Inkjet head and method of manufacturing the same

Abstract

An ink jet head according to the present invention has first and second flow path substrates, wherein at least one among the first and second flow path substrates is formed of silicon, and a bonding interface of the first and second flow path substrates is bonded through an adhesive layer, and a protective film containing a compound having a Si-C bond is formed on: an ink flow path surface formed of silicon among the first and second flow path substrates; and the surface of the flow path substrate side formed of silicon in the adhesive layer.

Description

[Technical field]

[0001] The present invention relates to an inkjet head and a method for manufacturing an inkjet head, and in particular to an inkjet head having a flow path substrate made of silicon, which is capable of preventing elution of silicon at an ink flow path surface or at a bonding interface between bonded flow path substrates, and suppressing leakage of ink from the bonding interface to the outside of the flow path. [Background technology]

[0002] Silicon processing is applied to ensure the processing accuracy of the nozzles and flow paths of the inkjet head. In particular, for structures with circulation paths, a process is performed in which the nozzle substrate and the circulation path substrate are processed and bonded together, and this process is very important because the reliability of the bond is directly related to the durability of the inkjet head. In addition, silicon has low chemical resistance to ink, and silicon dissolves, especially in alkali, so a chemical-resistant protective film may be formed. Since the protective film is also formed at the bonding interface between the nozzle substrate and the flow path substrate, the protective film material is also an important factor for the reliability of the bonding strength.

[0003] For example, Patent Document 1 discloses a manufacturing method in which a SiO2 protective film is formed on each of a nozzle substrate and a flow path substrate and then the substrates are bonded together. Although SiO2 has higher chemical resistance to ink than silicon, it is insufficient for the reliability required in recent industrial applications, etc. In particular, if the SiO2 protective film near the bonding interface between the nozzle substrate and the flow path substrate dissolves into the ink, the bonding strength between the substrates decreases, causing ink to leak outside the flow path. In addition, in the above-mentioned Patent Document 1, the SiO2 protective film is formed by thermal oxidation and the substrate is directly bonded, but there is a concern that the adhesion of foreign matter during manufacturing may adversely affect the reliability of the bond. From the viewpoint of productivity, a bonding process that is highly robust against foreign matter is desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5361466 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above problems and circumstances, and an object of the present invention is to provide an inkjet head and a manufacturing method for an inkjet head, which can prevent elution of silicon from the ink flow path surface and the bonding interface between the bonded flow path substrates, and can suppress leakage of ink from the bonding interface to the outside of the flow path, for an inkjet head having a flow path substrate formed of silicon. [Means for solving the problem]

[0006] In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that by forming a protective film containing a compound having a Si-C bond on the ink flow path surface of each of the two flow path substrates, which is made of silicon, and on the surface of the adhesive layer formed at the bonding interface between the two substrates that is on the flow path substrate side, which is made of silicon, it is possible to prevent the elution of silicon and suppress the leakage of ink from the bonding interface to outside the flow path, which led to the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1 . An inkjet head including first and second flow path substrates, At least one of the first and second flow path substrates is made of silicon and includes a nozzle; the bonding interfaces of the first and second flow path substrates are bonded via an adhesive layer; a protective film containing a compound having a Si-C bond is formed on an ink flow path surface of the substrate including the nozzle, which is made of silicon, and on a surface of the adhesive layer facing the flow path substrate, which is made of silicon; the protective film is formed on a nozzle opening surface of a substrate including the nozzle, A liquid-repellent film containing a fluorine-based compound having a siloxane bond is formed on the protective film of the nozzle opening surface. Rui Ink jet head.

[0009] 2 The first and second flow path substrates are both made of silicon. In the section The inkjet head described herein.

[0011] 3 The protective film has a maximum peak in the energy band (99.9 to 100.9 eV) derived from the Si-C bond detected by X-ray photoelectron spectroscopy. or No. In item 2 The inkjet head described herein.

[0012] 4 The surface layer of the protective film formed at the bonding interface is oxidized, The adhesive layer contains a silane coupling agent. 3 Item 1. The ink-jet head according to any one of items 1 to 9.

[0013] 5 .Items 1 to 5 4 A method for manufacturing an inkjet head according to any one of claims 1 to 5, comprising the steps of: forming a protective film containing a compound having a Si-C bond on ink flow path surfaces of the first and second flow path substrates made of silicon and on a surface of the adhesive layer facing the flow path substrate made of silicon; A method for manufacturing an inkjet head, comprising: bonding the bonding interfaces of the first and second flow path substrates via the adhesive layer. Effect of the Invention

[0014] By the above-mentioned means of the present invention, it is possible to provide an inkjet head having a flow path substrate made of silicon, which can prevent elution of silicon at the ink flow path surface and at the bonding interface between the bonded flow path substrates, and can suppress leakage of ink from the bonding interface to the outside of the flow path, and a method for manufacturing an inkjet head. Although the mechanism by which the effects of the present invention are manifested or the mechanism by which the effects of the present invention are acted upon has not been clearly understood, it is speculated as follows. At least one of the first and second flow path substrates is made of silicon, and a protective film containing a compound having a Si-C bond is formed on the ink flow path surfaces of the first and second flow path substrates made of silicon and on the flow path substrate side surface of the adhesive layer formed at the bonding interface between the two substrates made of silicon, and since the compound having a Si-C bond has a very high chemical resistance, the protective film has a chemical resistance function. As a result, it is possible to prevent elution of silicon at the ink flow path surfaces and the bonding interface, and to suppress leakage of ink from the bonding interface to the outside of the flow path. In addition, since the bonding interface between the first and second flow path substrates is bonded via an adhesive layer, the compound having a Si-C bond contained in the protective film formed at the bonding interface is easily bonded to the adhesive layer, improving the reliability of the bonding at the bonding interface and suppressing ink leakage from the bonding interface to the outside of the flow path. Furthermore, bonding with an adhesive layer allows the adhesive layer to embed foreign matter compared to direct bonding of silicon substrates, and in this respect, the reliability of the bonding at the bonding interface is also improved. Also, compatibility with foreign matter during the formation of the protective film is high. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a state in which first and second flow path substrates according to a first embodiment of the present invention are joined together; [Figure 2A] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2B] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2C] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2D] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2E] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2F] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2G] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 2H] 2 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Diagram 3] FIG. 11 is a cross-sectional view showing a state in which first and second flow path substrates according to a second embodiment of the present invention are joined together. [Figure 4A] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4B] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4C] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4D] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4E] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4F] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4G] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4H] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Figure 4I] 4 is a cross-sectional view showing a manufacturing process of the inkjet head in FIG. [Diagram 5] Schematic diagram showing an inkjet recording apparatus [Figure 6] Bottom view of the head unit [Figure 7A] A perspective view of an inkjet head [Figure 7B]Cross-sectional view of an inkjet head [Figure 8] Exploded perspective view of an inkjet head [Figure 9] An exploded perspective view of a head chip [Figure 10A] Plan view of pressure chamber substrate [Figure 10B] Bottom view of pressure chamber substrate [Figure 11A] Plan view of the flow channel substrate [Figure 11B] Bottom view of the flow channel substrate [Figure 12] Plan view of nozzle substrate [Figure 13A] Cross-sectional view of the head chip when cut with IXA-IXA [Figure 13B] Cross-sectional view of the head chip when cut at IXB-IXB [Figure 14A] Cross-sectional view of the head chip when cut with XA-XB [Figure 14B] Cross-sectional view of the head chip when cut with XA-XB [Figure 15] Schematic diagram showing the ink circulation system [Figure 16] This is a cross-sectional view showing a state in which two flow path substrates are joined together, to illustrate a conventional example. [Figure 17] Enlarged view of the main part of Figure 16 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The inkjet head of the present invention is an inkjet head including first and second flow path substrates, At least one of the first and second flow path substrates is made of silicon, the bonding interfaces of the first and second flow path substrates are bonded via an adhesive layer; A protective film containing a compound having a Si-C bond is formed on the ink flow path surfaces of the first and second flow path substrates, which are made of silicon, and on the surface of the adhesive layer facing the flow path substrate, which is made of silicon. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0017] At least one of the first and second flow path substrates is made of silicon and includes a nozzle, a protective film containing a compound having a Si-C bond is formed on an ink flow path surface of the substrate including the nozzle, which is made of silicon, and on a surface of the adhesive layer facing the flow path substrate, which is made of silicon, the protective film is further formed on a nozzle opening surface of the substrate including the nozzle, and a liquid-repellent film containing a fluorine-based compound having a siloxane bond is formed on the protective film on the nozzle opening surface. This allows the protective film to function as a base film for the liquid-repellent film containing the fluorine-based compound, and ensures the durability of the liquid-repellent film containing the fluorine-based compound.

