Patent ID: 12246537

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the nozzle plate, the inkjet head including the nozzle plate, the nozzle plate manufacturing method, and the inkjet head manufacturing method will be described based on the drawings.

FIG.1Ais an overall view of the inkjet head1according to the embodiment, andFIG.1Bis a cross-sectional view of the inkjet head1ofFIG.1Aviewed from the side (−X direction side) along the IB-IB line.FIG.1Bshows a cross-section of the inkjet head1in the surface containing the four nozzles14included in four nozzle rows.

The inkjet head1includes a head chip2, a common ink chamber70, a support substrate80, a wiring member3, a drive section4, and the like.

The head chip2is configured to eject ink from the nozzles14, and is made up of multiple (in this case, four) board-like substrates that are stacked and formed. The lowest substrate in the head chip2is the nozzle plate10. The nozzle plate10has multiple nozzles14, and ink can be ejected nearly perpendicularly to the ink ejection surface (the exposed surface of the nozzle plate10) where the openings of the nozzles14are provided. On the opposite side of the nozzle plate10from the ink ejection surface, the pressure chamber substrate20(chamber plate), spacer substrate40, and wiring substrate50are bonded and stacked by adhesive or the like in order toward the upper direction (+Z direction). In the following, the nozzle plate10, pressure chamber substrate20, spacer substrate40, and wiring substrate50are also individually or collectively referred to as channel substrates10,20,40,50, and the like.

These channel substrates10,20,40, and50are provided with ink channels that are connected to the nozzles14, and are open on the surface on the exposed side (+Z direction side) of the wiring substrate50. On the exposed surface of the wiring substrate50, a common ink chamber70is provided to cover all openings. The common ink chamber70has, at the upper section, an ink supply portion70athat supplies ink to the ink chamber forming member70cand an ink discharge portion70bthat discharges ink from the ink chamber forming member70c. The ink stored in the ink chamber forming member70cof the common ink chamber70is supplied to each nozzle14from the opening of the wiring substrate50.

In the middle of the ink channel, a pressure chamber21is provided. The pressure chamber21is provided through the pressure chamber substrate20in the vertical direction (Z direction), and the top surface of the pressure chamber21is composed of a diaphragm30provided between the pressure chamber substrate20and the spacer substrate40. The pressure change is imparted to the ink in the pressure chamber21by the deformation of the diaphragm30(pressure chamber21) due to the displacement (deformation) of the piezoelectric element60in the storage section41which is provided adjacent to the pressure chamber21via the diaphragm30. By an appropriate pressure change being applied to the ink in the pressure chamber21, the ink in the ink channel is ejected as a droplet from the nozzle14that is connected to the pressure chamber21.

The support substrate80is bonded to the top surface of the head chip2and holds the ink chamber forming member70cof the common ink chamber70. The support substrate80is provided with the opening of approximately the same size and shape as the opening on the bottom surface of the ink chamber forming member70c. The ink in the common ink chamber70is supplied to the top surface of the head chip2through the opening in the bottom surface of the ink chamber forming member70cand the opening in the support substrate80.

The wiring member3is, for example, an FPC (Flexible Printed Circuits), or the like, and is connected to the wiring of the wiring substrate50. The piezoelectric element60is displaced by the drive signal transmitted to the wiring51and the connection52(conductive member) in the storage section41via this wiring. The wiring member3is drawn through the support substrate80and connected to the drive section4.

The drive section4receives control signals from the control section of the inkjet recording device and power supply from the power supply section. The drive section4outputs appropriate drive signals of the piezoelectric element60to the wiring member3according to the ink ejection or non-ejection operation from each nozzle14. The drive section4is composed of an IC (Integrated Circuit) or the like.

FIG.2is a cross-sectional view showing the configuration of the nozzle plate10.FIG.2shows an enlarged cross-sectional view of the nozzle plate10.

The nozzle plate10consists of a substrate11cut from a base material and provided with nozzles14, a protective film12provided on the plate surface of the substrate11and the inner wall surfaces of the nozzles14, a water repellent film13formed on the underside of substrate11to be overlaid on the protective film12, a step151that is a cut provided at the edge, and glue guards16provided on both sides of each nozzle14.

