JPH0415096B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an inkjet recording head, and more particularly to an inkjet recording head for generating recording ink droplets used in so-called inkjet recording systems. An inkjet recording head applied to an inkjet recording system generally includes a fine ink ejection opening (orifice), an ink passage, and an ink ejection pressure generating section provided in a part of the ink passage. Conventionally, such an inkjet recording head has been manufactured by forming fine grooves on a glass or metal plate by cutting or etching, and then bonding the plate with the grooves to another suitable plate. There is a known method for forming ink passages. However, in heads manufactured by such conventional methods, the roughness of the inner wall surface of the ink passages to be cut is too large, and distortion occurs in the ink passages due to differences in etching rate. It is difficult to obtain the desired characteristics, and variations tend to occur in the ink ejection characteristics of the inkjet recording head after manufacture. Further, there is also the problem that the plate is likely to chip or crack during cutting, resulting in poor manufacturing yield. When etching is performed, there are many manufacturing steps, which leads to an increase in manufacturing costs. Furthermore, a problem common to the above-mentioned conventional methods is that the grooved plate in which the ink passage grooves are formed and the lid plate provided with drive elements such as piezoelectric elements and heating elements that generate energy that acts on the ink. During lamination, it is difficult to align the respective positions with high precision, and mass production is lacking. An inkjet recording head having a configuration that solves these problems involves forming an ink passage wall made of a cured film of a photosensitive resin on a substrate on which an ink ejection pressure generating element is installed, and then covering the passage. An inkjet recording head is known, for example, from JP-A-57-43876. The inkjet recording head manufactured using this photosensitive resin is superior in that it solves the problems of conventional heads, such as the precision of the ink passage finish, the complexity of the manufacturing process, and poor manufacturing yield. It is something that However, there remains a problem in the bonding strength between the substrate on which the ink ejection pressure generating element is installed and the passage wall of the cured photosensitive resin film formed thereon. In other words, if the adhesiveness of the photosensitive resin cured film to the substrate is not sufficient and ink droplets are ejected for a long time, the ink droplets may be damaged due to the impact during ejection or due to changes over time. , the substrate at the ink ejection port and the passage wall peeled off, albeit very slightly, and the straightness of the ink droplets deteriorated.
In other words, it affects the accuracy of the ink landing point.
This has become a major hindrance in recent years as the demand for high-resolution image quality in inkjet recording systems has increased due to the use of high-density nozzles. The present invention was made in view of the above problems.
The object of the present invention is to provide an inkjet recording head that is precise, highly reliable, and has excellent durability in use, and is capable of producing high-density, high-quality images. The inkjet recording head of the present invention, which achieves these objects, has an ink passage formed on a substrate that communicates with an ejection port through which ink is ejected, using a film formed using a photosensitive resin. In the inkjet recording head, the substrate near the ejection port has, in this order, a band-shaped layer made of at least one of an inorganic oxide and an inorganic nitride, an adhesion improver layer, and the above film. It is characterized by Hereinafter, the present invention will be explained in detail based on the drawings. First, an embodiment of the present invention will be described according to the manufacturing steps shown in FIGS. 1-a to 7-c. In the process shown in Figure 1-a, glass, ceramic,
On a substrate 1 made of plastic, metal, etc., a heating element or piezoelectric element that generates thermal energy is installed as an energy generating element 2 that generates energy used to eject ink from an ink ejection port, corresponding to an ink passage. A desired number of elements etc. are arranged. Next, for the purpose of imparting electrical insulation, SiO ₂ ,
Coated with inorganic oxides and inorganic nitrides such as Ta ₂ O ₅ , Al ₂ O ₃ , glass, Si ₃ N ₄ and BN, and noble metals such as Au, Pd and Pt, Ti and Cr to provide further ink resistance. ,Ni,
A corrosion-resistant metal such as Ta, Mo, W, or Nb or a corrosion-resistant alloy such as SUS or Monel metal is coated as a protective layer. Note that these protective layers are not shown, and a signal input electrode is connected to the ink ejection pressure generating element 2. FIG. 1-b is a sectional view of the substrate. In the subsequent step of FIG. 1-c, inorganic oxide and/or inorganic oxide and/or
Or, as the inorganic nitride 3, SiO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , Si ₃ N ₄ , BN,
Forms a thin film of glass, etc. In this case, the thickness of the inorganic oxide and/or inorganic nitride layer is preferably 5 .mu.m or less so as not to become a hindrance during later coating with a photosensitive resin film. In the step of FIG. 1-d, the inorganic oxide and/or inorganic nitride 3 is left only on the portion facing the end face where the ink ejection port is formed of the substrate 1 on which the ejection pressure generating element is arranged. covered with a photoresist image by the photolithographic method of
Remove unnecessary parts by etching. However, if the method described above is not used, in other words, the inorganic oxide and/or inorganic nitride 3 is newly added to the surface of the substrate 1.
The thin metal layer that has been coated in advance to improve the ink resistance of the substrate 1 is removed by photolithography only in the necessary areas, without coating the thin metal layer below the thin metal layer. Another method is to expose a layer of inorganic oxide and/or inorganic nitride. Figure 2 shows what was obtained through the above steps.
a, and its cross-sectional view is shown in FIG. 2-b. As shown in FIG. 2-a, the inorganic oxide and/or inorganic nitride layer 3 is formed in a band-like manner on the part facing the end surface of the substrate where the ink ejection openings, which require particularly high adhesive strength, are formed. Although it is preferable to provide this layer, since this layer is not necessary in the portion where the ink passage is formed, a comb-shaped layer of inorganic oxide and/or inorganic nitride may also be provided. However, if an inorganic oxide or inorganic nitride is provided in a band shape, the surface of the substrate near the discharge port can be made uniformly flat, and the adhesive force between the substrate side and the film made of photosensitive resin can be improved. can be improved. Next, the surface of the substrate 1 obtained in the process shown in Fig. 2 is cleaned and dried at 80 to 110°C for 10 minutes or more. ₂ (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃
(1% solution of ethyl alcohol) at 1000 to 6000 rpm
Coat with a spinner and then heat at 80°C for 10-20 minutes. In the method of the present invention, in addition to the above-mentioned γ-aminopropyltriethoxysilane, generally known organic silane compounds, organic titanium compounds, organic aluminum compounds, and organic zinc compounds can be used as adhesion improvers. For these adhesives, it is preferable to select and use an adhesion improver having a functional group that reacts with the photosensitive resin, depending on the composition of the photosensitive resin used. Tables 1 and 2 summarize typical organic silane compounds and organic titanium compounds by functional group.