[0018] It is preferable that both the first and second flow path substrates are made of silicon, in that this ensures processing precision for the ink flow paths.

[0019] It is preferable that both the first and second flow path substrates are made of silicon, and at least one of them is a substrate including a nozzle, a protective film containing a compound having a Si-C bond is formed on the ink flow path surface of the substrate including the nozzle, which is made of silicon, and on the surface of the adhesive layer facing the flow path substrate, which is made of silicon, and the protective film is further formed on the nozzle opening surface of the substrate including the nozzle, and a liquid-repellent film containing a fluorine-based compound having a siloxane bond is formed on the protective film on the nozzle opening surface. This allows the protective film to function as a base film for the liquid-repellent film containing the fluorine-based compound, and ensures the durability of the liquid-repellent film containing the fluorine-based compound.

[0020] It is preferable that the protective film has a maximum peak in the energy band (99.9 to 100.9 eV) derived from the Si-C bond as detected by X-ray photoelectron spectroscopy, in terms of excellent chemical resistance and prevention of silicon elution.

[0021] When the surface layer of the protective film formed at the bonding interface is oxidized and the adhesive contains a silane coupling agent, this is preferable in that the protective film and the silane coupling agent form a siloxane bond, thereby increasing the bonding strength.

[0022] The method for manufacturing an inkjet head of the present invention includes the steps of forming a protective film containing a compound having a Si-C bond on the ink flow path surfaces of the first and second flow path substrates made of silicon and on the surface of the adhesive layer facing the flow path substrate made of silicon, and bonding the bonding interface of the first and second flow path substrates via the adhesive layer. This makes it possible to prevent elution of silicon from the ink flow path surfaces and the bonding interface between the bonded flow path substrates in an inkjet head having a flow path substrate made of silicon, and to suppress leakage of ink from the bonding interface to the outside of the flow path.

[0023] The present invention, its components, and embodiments for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after the symbol "to" are included as lower and upper limits.

[0024] [Outline of the inkjet head of the present invention] The inkjet head of the present invention is an inkjet head comprising first and second flow path substrates, at least one of which is made of silicon, the bonding interfaces of the first and second flow path substrates being bonded via an adhesive layer, and a protective film containing a compound having a Si-C bond being formed on the ink flow path surfaces of the first and second flow path substrates which are made of silicon and on the surface of the adhesive layer which faces the flow path substrate and is made of silicon.

[0025] 5, 8, 9, and 13A, each of the inkjet heads 100 has a plurality of nozzles 111. The inkjet head 100 ejects ink (droplets) from nozzle holes of the plurality of nozzles 111 provided in the bottom surface (nozzle opening surface 11a), and causes the ink droplets to land on a recording medium M carried on the transport surface of a transport drum 221. Furthermore, the inkjet head 100 has a head chip 1, and the head chip 1 is configured by laminating a nozzle substrate 13, a flow path substrate 12, and a pressure chamber substrate 13 in this order from the nozzle opening surface 11a upward.

[0026] (1) First embodiment In the following, a case will be described in which the flow path substrate 12 is a first flow path substrate according to the present invention, and the nozzle substrate 13 is a second flow path substrate according to the present invention. Also, an example will be described in which the second flow path substrate is made of silicon and the first flow path substrate is made of a material other than silicon. FIG. 1 is a cross-sectional view showing a state in which first and second flow path substrates are joined together.

[0027] <First flow path substrate> The first flow path substrate (flow path substrate 12) has a thickness in the range of, for example, 100 to 1000 μm, and is made of a material other than silicon, such as stainless steel (SUS), nickel, or an alloy (42 alloy) made of iron and nickel.

[0028] A plurality of pressure chambers 131 are formed in the first flow path substrate 12 (only one pressure chamber 131 is shown in FIG. 1 due to the limitations of the drawing). Further, in the first flow path substrate 12, individual ink discharge paths 121 branched off from the pressure chambers 131 are formed. One end of the individual ink discharge path 121 is connected to the pressure chamber 131, and the other end is connected to a first common ink discharge path 134 (see Figure 13A) described later, forming a flow path that discharges ink from the pressure chamber 131 to the first common ink discharge path 134. From the viewpoint of facilitating the discharge of air bubbles, foreign matter, and the like together with the ink, it is preferable that at least two individual ink discharge paths 121 are provided for each pressure chamber 131. Note that Fig. 1 illustrates a case where two individual ink discharge paths are provided.

[0029] <Second flow path substrate> The second flow path substrate (nozzle substrate 11) is configured with a substrate made of a silicon single crystal layer having a thickness in the range of, for example, 10 to 100 μm.

