JPH05335861A - Manufacture of piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To manufacture a piezoelectric vibrator with a high bonding strength and sufficient close bonding between a piezoelectric ceramics and a silver electrode when the piezoelectric vibrator is bonded to an external conductor and a board or the like. CONSTITUTION:Silver paste is coated to the surface of a piezoelectric ceramics 1, the ceramics is baked to manufacture a piezoelectric vibrator on the surface of which a silver electrode 2 is processed. After the silver paste is coated, the silver electrode 2 is formed by baking the silver paste at the temperature of 550-580 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a piezoelectric vibrator which is an electronic component for generating ultrasonic waves.

[0002]

2. Description of the Related Art Generally, as a piezoelectric vibrator, one in which a conductive paste is applied to piezoelectric ceramics and which is fired to form electrodes is used. For example, a case of a disk-shaped piezoelectric vibrator as shown in FIG. 1 will be described. A silver paste containing powder having a silver particle size of about 3 microns in average particle size is used for both surfaces of the disk-shaped piezoelectric ceramic 1. To a predetermined position by screen printing or the like, and baking is performed in the atmosphere at a temperature of about 650 to 700 ° C. for about 20 to 40 minutes to form the silver electrode 2. I was manufacturing a piezoelectric vibrator. To the silver electrode 2 of this piezoelectric vibrator, a substrate 5 is usually used by being adhered and fixed by an adhesive 3 as shown in FIG. 2, or an external conductor (not shown) is adhered and fixed by an adhesive. . The surface of the silver electrode processed by the conventional manufacturing method grows into silver particles 8 having a particle diameter of about 8 to 12 microns as shown in FIG.
There are almost no holes 9 (pores) on the surface, and the surface roughness (R
z) forms a relatively smooth surface of about 5 microns. This silver electrode has a relatively high bonding strength with the piezoelectric ceramics, but when a substrate having a copper foil or the like processed on its surface with an epoxy adhesive is adhered to this silver electrode, the silver electrode and the substrate are There is a problem that the adhesive strength with A 5 mm wide flexible tape 6 as shown in FIG. 3 is adhered to the surface of the silver electrode 2 with the adhesive 3, and the adhesive strength indicated by the tensile strength when peeled off from the surface of the silver electrode 2 is about 1 kgf. However, there is a problem that vibration due to external factors and peeling when installed in a place where a large external force is applied are lacking in long-term reliability.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and has a high adhesive strength when bonded to an external conductor or a substrate, and the bonding between the piezoelectric ceramic and the silver electrode is sufficient. It is to provide a method of manufacturing a piezoelectric vibrator having high strength.

[0004]

The present inventor adheres a conductor, a substrate or the like to a silver electrode of the piezoelectric vibrator in order to fix the substrate, the conductor or the like to the piezoelectric vibrator, but has an electrode capable of being firmly adhered. The method of manufacturing the piezoelectric vibrator was examined from the structure of the silver electrode, and especially during the manufacturing process of the silver electrode, the growth of silver particles on the surface of the silver electrode was suppressed without lowering the bonding strength between the piezoelectric ceramics and the electrode. However, by leaving sufficient pores (pores) on the surface, a silver electrode is formed that can secure a sufficient adhesive area and secure the adhesive strength with the adherend. The average particle size is 3 on the surface of piezoelectric ceramics.
When a silver paste containing silver particles of about micron is applied and baked in the air, the baking temperature is 550 ° C ± 30 ° C.
The average particle size of silver particles on the surface of the electrode is suppressed to about 5 μm by firing in the temperature range of 3 to form a silver electrode in which a large number of pores (pores) of about 3 μm are scattered to form an adhesive. We have found a method to manufacture a piezoelectric vibrator with high strength.

That is, the present invention provides a method for manufacturing a piezoelectric vibrator, in which a silver paste is applied to the surface of a piezoelectric ceramic, and the silver paste is baked to manufacture a piezoelectric vibrator having a silver electrode formed on the surface. After applying 550 to 580 ° C
A piezoelectric vibrator manufacturing method is characterized in that the silver electrode is formed by firing at a temperature in the range of ° C.

[0006]

Function: The baking temperature for processing the silver electrode is about 13
By firing at a temperature of 520 ° C. to 580 ° C., which is low by about 0 ° C., as shown in FIG. 5, grain growth of silver particles on the surface of the silver electrode is suppressed without substantially lowering the bonding strength with the ceramics. Since the silver electrode is formed with the pores (pores) left on the surface sufficiently, the surface area of the silver electrode can be made large and the irregularities can be made large. It is possible to obtain a piezoelectric vibrator that is large and has high adhesion strength between the silver electrode and the adherend such as the substrate.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a generally used disk-shaped piezoelectric vibrator, FIG. 1 (a) is a front view, FIG. 1 (b) is a side sectional view, and FIG. 2 is a piezoelectric vibrator bonded to a substrate. FIG. 3 is a side view showing the state in which the peeling is performed, FIG. 3 is an explanatory view for explaining a method for measuring peeling strength, which shows the adhesive strength when the piezoelectric vibrator is bonded to the electrode, and FIG. In the schematic diagram showing an enlarged surface of the silver electrode of the piezoelectric vibrator obtained in the example,
4A shows the conventional silver electrode, and FIG. 4B shows the silver electrode of this embodiment. FIG. 5 is a diagram showing the relationship between the adhesive strength between the silver electrode and the adherend, the peel strength representing the bonding strength between the piezoelectric ceramic and the silver electrode, and the firing temperature.

