JP2003182077A - Ink jet print head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high density ink jet head exhibiting excellent long term reliability in which variation of liquid drops is suppressed. <P>SOLUTION: The ink jet print head comprises a plurality of pressure chambers partitioned by a barrier wall, a diaphragm sealing one surface of these pressure chambers, insular protrusions arranged on the outside of the diaphragm in correspondence with the pressure chambers, pressure generating elements arranged in correspondence with the insular protrusions, and a nozzle plate having nozzles arranged in correspondence with the pressure generating elements. The insular protrusions are formed while penetrating one single crystal silicon surface of an SOI substrate having single crystal silicon on the opposite sides of a silicon oxide layer, and the pressure chambers are formed at positions corresponding to the insular protrusions on the other single crystal silicon surface while penetrating it. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet head for ejecting ink droplets when receiving print data and forming dots on a recording sheet by the ink droplets, and a method for manufacturing the same. Is.

[0002]

2. Description of the Related Art In a conventional ink jet head, as a method of forming an ink flow path, a method of laminating and adhering a plurality of thin metal plates having ink flow paths formed in advance by etching or the like is disclosed. 4266
As can be seen in Japanese Patent Laid-Open No. 9-93, there is a method of forming an ink flow path by forming a groove for forming a flow path using a cured film of a photosensitive resin and then adhering or pressure-bonding it to a cover plate.

Further, as a method of arranging ink channels in high density, a method of forming ink channels by utilizing anisotropic etching of a silicon single crystal is disclosed in Japanese Patent Laid-Open No. 6-55733. This method discloses a method of manufacturing an inkjet head for forming an ink flow path with high accuracy by applying a photolithography technique and wet anisotropic etching to a silicon single crystal.

Further, in order to reduce the speed variation of the ink ejected from each nozzle, island-shaped protrusions are formed on the vibration plate to which the piezoelectric element serving as a pressure generating element is adhered, and the island-shaped protrusions are piezoelectric. Japanese Patent No. 3070625 discloses an invention that absorbs positional deviation by adhering elements.

[0005]

However, in the conventional method for processing the island-shaped protrusions, the island-shaped protrusions are formed by electroforming on the diaphragm made of metal.
Variations in the height and shape of protrusions between nozzles have been a problem.

As a method for solving the above problem, a material having a two-layer structure of a resin film and a thin metal plate is used for the diaphragm,
A method of forming island-shaped projections by wet etching a thin metal plate has also been devised. However, even in this method, since the diaphragm and the island-shaped protrusions are adhered with an adhesive, there is a problem of reliability against long-term vibration.

The present invention has been made in view of the above problems. An object of the present invention is to form island-shaped projections and pressure chambers located on both sides of a diaphragm by dry etching an SOI substrate. By reducing the shape variation between the nozzles and forming the diaphragm, island-shaped protrusions and pressure chambers integrally, it is possible to reduce the speed variation, and also the long-term reliability and the high-density inkjet with excellent printing quality. To provide a printhead.

[0008]

In order to solve the above-mentioned problems, the present invention provides a plurality of pressure chambers partitioned by partition walls, a diaphragm for sealing one surface of these pressure chambers, and a diaphragm for the diaphragm. A nozzle having an island-shaped protrusion arranged outside corresponding to the pressure chamber, a pressure generating element arranged corresponding to the island-shaped protrusion, and a nozzle arranged corresponding to the pressure generating element. In an ink jet print head including a plate, the island-shaped protrusions are formed by penetrating one of the single crystal silicon surfaces of an SOI substrate having single crystal silicon on both surfaces of a silicon oxide layer and the other single crystal silicon. The pressure chamber is characterized by penetrating the silicon surface at a position corresponding to the island-shaped projection on the surface.

Further, a length of a penetrating portion of the island-shaped projection on the diaphragm in the direction of arrangement is larger than a length of a penetrating portion of the pressure chamber formed on the other surface in the direction of arrangement. .

Further, it is characterized in that all the side surfaces of the island-shaped protrusion and the pressure chamber are formed perpendicularly to the diaphragm.