[0030] Nozzles 111, which are holes penetrating in the thickness direction (vertical direction), are provided in the second flow path substrate 11. The nozzles 111 communicate with the pressure chambers 131 and serve as ejection openings for ejecting the ink stored in the pressure chambers 131 when pressure is applied to the ink in the pressure chambers 131.

[0031] A protective film 91 containing a compound having an Si-C bond is formed on the ink flow path surfaces 11b and 11c of the second flow path substrate 11. That is, the protective film 91 containing the compound having an Si-C bond is formed on the surface 11b of the second flow path substrate 11 facing the first flow path substrate 12, which forms an ink flow path when joined to the first flow path substrate 12, and on the wall surface 11c forming the nozzle 111 of the second flow path substrate 11.

[0032] Furthermore, a protective film 91 containing a compound having a Si-C bond is formed on the bonding interface 11d of the second flow path substrate 11 with the first flow path substrate 12 and on the nozzle opening surface (bottom surface) 11a.

[0033] The composition of the protective film 91 can be analyzed by a conventional method using an X-ray photoelectron spectrometer (XPS) described below.

[0034] For example, a protective film for measurement having a layer thickness of about 200 nm is formed on a silicon substrate, and this is used as a sample for measuring the Si-C bonds or Si-O bonds in the protective film. The Si-C bonds or Si-bonds can be measured by the XPS composition analysis described below.

[0035] (XPS composition analysis) ·Device name: X-ray photoelectron spectrometer (XPS) ·Device model: Quantera SXM Equipment manufacturer: ULVAC-PHI Measurement conditions: X-ray source = monochromatic AlKα ray 25W-15kV ·Vacuum degree: 5.0×10 -8 Pa Furthermore, when performing composition analysis in the thickness direction, depth direction analysis may be performed by repeating argon ion etching and XPS analysis. Data processing is performed using MultiPak manufactured by ULVAC-PHI.

[0036] It is preferable that the protective film 91 has a maximum peak in the energy band (99.9 to 100.9 eV) derived from the Si--C bond detected by XPS, in that it has excellent chemical resistance and can prevent the elution of silicon.

[0037] In addition, it is preferable that the surface layer of the protective film 91 formed at the bonding interface 11d is oxidized. The oxidation method is air oxidation, and more preferably, for example, oxygen plasma treatment, UV ozone treatment, RCA cleaning, ozone water treatment, etc. This is preferable because it forms a siloxane bond with a silane coupling agent contained in the adhesive layer 93 described later, thereby increasing the bonding strength at the bonding interface 11d.

[0038] It is preferable that a liquid-repellent film 92 is further formed on the protective film 91 formed on the nozzle opening surface 11a of the second flow path substrate 11. The liquid-repellent film 92 is a film containing a fluorine-based compound having a siloxane bond, and has a configuration in which fluorine is formed on the surface of perfluoropolyether (PFPE), for example, and has liquid repellency (ink repellency). Therefore, since the protective film 91 formed as the base of the liquid-repellent film 92 is a film having Si-O bonds, the liquid-repellent film 92 and the protective film 91 are bonded together by siloxane bonds.

[0039] The first flow path substrate 12 and the second flow path substrate 11 as described above are bonded to each other via an adhesive layer 93 at the bonding interface. The thickness of the adhesive layer 93 is preferably within a range of 0.5 to 100 μm, since this allows foreign matter to be embedded in the adhesive layer 93, prevents adhesive loss, and improves the reliability of bonding at the bonding interface. The thickness is more preferably within a range of 0.5 to 2 μm.

[0040] The adhesive layer 93 is preferably made of an adhesive such as KBM-403 (Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent or Epotek353ND (Epoxy Technology Co., Ltd.) as an adhesive material. Therefore, since the protective film 91 formed at the bonding interface 11d of the second flow path substrate 11 with the first flow path substrate 12 is a film having Si-O bonds, a siloxane bond is formed by the protective film 91 and the silane coupling agent contained in the adhesive layer 93, and as a result, the bonding strength between the first flow path substrate 12 and the second flow path substrate 11 can be increased.

[0041] In this manner, the first flow path substrate 12 and the second flow path substrate 11 are bonded together via the adhesive layer 93, and a pressure chamber substrate 13 (see Figures 9 and 13A) described later is provided on the first flow path substrate 12. A voltage is applied to a driving electrode provided on the pressure chamber substrate 13, and pressure is applied to the ink in the pressure chamber 131, causing the ink to be ejected from the nozzle 111 of the second flow path substrate 11.

[0042] As described above, the second flow path substrate 11 of the first and second flow path substrates 12 and 11 is a substrate formed of silicon and including a nozzle, and a protective film 91 containing a compound having a Si-C bond is formed on the ink flow path surfaces 11b and 11c formed of silicon of the second flow path substrate 11 and the bonding interface 11d of both substrates 12 and 11, and the protective film 91 is further formed on the nozzle opening surface 11a of the second flow path substrate 11, and a liquid-repellent film 92 containing a fluorine-based compound having a siloxane bond is formed on the protective film 91 on the nozzle opening surface 11a. Since the compound having a Si-C bond has a very high chemical resistance, the protective film 91 has a function of chemical resistance. As a result, it is possible to prevent the elution of silicon on the ink flow path surfaces 11b and 11c, the bonding interface 11d, and the nozzle interface 11a. In particular, it is possible to suppress the leakage of ink from the bonding interface 11d to the outside of the flow path. For example, as shown in Figures 16 and 17, when a SiO2 film 900 is provided on the ink flow path surface or the bonding interface, the SiO2 film 900 has low chemical resistance and is dissolved by ink, the ink flow paths are connected at the bonding interface, and ink leaks between adjacent pressure chambers 131, causing ejection defects. However, according to the present invention, since the protective film 91 contains a compound having the Si-C bond, it is possible to suppress such ink leakage and ejection defects. Note that in Figures 16 and 17, the same components as those in Figure 1 are denoted by the same reference numerals.

[0043] [Inkjet head manufacturing method] Next, a method for manufacturing the inkjet head 100 will be described. The method for manufacturing an inkjet head of the present invention includes a step of forming a protective film containing a compound having a Si-C bond on the ink flow path surfaces of the first and second flow path substrates made of silicon and on the bonding interface between both substrates (protective film forming step), and a step of bonding the bonding interface between the first and second flow path substrates via an adhesive layer (bonding step).

[0044] Figures 2A to 2H are cross-sectional views showing the manufacturing process of the inkjet head 100 shown in Figure 1. Note that in the manufacture of the inkjet head 100, a plurality of pressure chambers 111 are formed in one first flow path substrate 12, but here, a case in which one pressure chamber 111 is formed is representatively shown.

