recording apparatus has a carriage movable inside the recording apparatus main body 211 in the main scanning direction, a recording head including the ink jet head according to the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. Printing mechanism section 21
A sheet feeding cassette (or a sheet feeding tray) 214 capable of accommodating a plurality of sheets of paper 213 from the front side can be detachably attached to the lower part of the apparatus main body 211. The manual feed tray 215 for manually feeding the paper 213 can be opened and closed, the paper 213 fed from the paper feed cassette 214 or the manual feed tray 215 is taken in, and a desired image is recorded by the printing mechanism unit 212. After that, the output tray 2 mounted on the rear side
The paper is discharged to 16.

The printing mechanism section 212 slides the carriage 223 in the main scanning direction (the direction perpendicular to the paper surface in FIG. 20) by the main guide rod 221 and the sub guide rod 222 which are guide members which are horizontally mounted on the left and right side plates (not shown). The carriage 223 is freely held, and yellow (Y), cyan (C),
A head 224, which is an ink jet head that is a droplet ejection head according to the present invention that ejects ink droplets of each color of magenta (M) and black (Bk), is arranged in a direction that intersects a plurality of ink ejection ports with the main scanning direction. , The ink droplet ejection direction is downward. Also the carriage 223
Each ink cartridge 225 for supplying each color ink to the head 224 is replaceably mounted. The ink cartridge integrated head described above may be mounted.

The ink cartridge 225 has an air port communicating with the atmosphere above, a supply port supplying ink to the ink jet head below, and a porous body filled with ink inside. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of.

Although the heads 224 for the respective colors are used here as the recording heads, one head having nozzles for ejecting ink droplets for the respective colors may be used.

Here, the carriage 223 is slidably fitted to the main guide rod 221 on the rear side (downstream side in the sheet conveying direction) and slidably fitted to the sub guide rod 222 on the front side (upstream side in the sheet conveying direction). It is placed in. Then, in order to move and scan the carriage 223 in the main scanning direction, a timing belt 230 is stretched between a drive pulley 228 and a driven pulley 229 which are rotationally driven by the main scanning motor 227, and the timing belt 230 is mounted on the carriage 223. The carriage 223 is reciprocally driven by forward and reverse rotations of the main scanning motor 227.

On the other hand, in order to convey the paper 213 set in the paper feed cassette 214 to the lower side of the head 224, the paper feed roller 231 and the friction pad 232 for separating and feeding the paper 213 from the paper feed cassette 214, and the paper 21.
Guide member 233 for guiding the sheet 3 and the fed paper 21
A conveyance roller 234 that reverses and conveys 3 is provided, and a conveyance roller 235 that is pressed against the peripheral surface of the conveyance roller 234 and a leading end roller 236 that defines the delivery angle of the sheet 213 from the conveyance roller 234. Transport roller 2
The sub-scanning motor 237 is rotationally driven through a gear train.

A print receiving member 239, which is a paper guide member for guiding the paper 213 sent out from the transport roller 234 in the lower side of the recording head 224 in correspondence with the movement range of the carriage 223 in the main scanning direction, is provided. There is. A transport roller 241 and a spur 242, which are driven to rotate in order to send the paper 213 in the paper discharge direction, are provided on the downstream side of the print receiving member 239 in the paper transport direction, and the paper 213 is further discharged to the paper discharge tray 216. Roller 243 and spur 2
44, and guide members 245 and 246 that form a paper discharge path.
And are arranged.

At the time of recording, by driving the recording head 224 according to the image signal while moving the carriage 223, ink is ejected onto the stopped paper 213 to record one line, and the paper 213 is printed by a predetermined amount. After transportation, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 213 reaches the recording area, the recording operation is ended and the paper 213 is ejected. In this case, the head 22
Since the ink jet head according to the present invention that composes No. 4 has high droplet ejection efficiency, it is possible to stably record an image with high image quality.

A recovery device 247 for recovering the ejection failure of the head 224 is disposed at a position outside the recording area on the right end side of the carriage 223 in the moving direction. The recovery device 247 has a cap unit, a suction unit, and a cleaning unit. The carriage 223 is moved to the recovery device 247 side during printing standby, the head 224 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying.
Also, by ejecting ink that is not related to recording during recording, etc., the ink viscosity of all ejection ports is made constant,
Maintains stable discharge performance.

