JP2000062195A - Bonding method for piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform an adhesive layer by bonding a piezoelectric element and a ceramic substrate through a conductive adhesive, arranging a support material on the opposite sides of the piezoelectric element on the ceramic substrate and then bonding the support material to the nonadhesive part of the conductive adhesive. SOLUTION: In order to prevent bonding strength from lowering due to adhesion of a foreign matter to a piezoelectric element 2 fixed to a ceramic substrate 1 or the electrode part of the ceramic substrate 1, ultrasonic cleaning is performed using an organic solvent followed by plasma processing. Conductive adhesive 3 is applied uniformly to couple the ceramic substrate 1 and the piezoelectric element 2 which is then pressed onto the ceramic substrate 1 and bonded thereto such that the conductive adhesive 3 projects from the opposite sides. Subsequently, a rectangular prism support material 5 is applied to the projecting part of the conductive adhesive 3 and thermally set while being pressed. According to the method, adhesive layer of the piezoelectric element 2 and the ceramic substrate 1 can be made uniform.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding method for bonding a piezoelectric element, which serves as an ink ejecting mechanism of an on-demand type multi-nozzle inkjet head, and a ceramic substrate.

2. Description of the Related Art Conventionally, a conductive adhesive has been used to bond a piezoelectric element and a ceramic substrate which is a base of the piezoelectric element. The purpose of use is the piezoelectric element 2
This is to establish electrical continuity between the electrode part (not shown) of the ceramic substrate 1. A conventional conductive adhesive coating method is shown in FIG.
As shown in FIG. 3, a method of applying the conductive adhesive 3 to the piezoelectric element 2 and the ceramic substrate 1 and thermosetting is applied.
However, in the above method, residual stress is generated due to the non-uniformity of the adhesive layer and the difference in the linear expansion coefficient of the adherends (piezoelectric element 2 and ceramic substrate 1). When slicing is performed to 0.2 mm, peeling occurs, electrical connection between the piezoelectric element 2 and the electrode cannot be established, the piezoelectric element 2 cannot perform expansion / contraction operation, and ink cannot be ejected.

As described above, when the conventional bonding method is used, residual stress is generated after bonding, the bonding strength is reduced, and the conductive adhesive is peeled off due to cutting load during the slicing process. , The electrical connection between the piezoelectric element and the electrode part cannot be established. Therefore, an object of the present invention is to provide a bonding method in which variations in strength are reduced by making the bonding layer uniform. Another object of the present invention is to provide a bonding method in which residual stress after bonding is reduced and strength is improved.

In order to solve the above problems, an ink for an on-demand type multi-nozzle ink jet head comprising a piezoelectric element, a ceramic substrate supporting the piezoelectric element, and an electrode portion provided on the ceramic substrate. A method of adhering the piezoelectric element and the electrode portion with a conductive adhesive to obtain electrical continuity, which is a jetting mechanism, in which the piezoelectric element and the ceramic substrate are bonded with a conductive adhesive, In order to make the non-adhesive part of the adhesive uniform, the support material was arranged on both sides of the piezoelectric element on the ceramic substrate and adhered to the non-adhesive part of the conductive adhesive. The support material is preferably selected from the same material as the ceramic substrate or a material having a low linear expansion coefficient. According to the present invention, the thickness of the adhesive layer can be made uniform by using the support material for the adhesive portion, and the variation in adhesive strength can be reduced. Further, according to the present invention, by using the same support material as that of the substrate or a material having a low linear expansion coefficient, the residual stress after bonding can be reduced, and the bonding strength can be improved.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. FIG. 2 is an external view of the support material 5 as an example of the present invention. The support material 5 is a ceramic of the same type as the ceramic substrate 1 to be bonded, or has a low linear expansion coefficient (1
^{0x10 -6} or less) material. Examples of the material having a low coefficient of linear expansion include glass and platinum iridium. FIG. 1 shows the work of bonding and slicing using the support material 5 of the present invention. First, ultrasonic cleaning is performed with an organic solvent so that foreign matter does not adhere to the piezoelectric element 2 attached to the ceramic substrate 1 and an electrode portion (not shown) of the ceramic substrate 1 and the adhesive strength is not reduced, and then plasma treatment is performed. I do. After the treatment, the conductive adhesive 3 is evenly applied so that the ceramic substrate 1 and the piezoelectric element 2 are connected, the piezoelectric element 2 is pressed onto the ceramic substrate 1, and the conductive adhesive 3 is adhered so as to protrude to both sides. . Next, the support material 5 having a rectangular parallelepiped shape is covered on the protruding portion (non-bonding portion) of the conductive adhesive 3, and the support material 5 is added so that the adhesive layer between the piezoelectric element 2 and the ceramic substrate 1 becomes uniform. Heat cure while pressing. By using the support material 5 to make the adhesive layer uniform, it is possible to reduce variations in adhesive strength. Further, by using a ceramic plate of the same material as the ceramic substrate 1 or a material having a low linear expansion coefficient as the support material 5, it is possible to reduce the residual stress after bonding and improve the bonding strength.

According to the present invention, by using a support material, it is possible to make the thickness of the adhesive layer uniform and reduce variations in adhesive strength. In addition, by using a material having a low linear expansion coefficient as the support material, it is possible to reduce the residual stress after bonding and improve the bonding strength.

[Brief description of drawings]

FIG. 1 is a perspective view showing a bonding method according to the present invention.

FIG. 2 is an external perspective view of a support material of the present invention.

FIG. 3 is a perspective view showing a conventional bonding method.

[Explanation of symbols]

Reference numeral 1 is a ceramic substrate, 2 is a piezoelectric element, 3 is a conductive adhesive, 4 is a slicing grindstone, and 5 is a support material.

Claims (2)

[Claims] 1. An ink ejecting mechanism for an on-demand type multi-nozzle ink jet head comprising a piezoelectric element, a ceramic substrate supporting the piezoelectric element, and an electrode portion provided on the ceramic substrate, the element being electrically conductive. Therefore, in the method of adhering the piezoelectric element and the electrode portion using a conductive adhesive, in order to make the non-adhesive portion of the conductive adhesive uniform after adhering the piezoelectric element and the ceramic substrate with the conductive adhesive. A method for adhering a piezoelectric element, wherein support materials are arranged on both sides of the piezoelectric element on a ceramic substrate and adhered to a non-adhesive portion of a conductive adhesive. 2. The method for adhering a piezoelectric element according to claim 1, wherein the support material is selected from the same materials as the ceramic substrate or materials having a low linear expansion coefficient.