In the following, the upper side surface of the substrate11is referred to as the first surface11a, the lower side surface of the substrate11is referred to as the second surface11b.

The substrate11is a plate-shaped member cut from a base material such as SUS (Steel Use Stainless, stainless steel) with a thickness of approximately 25 μm to 300 μm. By using SUS as the base material, the nozzle plate10can be formed with excellent chemical stability against ink and mechanical friction durability. As described below, when a silicon substrate is used as the substrate11, a thermal oxide film may be formed on the outer layer of the substrate11.

The nozzle14is a cylindrical hole with a circular opening on the second surface11bof the substrate11. The diameter of opening of the nozzle14can be approximately 15 μm to 30 μm.

For the protective film12, a material that does not dissolve upon contact with the ink, such as silicon carbide (SiC), silicon oxi carbide (SiOC), and silicon oxide (SiO2), as well as metal oxide films such as aluminum oxide (Al2O3), zirconium oxide (ZrO2), titanium oxide (TiO2), hafnium oxide (HfO2) and tantalum oxide (Ta2O3), and metal silicate films containing silicon in metal oxide films (tantalum silicate (TaSiO), etc.) can be used.

The thickness of the protective film12is not limited, but is desirably, for example, 50 nm to 500 nm.

The protective film12made of such ink-resistant material inhibits the substrate11from being eroded by ink (especially, alkaline or acidic ink). The protective film12may also be used as a base film for the water repellent film13described below. Since the ink-resistant protective film12is not easily peeled off when it comes into contact with ink, by using the protective film12as the base film, it is possible to suppress the peeling of the water repellent film13together with the protective film12as the base film.

The water repellent film13is formed on top of the protective film12, and its surface forms the ink ejection surface. The water repellent film13is a layer provided to have water repellency against ink and to inhibit adhering of ink and foreign matter. As the water repellent film13, the water repellent film13is formed by vapor deposition of a silane coupling agent having perfluoroxyl groups, using the protective film12made of the aforementioned material as the base film.

The water repellent film13has openings through the water repellent film13at the positions where the nozzles14are formed, and ink ejected from the nozzles14is ejected through the openings.

The step151is a cut provided along the periphery of the first surface11a, and dross152generated by laser processing, which will be described later, is attached to the edge. The step151is a space that prevents the dross152from interfering with the bonding of the nozzle plate10and the channel substrate20, the dross152being generated when external shaping is performed to the recess15of the nozzle plate10.152. The step151is also a space to contain the adhesive that protrudes from the edge surface of the nozzle plate10during the bonding of the nozzle plate10and the channel substrate20.

The depth of the step151is not limited, but is preferably 5 μm to 10 μm.

The glue guard16is a recessed groove section provided so that it is nearly parallel to the row of nozzles14. By providing the glue guard16, when the nozzle plate10is bonded to the pressure chamber substrate20, which is the upper layer substrate, with adhesive, there is less risk of excess adhesive getting into the nozzle14.

InFIG.2, one glue guard16is provided on each side of the nozzle14, but the position and number of glue guards are not limited to this.

Next, the manufacturing method of the inkjet head1of the embodiment is described, focusing on the manufacturing method of the nozzle plate10.

FIG.3is a flowchart showing the procedure of the process for manufacturing the nozzle plate10(nozzle plate manufacturing process).FIGS.4A to4Dare top views and cross-sectional views along the A-B line illustrating the nozzle plate manufacturing process.

As shown inFIG.4AtoFIG.4D, according to the nozzle plate manufacturing process for the embodiment, multiple nozzle plates10can be manufactured simultaneously from a single base material.

In the nozzle plate manufacturing process, first, as shown inFIG.4A, the portion of the first surface11aof the substrate11that is to be subjected to external shaping in step S106which is a later process is subjected to grooving (half etching) by a wet etching process to form the recess15(Step S101).