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[Table] In the step shown in FIG. 3, the surface of the substrate 1 obtained through the step shown in FIG. Dry film photoresist 5 (film thickness, approx.
25μm~100μm) at a speed of 0.5~4f/min, 1~3
Laminate under pressure conditions of Kg/ ^cm2 . At this time, the dry film photoresist 5 exhibits self-adhesive properties and is fused and fixed to the surface of the substrate 1, and will not peel off from the substrate 1 even if considerable external pressure is applied thereafter. In particular, in this example, an inorganic oxide or inorganic nitride is provided on the substrate using the same semiconductor manufacturing process as that used to form heating elements, electrodes, etc. It has strong adhesion to the substrate side, and also has good bonding with the adhesion improver at the molecular level (bonding due to chemical bonding force), resulting in strong adhesion to the dry film photoresist 5. It will be held on. Subsequently, as shown in FIG. 4, a photomask 6 having a predetermined pattern is superimposed on the dry film photoresist 5 provided on the substrate surface, and then the photomask 6 is exposed to light from above. At this time, it is necessary to align the installation position of the ink ejection pressure generating element 2 and the pattern using a known method. FIG. 5 is an explanatory diagram showing a process in which the unexposed portions of the exposed dry film photoresist 5 are dissolved and removed using a developer made of a predetermined organic solvent. Next, in order to improve the ink resistance of the exposed portion 5p of the dry film photoresist left on the substrate 1, heat curing treatment (for example, at 150°C to 250°C) is performed.
heating for 30 minutes to 6 hours) or ultraviolet irradiation (e.g.
(with UV intensity of 50-200mW/ ^cm2 or higher)
to sufficiently advance the polymerization and curing reaction. It is also effective to use both the above-mentioned heat curing and ultraviolet curing. FIG. 6 shows the cured dry film resist 5p that has been sufficiently polymerized as described above, and a flat plate 8 serving as a cover is fixed to the substrate 1 in which grooves 9 serving as ink passages are formed, either by gluing or simply crimping the resist 5p. FIG. In the process shown in Figure 6, the specific method for attaching the cover is as follows: (1) Apply epoxy adhesive to a thickness of 3 to 4 μm on a flat plate 8 made of glass, ceramics, metal, plastic, etc.
After applying spinner coating to the photoresist film 5p, the adhesive is preheated to bring it to the so-called B stage, and this is bonded onto the cured photoresist film 5p to fully cure the adhesive. Alternatively, (2) there is a method of directly heat-sealing a flat plate 8 of thermoplastic resin such as acrylic resin, ABS resin, polyethylene, etc. onto the hardened photoresist film 5p. Here, the appearance of the head after the process shown in FIG. 6 is completed is shown in a schematic perspective view in FIG. 7-a. Figure 7-a
Inside, 9-1 is an ink supply chamber, 9 is an ink narrow flow path,
Reference numeral 10 indicates a through hole for connecting an ink supply pipe (not shown) to the ink supply chamber 9-1. After the substrate in which the grooves have been formed and the flat plate are bonded together in this way, the substrate is cut along line CC' in FIG. This is done to optimize the distance between the ink ejection pressure generating element 2 and the ink ejection opening 7 in the ink narrow flow path 9, and the area to be cut here is determined as appropriate. For this cutting, a dicing method commonly used in the semiconductor industry is used. FIG. 7-b is a cross-sectional view taken along line A-A' in FIG. 7-a. Then, the cut surface is polished to make it smooth, and the ink supply tube 11 is attached to the through hole 10 to complete the inkjet recording head. (Fig. 7-c) In the embodiments described above based on the drawings, the photosensitive composition (photoresist) for creating grooves is
Although a dry film type, that is, a solid composition was used as the composition, the present invention is not limited to this, and of course, a liquid photosensitive composition can also be used. In the case of a liquid, the photosensitive composition coating film is formed on the substrate by using a squeegee, which is used when producing a relief image. In this method, excess composition is removed using a squeegee. In this case, the appropriate viscosity of the photosensitive composition is 100 cp to 300 cp. Further, the height of the wall around the substrate must be determined in consideration of the reduction in evaporation of the solvent component of the photosensitive composition. On the other hand, in the case of a solid, the photosensitive composition sheet is attached to the substrate by heat-pressing. In the present invention, it is advantageous to use a solid film type material in terms of its handling and the fact that the thickness can be easily and precisely controlled. Such solid materials include, for example, DuPont's permanent photopolymer coatings.
