JPS58224758A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To provide an ink jet head which is excellent in durability by such an arrangement wherein a membrance of hardened photosensitive resin at the end of an ink discharge nozzle is tightly adhered to a substrate through a layer of inorganic oxide and/or inorganic nitride and a layer of adhesion improving agent, and thereby, the occurrence of separation between layers is prevented. CONSTITUTION:On the surface of a substrate 1, a desired number of ink discharge pressure generating element 2 such as a heat generating element or a piezo element, etc. are arranged, and preferably its surface is covered with an electric insulation layer and an ink resistive protective layer, and after that, on its surface, a layer 3 of inorganic oxide and/or inorganic nitride is formed by the sputtering method, etc. Next, the layer 3 is removed by well known photolithography except such a portion which faces the end of a substrate 1 where ink discharge nozzles are to be formed. Next, the layer is cleaned and it is coated with an adhesion improving agent such as organic silane compound, organic zinc compound, etc., and a photosensitive resin is coated on the surface and an ink passage is provided by photolithography and an ink jet head is obtained by covering its surface with a lid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording head for generating recording ink droplets used in a so-called inkjet recording system.

An inkjet recording head applied to an inkjet recording method 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 bond the plate with these grooves to another suitable plate. There is a known method for forming ink passages.

However, with the blades and blades made by such conventional methods, the roughness of the inner wall surface of the ink passage to be cut is too large, and distortion occurs in the ink passage due to the difference in etching rate. is difficult to obtain, and the ink ejection characteristics of the manufactured inkjet recording head tend to vary. Also, during cutting, the plate is likely to chip or crack.
Another disadvantage is that the manufacturing yield is poor. When etching is performed, there are many manufacturing steps, which is disadvantageous in that it increases manufacturing costs. Furthermore, common shortcomings of the conventional methods described above include the grooved plate in which the ink passage grooves are formed, the piezoelectric element that generates the energy that acts on the ink,
When bonding to a screen plate provided with drive elements such as heat generating elements, it is difficult to align each element with high accuracy, resulting in a lack of mass productivity.

As an inkjet recording head having a configuration that solves these drawbacks, an ink passage wall made of a cured film of photosensitive resin is formed on a substrate on which an ink ejection pressure generating element is installed, and then a cover is provided on the passage. The inkjet recording head is, for example, disclosed in Japanese Patent Application Laid-Open No. 37-1/13. ! ? It is known by No. 7 Otsu.

The inkjet recording head manufactured using this photosensitive resin is superior in that it solves the drawbacks of conventional heads, such as ink passage finishing accuracy, complexity of the manufacturing process, and poor manufacturing yield. It is something. 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 adhesion 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 of the ink droplet ejection or due to changes in the ink droplet itself over time. The substrate at the ink ejection port portion and the passage wall are peeled off, although very slightly, which affects the straightness of the ink droplet, that is, the accuracy of the ink landing point. This has been a major hindrance in recent years, as inkjet recording systems have been increasingly required to provide high-resolution image quality due to high-density nozzles.

The present invention was made in view of the above-mentioned drawbacks, and an 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 obtaining high-density, high-quality uniformity. The purpose is

The present invention, which has achieved such an object, is an inkjet recording head formed by laminating a substrate, a cured photosensitive resin film that forms an ink passage on the surface of the substrate, and a cover for the passage, in which ink ejection ports are formed. An inkjet recording characterized in that a portion of the photosensitive resin cured film facing the cured end surface is in close contact with a layer made of an inorganic oxide and/or an inorganic nitride on the substrate via an adhesion promoter layer. It is the head.

Hereinafter, the present invention will be explained in detail based on the drawings.

First, the present invention will be explained in detail according to the manufacturing steps shown in FIGS. 1-a to 7-0.

In the process shown in Figure 1-a, glass and ceramics are used.

A desired number of ink ejection pressure generating elements 2 such as heating elements and piezo elements are arranged on a substrate made of plastic, metal, etc. Next, for the purpose of imparting electrical insulation, Si
O! + Ta205 + Altos + glass,
In order to coat inorganic oxides and inorganic nitrides such as Sis N4 + BN, and further provide ink resistance, noble metals such as Au, Pd, and Pt, Ti, Cr+ Ni+ Ta+ Mo,
Corrosion-resistant metals such as W and Nb or SUS.

Cover with a corrosion-resistant alloy such as Monel metal 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. FIG. 1-b is a sectional view of the substrate.

In the subsequent step shown in FIG. 1-0, St O is applied as an inorganic oxide and/or inorganic nitride 3 to the surface of the substrate having the ink ejection pressure generating element 2 by vapor deposition, sputtering, etc.
x, Tag's, Alx Os, 5isN4
．． B.N.