When ejection failure occurs, the ejection port (nozzle) of the head 224 is sealed with a capping means.
Bubbles and the like are sucked out together with the ink from the discharge port by the suction means through the tube, and the ink and dust adhering to the surface of the discharge port are removed by the cleaning means to recover the discharge failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed in the lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

As described above, in this ink jet recording apparatus, since the ink jet head embodying the present invention (including the head-integrated ink cartridge) is mounted, stable ink droplet ejection characteristics are obtained and the image quality is improved. improves.

In the above embodiment, the droplet discharge head according to the present invention is applied to an ink jet head. However, a droplet discharge head for discharging a droplet of liquid other than ink, for example, a liquid resist for patterning, a gene. It can also be applied to a droplet discharge head that discharges an analysis sample. Further, in each of the above-described embodiments, the head using the piezoelectric element has been described, but the thermal type or the electrostatic type head as described above can be similarly applied.

Further, since the liquid chamber forming member may be any member that forms a liquid flow path, for example, when the lid member of a head in which the lid member is joined to the flow path forming member is formed of silicon, It is included in the liquid chamber forming member referred to in the invention.

[0089]

As described above, according to the droplet discharge head of the present invention, the liquid chamber forming member is made of silicon, and the surface of the surface forming the wall surface of the liquid flow path of the liquid chamber forming member. Since the roughness is such that Ra does not exceed 2 μm, reliability is improved and stable droplet ejection can be performed.

According to the droplet discharge head of the present invention, the liquid chamber forming member is made of silicon, and the surface roughness of the wall surface of the liquid flow path facing the diaphragm of the liquid chamber forming member is Ra = 2.
Since the structure does not exceed μm, reliability is improved and stable droplet ejection can be performed.

In the droplet discharge head according to the present invention, the liquid chamber forming member is made of silicon, and the surface roughness of the wall surface of the nozzle communication passage of the liquid chamber forming member does not exceed 2 μm in Ra. The reliability is improved, and stable droplet ejection can be performed.

According to the method of manufacturing a droplet discharge head according to the present invention, the method of manufacturing a droplet discharge head according to the present invention, wherein a potassium hydroxide aqueous solution having a solution concentration of 25% or more is used and the treatment temperature is Since the liquid chamber forming member is formed by wet etching the silicon substrate at 80 ° C. or higher,
A liquid chamber forming member having a surface roughness Ra of 2 μm or less can be formed.

According to the method of manufacturing a droplet discharge head of the present invention, which is a method of manufacturing the droplet discharge head of the present invention, a silicon substrate is wet-etched to form a liquid chamber forming member. Since the forming step includes a step of preventing bubbles generated during etching from adhering to the etching surface, it is possible to form a liquid chamber forming member whose surface roughness Ra does not exceed 2 μm.

The ink jet recording apparatus according to the present invention is
Since the inkjet head is the droplet discharge head according to the present invention, the reliability is improved and a high quality image can be stably recorded.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating an inkjet head according to a first embodiment of a droplet discharge head of the invention.

FIG. 2 is an explanatory cross-sectional view of the same head taken along the longitudinal direction of the liquid chamber.

FIG. 3 is an explanatory cross-sectional view of a main part of the same head along the lateral direction of the liquid chamber.

FIG. 4 is an explanatory view of a liquid chamber forming member of the head.

FIG. 5 is an explanatory view of a nozzle plate joining surface of the flow path plate according to the embodiment of the present invention.

FIG. 6 is an explanatory view of a vibration plate bonding surface of the flow path plate.

7 is an enlarged cross-sectional explanatory view taken along the line AA of FIG.

FIG. 8 is an explanatory view of a nozzle plate joint surface of a flow path plate according to a comparative example.

FIG. 9 is an explanatory view of a vibration plate bonding surface of the flow channel plate.

10 is an enlarged cross-sectional explanatory view taken along the line BB of FIG.

