JPH06286150A - Production of ink jet printer head - Google Patents

Abstract

PURPOSE:To obtain a head having stable lyophilic properties in ink flow paths and a high reliability by improving adhesion of a silicon oxide film deposited on a Parylene film in the ink flow paths in a piezoelectrically-driven ink jet printer. CONSTITUTION:A head comprising ink flow paths 4 specified by a large number of grooves formed in parallel to each other in a piezoelectric substrate 1 made of a piezoelectric ceramic and a flat cover bonded on the grooves and a nozzle plate with ink delivery pores bonded on one end of the substrate 1 on the side of the flow paths 4 is provided with a driving electrode film 10 on the inner surfaces of the ink flow paths. In this piezoelectrically-driven ink jet printer head, a Parylene film 12 and a silicon oxide film 14 are deposited in order on the electrode film 10. After that, the surface of the silicon oxide film 14 is bombarded with ions in oxygen-containing gaseous atmosphere. As a result, head keeping lyophilic properties in the ink flow paths and having stable ink delivery characteristics and a high reliablity can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a head portion of a piezoelectric drive type ink jet printer, and more particularly to a method of forming an insulating film covering the surface of an electrode film.

[0002]

2. Description of the Related Art Conventionally, a method of applying a piezoelectric action of a piezoelectric body to a driving force of ink ejection in an inkjet printer, which is one of non-impact printers in application fields such as computer output, is disclosed in Japanese Examined Patent Publication No. 4-48622 and Japanese Patent Laid-Open Publication No. Sho. 63-247051 and the like. The typical manufacturing method and structure thereof is that after processing a fine penetrating groove for an ink flow path on a piezoelectric substrate, an electrode film is formed on the surface, the surface is polished, and the electrode film is formed inside the groove. Then, a parylene film made of polyparaxylylene resin is formed on the inner surface of the groove as an insulating film by a vapor phase synthesis method. This insulating film is positioned as an important constituent for preventing the generation of bubbles and the deterioration of the ink due to the electrolysis of the ink, which causes the unstable ejection of the ink. The method for producing a parylene film is formed by vaporizing and thermally decomposing the raw material diparaxylylene solid dimer, and the generated stable diradical paraxylylene monomer causes a simultaneous reaction of adsorption and polymerization on the substrate. This coating film enables precise coating that cannot be achieved with conventional liquid coating or powder coating, and it can be coated at room temperature regardless of the shape and material of the adherend, and it is unique. It has many excellent characteristics. Therefore, it is attracting attention as an optimal conformal coating film for coating ultra-precision parts as well as general-purpose products.

An ink flow path is formed by adhering the grooved surfaces of the piezoelectric substrate thus produced to each other so as to face each other, or by adhering a flat plate made of glass, ceramic, metal or plastic on the grooved surface. To do. Further, it has an ink discharge hole at one end of the ink flow path, and a nozzle plate coated with a liquid repellent film typified by Teflon is adhered to the surface, and then a drive circuit is connected to the electrode. It

The driving principle of this ink jet printer head is modified such that when a voltage is applied to the electrodes formed in each groove, the partition wall forming the groove increases or decreases the volume of the ink flow path due to its piezoelectric action. To do. The pressure generated by this reduced deformation propagates to the ink filled in the groove and is ejected as an ink droplet from the nozzle hole.

The parylene film, which is an insulating film used in the structure of the above-mentioned ink jet printer head, exhibits extremely high liquid repellency, so that it is very difficult to inject the ink, particularly the water-based ink. The air is mixed in, and the pressure due to the displacement of the piezoelectric body serving as the drive source is relieved. For this reason, the generated pressure did not sufficiently propagate to the ink fluid, which was a major cause of unstable ejection of the ink. As a countermeasure against this, the applicant has already laminated a silicon oxide film on the parylene film to form the parylene film. It is possible to provide an inkjet printer head with stable ink ejection characteristics and high reliability by making the ink lyophilic with respect to the ink, facilitating ink injection, and preventing air from mixing during ink injection. Propose to become.

[0006]

However, the silicon oxide film deposited on the parylene film constituting the above-mentioned ink jet printer head has very poor adhesion due to its internal stress. Will peel off. Further, even if the thickness is 0.05 μm or less, a phenomenon of gradually peeling is often observed when left for a long time. As a result, the liquid-repellent parylene film is exposed, and it becomes difficult to maintain the lyophilicity of the ink flow path with respect to the ink, resulting in problems such as difficult ink injection and unstable ink ejection. It will happen again. The applicant has also confirmed that if the thickness of the silicon oxide film is less than 0.01 μm, the surface of the parylene film cannot be completely covered and the lyophilic property becomes unstable.

An object of the present invention is to stabilize the lyophilicity of the surface of the parylene film by improving the adhesion of the silicon oxide film deposited on the parylene film. Another object of the present invention is to provide a method for manufacturing an inkjet printer having stable ink ejection characteristics and high reliability by facilitating the injection of ink into an inkjet printer head and preventing the mixing of air during the ink injection.

[0008]

In order to achieve the above object, a method of manufacturing an ink jet printer head according to the present invention is a piezoelectric substrate having a penetrating groove made of piezoelectric ceramic, and an electrode film is formed inside the groove. After the formation, a parylene film and a silicon oxide film are sequentially deposited on the silicon oxide film by a gas phase synthesis method, and then the silicon oxide film is subjected to ion bombardment in a gas atmosphere containing oxygen.

