JPH0415102B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an inkjet recording head, and more particularly to a method for manufacturing an inkjet recording head for generating recording ink droplets for use 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, the method for creating such an inkjet recording head is to form fine grooves on a glass or metal plate by cutting or etching, and then combine the plate with the grooves with another suitable plate. A method of forming an ink passage by joining is known. 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 a high quality inkjet recording head, 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 is a problem in that there are many manufacturing steps, leading to an increase in manufacturing costs. Furthermore, a problem common to the conventional methods described above is that the grooved plate in which the ink passage grooves are formed is attached to the substrate on which driving elements such as piezoelectric elements and heating elements that generate energy that acts on the ink are provided. At the time of alignment, it is difficult to perform each position alignment with high precision, and mass production is lacking. As a manufacturing method of an ink jet head that can solve these problems, a method of forming ink passage walls with a cured film of a photosensitive resin has been proposed, for example, in Japanese Patent Laid-Open No. 57
-Known from No. 43876. According to this method, the ink passages are microfabricated with high precision, accuracy, and high yield. Furthermore, it can be said to be an excellent method because it is easy to mass-produce and can provide an inexpensive inkjet recording head. However, although the inkjet recording head provided by this improved manufacturing method has solved the above problems, the adhesion between the substrate and the photosensitive resin cured film gradually decreases due to long-term immersion in ink. Minute peeling occurs, which affects the straightness of the ink droplet, that is, the accuracy of the landing point. This has become a major obstacle in recent years as inkjet recording systems are required to provide high resolution image quality with high density nozzles. The present invention has been made in view of the above problems, and
It is an object of the present invention to provide a new method for manufacturing an inkjet recording head that is precise and highly reliable. Another object of the present invention is to provide a method for manufacturing an inkjet recording head in which the ink passages are microfabricated precisely and faithfully to the design, by a simple method and with a high yield. Another object of the present invention is to provide a method for manufacturing an inkjet recording head that has excellent durability in use. The inkjet recording head manufacturing method of the present invention, which achieves these objects, comprises a substrate, a wall, and a cover provided with a heating element that generates thermal energy used to eject ink from an ejection port. In the method for manufacturing an inkjet recording head in which an ink passage communicating with the ejection port is provided, a layer made of a corrosion-resistant metal and a corrosion-resistant alloy excluding noble metals is applied as a protective layer to a heat-generating element on a substrate provided with the heat-generating element. a step of treating the surface of the protective layer with one or more metal organic compounds selected from the group consisting of metal alcoholates, metal acylates, and metal chelate compounds; The method is characterized by comprising the steps of: forming a wall of the ink passage using a photosensitive resin. Hereinafter, the present invention will be explained in detail based on the drawings. 1 to 6 are schematic diagrams illustrating the manufacturing process of an inkjet recording head according to the method of the present invention. In the process shown in FIG. 1, an energy generating element (ink ejection pressure generating element) 2 that generates energy used to eject ink onto a substrate 1 made of glass, ceramic, plastic, or metal is used to generate thermal energy. SiO ₂ , Ta ₂ O ₅ ,
A protective layer (not shown) of inorganic oxide or inorganic nitride such as Al ₂ O ₃ , glass, Si ₃ N ₄ or BN may be coated. In the present invention, a protective layer 3 made of metal is provided on the substrate 1 mainly for the purpose of improving ink resistance.
Cover. The metal forming the protective layer 3 is as follows:
Corrosion-resistant metals such as Ti, Cr, Ni, Ta, Mo, W, and Nb
Corrosion-resistant alloys such as SUS and Monel metal can be used.
Precious metals such as Au, Pd, and Pt have good ink resistance, but
This is not preferred because the matching performance with the metal organic compound described below is insufficient. The thus obtained substrate of FIG.
After drying for 10 minutes at
Made by KK, molecular structure formula

Spinner coat a 1% toluene solution of [Formula]) at 1000 to 6000 rpm, apply it uniformly on the substrate to form a thin film, and then apply it at 80°C.
Heat and dry for 10 minutes to scatter the solvent. In the method of the present invention, in addition to the isopropyl triisostearoyl titanate, one or more metal organic compounds selected from the group consisting of metal alcoholates, metal acylates, and metal chelate compounds can be used on the metal protective layer. The metals constituting these metal-organic compounds are preferably aluminum, zirconium, cobalt, titanium, etc. Other metals are also effective, but have problems in terms of cost and toxicity. Metal alcoholates include ethylate, propylate, butyrate, etc., and industrially easily available metal alcoholates include aluminum isopropylate, titanium isopropylate, and zirconium tert-butyrate. Chelate compounds of these metal alcoholates include generally known acetylacetone, 3-ethylacetylacetone, 3-phenylacetylacetone, 3-methoxyacetylacetone, dibenzoylacetone,
It is obtained by reacting with a chelating agent such as methoxycarbonium acetone. As the metal organic compound, it is preferable to select and use a metal organic compound having a functional group that reacts with the photosensitive resin, depending on the composition of the photosensitive resin used. Table 1 lists representative examples of these metal-organic compounds.
-4 are summarized by metal.