Further, the island-shaped protrusions and the pressure chambers are penetrated by a dry etching apparatus.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of an ink jet print head of the present invention, in which a piezoelectric element substrate 1 to which a piezoelectric element serving as a pressure generating element is attached, and the pressure generated by the pressure generating element are projected on an island-shaped protrusion. A vibration plate 2 for transmitting, a manifold for supplying ink to each nozzle, a pressure chamber for pressurizing the ink, a chamber substrate 3 having a chamber connected to the nozzle, and a nozzle substrate 4 having a plurality of nozzles.
Each of them is bonded and attached to the head holder 15.

Here, the arrangement pitch of the nozzles is 1/100 inch, about 254 μm, and 96 nozzles are arranged in one row, but the number of nozzles, the number of rows, and the unit configuration are limited in any combination. Not a thing.

FIG. 2 is a sectional view of the head taken along a plane parallel to the ink flow direction of the pressure chamber 5, where 9 is a nozzle in the nozzle plate 4, 6 is a manifold, and 7 is a restrictor.
8 is a chamber, 13 is a diaphragm, 10 is an island-shaped protrusion, 11
Is ink in the arranged pressure chambers 5. The laminated piezoelectric element 12, which is a pressure generating element, is mechanically fixed to a fixed substrate (not shown) having sufficient rigidity, and the mechanical energy generated in the laminated piezoelectric element 12 is the vibration plate 13.
Is transmitted to the ink in the pressure chamber 5 via.

Here, the principle of ink ejection will be briefly described. Although the diaphragm 13 is not bent during standby, when a voltage having the same polarity as the polarization direction is applied, the laminated piezoelectric element 12 contracts in the length direction (downward in the drawing) due to the piezoelectric effect, and the diaphragm 13 is deformed and displaced in the arrow direction. . After that, when the voltage application is stopped, the laminated piezoelectric element 12 is displaced in the direction returning to the original position, so that the ink 11 in the pressure chamber 5 flowing from the manifold 6 is ejected from the nozzle 9 by the pressure generated by the vibrating plate 13. To do. The generated pressure is isotropically applied,
It is efficiently transmitted to the nozzle 9 side by the restrictor 7 attached to the pressure chamber 5.

A method of manufacturing the ink jet head of the present invention will be described with reference to FIG. The diaphragm 13 is an SOI substrate having silicon single crystals formed on both sides of a silicon oxide layer, and is processed by a dry etching method. Note that, unlike the anisotropic wet etching, the plane orientation of the silicon single crystal substrate used is not limited, and thus an inexpensive (100) wafer generally used for semiconductors or the like can be used.

The chamber substrate 3 is preferably made of a silicon single crystal substrate so as to have the same thermal expansion coefficient as that of the vibration plate 13, and the processing method may be either dry etching or anisotropic etching. The SOI substrate 14 to be the vibration plate 13 is bonded to the chamber substrate 3 formed by the above method. Although an adhesive may be used for joining, the compliance of the diaphragm changes due to the protrusion of the adhesive and the like, which causes variation between nozzles. Therefore, it is desirable to sputter the SOI substrate 14 or the chamber substrate 3 by a sputtering method or the like. After forming the glass thin film, the chamber substrate 3 and the silicon substrate 14 made of the diaphragm material are joined by anodic bonding.

First, a silicon oxide film 15 is formed on the surface of the SOI substrate 14 by a thermal oxidation method or the like, and patterning is performed by a photolithography method according to the shape of the island-shaped protrusions 10 to completely remove the silicon oxide film 15. . The etching of the silicon oxide film 15 is performed using a mixed solution of hydrofluoric acid and ammonium fluoride. Silicon oxide film 15
The thickness T of the silicon single crystal substrate 14 is r1, the etching rate of the silicon oxide film 15 is r2, and the height of the island-shaped projections 10 is t1.
Then, a thickness of T1 = r2 · (1-t1) / r1 or more is required. (A) Next, the island-shaped protrusions 10 are etched by dry etching. As etching conditions, CF4 gas and SF6 gas are alternately used as etching gas, and etching is performed at an etching rate of 4 microns per minute.
Here, CF4 gas is used to protect the side surfaces of the island-shaped projections 10 to be formed so that etching does not proceed, and SF6 gas is used to promote vertical etching of the silicon wafer. , Island projection 1
0 can form a wall perpendicular to the substrate. (B) The island-shaped protrusions 10 are formed by the above steps. Next, the silicon oxide film 15 is completely removed by patterning the surface facing the formed island-shaped projections 10 by photolithography according to the shapes of the pressure chamber 5 and the restrictor 7. (C) Next, the pressure chamber 5 and the restrictor 7 are formed by dry etching until the silicon single crystal penetrates to form the pressure chamber and the restrictor. (D) Here, as shown in FIG. 4, the width of the pressure chamber in the nozzle arrangement direction is made larger than the width of the penetrating portion of the island-shaped projection, so that the variation in the area of the diaphragm due to the deviation during patterning is caused. Can be prevented.

