JP2003062999A - Ink-jet head and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding method capable of achieving strength improvement and vapor proofing of a piezoelectric element, and repairing a piezoelectric element having a damage such as minute crack by a slicing process. SOLUTION: By coating a piezoelectric element with an epoxy adhesive having a low viscosity (dilution possible) and a low contraction coefficient, strength improvement and vapor proofing effects can be obtained. At the same time, damage caused at the time of a slicing process can be repaired so that the reliability of the piezoelectric element can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head used in an ink jet printer, and more particularly to a method for processing a laminated piezoelectric element having a multi-layer structure which is an ink jet mechanism component of an on-demand type multi-nozzle ink jet head.

[0002]

2. Description of the Related Art Regarding a method for coating a single piezoelectric element, Japanese Patent Laid-Open No. 5-160458 discloses a method for preventing migration of silver by coating a surface of a laminated piezoelectric element with a silicone resin. Further, Japanese Patent Application Laid-Open No. 9-162452 discloses a method of applying a coating agent to the surface of a piezoelectric element in a thickness of several μm to improve the moisture resistance. Further, Japanese Patent Laid-Open No. 11-179905 discloses a method of filling voids of a piezoelectric element with an impregnating material such as epoxy resin in an inkjet head using the piezoelectric element. All of these are considered to be effective methods individually.

[0003]

Conventionally, the slicing process of the piezoelectric element 2 mounted on the ink jet head is carried out by using a slicing grindstone 5 as shown in FIG. After the slicing process, the capacitance and the natural resonance frequency are inspected and measured and mounted on the inkjet head. However, in the measurement of the natural resonance frequency after the slicing process, the piezoelectric element 2 which is out of the standard value
When this piezoelectric element 2 is incorporated into an ink jet head, there is a problem that the ink speed is reduced compared to other piezoelectric elements. In this way, the piezoelectric element whose natural resonance frequency is out of specification due to the cutting load during slicing must be discarded.

Further, there has been a problem that a piezoelectric element, which is regarded as normal, suddenly causes an internal discharge and fails. Furthermore, it has been found that even a normal piezoelectric element may be broken from the internal electrode due to aging.

Regarding these problems, the above-mentioned conventional techniques (Japanese Patent Laid-Open No. 5-160458, Japanese Patent Laid-Open No. 9-162452,
Considering application to JP-A-11-179905),
In the method described in Japanese Patent Laid-Open No. 5-160458, it is unclear whether the method can be applied to a piezoelectric element subjected to slicing treatment, and the strength of the coating material is unclear because the coating material is a silicone resin.

In the method described in Japanese Patent Application Laid-Open No. 9-162452, the coating material has a thickness of several μm, and there is no possibility of coating the piezoelectric element after slicing. It seems that a coating treatment is performed as a wettability treatment during molding. Further, the purpose of coating the piezoelectric element is a wettability treatment, and the strength of the coating layer is not positively improved. The method described in Japanese Patent Application Laid-Open No. 11-179905 describes that the piezoelectric element portion itself can be reinforced by sealing the voids of the piezoelectric element. Further, there is an advantage that the impregnating material can be filled by vacuum impregnation or vacuum pressure impregnation. However, the crack after slicing is 2μ thick
It is an internal electrode layer of about m and cannot cope with this.

Therefore, an object of the present invention is to make the natural resonance frequencies after slicing uniform and reduce defective products due to machining of piezoelectric elements. Another object of the present invention is to improve reliability and strength of the piezoelectric element after slicing.

[0008]

In order to solve the above problems, in the present invention, an ink chamber, a nozzle hole communicating with the ink chamber, a pressure is generated in the ink chamber, and the ink liquid is discharged from the nozzle hole. In an ink jet head having a piezoelectric element for ejecting drops and a substrate for fixing the piezoelectric element, the piezoelectric element is covered with an epoxy adhesive. It is preferable to coat the epoxy adhesive to 10 μm or less.

In order to solve the above-mentioned problems, in the method of manufacturing an ink jet head of the present invention, a step of slicing a single piezoelectric element plate fixed to a substrate into individual piezoelectric elements and an epoxy on the sliced piezoelectric elements. The method includes a step of applying a system adhesive and a step of curing the adhesive applied to the piezoelectric element. At this time, the epoxy-based adhesive is a low-viscosity adhesive that can be dip-coated, and it is preferable that the epoxy-based adhesive can be diluted with a specific organic solvent (for example, acetone or methyl ethyl ketone).