The wet etching process can be performed by forming a resist mask on the substrate11, excluding the grooving area, and immersing it in the etchant. It is sufficient that the resist mask is able to protect the substrate11against the etchant, and the resist mask can be made of inorganic material such as silicon, for example. As an etchant, for example, if the substrate11is a SUS base material, a neutral salt etchant, which is an aqueous solution containing ferric chloride (FeCl2), copper chloride (CuCl2) or the like is generally used. When the substrate11is a silicon substrate, a mixture of nitric acid (HNO3) and hydrofluoric acid (HF) is generally used. However, it is not limited to this, and any of the known etchants can be selected.

After the wet etching process, the resist mask is removed from the surface of the substrate11.

In the grooving process, the glue guard16which is the concave groove section parallel to the row of nozzles14to be formed is formed at the same time.

Next, as shown inFIG.4B, punching is performed on the substrate11to form the nozzles14(Step S102).

As the punching, the tool is used to press the substrate11. Specifically, one side of the nozzle forming portion of the tool and the first surface11aof the substrate11are made to face each other, and the nozzle forming portion is pressed against the first surface11a. As a result, nozzle recesses which are concave toward the second surface11bare formed on the first surface11a, and nozzle convex portions are formed on the second surface11b.

Next, the nozzle convex portions protruding from the second surface11bare polished and removed (Step S103). Then, the nozzles14are opened on the second surface11b.

As a result, the substrate11has nozzles14that penetrate from the first surface11ato the second surface11b.

Next, the protective film12is formed on the nozzle plate10, and the water repellent film13is formed on the second surface11b, which is the ink ejection surface side (Step S104).

First, the surface of the substrate11is cleaned to remove foreign matter adhering to the substrate11. The method of cleaning the substrate11can be, for example, US cleaning.

After cleaning the substrate11, an ion bombardment treatment is performed on the surface of the substrate11. Ion bombardment treatment is a treatment in which physical effects are exerted on the material to be treated by bombarding the material to be treated with ions in a reduced pressure environment.

This ion bombardment treatment removes impurities and thin oxide films from the surface of the substrate11to clean it and improve the adhesion property of the protective film12. In addition, oxidation of the surface of the substrate11is suppressed.

After ion bombardment treatment, the protective film12is formed on the surface of the substrate11by the plasma CVD method, and the substrate11having the protective film12is cleaned to remove foreign matter adhering to the protective film12. The method of cleaning the protective film12can be US cleaning as described above.

After cleaning the protective film12, as shown inFIG.4C, the water repellent film13is formed on the protective film12. The water repellent film13is formed by a dry process, such as vacuum evaporation, using a silane coupling agent having perfluoroxyl groups, for example. As the silane coupling agents, amino silane coupling agents such as γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane, and epoxysilane coupling agents such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, and γ-glycidoxypropyl methyl diethoxysilane are applicable.

The method of forming the water repellent film13is not limited to this. The water repellent film13may be formed on the basis of conventionally known components and methods, for example, by immersing the substrate11in a solution of a fluorine-containing organosilicon compound diluted with a fluorinated solvent and then thermally drying it.

Next, the water repellent film13formed on surfaces other than the second surface11bis removed (Step S105). Specifically, first, the second surface11bis masked with polyimide tape and the substrate11is installed in an ashing machine. Exposure to O2plasma is made for several tens of seconds to remove the water repellent film13formed on the surfaces other than the second surface11b. The polyimide tape is then removed and cleaned. By the method described above, the protective film12is formed on the entire surface of the substrate11, and the water repellent film13is formed only on the second surface11b.

Next, as shown inFIG.4D, external shaping is performed on the substrate11by laser processing (external shaping process, step S106).

In the external shaping process, the nozzle plate10is cut out from the base material by performing the laser processing with the laser equipment along the recess15of the substrate11on which the grooving was performed in step S101which is a previous process, and by cutting the recess15. For example, excimer laser light can be preferably used as the laser light generated by the laser equipment. This is because excimer laser light has a short wavelength and is capable of desirable microprocessing. The wavelength of excimer laser light ranges from 190 nm to 355 nm. Specifically, for example, ArF (wavelength of 193 nm), KrF (248 nm), XeCl (wavelength of 308 nm), XeF (wavelength of 351 nm), and the like are preferably cited. Conventional known laser beams such as YAG laser, CO2laser, and the like may be used as laser beams.