[0045] As shown in Fig. 2A, first, a wafer-shaped substrate 300 is prepared. Crystalline silicon (Si), which is widely used in MEMS (MicroElectroMechanical Systems), can be used as the wafer-shaped substrate 300. In this case, it is preferable to use an SOI (Silicon on Insulator) substrate structure in which an active layer 301 in which the nozzles 111 are formed and which becomes the second flow path substrate 11, and a support layer 303 are formed on the active layer 301 via an etching stopper layer 302. The active layer 301 is made of silicon and serves as the second flow path substrate 11 in which the nozzle 111 is formed. The nozzle 111 is formed by performing resist patterning using photolithography and processing using dry etching or wet etching. The thickness of the active layer 301 is preferably within the range of 10 to 100 μm.

[0046] The etching stopper layer 302 functions as an etching stopper when forming the nozzle holes, and contains SiO2. The thickness of the etching stopper layer 302 is preferably within the range of 0.1 to 5 μm.

[0047] The support layer 303 is made of silicon like the active layer 301 , and supports the active layer 301 via the etching stopper layer 302 . The thickness of the support layer 303 is preferably within the range of 200 to 800 μm.

[0048] 2B, in order to remove the support layer 303, a temporary fixing substrate 304 is temporarily attached to the surface of the active layer 301 opposite to the etching stopper layer 302. By temporarily attaching the temporary fixing substrate 304, the active layer 301 having a thickness of 100 μm or less can be easily handled. The temporary fixing substrate 304 is preferably made of silicon, glass, ceramics (alumina), etc. Examples of the bonding method include a foam sheet (Revalfa (manufactured by Nitto Denko Corporation)).

[0049] 2C, the support layer 303 and the etching stopper layer 302 are removed by etching, and the active layer 301 becomes the second flow path substrate 11. Specifically, it is preferable to perform dry etching using SF6 gas or the like on the support layer 303 and wet etching using hydrofluoric acid or the like on the etching stopper layer 302.

[0050] Next, as shown in FIG. 2D, a protective film 91 containing a compound having a Si-C bond is formed on the surface of the second flow path substrate 11 facing the first flow path substrate 12, on the surface 11b that forms an ink flow path when bonded to the first flow path substrate 12, on the wall surface 11c that forms the nozzle 111, and on the bonding interface 11d with the first flow path substrate 12 (protective film formation process). Examples of the method for forming the protective film 91 include CVD and sputtering. After the protective film 91 is formed, it is preferable to clean the second flow path substrate 11 to remove foreign matter. Here, since the second flow path substrate 11 is made of silicon, RCA cleaning is preferably used.

[0051] 2E, a first flow path substrate 12 is prepared, which is made of a material other than silicon and has the pressure chambers 131 and the individual ink discharge paths 121 formed therein. The pressure chambers 131 and the individual ink discharge paths 121 are processed by, for example, photolithography and etching processes.

[0052] 2F, the first flow path substrate 12 is bonded to the second flow path substrate 11 to which the temporary fixing substrate 304 has been bonded via the adhesive layer 93 (bonding step). The adhesive layer 93 can be formed, for example, by applying the adhesive by screen printing or the like.

[0053] Next, as shown in FIG. 2G, the temporary fixing substrate 304 is removed by peeling off the foam sheet by heat treatment.

[0054] Finally, as shown in FIG. 2H, the protective film 91 is formed on the nozzle opening surface 11a of the second flow path substrate 11 after the temporary fixing substrate 304 has been removed, and further, the liquid-repellent film 92 is formed on the protective film 91 formed on the nozzle opening surface 11a (see FIG. 1).

[0055] The protective film 91 is preferably formed by CVD or sputtering. The liquid-repellent film 92 is preferably formed by a dip treatment. In the dip treatment, the nozzle opening surface 11a of the second flow path substrate 11 is immersed in a liquid-repellent agent (dip coating), so that the liquid-repellent agent is applied onto the nozzle opening surface 11a. The liquid repellent may be, for example, a liquid obtained by diluting a specific perfluoropolyether (PFPE) with a fluorine-based solvent. This liquid repellent may further contain water as a solvent and may also contain a surfactant. As the coating method, in addition to the above-mentioned dipping treatment, CVD, spray coating, spin coating, wire bar coating (when a siloxane graft type polymer is used, etc.) can be used.

[0056] After forming the liquid-repellent film 92, a pressure chamber substrate 13 (described later) is further bonded onto the first flow path substrate 12 of the bonded first and second flow path substrates 12, 11 to form the head chip 1, and then a drive circuit substrate 4 and ink supply paths are connected via a wiring substrate 2 and a flexible substrate 3 to form the inkjet head 100 (see Figures 7A, 7B and 8).

[0057] (2) Second embodiment In the second embodiment, both the first flow path substrate 12 and the second flow path substrate 11 are made of silicon, and are similar to the first embodiment except that the protective film 91 is formed on the ink flow path surfaces 12b, 12e, and 12f of the first flow path substrate 12 and the bonding interface 12c between the ink flow path surfaces 12b, 12e, and 12f of the first flow path substrate 12 and the second flow path substrate 11 of the first flow path substrate 12. That is, the second flow path substrate 11 according to the second embodiment is made of silicon like the second flow path substrate 11 according to the first embodiment, and the protective film 91 is formed at the same location. The first flow path substrate 12 will be described below. FIG. 3 is a cross-sectional view showing a state in which the first and second flow path substrates are joined together.

[0058] <First flow path substrate> The first flow path substrate 12 according to the second embodiment is configured as a semiconductor substrate or an SOI substrate made of single crystal Si (silicon) alone and having a thickness within a range of, for example, 200 to 800 μm.

[0059] The first flow path substrate 12 according to the second embodiment has pressure chambers 131 and individual ink discharge paths 121 formed therein, similarly to the first flow path substrate 12 according to the first embodiment.

[0060] Furthermore, a protective film 91 containing a compound having a Si-C bond is formed on the ink flow path surfaces 12b, 12e, and 12f of the first flow path substrate 12. That is, the protective film 91 is formed on the surface of the first flow path substrate 12 facing the second flow path substrate 11, on the surface 12b that forms the ink flow path when joined to the first flow path substrate 12, on the wall surface 12e that forms the pressure chamber 131, and on the wall surface 12f that forms the individual ink discharge path 121. Also, at the bonding interface 12d of the first flow path substrate 12 with the second flow path substrate 11, a protective film 91 containing a compound having a Si--C bond is formed.

[0061] [Inkjet head manufacturing method] Next, a method for manufacturing the inkjet head 100 according to the second embodiment will be described. Figures 4A to 4I are cross-sectional views showing the manufacturing process of the inkjet head 100. Note that Figures 4A to 4D and 4G to 4I are similar to the processes shown in Figures 2A to 2D and 2F to 2H, respectively, described in the manufacturing method for the inkjet head 100 according to the first embodiment, and therefore descriptions thereof will be omitted.