Forms a thin film of glass, etc. In this case, the thickness of the inorganic oxide and/or inorganic nitride layer is preferably jμ or less so as not to become an obstacle when later covering with a photosensitive resin film.

In the step shown in 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 on which the ejection pressure generating element is arranged.
It is covered with a photoresist image using well-known photolithography, and then unnecessary portions of the inorganic oxide and/or inorganic nitride 3 are removed by etching using well-known methods.

However, without using the above method, that is, without newly coating the surface of the substrate with a thin layer of inorganic oxide and/or inorganic nitride 3, it is possible to coat the substrate in advance for the purpose of increasing the ink resistance. There is also a method in which a certain thin metal layer is removed only in a necessary region by photophosphorography to expose an inorganic oxide and/or inorganic nitride layer underlying the thin metal layer. The result obtained through the above steps is shown in Figure 2-a.
, whose cross-sectional view is shown in FIG. 2-b.

The layer 3 of inorganic oxide and/or inorganic nitride is shown in FIG.
As shown in , it is preferable to provide a band-like layer on the end face of the substrate where the ink discharge ports, which require particularly high adhesive strength, are formed, but this layer is not necessary in the area where the ink passages are formed. It is also possible to provide a comb-shaped layer of inorganic oxide and/or inorganic nitride.

Next, the surface of the substrate obtained in the process shown in Fig. 2 was cleaned and dried at 0 to 710°C for 70 minutes or more, and then an adhesion improver (γ-aminopropyltriethoxysilane, molecular structure: N'H='(CHz)-S1(OC!H
l) - 7% ethyl alcohol solution) /θθθ ~ Otsuθ
Spin Soto heel at 00 rpm and then 70~,2 at 0°C.
Heat for θ minutes.

In the method of the present invention, generally known organic silane compounds, organic titanium compounds, organic aluminum compounds, and organic zinc compounds can be used as adhesion improvers in addition to the above-mentioned γ-aminopropyltriethoxysilane. . 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 according to their functional systems.

Table / Table - In the process shown in Figure 3, the substrate obtained through the process shown in Figure 2 /
After cleaning and drying the surface, the surface is heated to θ℃~/
A dry film photoresist j (thickness, about 2Sμ to /θθμ) heated to about θS°C is laminated at a speed of θS-gf/min and under pressure of /~3kg/cd.

At this time, the dry film photoresist j exhibits self-adhesive properties and is fused and fixed to the surface of the substrate/, and will not peel off from the substrate/ even if a considerable external pressure is applied afterwards ◇ Especially improved adhesion It is firmly adhered to the layer made of inorganic oxide and/or inorganic nitride treated with the agent.

Subsequently, as shown in FIG. 9, a photomask g'lc having a predetermined pattern is superimposed on a dry film photoresist j provided on the substrate surface, and then the upper part of this photomask B is exposed to light. At this time, it is necessary to align the installation position of the ink ejection pressure generating element with the pattern using a well-known method.

FIG. S is an explanatory diagram showing a process of dissolving and removing the unexposed portions of the dry film photoresist j in the exposure barrel using a developer made of a predetermined organic solvent. Next, heat curing treatment (for example, /
The polymerization and curing reaction is sufficiently advanced by heating at Sθ°C~2Sθ°C for 3θ minutes~2 hours or by irradiating with ultraviolet light (e.g., at an ultraviolet intensity of jO~, 20θmW/crl or more).

It is also effective to use both the above-mentioned heat curing and ultraviolet curing.

Figure 6 shows a cured dry film resist jp that has undergone polymerization with the above distribution and is fixed by adhering or simply press-bonding a flat plate to serve as a cover to a substrate/with grooves 2 forming ink passages. FIG. In the process shown in Fig. 3, the specific method for attaching the cover is as follows: /) Apply epoxy adhesive to a flat plate of glass, ceramics, metal, plastic, etc. and apply spinner coating to a thickness of 3 to 30 cm. Thereafter, the adhesive is heated to a so-called B stage by heating, and is bonded onto the cured photoresist film jp to fully cure the adhesive. Alternatively, 2) There is a method of directly heat-sealing a flat plate of thermoplastic resin such as acrylic resin, ABS resin, or polyethylene to a hardened photoresist film TP soil.

Here, the appearance of the head after the process shown in Figure 3 is shown in Figure 7-
A is shown in a schematic perspective view. In Figure 7-a, ? - / is ink supply chamber, S is ink narrow channel, 10 is ink supply chamber 2
- / indicates a through hole for connecting an ink supply pipe (not shown).