A disk-shaped lead zirco titanate-based piezoelectric ceramic 1 having a diameter of about 20 mm as shown in FIG. For the silver electrode paste, a paste containing silver particles having an average particle size of about 3 microns is printed and applied by a screen printing method, and the paste is applied in the air at 5
It was baked at 50 ° C. for about 30 minutes. Usually, this piezoelectric vibrator is thereafter polarized at a predetermined voltage under a predetermined temperature, and then, as shown in FIG. 2, the substrate 5 and the conductor 12 are attached to the silver electrode 2 to form a piezoelectric vibrator. Complete. Enlarging the surface condition of the silver electrode 2 of the element just after firing the silver electrode,
As shown in FIG. 4 (b), silver particles 10 having a size of about 5 μm and slightly larger than the silver particles in the paste can be seen, and voids 11 of the same size are scattered between them. For reference, as compared with the enlarged schematic view of the surface of the silver electrode of the conventional piezoelectric vibrator prepared under the same conditions as in Example, except that the baking was performed at the baking temperature of 650 ° C. for 30 minutes in FIG. It can be seen that in the manufacturing method, the surface of the silver electrode has grown to a size of about 10 microns, which is twice as large as the silver particles 8 on the surface, pores 9 (pores) are scarcely seen, and surface irregularities are small. Next, in order to compare the adhesive strength, as shown in FIG. 3, a flexible tape 6 having a width of 5 mm was adhered with an epoxy adhesive, and then the tape 6 was pulled perpendicular to the adhered surface and peeled off. The relationship between the adhesive strength indicated by the peeling strength of the tape 7 and the firing temperature when the tape is heated is shown in the curve of the adhesive strength of FIG. 5 for the samples whose firing temperature is 500 ° C. to 650 ° C. It can be seen from the curve of the adhesive strength in FIG. 5 that the maximum is around 530 ° C., and it is reduced to one third at around 650 ° C. Further, the bonding strength between the piezoelectric ceramics and the silver electrode of the sample having a baking temperature of 500 ° C. to 650 ° C. is shown by the relationship between the peeling strength per unit area and the baking temperature, and the curve of the bonding strength is shown in FIG. As can be seen from the bond strength curve in FIG. 5, the maximum firing temperature is about 630 ° C., but there is a slight decrease up to about 520 ° C. In the present invention, both of the strengths that contribute to the quality of the piezoelectric vibrator are set to a range of firing temperature in which the strength is relatively high. As a result of being manufactured by the method for manufacturing a piezoelectric vibrator of the present invention, the adhesive strength (peeling strength) is increased to about 3 kgf, which is three times the conventional strength, and a highly reliable piezoelectric vibrator can be manufactured.

[0009]

As described above, according to the present invention,
In the piezoelectric vibrator formed with the silver electrode, it is possible to obtain a piezoelectric vibrator that has excellent adhesive strength with other adherends and has sufficient electrode bonding strength.

[Brief description of drawings]

1A and 1B show a generally used disk-shaped piezoelectric vibrator, FIG. 1A is a front view, and FIG. 1B is a side sectional view.

FIG. 2 is a side view showing a state in which a piezoelectric vibrator is bonded to a substrate.

FIG. 3 is an explanatory diagram illustrating a peel strength measuring method showing the bonding strength when a conductor or a substrate is bonded to an electrode of a piezoelectric vibrator.

FIG. 4 is a schematic view showing an enlarged surface of a silver electrode of a piezoelectric vibrator obtained in an example of the present invention and a conventional example.
4A shows the silver electrode of this embodiment, and FIG. 4B shows the conventional silver electrode.

FIG. 5 is a graph showing the relationship between the bonding strength between a silver electrode and an adherend and the bonding strength between a piezoelectric ceramic and a silver electrode and the firing temperature as peel strength.

[Explanation of symbols]

 1 Piezoelectric Ceramics 2 Silver Electrode 3 Adhesive 4 Copper Foil 5 Substrate 6 Tape 7 Tape 8 Silver Particles 9 Pores 10 Pores 10 Silver Particles 12 Conductors

Claims (1)

[Claims] 1. A method for manufacturing a piezoelectric vibrator, wherein a silver paste is applied to the surface of a piezoelectric ceramic, and this is fired to manufacture a piezoelectric vibrator having a silver electrode processed on the surface. A method for manufacturing a piezoelectric vibrator, comprising: firing at a temperature in the range of 520 ° C. to 580 ° C. to form a silver electrode.