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[Table] Dry film photoresist 5 (film thickness, approximately 25 μm to 100 μm), which is a photosensitive resin, is then heated to approximately 80°C to 105°C on the substrate whose surface has been treated with a metal-organic compound in this manner. 0.5~0.4f/
Laminate at a speed of 1 minute under pressure conditions of 1-3 Kg/ ^cm2 . At this time, the dry film photoresist 5 exhibits self-adhesion and is fused and fixed to the surface of the substrate 1, and will not peel off from the substrate 1 even if a considerable external force is applied thereafter. Subsequently, as shown in FIG. 3, 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. 4 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 such as trichloroethane, and an ink passage 9 is formed. . Next, the ink resistance of the exposed portion 5P of the dry film photoresist left on the substrate 1 is improved;
In order to further increase the adhesion between the dry film photoresist and the substrate through the isopropyltriisostearoyl titanate layer, heat curing treatment (for example, heating at 150 to 250°C for 30 minutes to 6 hours) or ultraviolet irradiation (for example, heating at 150 to 250°C for 30 minutes to 6 hours) (with an ultraviolet intensity of 200 mW/cm ² or higher). It is also effective to use both the above-mentioned heat curing and ultraviolet curing. By the way, if the used isopropyl triisostearoyl titanate layer remains in the groove 9, it may dissolve into the ink and change the quality of the ink, or the function of the ink ejection pressure generating element 2 may be impaired. The exposed isopropyl triisostearoyl titanate layer is preferably removed by ashing with oxygen plasma or the like (FIG. 5). FIG. 6 shows a flat plate 8 serving as a cover on a substrate 1 in which grooves 9 serving as ink passages are formed using dry film photoresist 5P that has been cured after sufficient polymerization.
Although this figure shows a state in which the parts are fixed by adhering with an adhesive layer 7 or simply by pressure bonding, they may be fixed by pressure bonding without using an adhesive. 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, ceramic, metal, plastic, etc.
After spinner coating, the adhesive 7 is preheated to a 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. FIG. 7 is a schematic perspective view of the appearance of the inkjet recording head after the process shown in FIG. 6 is completed. In FIG. 7, reference numeral 9-1 indicates an ink supply chamber, 9-2 indicates an ink narrow flow path, and 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 are formed and the flat plate are bonded together as described above, the substrate is cut along the line CC' in FIG. This is done to optimize the distance between the ink ejection pressure generating element 2 and the ink ejection port 9-3 in the ink narrow flow path 9-2, 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. 8 is a sectional view taken along the line Z--Z' in FIG. 7. 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. 9). In the embodiments described above based on the drawings, a photosensitive composition (photoresist) for creating grooves was used.
Although a dry film type, that is, a solid composition was used, the present invention is not limited to this, and a liquid photosensitive composition can of course also be used. In the case of a liquid, the method of forming the photosensitive composition coating film on the substrate is a method using a squeegee, which is used when producing a relief image, that is, a method of forming a coating film of the photosensitive composition on the substrate, that is, a method using a squeegee that is used when producing a relief image, that is, a wall of a height corresponding to the desired thickness of the photosensitive composition film. An applicable method is to place the composition around the substrate and remove the excess composition using a squeegee. In this case, the viscosity of the photosensitive composition is preferably in the range of 100 CP to 300 CP, and the height of the wall must be determined by taking into account 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 accurately controlled. Examples of such solid materials include Dupont's permanent photopolymer coating RISTON (solder mask) 730S, 740S, 730FR, 740FR,
There are photosensitive resins commercially available under product names such as SM/. In addition, photosensitive compositions that can be used in the present invention include many photosensitive compositions used in the field of ordinary photolithography, such as photosensitive resins and photoresists, such as diazoresin, , P-diazoquinone, as well as photopolymerizable photopolymers using a vinyl monomer and a polymerization initiator, dimerized photopolymers using polyvinyl cinnamate, etc. and a sensitizer, orthonaphthoquinonediazide and novolac type phenolic resins. mixtures of polyvinyl alcohol and diazo resins, polyether type photopolymers obtained by copolymerizing 4-glycidyl ethylene oxide with benzophenone or glycidyl chalcone, copolymers of N,N-dimethyl methacrylamide with e.g. acrylamide benzophenone. A combination of unsaturated polyester photosensitive resins (e.g. APR (Asahi Kasei), Tevista (Teijin), Sonne (Kansai Paint), etc.), unsaturated urethane oligomer photosensitive resins, difunctional acrylic monomers, photopolymerization initiators and polymers. photoresists, dichromate-based photoresists, non-chromium-based water-soluble photoresists, polyvinyl cinnamate-based photoresists, cyclized rubber-azide-based photoresists, 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.

[Brief explanation of drawings]

1 to 6 are schematic diagrams showing the manufacturing process of the inkjet recording head of the present invention. FIG. 7 is a perspective view of an inkjet recording head obtained by the method of the present invention, and FIGS. 8 and 9 are sectional views. 1: Substrate, 2: Ink ejection pressure generating element, 3: Protective layer, 4: Metal organic compound layer, 5: Photosensitive resin,
5P: Ink passage wall, 6: Photomask, 7: Adhesive layer, 8: Cover, 9: Groove, 9-1: Ink supply chamber, 9-2: Ink narrow channel, 10: Through hole, 1
1: Ink supply pipe.

Claims (1)

[Scope of Claims] 1. An ink passage communicating with the ejection port is provided by a substrate, a wall, and a cover provided with a heating element that generates thermal energy used to eject ink from the ejection port. A method of manufacturing an inkjet recording head according to the present invention includes the steps of: providing a layer made of a corrosion-resistant metal and a corrosion-resistant alloy other than noble metals as a protective layer for the heating element on the substrate on which the heating element is provided; a step of treating the surface with one or more metal organic compounds selected from the group consisting of metal alcoholates, metal acylates, and metal chelate compounds; and using a photosensitive resin on the protective layer treated with the metal organic compound. A method of manufacturing an inkjet recording head, comprising: forming the wall of the ink passage.