[0062] 4A to 4D, a first flow path substrate 12 made of silicon in which the pressure chambers 131 and the individual ink discharge paths 121 are formed is prepared as shown in Fig. 4E. The pressure chambers 131 and the individual ink discharge paths 121 are processed by, for example, photolithography and etching processes.

[0063] As shown in FIG. 4F, the protective film 91 is formed on the ink flow path surface of the first flow path substrate 12, i.e., the surface of the first flow path substrate 12 facing the first flow path substrate 12, on surface 12b forming the ink flow path, wall surface 12e forming pressure chamber 131, and wall surface 12f forming individual ink discharge path 121 when joined to the first flow path substrate 12. Moreover, the protective film 91 is also formed on the bonding interface 12d of the first flow path substrate 12 with the second flow path substrate 11. Examples of the method for forming the protective film 91 include CVD and sputtering. After the protective film 91 is formed, it is preferable to clean the first flow path substrate 12 to remove foreign matter. Here, since the first flow path substrate 12 is made of silicon, RCA cleaning is preferably used.

[0064] Thereafter, the first and second flow path substrates 12, 11 are bonded together through the steps shown in FIGS. 4G to 4I.

[0065] [Inkjet recording device] Next, an ink-jet recording apparatus equipped with the ink-jet head of the present invention will be described. For the sake of convenience, in the following description, the print width direction, which is the arrangement direction of the nozzles 111 of the inkjet head 100, is defined as the left-right direction, the direction in which the recording medium is transported below the nozzles 111 is defined as the front-rear direction, and the direction perpendicular to the left-right direction and the front-rear direction is defined as the up-down direction. Also, the arrows in the flow paths in the drawings indicate the direction in which the ink flows.

[0066] 5, the inkjet recording device 200 includes a paper feed section 210, an image recording section 220, a paper discharge section 230, and an ink circulation system 8 (see FIG. 15) as an ink supply means. The inkjet recording device 200 transports a recording medium M stored in the paper feed section 210 to the image recording section 220, forms an image on the recording medium M in the image recording section 220, and transports the recording medium M with the image formed thereon to the paper discharge section 230.

[0067] The paper feed unit 210 has a paper feed tray 211 that stores the recording medium M, and a medium supply unit 212 that transports and supplies the recording medium M from the paper feed tray 211 to the image recording unit 220. The medium supply unit 212 has a ring-shaped belt supported by two rollers on the inside, and transports the recording medium M from the paper feed tray 211 to the image recording unit 220 by rotating the rollers with the recording medium M placed on this belt.

[0068] The image recording section 220 includes a transport drum 221, a delivery unit 222, a heating section 223, a head unit 224, a fixing section 225, a delivery section 226, and the like.

[0069] The transport drum 221 has a cylindrical surface, and its outer circumferential surface serves as a transport surface on which the recording medium M is placed. The transport drum 221 transports the recording medium M along the transport surface by rotating in the direction of the arrow in Fig. 5 while holding the recording medium M on the transport surface. The transport drum 221 also has a claw portion and an air intake portion (not shown), and holds the recording medium M on the transport surface by pressing down the edge of the recording medium M with the claw portion and sucking the recording medium M to the transport surface with the air intake portion.

[0070] The transfer unit 222 is provided at a position between the medium supply section 212 of the paper feeding section 210 and the transport drum 221, and holds and picks up one end of the recording medium M transported from the medium supply section 212 with the swing arm section 222a, and transfers it to the transport drum 221 via the transfer drum 222b.

[0071] The heating unit 223 is provided between the position where the delivery drum 222b is arranged and the position where the head unit 224 is arranged, and heats the recording medium M conveyed by the conveying drum 221 so that the temperature of the recording medium M falls within a predetermined temperature range. The heating unit 223 has, for example, an infrared heater, and energizes the infrared heater based on a control signal supplied from a control unit (not shown) to cause the heater to generate heat.

[0072] The head unit 224 forms an image by ejecting ink onto the recording medium M at an appropriate timing according to the rotation of the transport drum 221 on which the recording medium M is held, based on image data. The head unit 224 is disposed at a predetermined distance with its ink ejection surface facing the transport drum 221. In the inkjet recording device 200 of this embodiment, for example, four head units 224 corresponding respectively to four colors of ink, yellow (Y), magenta (M), cyan (C), and black (K), are arranged at predetermined intervals from the upstream side in the transport direction of the recording medium M in the order of Y, M, C, and K.

[0073] 6, the head unit 224 has a pair of inkjet heads 100 adjacent to each other in the front-rear direction, which are arranged in a staggered pattern at different positions in the front-rear direction. Furthermore, the head unit 224 is used while its position relative to the rotation axis of the transport drum 221 is fixed when recording an image. In other words, the inkjet recording apparatus 200 is an inkjet recording apparatus that records images by a one-pass drawing method using a line head.

[0074] The fixing unit 225 has a light-emitting unit arranged across the width of the transport drum 221 in the X direction, and irradiates the recording medium M placed on the transport drum 221 with energy rays such as ultraviolet rays from the light-emitting unit to harden and fix the ink ejected onto the recording medium M. The light-emitting unit of the fixing unit 225 is arranged downstream of the position where the head unit 224 is arranged and upstream of the position where the delivery drum 226a of the delivery unit 226 is arranged in the transport direction, facing the transport surface.

[0075] The delivery section 226 has a belt loop 226b having a circular belt supported on the inside by two rollers, and a cylindrical transfer drum 226a that transfers the recording medium M from the transport drum 221 to the belt loop 226b. The recording medium M transferred from the transport drum 221 to the belt loop 226b by the transfer drum 226a is transported by the belt loop 226b and sent to the paper discharge section 230.

[0076] The paper discharge section 230 has a plate-shaped paper discharge tray 231 on which the recording medium P sent out from the image recording section 220 by the delivery section 226 is placed.

[0077] [Inkjet head] As shown in Figures 7A, 7B, 8, etc., the inkjet head 100 comprises a head chip 1, a wiring board 2 on which the head chip 1 is arranged, a drive circuit board 4 connected to the wiring board 2 via a flexible board 3, a manifold 5 that stores ink to be supplied to a pressure chamber 131 in the head chip 1, a housing 6 inside which the manifold 5 is housed, a cap receiving plate 7 attached to cover the bottom opening of the housing 6, and a cover member 9 attached to the housing 6. It should be noted that the manifold 5 is omitted in FIG. 7A, and the cover member 9 is omitted in FIGS. 7B and 8. In addition, in this embodiment, an example is described in which the number of rows of nozzles 111 on head chip 1 is four, but the number and arrangement of the rows of nozzles 111 can be changed as appropriate, and may be, for example, any one of one to three rows, or may be five or more rows.

