JPH0415099B2 - - 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 an ink ejection opening (orifice), an ink passage, and an ink ejection pressure generating section provided in a portion 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 distortions occur in the ink passages due to differences in etching, etc. 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. One problem is that it is difficult to accurately align the respective positions during lamination, 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, this method is considered 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 a precise and reliable inkjet recording head. 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 precisely and faithfully to the design, by a simple method and with a 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. In a method for manufacturing an inkjet recording head in which an ink passage communicating with an ejection port is provided, a step of providing a layer made of an inorganic nitride as a protective layer for a heat generating element on a substrate provided with the heat generating element. and a step of treating the surface of the protective layer with a silane coupling agent, and a step of forming walls of ink passages using a photosensitive resin on the protective layer treated with the silane coupling agent. I have to. 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, a heating element or piezoelectric element that generates thermal energy is placed on a substrate 1 made of glass, ceramic, plastic, or metal as an energy generating element 2 that generates energy used to eject ink. Arrange the desired number of elements, etc.
For the purpose of imparting electrical insulation, SiO ₂ , Ta ₂ O ₅ ,
A protective layer 3 made of an inorganic oxide and/or an inorganic nitride such as Al ₂ O ₃ , glass, Si ₃ N ₄ or BN is coated. These inorganic oxides and inorganic nitrides are materials that fully exhibit the effect of the silane coupling agent treatment performed to improve the adhesion with the photosensitive resin cured film described below. 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. ( _CH2 ) _3Si
(OCH ₃ ) ₃ , 1% solution of ethyl alcohol
10 at 80℃ after spinner coating at ~6000rpm
The substrate 1 is heated for 1 minute to promote the reaction between the substrate 1 and the silane coupling agent, and the silane coupling agent layer 4 is laminated to a thickness of 0.3 μm or less.
The substrate shown in the figure is obtained. In the method of the present invention, all commonly known silane coupling agents can be used, and Table 1 summarizes representative ones by functional group. As the silane coupling agent, it is preferable to use a silane coupling agent having an appropriate functional group that reacts with the photosensitive resin side, based on the composition of the photosensitive resin used.

【table】

【table】

[Table] Next, apply silane coupling agent layer 4 at 80℃~
Dry film photoresist 5, which is a photosensitive resin heated to about 105°C (film thickness, about 25 μm ~
100 μm) at a speed of 0.5 to 4 f/min and a pressure of 1 to 3 Kg/cm ² . 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 with the above pattern using a well-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, heat curing treatment (for example, (heating at 250° C. for 30 minutes to 6 hours) or UV irradiation (for example, at a UV intensity of 50 to 200 mW/cm ² or more). It is also effective to have both the above-mentioned heat curing and UV curing. If the used silane coupling agent layer 4 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, so it should not be exposed in the groove 9. It is preferable to remove the silane coupling agent layer 4 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. The specific method for attaching the cover in the process shown in Fig. 6 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 bring it to the 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 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 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 embodiment described above based on the drawings,
Although a dry film type, that is, a solid one, was used as the photosensitive composition (photoresist) for creating grooves, the present invention is not limited to this, and of course, a liquid photosensitive composition may also be used. can do. 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. is placed around the substrate, and excess composition is removed 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 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. Incidentally, in the present invention, it is advantageous to use a solid film type material in terms of handling and the fact that the thickness can be easily and accurately controlled. Examples of such solid sheets include Dupont's permanent photopolymer coating RISTON (solder mask) 730S, 740S,
There are photosensitive resin sheets 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 of the photosensitive compositions used in the field of ordinary photolithography such as photosensitive resins and photoresists are mentioned, such as diazoresins, P-diazoquinones, and even those containing vinyl monomers and polymerization initiators. The photopolymerizable photopolymer used, the double photopolymer using polyvinyl cinnamate, etc. and a sensitizer, the mixture of orthonaphthoquinone diazide and volac type phenolic resin, the copolymerization of 4-glycidyl ethylene oxide and benzophenone or glycidyl chalcone. polyether type photopolymer, N,
Copolymers of N-dimethylmethacrylamide and acrylamide benzophenone, unsaturated polyester photosensitive resins [e.g. APR (Asahi Kasei),
Tevista (Teijin), Sonne (Kansai Paint), etc.],
Unsaturated urethane oligomer photosensitive resin, photosensitive composition containing a difunctional acrylic monomer mixed with a photopolymerization initiator and polymer, dichromic acid photoresist, non-chromium water-soluble photoresist, polyvinyl cinnamate photoresist Examples include resist, 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 specifically explained by the examples shown below. Examples 1 to 3 and Comparative Examples 1 to 3 Except that the material of the surface of the protective layer was changed between each example and the treatment with γ-mercaptopropyltrimethoxysilane was performed or not. The steps of the embodiment shown in (Figs. 1 to 6)
A number of trial inkjet recording heads with 10 ink ejection ports were fabricated according to the method shown in Figure 1. Among these prototype heads, for normal ones with no peeling of the substrate and photosensitive resin, 20% water and ethylene glycol were added.
A 1000 hour immersion test was conducted in a solution of 80% composition at 80°C. These results are shown in Table 2. 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]

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 discharge pressure generating element, 3: Protective layer, 4: Silane coupling agent layer, 5: Photosensitive resin, 5P: 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 the steps of: providing a layer made of inorganic nitride as a protective layer for the heating element on the substrate provided with the heating element; and coating the surface of the protective layer with silane. An inkjet recording head characterized by comprising the steps of: treating the ink passage with a coupling agent; and forming the wall of the ink passage using a photosensitive resin on a protective layer treated with a silane coupling agent. Production method.