RISTON (solder mask) 730S, 740S, RISTON
There are photosensitive resins commercially available under trade names such as 730FR, 740FR, and SM1. In addition, the photosensitive composition used in the present invention includes many photosensitive compositions used in the field of ordinary photolithography, such as photosensitive resins and photoresists. These photosensitive compositions include, for example, diazoresin, P-diazoquinone, photopolymerizable photopolymers using a vinyl monomer and a polymerization developer, and dimerized photopolymers using polyvinyl cinnamate and a sensitizer. Photopolymer, mixture of orthonaphthoquinone diazide and novolac type phenolic resin, mixture of polyvinyl alcohol and diazo resin, 4-
Polyether-type photopolymers made by copolymerizing glycidyl ethylene oxide with benzophenone or glycidyl chalcone, copolymers of N,N-dimethylmethacrylamide with, for example, acrylamide benzophenone, unsaturated polyester-based photosensitive resins [for example, APR (Asahi Kasei Co., Ltd.)] ), Tevista (Teijin), Sonne (Kansai Paint), etc.], unsaturated urethane oligomer-based photosensitive resins, photosensitive compositions in which a difunctional acrylic monomer is mixed with a photopolymerization initiator and a polymer, dichromic acid-based photosensitive resins, etc. resist, non-chromium water-soluble photoresist, polyvinyl cinnamate photoresist, cyclized rubber-azide photoresist, and the like. The effects of the present invention described in detail above include the following. 1. Due to the increased adhesion between the substrate and the photosensitive resin, the photosensitive resin no longer peels off from the substrate even when cutting the ink ejection port formation, which is particularly impactful. 2. The solvent resistance of the bonded portion has been improved, and the passage wall between the substrate and the photosensitive resin cured film no longer peels off even when ink containing a solvent such as ethylene glycol is used. 3. Since the shape stability of the ink ejection port is high, the accuracy of the ink landing point over time is high. These effects of the present invention will be explained more specifically by the examples shown below. Examples 1 to 6 and Comparative Examples 1 to 3 Between each example, an inorganic oxide or inorganic nitride layer was provided or not provided on a portion of the protective layer facing the end face where an ink ejection port is formed, and layer(a)
The inks were prepared according to the steps of the examples set forth above (Figures 1 to 7), with or without treatment with gamma-aminopropylethoxysilane or (b) tetrastearyl titanate. outlet
A number of trial inkjet recording heads with 10 heads were manufactured. Among these prototype heads, normal ones with no peeling between the substrate and the photosensitive resin were soaked in a solution of 20% water and 80% ethylene glycol at 80°C.
A 1000 hour immersion test was conducted. These results are shown in Table 3. Furthermore, when a 10 ⁸ pulse durability printing test was conducted on the inkjet recording heads obtained in Example 1 and Comparative Example 1, the impact point accuracy was ±12 μm/2 mm flight distance in the example head. In contrast, the flight distance of the comparative head was ±60 μm/2 mm. The photosensitive resin used was RISTON730S dry film photoresist (manufactured by DuPont, trade name).

【table】 [Brief explanation of drawings]

FIGS. 1-a to 7-c are schematic diagrams for explaining the inkjet recording head of the present invention according to its manufacturing process. 1: Substrate, 2: Ink discharge pressure generating element, 3: Inorganic oxide and/or inorganic nitride layer, 4: Photoresist image, 5: Dry film photoresist,
6: Photomask, 7: Ink discharge port, 8: Cover, 9: Ink narrow channel, 9-1: Ink supply chamber,
10: Through hole, 11: Ink supply pipe.

Claims (1)

[Scope of Claims] 1. An inkjet recording head in which an ink passage communicating with an ejection port through which ink is ejected is provided on a substrate using a film formed using a photosensitive resin, the ejection port comprising: An inkjet recording head characterized in that it has a strip-shaped layer made of at least one of an inorganic oxide and an inorganic nitride, an adhesion improver layer, and the film on the substrate nearby, in this order. . 2. The ink jet according to claim 1, wherein an energy generating element that generates energy used for ejecting ink from the ejection port is provided corresponding to the ink passage. Record head. 3. The inkjet recording head according to claim 2, wherein the energy generating element is an element that generates thermal energy as the energy. 4. The inkjet recording head according to claim 2, wherein the energy generating element is a piezo element.