As in the present invention, by coating the piezoelectric element after slicing with an epoxy adhesive, the floating pieces of the internal electrodes are fixed, and the microcracks in the internal electrodes generated during slicing are filled with the adhesive. By doing so, it becomes possible to improve strength and prevent moisture.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 3 is an external view of the piezoelectric element after the slicing process, which is an example of the present invention.

The piezoelectric element 2 is adhesively fixed to the substrate 1, and a conductive adhesive (conductive epoxy adhesive or the like) 3 is applied to the piezoelectric element 2 for electrical conduction.

Now, the method of coating the piezoelectric element of the present invention will be described.

First, the piezoelectric element 2 to which foreign matter adheres during the slicing process is ultrasonically cleaned with an organic solvent to improve the adhesiveness.

After cleaning, as shown in FIG. 1, the piezoelectric element 2 is dipped by diluting it or placing it in a container filled with an epoxy adhesive 7 having a low viscosity and a low shrinkage, with the piezoelectric element facing downward. The epoxy adhesive for coating used in the present invention is a low-viscosity adhesive that allows dip coating,
It can be diluted with a specific organic solvent (eg, acetone, methyl ethyl ketone). As an alternative to FIG. 1, a method of spraying a low-viscosity epoxy adhesive 7 on the piezoelectric element 2 with a spray nozzle 6 as shown in FIG. 2 and performing coating may be used. In either method, the epoxy adhesive 7 is preferably applied to a film thickness of 10 μm or less.

Thereafter, the adhesive 7 dipped by natural drying or heat curing is temporarily cured to facilitate handling.

After the temporary curing, the adhesive attached to the tip of the piezoelectric element (adhesion surface to other parts) is wiped completely by adding an organic solvent to the wiping material.

Epoxy adhesive 7 to be used after wiping
Natural drying and heat curing are performed according to the curing conditions.

By applying the above coating treatment, the strength of the piezoelectric element 2 can be improved and the moisture-proof effect can be achieved. At the same time, it is possible to repair the internal electrodes 4 of the piezoelectric element in which minute cracks have been generated due to the load during the slicing process.

[0021]

According to the present invention, the floating piece of the internal electrode material generated during the processing can be fixed by performing the coating processing with the epoxy adhesive after the slicing processing of the laminated piezoelectric element. It is possible to prevent a short circuit between the electrodes and a failure due to discharge, and thus to extend the life of the inkjet head and stabilize the ink ejection speed.

Further, the piezoelectric element can be repaired by applying a coating treatment with an epoxy adhesive to the minute crack generated by the cutting load or the micro crack between the internal electrodes at the time of generating the piezoelectric element. It is possible to reduce defective parts of the element.

[Brief description of drawings]

FIG. 1 is a perspective view showing a bonding operation state of a coating process as an example of the present invention.

FIG. 2 is a perspective view showing a bonding operation state of a coating process as another example of the present invention.

FIG. 3 is an external perspective view showing the state of the piezoelectric element after slicing.

[Explanation of symbols]

Reference numeral 1 is a substrate, 2 is a piezoelectric element, 3 is a conductive adhesive, 4 is an internal electrode of the piezoelectric element, 5 is a grindstone for slicing, 6 is a spray nozzle, and 7 is an epoxy adhesive.

Claims (4)

[Claims] 1. An ink chamber, a nozzle hole communicating with the ink chamber, a piezoelectric element for generating pressure in the ink chamber to eject ink droplets from the nozzle hole, and the piezoelectric element is fixed. An ink jet head having a substrate for, wherein the piezoelectric element is coated with an epoxy adhesive. 2. The ink jet head according to claim 1, wherein the epoxy adhesive is coated to a thickness of 10 μm or less. 3. A step of slicing a single piezoelectric element plate fixed to a substrate into individual piezoelectric elements, a step of applying an epoxy adhesive to the sliced piezoelectric elements, and an adhesive applied to the piezoelectric elements. A method of manufacturing an inkjet head, the method including a step of curing treatment. 4. The method of manufacturing an ink jet head according to claim 3, wherein the epoxy adhesive has a viscosity low enough to allow dip coating.