After the substrate in which the grooves are formed and the flat plate are bonded together in this way, the substrate is cut along the line cc' in FIG. 7. This is done to optimize the distance between the ink ejection pressure generating element and the ink ejection lower in the ink narrow flow path 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. 7-a is a sectional view taken along the line A-A' of FIG. 7-a. Then, the cut surface is polished to make it smooth and penetrate.In the embodiment described based on the drawings, a dry film type, that is, a solid one, is used as the photosensitive composition (photoresist) for creating the groove. However, the present invention is not limited to this only, and 1. Of course, liquid photosensitive compositions are also available.
can 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 viscosity of the photosensitive composition is /θOcp~30θc
p is appropriate. 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 handling and the fact that the thickness can be easily and precisely controlled.

Examples of such solid materials include Devon's permanent photopolymer coating RISTON (
Solder mask) 73θS, 7gθS, 73θFR
There are photosensitive resins commercially available under trade names such as , 74tθFR, and SM/. 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
- Diazoquinones, as well as photopolymerizable photopolymers using vinyl monomers and polymerization initiators, trimerized photopolymers using polyvinyl cinnamate, etc. and sensitizers, mixtures of ornaphthoquinone diazides and novolac-type phenolic resins; , mixed ether type photopolymer of polyvinyl alcohol and diazo resin, copolymer of N,N-dimethylmethacrylamide and, for example, acrylamidobenzophenone, unsaturated polyester photosensitive resin [for example, APR (chemical-free), Tevista ( (Kanairi), Sonne (Kansai Paint), etc.], unsaturated urethane oligomer-based photosensitive resins, photosensitive compositions in which trifunctional acrylic monomers are mixed with photopolymerization initiators and polymers, dichromate-based photoresists, non-chromium Examples include water-soluble photoresists, polyvinyl cinnamate photoresists, cyclized rubber-azide photoresists, and the like.

The effects of the present invention described in detail above include the following.

Due to the increased adhesion between the substrate and the photosensitive resin, the photosensitive resin no longer peels off from the substrate even when the ink ejection port formation is cut, which is particularly impactful.

2. The solvent resistance of the bonded portion has been improved, and the passage walls between the substrate and the photosensitive resin cured film no longer separate from each other even when insulators containing solvents such as ethylene glycol are 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.

Example 7 - B and Comparative Example / - 3 An inorganic oxide or inorganic nitride layer was provided or not provided on the protective layer in the portion facing the end face where the ink ejection port was formed on each side, and except that the layer was treated with or without treatment with (a) γ-aminopropylethoxysilane or (b) tetrastearyl titanate.
A large number of inkjet recording heads having 70 ink ejection orifices were experimentally manufactured according to the steps of the example shown above (FIGS. 1 to 7). Among these prototype heads, a normal one with no peeling of the substrate and photosensitive resin was soaked in a solution of 20% water, ethylene glycol, and θ at 0°C for 70 minutes.
A immersion test was conducted for 00 hours. These results are shown in Table 3.

In addition, when the inkjet recording head obtained in Example/and Comparative Example/ was subjected to a /θ° pulse durability printing test, the landing point accuracy of the head of Example was 7.2μ//.
, 2WrM flight distance, whereas the comparison head had a 2WrM flight distance of 0, 2WrM, and 0.The photosensitive resin was all RISTON 73θS dry film photoresist (manufactured by DuPont, commercial product). name) was used.

Table 3

[Brief explanation of the drawing]

FIG. 1-a to FIG. 7-0 are schematic diagrams for explaining the inkjet recording head of the present invention according to its manufacturing process. /: Substrate, 2 = Ink discharge pressure generating element 3: Inorganic oxide and/or inorganic nitride layer: 7 Photoresist image j: Dry film photoresist B: Photomask 7: Ink discharge port and: Cover ?
= Narrow channel saw /: Ink supply chamber /θ: Through hole //: Ink supply tube Patent applicant Canon Co., Ltd. Fig. 5-〇No. 6tl-G Fig. 5-b Fig. 6-b

Claims (1)

[Claims] /) An inkjet recording head in which ink ejection ports are formed by laminating a substrate, a photosensitive resin cured film forming an ink passage on the surface of the substrate, and a cover for the passage. An inkjet recording head characterized in that a portion of the cured photosensitive resin film facing the end surface is in close contact with a layer made of an inorganic oxide and/or an inorganic nitride on the substrate via an adhesion promoter layer. , 2) The inkjet according to claim 1, wherein the layer made of the inorganic oxide and/or inorganic nitride is provided in a band shape as the uppermost layer of a protective layer provided on the substrate. recording head. 3) The layer made of inorganic oxide and/or inorganic nitride is in the form of a band formed by removing a part of a protective layer provided on the substrate. Inkjet recording head.