[0078] Head chip 1 is a generally rectangular prism-shaped member that is long in the left-right direction, and is configured by laminating a pressure chamber substrate 13, a flow path substrate 12, and a nozzle substrate 11 in this order (see FIGS. 9 to 15).

[0079] As described above, in such a head chip 1, the flow path substrate 12 is the first flow path substrate of the present invention described above, the nozzle substrate 13 is the second flow path substrate of the present invention, at least one of the first and second flow path substrates is formed of silicon, the bonding interfaces of the first and second flow path substrates 12, 11 are bonded via an adhesive layer 92, and a protective film 91 containing a compound having a Si-C bond is formed on the ink flow path surfaces of the first and second flow path substrates 12, 11 made of silicon and on the flow path substrate side surface of the adhesive layer 92 made of silicon (see Figures 1 and 3, etc.). 7B, 13A, 13B, 14A and 14B, the protective film 91, the adhesive layer 93, the liquid-repellent film 92 and the like are omitted.

[0080] The pressure chamber substrate 13 is provided with a pressure chamber 131, an air chamber 132, a common ink discharge path 133, and the like (see FIGS. 9, 10A, 10B, and the like). A large number of pressure chambers 131 and air chambers 132 are provided so as to be alternately arranged in the left-right direction, and are provided in four rows in the front-rear direction. The pressure chamber 131 has a substantially rectangular cross section and is formed along the vertical direction, with an inlet on the upper surface and an outlet on the lower surface of the pressure chamber substrate 13. The pressure chamber 131 also communicates with the ink storage section 51 at the upper end, and ink is supplied to the pressure chamber 131 from the ink storage section 51, and ink to be ejected from the nozzle 111 is stored inside the pressure chamber 131. In addition, the pressure chamber 131 is formed in the vertical direction across the pressure chamber substrate 13 and the flow path substrate 12 so as to have a substantially rectangular cross-section of the same area, and is connected to the nozzle 111 at its downward end (see Figures 13A, 13B, etc.).

[0081] The air chamber 132 has a generally rectangular cross section that is slightly larger than the pressure chamber 131, and is formed so as to be parallel to the pressure chamber 131 along the vertical direction. Unlike the pressure chamber 131, the air chamber 132 does not communicate with the ink storage section 51, so that ink does not flow into the air chamber 132. The air chamber 132 also does not communicate with the nozzle 111 (see Figures 13A, 13B, etc.).

[0082] The pressure chambers 131 and the air chambers 132 are separated by a partition wall 136 serving as a pressure generating means formed of a piezoelectric material (see FIG. 14A). A drive electrode (not shown) is provided on the partition wall 136, and when a voltage is applied to the drive electrode, the portion of the partition wall 136 between adjacent pressure chambers 131 repeats a shear mode type displacement, thereby applying pressure to the ink in the pressure chambers 131. In the pressure chambers 131 shown in FIGS. 9 to 14, the pressure chambers 131 located at the ends in the left and right direction that have a partition wall 136 on only one side are not used, and the other pressure chambers 131 that have partition walls 136 on both sides are used.

[0083] Although it is possible to form only the pressure chambers 131 without providing the air chambers 132, as described above, it is preferable to provide the pressure chambers 131 and the air chambers 132 alternately. This makes it possible to prevent the pressure chambers 131 from being adjacent to each other, so that when the partition wall 136 adjacent to one pressure chamber 131 is deformed, it does not affect the other pressure chambers 131.

[0084] The common ink discharge path 133 is configured by connecting a first common ink discharge path 134 and a second common ink discharge path 135 (see FIG. 9, FIG. 10B, etc.). The first common ink discharge paths 134 are provided in three rows along the left-right direction on the lower surface side of the pressure chamber substrate 13, at the front side, rear side, and center portion of the head chip 1, so as to avoid the portion where the pressure chamber 131 and the air chamber 132 are provided. In addition, a plurality of individual ink discharge paths 121 provided in the flow path substrate 12 are connected to the lower surface side of the first common ink discharge path 134, so that ink flowing from the individual ink discharge paths 121 (second individual ink discharge paths 123) can merge at the first common ink discharge path 134 (see FIG. 10B, FIG. 11A, and FIG. 13A). In addition, the first common ink discharge path 134 is connected near the right end portion to a second common ink discharge path 135 that can discharge ink to the outside of the head chip 1. Therefore, the first common ink discharge path 134 is a flow path through which the ink flowing from the individual ink discharge path 121 (second individual ink discharge path 123) flows toward the second common ink discharge path 135.

[0085] The second common ink discharge path 135 is formed along the up-down direction, similar to the pressure chambers 131. The lower surface side of the second common ink discharge path 135 communicates with the first common ink discharge path 134 of the pressure chamber substrate 13, and the upper surface side communicates with the discharge liquid chamber 57, and serves as a flow path for discharging ink flowing from the first common ink discharge path 134 toward the upper side (the side opposite the nozzle substrate 11) to the outside of the head chip 1. The second common ink discharge path 135 is provided near the right end of the head chip 1, and communicates with the first common ink discharge path 134. The second common ink discharge path 135 is provided to have a larger volume than each pressure chamber 131, thereby improving the efficiency of discharging ink.

[0086] In the flow path substrate 12, a pressure chamber 131 and an individual ink discharge path 121 branched off from the pressure chamber 131 are formed (see FIGS. 13A and 13B, etc.). The pressure chambers 131 are formed in the vertical direction across the flow path substrate 12 and the pressure chamber substrate 13 so as to have substantially rectangular cross sections of the same area.

[0087] The individual ink discharge path 121 has one end connected to the pressure chamber 131 and the other end connected to the first common ink discharge path , and serves as a flow path for discharging ink from the pressure chamber 131 to the first common ink discharge path . From the viewpoint of facilitating the discharge of air bubbles, foreign matter, and the like together with the ink, it is preferable that at least two individual ink discharge channels 121 are provided for each pressure chamber 131. Also, for example, as shown in Figures 13A and 13B, it is preferable to provide a total of two individual ink discharge channels 121, one each in the front and rear directions of the pressure chamber 131, because this can obtain the effect of facilitating the discharge of air bubbles, foreign matter, and the like together with the ink and also provides high manufacturing efficiency.

[0088] From the viewpoint of ease of processing (high precision) of the individual ink discharge paths 121 and of being able to easily maintain a uniform ink temperature due to high thermal conductivity, the flow path substrate 12 is preferably a substrate made of the above-mentioned silicon, stainless steel (SUS), nickel, or alloy 42. Of these, it is preferable to use a substrate made of a material that has a thermal expansion coefficient close to that of the material forming the pressure chamber substrate 13.