Next, the vibration plate substrate 2 and the nozzle substrate 4 are adhered to the chamber substrate 3 to form an ink flow path.
(E) In this embodiment, the substrates are bonded by anodic bonding, but an adhesive may be used.

The dimensional variation among the nozzles of the island-shaped protrusions 10 on the diaphragm 13 manufactured in the above process could be formed with an accuracy of ± 5% with respect to the design dimension. On the other hand, the dimensional variation between nozzles produced by metal wet etching was ± 15%. Variations in the dimensions of the diaphragm cause variations in the compliance of the diaphragm, which greatly affects the variations in speed. Furthermore, since the island-shaped protrusion according to the present invention has an integrated structure with the diaphragm, it is possible to reduce the displacement by 0.5 μm.
Stable displacement characteristics were observed even at 0 kHz and 100 billion pulse driving.

[0021]

According to the present invention, it is possible to accurately form island-shaped projections on a diaphragm by a photolithography method, and to form island-shaped projections and pressure chambers on both sides of the diaphragm. It is possible to form a part integrally, and it is possible to realize a high-quality inkjet printhead that has high density, high accuracy, and excellent long-term reliability.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a sectional view of an inkjet head according to an embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the inkjet head in the embodiment of the present invention.

FIG. 4 is a cross-sectional view in the column direction of a vibration plate substrate of an inkjet head according to an embodiment of the present invention.

[Explanation of symbols]

1 is a piezoelectric element substrate, 2 is a vibration plate substrate, 3 is a chamber substrate, 4 is a nozzle plate, 5 is a pressure chamber, 6 is a manifold, and 7
Is a restrictor, 8 is a chamber, 9 is a nozzle, 10 is an island-shaped protrusion, 11 is ink, 12 is a laminated piezoelectric element, 13 is a vibrating plate, 14 is a silicon substrate, 15 is a silicon oxide film,
16 is a resist, 17 is a head holder, and 18 is a support.

Claims (5)

[Claims] 1. A plurality of pressure chambers partitioned by partition walls,
A vibration plate that seals one surface of these pressure chambers, an island-shaped projection that is arranged outside the vibration plate so as to correspond to the pressure chamber, and a pressure generation that is arranged so as to correspond to the island-shaped projection. In an ink jet print head comprising a device and a nozzle plate having nozzles arranged corresponding to the pressure generating device, the island-shaped protrusion has an SOI having single crystal silicon on both surfaces of a silicon oxide layer. An inkjet formed by penetrating one single crystal silicon surface of a substrate, and the pressure chamber penetrating the silicon surface at a position corresponding to the island-shaped protrusion on the other single crystal silicon surface. Print head. 2. A length of a penetrating portion of the island-shaped projection on the vibration plate in the arrangement direction is made larger than a length of a penetrating portion of the pressure chamber formed on the other surface in the arrangement direction. The inkjet printhead according to claim 1. 3. The ink jet print head according to claim 1, wherein all the side surfaces of the island-shaped protrusion and the pressure chamber are formed perpendicularly to the vibrating plate. 4. A plurality of pressure chambers partitioned by partition walls,
A vibration plate that seals one surface of these pressure chambers, an island-shaped projection that is arranged outside the vibration plate so as to correspond to the pressure chamber, and a pressure generation that is arranged so as to correspond to the island-shaped projection. In an ink jet print head comprising a device and a nozzle plate having nozzles arranged corresponding to the pressure generating device, the island-shaped protrusions of an SOI substrate having single crystal silicon on both sides of a silicon oxide layer. An ink jet print head, characterized in that it is formed so as to penetrate through one of the single crystal silicon surfaces, and that the island-shaped protrusions penetrate through the silicon surface at positions corresponding to the pressure chambers on the other single crystal silicon surface. Manufacturing method. 5. The method for manufacturing an ink jet print head according to claim 4, wherein the penetrating process between the island-shaped protrusions and the pressure chamber is performed by a dry etching device.