Since the laser processing in this process is performed by cutting the recess15of the nozzle plate10as described above, the step151as shown inFIG.2is formed at the edge of the nozzle plate10after the external shaping process.

In addition, when the external shaping is performed on the substrate11which is SUS by laser processing, in general, the dross152is formed near the processed portion. However, in the present invention, laser processing is performed along the recess15, and thus the dross152is formed at the edge of the step151as shown inFIG.2.

By the method described above, the nozzle plate10having the step151with the dross152formed on the edge of the substrate11is obtained. The head chip2is manufactured by stacking the nozzle plate10and the channel substrates20,40, and50, and is combined with the common ink chamber70, the support substrate80, the wiring member3, and the drive section4to be incorporated into a predetermined exterior member. Thereby, the inkjet head1is completed.

Next, the experiment conducted to confirm the height of the dross formed by the external shaping in the embodiment will be explained.

In this experiment, the height of the dross152formed when SUS is laser processed was evaluated.

Specifically, SUS304HTA material with a thickness of 50 μm was used as the base material, and a solid-state laser system using YVO4 crystals, MD-U1000C (manufactured by Keyence Corporation, wavelength: 355 nm, pulse width: 14 nsec, switch: 40 kHz, scan speed: 200 mm/sec) was used to perform laser processing by 20 scans at a time for each level of laser output (2.4 W/1.8 W/1.2 W/0.6 W) with or without assist gas. Next, 20 minutes of US cleaning was performed in pure water using 40 kHz ultrasonic waves. After the US cleaning, a laser microscope, VK-X250 (manufactured by Keyence Corporation) was used to measure the height of the dross152generated near the processed portion, and the average value was calculated.

Table I is a table showing the results of this experiment.

[Table 1]

TABLE ILEVEL12345678ASSISTNOTNOTNOTNOT USEUSEUSEUSEUSEGASUSEUSEUSEOUTPUT2.41.81.20.62.41.81.20.6(W)DROSS7.65.73.9—3.94.24.3—HEIGHT(PROCESSING(PROCESSING(μm)NOT POSSIBLE)NOT POSSIBLE)

As shown in levels 1 to 3 of Table 1, as the laser output is reduced, the height of the dross152can be reduced. However, as shown in levels 4 and 8, if the output is reduced to 0.6 W or lower, it is not preferable because it is no longer possible to perform the external shaping.

In addition, as shown in levels 5 to 7, the use of an assist gas can reduce the change in the height of the dross152due to changes in laser output, and the height can be stabilized at 5 μm or less.

As shown in Experiment 1, the height of dross152generated during laser processing is approximately 5 μm, especially 10 μm or less. Therefore, if the depth of the step151is approximately 5 μm, the dross152is less likely to cause bonding defects or void generation when bonding to the pressure chamber substrate20. If the depth of the step151is approximately 10 μm, the dross152can be prevented from becoming an obstacle to bonding after external shaping, regardless of the conditions at the time of laser processing.

As described above, the method for manufacturing the nozzle plate10according to the embodiment at least includes a grooving process that is forming multiple recesses15in a single substrate by grooving in the wet etching on the portion to be subjected to the external shaping, a nozzle forming process that is forming multiple nozzles14by punching and polishing, and an external shaping process that is performing external shaping of the multiple nozzle plates10along the recesses15by laser processing.

According to such a method, the dross152generated by the external shaping process is generated in the step151formed by the grooving process. Therefore, when the nozzle plate10is bonded to the pressure chamber substrate20, the occurrence of defects such as bonding defects and void generation can be suppressed.

In addition, in the method for manufacturing the nozzle plate10according to the embodiment, it is not necessary to remove the dross152generated at the edge of the nozzle plate10by polishing in order to suppress the occurrence of the aforementioned defects. Therefore, the nozzle plate10can be manufactured efficiently and the productivity is excellent.

