JPH0415100B2 - - 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, for example, form fine grooves on a glass or metal plate by cutting or etching, and then bond the plate with these grooves to another suitable plate. A method of forming an ink passage using a method 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 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. As a method of manufacturing an inkjet recording head that can solve these problems, a method of forming ink passage walls with a cured film of a photosensitive resin is known, for example, from Japanese Patent Laid-Open No. 57-43876. 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 above-mentioned problems have been solved in the inkjet recording head provided by this improved manufacturing method, the adhesion between the substrate and the photosensitive resin cured film gradually decreases due to long-term immersion in ink. Slight peeling occurs, which affects the straightness of the ink droplets, 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 finely machined with high precision and faithful to the design, by a simple method and with high yield. Furthermore, it is another object of the present invention 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. Accordingly, in a method of manufacturing an ink jet recording head in which an ink passage communicating with an ejection port is provided, a layer made of at least one of an inorganic oxide and an inorganic nitride is used as a protective layer for a 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 step of forming the wall of the ink passage using a photosensitive resin on the protective layer. 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, thermal energy is transferred onto a substrate 1 made of glass, ceramic, plastic, metal, etc. as an energy generating element (ink ejection pressure generating element) 2 that generates energy used to eject ink. SiO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , glass, Si ₃ N ₄ , BN, etc. are used for the purpose of arranging the desired number of heat generating elements or piezo elements and imparting ink resistance and electrical insulation properties. A protective layer 3 made of an inorganic oxide and/or is coated. These inorganic oxides and inorganic nitrides are treated with metal alcoholate,
It is a material that fully exhibits the effects of treatment with one or more metal organic compounds selected from the group consisting of metal acylates and metal chelate compounds. Although not shown, a signal input electrode is connected to the ink ejection pressure generating element 2. Next, the surface of the substrate 1 obtained in the process shown in Fig. 1 was purified and dried at 80°C to 150°C for 10 minutes.

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 heat it at 80℃.
Heat and dry for 10 minutes to scatter the solvent. In the present invention, in addition to the isopropyl triisostearoyl titanate, a metal alcoholate,
One or more metal organic compounds selected from the group consisting of metal acylates and metal chelate compounds can be used. 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,
Metal alcoholates that are industrially easy to obtain include aluminum usopropylate, butyrate, etc.
Examples include titanium isopropylate and zirconium tertiary butyrate. In addition, as the chelate compound, these metal alcoholates can be combined with commonly known chelating agents such as acetylacetone, 3-ethylacetylacetone, 3-phenylacetylacetone, 3-methoxyacetylacetone, dibenzoylacetone, and methoxycarbonium acetone. It is obtained by reaction. 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) as a photosensitive resin was heated to approximately 80°C to 105°C on the substrate whose surface was treated with a metal-organic compound in this manner. from 0.5
Lamination is carried out at a speed of 0.4 f/min 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, 50 to 200 mW) / ^cm2 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 impair the function of the ink ejection pressure generating element 2. 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 bonded and fixed with an adhesive layer 7, they may be fixed by pressure bonding without using an adhesive. In the process shown in Fig. 6, the specific method for attaching the cover is as follows: (1) After applying an epoxy adhesive to a thickness of 3 to 4 μm on a flat plate 8 made of glass, ceramic, metal plastic, etc. using a spinner, The adhesive 7 is heated to a so-called B stage, and 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 as the composition, 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 for forming the photosensitive composition coating film on the substrate is a method using a squeegee, which is used when producing a relief image. 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 needs to be determined in consideration of the evaporation loss 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 permanent photopolymer coatings RISTON (solder mask) 730S, 740S, and RISTON (solder mask) manufactured by DuPont.
There are photosensitive resins commercially available under trade names such as 730FR, 740FR, and 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. photosensitive composition mixed with dichromate photoresist,
Examples include non-chromium water-soluble photoresists, polyvinyl cinnamate photoresists, and cyclized rubber-azide photoresists. 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 3 and Comparative Examples 1 to 3 The material of the surface of the protective layer was changed between each example, and treatment with isopropyl triisostearoyl titanate (trade name TTS, manufactured by Ajinomoto KK) was performed or not. Except for this, a large number of inkjet recording heads having 10 ink ejection ports were fabricated as prototypes in accordance with the steps of the embodiment shown above (FIGS. 1 to 6). Among these prototype heads, regarding the normal ones with no peeling of the substrate and photosensitive resin,
80℃ with a composition of 20% water and 80% ethylene glycol
A 1000 hour immersion test was conducted in a solution of These results are shown in Table 5. 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 ±13 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]

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. DESCRIPTION OF SYMBOLS 1: Substrate, 2: Ink ejection pressure generating element, 3: Protective layer, 4: Metal organic compound, 5: Photosensitive resin, 5
P: ink passage wall, 6: photomask, 7: adhesive, 8: cover, 9: groove, 9-1: ink supply chamber,
9-2: Ink narrow channel, 10: Through hole, 11: 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: providing a layer made of at least one of an inorganic oxide and an inorganic nitride as a protective layer for the heating element on the substrate on which the heating element is provided; 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; and applying a photosensitive layer on the protective layer treated with the metal organic compound. A method of manufacturing an inkjet recording head, comprising the steps of: forming the wall of the ink passage using a resin.