[0089] The nozzle substrate 11 is provided with nozzles 111, which are holes penetrating in the thickness direction (vertical direction) (see FIG. 12). The nozzles 111 communicate with the pressure chambers 131, and function as ejection ports for ejecting ink stored in the pressure chambers 131 when pressure is applied to the ink in the pressure chambers 131. In this embodiment, the nozzles 111 are arranged in the left-right direction and in four rows in the front-back direction.

[0090] 13A and 13B, the nozzle substrate 11 preferably constitutes one of the flow path walls of the first individual ink discharge path 122. Since the nozzle substrate 11 is thin, it can function as a damper that can change the volume of the flow path by slightly elastically deforming under pressure.

[0091] As described above, the nozzle substrate 11 is manufactured by etching a silicon substrate.

[0092] As shown in FIG. 8, a wiring board 2 is disposed on the upper surface of the head chip 1, and two flexible boards 3 connected to a drive circuit board 4 are disposed on both edges of the wiring board 2 along the front-to-rear direction.

[0093] Wiring board 2 is formed in a generally rectangular plate shape that is long in the left-right direction, and has an opening 22 in its approximate center. The widths of wiring board 2 in the left-right direction and the front-rear direction are each formed larger than head chip 1.

[0094] Opening 22 is formed in a roughly rectangular shape that is elongated in the left-right direction, and when head chip 1 is attached to wiring substrate 2, the inlets of each pressure chamber 131 in head chip 1 and the outlet of second common ink discharge path 135 are exposed on the upper side.

[0095] The flexible substrate 3 electrically connects the drive circuit substrate 4 and the electrode portion of the wiring substrate 2, so that a signal from the drive circuit substrate 4 can be applied via the flexible substrate 3 to a drive electrode provided on the partition wall 136 inside the head chip 1.

[0096] In addition, a lower end portion of manifold 5 is attached and fixed by adhesive to the outer edge portion of wiring substrate 2. That is, manifold 5 is disposed on the inlet side (upper side) of pressure chamber 131 of head chip 1, and is connected to head chip 1 via wiring substrate 2.

[0097] Manifold 5 is a member molded from resin, and is provided above pressure chambers 131 of head chip 1 to store ink to be introduced into pressure chambers 131. Specifically, as shown in Fig. 7B etc., manifold 5 is formed long in the left-right direction, and includes hollow main body 52 that constitutes ink storage section 51, and first to fourth ink ports 53 to 56 that constitute ink flow paths. In addition, ink storage section 51 is partitioned into two, an upper first liquid chamber 51a and a lower second liquid chamber 51b, by filter F for removing dust from the ink.

[0098] The first ink port 53 is connected to an upper right end of the first liquid chamber 51a, and is used to introduce ink into the ink storage section 51. In addition, a first joint 81a is fitted onto the tip of the first ink port 53. The second ink port 54 is connected to the upper left end of the first liquid chamber 51a and is used to remove air bubbles from the first liquid chamber 51a. A second joint 81b is fitted onto the tip of the second ink port 54. The third ink port 55 is connected to the upper left end of the second liquid chamber 51b and is used to remove air bubbles from the second liquid chamber 51b. A third joint 82a is fitted onto the tip of the third ink port 55. The fourth ink port 56 is connected to a discharge liquid chamber 57 which is connected to the second common ink discharge path 135 of the head chip 1, and the ink discharged from the head chip 1 is discharged to the outside of the inkjet head 100 through the fourth ink port 56.

[0099] The housing 6 is a member formed by die casting using aluminum as a material, for example, and is formed long in the left-right direction. The housing 6 is formed so as to be able to house the manifold 5 to which the head chip 1, the wiring board 2, and the flexible board 3 are attached inside, and the bottom surface of the housing 6 is open. At both ends of the housing 6 in the left-right direction, mounting holes 68 are formed for mounting the housing 6 to the printer main body.

[0100] The cap receiving plate 7 has a nozzle opening 71 that is long in the left-right direction formed in approximately the center, and is attached to cover the bottom opening of the housing 6 so that the nozzle substrate 11 is exposed through the nozzle opening 71.

[0101] [Ink Circulation System] The ink circulation system 8 is an ink supply means for generating a circulating flow of ink from the pressure chambers 131 in the inkjet head 100 to the individual ink discharge paths 121. The ink circulation system 8 is composed of a supply sub-tank 81, a circulation sub-tank 82, a main tank 83, etc. (see FIG. 15).

[0102] The supply sub-tank 81 is filled with ink to be supplied to the ink storage portion 51 of the manifold 5, and is connected to the first ink port 53 by an ink flow path . The circulation sub-tank 82 is filled with the ink discharged from the discharge liquid chamber 57 of the manifold 5 , and is connected to the fourth ink port 56 by an ink flow path 85 . Furthermore, the supply sub-tank 81 and the circulation sub-tank 82 are provided at different positions in the vertical direction (gravity direction) with respect to the nozzle surface (hereinafter also referred to as the "position reference surface") of the head chip 1. This generates a pressure P1 due to the head difference between the position reference surface and the supply sub-tank 81, and a pressure P2 due to the head difference between the position reference surface and the circulation sub-tank 82. The supply sub-tank 81 and the circulation sub-tank 82 are connected by an ink flow path 86. Ink can be returned from the circulation sub-tank 82 to the supply sub-tank 81 by pressure applied by a pump 88.

[0103] The main tank 83 is filled with ink to be supplied to the supply subtank 81, and is connected to the supply subtank 81 by an ink flow path 87. Then, ink can be supplied from the main tank 83 to the supply subtank 81 by pressure applied by a pump 89.

[0104] Moreover, pressures P1 and P2 can be adjusted by appropriately changing the amount of ink filled in each sub-tank and the vertical (gravity) position of each sub-tank. Then, the ink in inkjet head 100 can be circulated at an appropriate circulation flow rate by the pressure difference between pressures P1 and P2. This makes it possible to remove air bubbles, foreign matter, etc. generated in head chip 1, and to suppress clogging of nozzle 111, ejection failure, etc.

[0105] Although the method of controlling the circulation of ink by the head difference has been described as an example of the ink circulation system 8, it can of course be modified as appropriate as long as the configuration can generate a circulating flow of ink.

[0106] Furthermore, in the above description, a shear mode type inkjet head is used, but for example, a bend mode type inkjet head may also be used.