In addition, in the method for manufacturing the nozzle plate10according to the embodiment, as shown inFIG.4, each process can be performed to produce multiple nozzle plates10from a single substrate11. Therefore, multiple nozzle plates10can be efficiently manufactured, and the productivity is excellent.

In addition, in the method for manufacturing the nozzle plate10according to the embodiment, since the external shaping is performed by laser processing, compared to the case where the external shaping is performed by wet etching, the process of forming and removing the resist mask becomes unnecessary, and resist residue inside the nozzle14is not generated. Therefore, the nozzle plate10can be manufactured efficiently and the productivity is excellent.

In addition, in the method for manufacturing the nozzle plate10according to the embodiment, even if the dross152is generated during the external shaping process, the occurrence of the aforementioned defects can be suppressed. Therefore, the nozzle plate10can be provided at a low cost without the need to use a short pulse laser device with a pulse width of picoseconds or femtosecond order.

In addition, the nozzle plate10manufactured by the manufacturing method according to the embodiment has the dross152at the step151. Therefore, in bonding with the pressure chamber substrate20, which is the upper layer substrate, with the adhesive, even if the amount of adhesive is large, it is possible to prevent the dross152from becoming a wall to make it protrude to the sides.

In addition, by using the nozzle plate10manufactured by the manufacturing method according to the embodiment, the inkjet head1can be manufactured inexpensively and efficiently, and the productivity is excellent.

The present invention is not limited to the embodiment, but can be modified in various ways.

For example, in the embodiment, the base material of the nozzle plate10is made of SUS, but the base material of the nozzle plate10is not limited to this. For example, other conventionally known materials such as a silicon substrate or electroformed metal such as Ni may be used.

In the embodiment, an example of forming the protective film12on the entire surface of the substrate11is used, but the range of forming the protective film12is not limited to this. The protective film12may be provided on at least a portion of the first surface11aand the inner wall surface of nozzle14in the surface of the substrate11(that is, any range which ink may come into contact with and requires the ink resistance).

Although the protective film12is a monolayer structure, the composition of the protective film12is not limited to this, and a multilayer structure is also acceptable. If the protective film12is unnecessary, the nozzle plate10does not need to be provided with the protective film12.

The inner wall surface of the nozzle14may be tapered so that the closer it is to the opening of the nozzle14, the smaller the cross-sectional area parallel to the first surface11ais.

The nozzle14in the nozzle plate10may include a connecting passageway having an opening wider than the nozzle14, an ink channel leading ink that is discharged without being ejected from the nozzle14, or the like. The shape of the nozzle14is not limited to the abbreviated conical shape as shown inFIG.2.

In cases where the inkjet head1does not need to have the water repellency in the ink ejection surface, the nozzle plate10does not necessarily need to be provided with the water repellent film13.

The embodiment illustrates, as an example, the inkjet head1in the vent mode that fluctuates the pressure of ink in the pressure chamber21by deforming the piezoelectric element60and causes ink to be ejected. However, this is not intended to be a limitation. For example, the present invention may be applied to the inkjet head in the shear mode, in which a pressure chamber is provided inside the piezoelectric body and the pressure of ink in the pressure chamber is fluctuated by generating the shear mode type displacement in the piezoelectric body on the wall of the pressure chamber. The present invention is not limited to the method of deforming the pressure chamber. For example, the present invention may also be applied to the inkjet head of the thermal method which ejects ink by generating bubbles in the ink by heating.

In the embodiment, in the grooving process, the recess15is formed by wet etching. However, the processing to form the recess15is not limited to this, and the recess15may be formed by laser processing. However, it is preferable to form the recess15by wet etching since laser processing may cause distortion and warping of the base material.

Although some embodiments of the present invention have been described, the scope of the present invention is not limited to the embodiments described above, but includes the scope of the invention as described in the claims and their equivalents.

INDUSTRIAL APPLICABILITY

The present invention is applicable to the nozzle plate to prevent bonding defects or voids during bonding.

EXPLANATION OF REFERENCE NUMERALS

1inkjet head10nozzle plate11afirst surface11bsecond surface13water repellent film14nozzle15recess20pressure chamber substrate (upper layer substrate)151step152dross