JPH11334088A - Manufacture of ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove residual stress or microcrack incident to subdividing process from a piezoelectric element in an ink jet recording head where a wide piezoelectric element is bonded to a diaphragm and then subdivided in accordance with pressurization chambers. SOLUTION: After being bonded to a diaphragm 5 (A), a piezoelectric element 6 is placed in grooves 9 and subdivided together with a pressurization chamber 3 by dicing (B). Subsequently, the piezoelectric element 6 is ground to a specified thickness (C) and an electrode 8 is formed on the upper surface of the piezoelectric element 6 through a mask 10 (D). Since the piezoelectric element 6 is ground after being subdivided, residual stress or microcrack incident to dicing can be removed from the piezoelectric element 6 in subsequent grinding process and the lifetime of the piezoelectric element 6 can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head used in a printer, and more particularly to a process for processing a piezoelectric element as an actuator.

[0002]

2. Description of the Related Art FIGS. 3A and 3B show an example of the configuration of an ink jet recording head, wherein FIG. 3A is a cross-sectional view, FIG. 3B is a plan view, and FIG. In FIG. 3, a plurality of rows of groove-shaped ink flow paths formed of a throttle unit 2, a pressure chamber 3, and a nozzle unit 4 are formed on the upper surface of a substrate 1 in parallel with each other.
The diaphragm 5 is joined so as to cover the ink flow path. Although not shown, diaphragm 5 provided with a conductive coating
A piezoelectric element 6 is bonded to the upper surface of the piezoelectric element 6 via an adhesive layer 7 in correspondence with each of the pressure chambers 3.
Are formed.

[0003] Such an ink jet recording head is
The diaphragm unit 2 is connected to an ink supply source via a tube (not shown), and a voltage signal as shown in FIG. 4 is applied between the upper and lower surfaces of the piezoelectric element 6. Displaced inside the pressurizing chamber 3, thereby causing the pressurizing chamber 3
The ink is ejected in the form of droplets from the nozzle unit 4 due to the decrease in the volume of the ink. Since the amount of deformation of the piezoelectric element 6 is proportional to the electric field strength, the thinner the piezoelectric element 6, the lower the voltage at which it can be driven.

FIG. 5 shows a conventional processing step of the piezoelectric element 1. In FIG. 5, a wide piezoelectric element 6 having a thickness of about 100 to 200 μm and a width across each pressurizing chamber 3 is joined to the upper surface of the diaphragm 5 (FIG. 5A), and the piezoelectric element is polished. 1 is reduced to 20 to 30 μm (FIG. 5B). Next, after forming the electrode 8 on the upper surface of the piezoelectric element 6 [FIG.
(C)], the piezoelectric element 6 is subdivided into each pressurizing chamber 3 by forming a groove 9 between the adjacent pressurizing chambers 3 with a dicing saw [FIG. 5 (D)].

As described above, conventionally, a wide piezoelectric element bonded to a vibration plate is thinned by polishing, and then finely divided by a dicing saw. However, in such a conventional method, residual stress and invisible microcracks are generated in the piezoelectric element during dicing, and such a piezoelectric element has a problem in terms of driving life, such as cracking and chipping during repeated deformation. there were. Therefore, an object of the present invention is to
It is to improve the life reliability of the piezoelectric element by devising a processing step.

[0006]

Means for Solving the Problems Conventionally, a piezoelectric element is thinly polished and then subdivided by dicing. In contrast, according to the present invention, the piezoelectric element is subdivided and processed to be thin. That is, according to the present invention, after a vibration plate is joined to a substrate on which a plurality of rows of ink channels having pressure chambers are formed, a piezoelectric element extending to each of the pressure chambers is bonded to the upper surface of the vibration plate. The piezoelectric element is divided into small grooves by dicing or laser processing between the adjacent pressure chambers, and then the piezoelectric element is formed to a predetermined thickness by polishing or etching.

The inventors of the present invention have observed minutely the residual stress and the state of occurrence of microcracks in the piezoelectric element subdivided by forming grooves, and found that most of these defects were in the upper part of the piezoelectric element adjacent to the grooves. Edge part, that is, FIG.
(D) was found to have occurred at the portion indicated as the P portion. Therefore, if the piezoelectric element is thinned after the subdivision, this portion is removed, and no defective portion remains in the subdivided piezoelectric element.