[0107] Furthermore, the first flow path substrate and the second flow path substrate according to the present invention are applied to the flow path substrate 12 and the nozzle substrate 11, respectively, but the present invention is not limited to this, and for example, the first flow path substrate may be applied to the pressure chamber substrate 13, and the second flow path substrate may be applied to the flow path substrate 12. This makes it possible to prevent elution of silicon on the ink flow path surfaces of the pressure chamber substrate 13 and the flow path substrate 12, and at the bonding interface between the bonded flow path substrates 13 and 12, and to suppress leakage of ink from the bonding interface to the outside of the flow path. EXAMPLES

[0108] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

[0109] (1) Example 1 [Preparation of Sample 1] A protective film made of SiC and having a thickness of 108 nm was formed on a substrate made of single crystal Si (silicon) by a CVD method under the following film formation conditions. (Film formation conditions) Device name: Samco PD-220NL Source gas: tetramethylsilane (TMS) Supply of raw gas: 30sccm (Standard Cubic Centimeter per Minute) Applied power from plasma generation power supply: 500W Film forming temperature: room temperature

[0110] [Preparation of Sample 2] Device name: KOKUSAI ELECTRIC (formerly Hitachi Kokusai Electric) DD-853V Raw gas: O2, H2 Method: Pyrogenic oxidation or dry oxidation Film formation temperature: 900℃ (for pyrogenic) Oxidation time: 9 minutes (for pyrogenic) Oxide film thickness: 37 nm

[0111] [Preparation of Sample 3] Device name: Samco PD-220NL Source gas: tetraethoxysilane Supply of raw gas: 3sccm (Standard Cubic Centimeter per Minute) Carrier gas (Ar) supply: 100sccm Applied power from plasma generation power supply: 600W Film forming temperature: room temperature

[0112] [Preparation of Sample 4] Device name: KOKUSAI ELECTRIC (formerly Hitachi Kokusai Electric) DJ-833V Source gas: tantalum tetrachloride (TaCl4), silicon tetrachloride (SiCl4) Oxidizing gas: H2O Film forming temperature: 200℃ Film thickness: 48 nm

[0113] For each of the prepared samples, the chemical composition ratio of the protective film was measured by XPS composition analysis shown below, and the results are shown in Table I below. (XPS Composition Analysis) · Equipment Name: X-ray Photoelectron Spectrometer (XPS) · Equipment Model: Quantera SXM · Equipment Manufacturer: ULVAC-PHI · Measurement Conditions: X-ray Source = Monochromatic AlKα Ray 25W - 15kV · Vacuum Degree: 5.0×10 -8 Pa Data processing uses MultiPak manufactured by ULVAC-PHI.

[0114] [Evaluation] <KOH Immersion Test> A KOH aqueous solution with a potassium hydroxide concentration of 40% was heated to 80°C, and each of the samples prepared above was immersed in the hot bath of the KOH aqueous solution. Using a film thickness gauge (Optical NanoGauge C1256 (manufactured by Hamamatsu Photonics)), the film thickness of the protective film before and after immersion was measured, and the film thickness change (dissolution rate [nm / min]) was calculated.

[0115] <Aqueous Ink Immersion Test> As a soluble dye ink, original ink (reactive dye) for inkjet textile printer "Nassenger" (manufactured by Konica Minolta) was prepared and heated to 60°C. 100 cc of the dye ink and each of the samples prepared above were sealed in a test bottle and stored in a baking oven. Using a film thickness gauge (Optical NanoGauge C1256 (manufactured by Hamamatsu Photonics)), the film thickness of the protective film before and after immersion was measured, and the film thickness change was calculated. Also, the color change on the film surface of the protective film was observed. In addition, for the cases where the storage period in the baking oven was 1 week and 4 weeks, evaluation was carried out according to the following criteria. (Criteria) ○: No film thickness change and no color change on the film surface are observed. ×: Film thickness change and color change on the film surface are observed.

[0116] [Table 1]

[0117] As shown in the above results, the Si substrate sample on which the SiCO protective film according to the present invention is formed has a elution rate below the detection limit in the KOH immersion test, and no change in film thickness or color of the film surface was observed in the aqueous ink immersion test, compared with the comparative sample. Therefore, it is found that the elution of silicon can be prevented by forming the SiCO protective film. Furthermore, since the elution of silicon can be prevented in this way, it is recognized that when the SiCO protective film is formed on the ink flow path surface and the bonding interface, the elution of silicon on the ink flow path surface and the bonding interface can be prevented, and the leakage of ink to the outside of the flow path at the bonding interface can be suppressed. [Industrial Applicability]

[0118] The present invention can be used in an inkjet head and a manufacturing method for an inkjet head, which can prevent the elution of silicon on the ink flow path surface and at the bonding interface between bonded flow path substrates, and suppress the leakage of ink from the bonding interface to outside the flow path. [Explanation of symbols]

[0119] 1 Head Chip 8 Ink Circulation System 11 Nozzle substrate (second flow path substrate) 11a Nozzle opening surface 11b Ink flow path surface 11c Ink flow path surface 11d Joint interface 111 Nozzle 12 Flow path substrate (first flow path substrate) 12b Ink flow path surface 12d Joint interface 12e Ink flow path surface 12f Ink flow path surface 121 Individual ink discharge path 122 First individual ink discharge path 123 Second individual ink discharge path 13 Pressure chamber substrate 131 Pressure Chamber 132 Air chamber 133 Common ink discharge path 134 First common ink discharge path 135 Second common ink discharge path 136 Bulkhead 91 Protective film 92 Liquid repellent film 93 Adhesive layer 100 Inkjet head 200 Inkjet recording device 300 SOI substrate 301 Active layer 302 Etching stopper layer 303 Support layer 304 Temporary Fixing Board

Claims

1. An inkjet head having first and second flow path substrates, At least one of the first and second flow path substrates is a substrate formed of silicon and including a nozzle; the bonding interfaces of the first and second flow path substrates are bonded via an adhesive layer; a protective film containing a compound having a Si-C bond is formed on an ink flow path surface of the substrate including the nozzle, which is made of silicon, and on a surface of the adhesive layer facing the flow path substrate, which is made of silicon; the protective film is formed on a nozzle opening surface of a substrate including the nozzle, an inkjet head, wherein a liquid-repellent film containing a fluorine-based compound having a siloxane bond is formed on the protective film of the nozzle opening surface;

2. The inkjet head according to claim 1 , wherein both the first and second flow path substrates are made of silicon.

3. 3. The ink jet head according to claim 1, wherein the protective film has a maximum peak in an energy band (99.9 to 100.9 eV) derived from a Si--C bond, as detected by X-ray photoelectron spectroscopy.

4. a surface layer of the protective film formed at the bonding interface is oxidized, 4. The ink jet head according to claim 1, wherein the adhesive layer contains a silane coupling agent.

5. A method for manufacturing an inkjet head according to any one of claims 1 to 4, comprising the steps of: forming a protective film containing a compound having a Si-C bond on ink flow path surfaces of the first and second flow path substrates made of silicon and on a surface of the adhesive layer facing the flow path substrate made of silicon; A method for manufacturing an inkjet head, comprising: bonding the bonding interfaces of the first and second flow path substrates via the adhesive layer.

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