FIG. 11 is an explanatory diagram of a flow path plate of an inkjet head according to a second embodiment of the droplet discharge head of the present invention.

FIG. 12 is an explanatory diagram for explaining the flow channel plate manufacturing process according to the first embodiment of the droplet discharge head manufacturing method of the present invention.

13 is an explanatory diagram illustrating a step following FIG.

FIG. 14 is an explanatory diagram for explaining the relationship between the concentration of potassium hydroxide and the temperature and surface property during anisotropic etching of silicon.

FIG. 15 is an explanatory diagram used for explaining a flow channel plate manufacturing process according to the second embodiment of the droplet discharge head manufacturing method of the present invention.

16 is an explanatory diagram illustrating a step following FIG.

FIG. 17 is an explanatory diagram for explaining the evaluation results of the liquid chamber surface roughness and the defect rate.

FIG. 18 is a perspective explanatory view of an ink cartridge integrated with a droplet discharge head according to the present invention.

FIG. 19 is a perspective explanatory view showing an example of an ink jet recording apparatus equipped with a droplet discharge head according to the present invention.

FIG. 20 is an explanatory side view of a mechanism section of the recording apparatus.

[Explanation of reference numerals] 1, 41 ... Flow path plate, 2 ... Vibration plate, 3 ... Nozzle plate, 4 ... Nozzle, 5 ... Nozzle communication passage, 6 ... Pressurized liquid chamber, 7 ... Fluid resistance part, 8 ... Common liquid Chamber, 10 ... Liquid resistant thin film, 12 ... Piezoelectric element, 13 ... Base substrate, 42 ... Nozzle surface side flow path, 43 ...
Diaphragm side flow path, 44, 45 ... Communication path, 214 ... Recording head.

Claims (9)

[Claims] 1. In a droplet discharge head provided with a liquid chamber forming member that forms a liquid flow passage communicating with a nozzle, the liquid chamber forming member is formed of silicon, and the liquid flow passage of the liquid chamber forming member is formed. The surface roughness of the surface forming the wall surface is Ra 2 μm
A droplet discharge head characterized in that it does not exceed. 2. A nozzle forming member forming a nozzle, and a liquid chamber forming member forming a liquid flow path communicating with the nozzle.
In a droplet discharge head provided with a vibrating plate forming a wall surface of the liquid channel, the liquid chamber forming member is formed of silicon, and the wall surface of the liquid channel facing the vibrating plate of the liquid chamber forming member. And a surface roughness Ra of 2 μm or less. 3. A nozzle forming member that forms a nozzle, a liquid flow path that connects the nozzle, and a liquid chamber forming member that forms a nozzle communication path that connects the liquid flow path and the nozzle. In a droplet discharge head including a vibrating plate forming a wall surface of the liquid flow path, the liquid chamber forming member is formed of silicon, and a surface roughness of a wall surface of the nozzle communication passage of the liquid chamber forming member is Ra. The liquid droplet ejection head is characterized in that it does not exceed 2 μm. 4. The droplet discharge head according to claim 1, wherein an oxide film or a titanium nitride film is formed on a wall surface of the liquid flow path. . 5. A method for manufacturing the droplet discharge head according to claim 1, wherein the solution concentration is 25%.
Using the above potassium hydroxide aqueous solution, the treatment temperature is 80 ° C.
A method for manufacturing a droplet discharge head, characterized in that the liquid chamber forming member is formed by wet etching the silicon substrate as described above. 6. The method of manufacturing a droplet discharge head according to claim 1, wherein the liquid chamber forming member is formed by wet etching a silicon substrate, and etching is performed in this forming step. A method of manufacturing a droplet discharge head, comprising a step of preventing bubbles generated at times from adhering to an etching surface. 7. The method of manufacturing a droplet discharge head according to claim 5, wherein the silicon substrate is swung when the wet etching is performed. 8. The method for manufacturing a droplet discharge head according to claim 5, wherein ultrasonic waves are applied to the silicon substrate when the wet etching is performed. 9. An ink jet recording apparatus comprising an ink jet head for ejecting ink droplets, wherein the ink jet head is the droplet ejecting head according to any one of claims 1 to 4.