In the present invention, the electrodes on the upper surface of the piezoelectric element are formed in a state in which the piezoelectric element is subdivided, and the mask having the through holes corresponding to each of the subdivided piezoelectric elements is vibrated. Arranged above the plate, forming an electrode on the upper surface of the piezoelectric element through the through hole by coating or vapor deposition, or embedding resin in a groove obtained by subdividing the piezoelectric element, and then forming an electrode on the upper surface of the piezoelectric element. This is possible by forming an electrode by vapor deposition or plating and then removing the resin.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Note that the same reference numerals are used for the portions corresponding to the conventional example, and the description of the same components is omitted as appropriate. FIG. 1 shows the processing steps of the first embodiment. In FIG. 1A, when an ink flow path having a pressure chamber 3 and the like is formed in a substrate 1 made of silicon by photolithography and etching,
A vibrating plate 5 made of borosilicate glass having a thermal expansion coefficient close to that of silicon is electrostatically bonded to the upper surface, and then the upper surface is polished.
The thickness is not more than μm. Subsequently, after a conductive film of a metal oxide film (Indium Tin Oxide) is formed on the upper surface of the diaphragm 5, a wide piezoelectric element 6 having a thickness of about 150 μm is formed thereon.
Are bonded so as to pass over each pressure chamber 3.

Next, as shown in FIG. 1 (B), an adjacent pressurizing chamber 3 is formed by a dicing saw or a laser beam machine.
The piezoelectric element 6 is subdivided according to the width of the pressurizing chamber 3 by inserting a groove 9 therebetween. Thereafter, as shown in FIG. 1C, the piezoelectric element 3 is polished or etched to a predetermined thickness of 100 μm or less. Finally, as shown in FIG.
Through holes 10a corresponding to each of the subdivided piezoelectric elements 6
Is disposed above the vibration plate 5, and Cr, Ni and Au are coated on the upper surface of the piezoelectric element 6 through the through holes 10a by 0.1 μm or 0.25 μm, respectively.
Then, an electrode 8 is formed by sequentially forming a film of 0.2 μm each.

FIG. 2 shows a processing step of a second embodiment in which an electrode forming method is different from that of the first embodiment.
(A) to (C) are the same as in the first embodiment. That is, in FIG. 2D for forming electrodes, the groove 9 is filled with a resin that can be removed later, for example, a water-soluble resin 11,
Cured by UV irradiation. The resin 11 protruding out of the groove 9 is removed by washing or etching. Next, an electrode 8 similar to the above is formed by vapor deposition or plating over the entire surface. Then, when the whole is ultrasonically cleaned in water, the cured resin 11 in the groove 9 is dissolved,
The electrode-forming metal film bridging the groove 9 is also removed by the impact of the ultrasonic wave, and the electrode 8 remains only on the upper surface of the piezoelectric element 6 as shown in FIG.

[0012]

As described above, according to the present invention, the edge portion of the piezoelectric element in which the residual stress or the micro-crack is generated by the subdivision processing is removed in a subsequent step, so that the piezoelectric element can be formed only by a sound element material. It can be configured, and its life reliability is greatly improved. Also, since cracks and breakage during use are less likely to occur, the thickness of the piezoelectric element can be made thinner than before, and the electric field strength acting on the piezoelectric element can be further increased. This makes it possible to manufacture a compact, multi-nozzle, compact inkjet recording head.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a processing step of a piezoelectric element according to an embodiment of the present invention, in which FIG. 1A is a joining step, FIG.
(C) is a polishing step, and (D) is an electrode forming step.

FIGS. 2A and 2B are process diagrams of a piezoelectric element showing different embodiments of the present invention, wherein FIG. 2A is a joining process, FIG. 2B is a fragmentation process, FIG. 2C is a polishing process, and FIG. And (E) is a resin removing step.

3A and 3B show an example of the configuration of an ink jet recording head, where FIG. 3A is a cross-sectional view, FIG. 3B is a plan view, and FIG. 3C is a cross-sectional view.

FIG. 4 is a waveform chart showing an example of an electric signal applied to the ink jet recording head of FIG.

FIG. 5 is a process chart of a piezoelectric element showing a conventional method,
(A) is a bonding step, (B) is a polishing step, (C) is a fragmentation step, and (D) is an electrode formation step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 3 Pressurization room 5 Vibration plate 6 Piezoelectric element 8 Electrode 9 Groove 10 Mask 10a Through hole 11 Resin

Claims (3)

[Claims] 1. A diaphragm is joined to a substrate on which a plurality of rows of ink channels having pressurizing chambers are formed, and a piezoelectric element extending to each of the pressurizing chambers is bonded to an upper surface of the vibrating plate. A method for manufacturing an ink jet recording head, comprising: subdividing an element by forming a groove between the adjacent pressure chambers; and forming the piezoelectric element to a predetermined thickness. 2. A mask having a through hole corresponding to each of the subdivided piezoelectric elements is arranged above the diaphragm.
2. The method according to claim 1, wherein an electrode is formed on an upper surface of the piezoelectric element through the through hole. 3. An ink jet recording method according to claim 1, wherein after the resin is buried in the groove obtained by subdividing the piezoelectric element, an electrode is formed on the upper surface of the piezoelectric element, and then the resin is removed. Head manufacturing method.