[0009]

It has been confirmed by the applicant of the present invention that the parylene film is most suitable for satisfying the insulating function of the electrode film inside the groove in the constitution of the present invention because of its covering property. Further, it is known that a silicon oxide film deposited on the parylene film constituting the present invention to impart lyophilicity generally has high critical surface free energy. Therefore, by coating with such a silicon oxide film, the lyophilic property of the surface of the ink, especially the aqueous ink containing water as a main component, is significantly improved. In addition, the ion bombardment in a gas atmosphere containing oxygen after the deposition of the silicon oxide film has the effect of relaxing the internal stress of the film while maintaining the lyophilic property of the surface of the silicon oxide film by the energy due to the ion bombardment. It has been confirmed by the present applicant that it contributes greatly to the improvement.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a piezoelectric substrate 1 used in an inkjet printer head according to the present invention. An electrode film having a lower layer of chromium and an upper layer of gold is formed by a sputtering method on the piezoelectric substrate 1 which is finely grooved by a diamond blade cutter. Typical dimensions of the groove are 100 microns wide, 400 microns deep, 10 length
In millimeters. By polishing the surface of the piezoelectric substrate 1, the electrode film 10 is left inside the groove. Next, a parylene film 12 of about 5 μm is formed on the surface of the piezoelectric substrate 1 and inside the groove by a vapor phase synthesis method. The parylene film 12 has insufficient smoothness inside the groove of the piezoelectric substrate 1 due to the processing method thereof, so that if the film thickness is less than 1 micron, the electrode film 1 is completely removed.
Since it is difficult to cover the entire surface, it is difficult to maintain the insulating property, and when the film thickness exceeds 10 microns, the displacement of the partition wall forming the groove is suppressed due to the rigidity of the parylene film itself. , It becomes impossible to eject ink. Therefore, the film thickness of the parylene film is 1 micron or more 10
Applicants have determined that sub-micron is optimal. Then, after the parylene film 12 is formed, the silicon oxide film 14 is laminated on the parylene film 12 by 0.02 micron by the sputtering method. In addition to the sputtering method, the silicon oxide film 14 is formed by a vapor phase synthesis method such as an ion plating method or a plasma CVD method, or a sol-coating method.
A wet process such as a gel method is also possible. Here, the silicon oxide film 14 is inferior in adhesiveness on the parylene film 12 due to its internal stress, and peels off when the film thickness exceeds 0.05 μm, and when the film thickness is less than 0.01 μm, the surface of the parylene film is completely removed. The lyophilic property is unstable because it cannot be coated on. Therefore, the optimum film thickness is 0.
It is appropriate that the size is 01 micron or more and 0.05 micron or less.
Then, the surface of the deposited silicon oxide film 14 is subjected to ion bombardment in an argon gas atmosphere containing oxygen. The typical conditions are shown below.

Gas atmosphere: In argon gas containing 20% oxygen Substrate-installed electrode: Cathode Excitation method: High frequency (13.56 MHz) Excitation output: 300 W Gas pressure: 5 × 10 ⁻³ Torr Treatment temperature: 150 degrees or less Treatment time: 5 minutes This ion bombardment treatment is preferably performed continuously when the silicon oxide film is coated by a vapor phase synthesis method such as sputtering. It is also known that under the ion bombardment conditions shown here, if the excitation output and the processing time are longer than this, the silicon oxide film 14 is gradually removed by the etching action of the ion bombardment.

FIG. 2 is an external view of the assembly of this ink jet printer head. The ink flow path 4 is formed by adhering the glass lid 2 having a thickness of about 1 mm on the piezoelectric substrate 1 processed as shown in FIG. An ink jet printer head is constructed by adhering a nickel nozzle plate 3 having a surface coated with a Teflon film to the end of the ink flow path 4 and further connecting a drive circuit to the electrodes.

In order to confirm the effect of the embodiment of the present invention, a head manufactured by the present invention and a head assembled in the same steps except for the step of ion bombarding the silicon oxide film 14 in the above manufacturing method as a comparative head were obtained. As a result of conducting a continuous discharge test with a water-based ink containing 75% by weight of water in an environment of a temperature of 60 degrees and a humidity of 75%, the comparative head was unable to discharge ink in about 50 hours. However, the head according to the present invention was capable of stable ejection even after 1000 hours. Further, as a result of examining the comparative head after the test at this time, the silicon oxide film formed in the ink flow channel was peeled off, and part of the ink flow channel was water repellent.

[0014]

As is apparent from the above examples, according to the present invention, it is possible to stabilize the lyophilicity of the surface of the parylene film by improving the adhesion of the silicon oxide film deposited on the parylene film. (EN) A method for manufacturing an ink jet printer having stable and high reliability of ink ejection characteristics by enabling ink injection to an ink jet printer head and preventing air from being mixed during ink injection. Is possible.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a piezoelectric substrate 1 used in an inkjet printer head in an example of the present invention.

FIG. 2 is an assembly external view of an inkjet printer head according to an embodiment of the present invention.

[Explanation of symbols]

 1 Piezoelectric Substrate 2 Glass Lid 3 Nozzle Plate 4 Ink Channel 5 Ink Discharge Hole 10 Electrode Film 12 Parylene Film 14 Silicon Oxide Film

Claims (2)

[Claims] 1. An ink flow path defined by a large number of parallel grooves formed on a piezoelectric substrate made of a piezoelectric ceramic and a flat plate lid bonded to the upper portions of the grooves, and the ink flow path. A piezoelectric drive type inkjet printer head having a drive electrode film on the inner surface of the ink flow path, which is composed of a nozzle plate having an ink ejection hole adhered to one end of the flow path, and parylene on the electrode film. A method for manufacturing an ink jet printer head, wherein after sequentially depositing a film and a silicon oxide film, the surface of the silicon oxide film is ion bombarded in a gas atmosphere containing oxygen. 2. The method for manufacturing an inkjet printer head according to claim 1, wherein the film thickness of the silicon oxide film is 0.01 micron or more and 0.05 micron or less.