JPS6046557B2 - Manufacturing method of piezoelectric ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a piezoelectric ceramic material, which can configure an energy confinement resonator related to vertical vibration, and has a mechanical quality coefficient QM and an electromechanical coupling coefficient. , to.

. The present invention provides a piezoelectric ceramic material suitable for use in high-frequency resonators, etc., which has a large surface area and can be processed into a thin plate. As the use of ICs in high-frequency circuits in television receivers and the like progresses, there is a strong demand for peripheral components of IC circuits, especially reactance circuits, to be solid-state, non-adjustable, and high-performance.

Piezoelectric ceramic resonators are expected to be able to meet this demand. When using a piezoelectric ceramic as a high-frequency resonator, it is advantageous to use thickness vibration, particularly thickness vertical vibration, in which the resonant frequency is determined by the thickness. The frequency constant of thickness vibration is about 2000H2-m, so if 50
In order to obtain the resonant frequency of MH2, the magnetic resonator must be processed into a very thin plate with a thickness of approximately 40 μm. Furthermore, when using thick vertical vibration in a resonator or filter, it is important to eliminate unnecessary resonance. The energy confinement method is effective in removing unnecessary vibrations. The conditions under which this energy confinement method can be applied to the fundamental wave resonance of thick vertical vibration are the Poisson's ratio σ given by (2-C g a- S g.)/(2-2 Cg. S g.) must be greater than 113. However, C
No. is elastic stiffness related to thickness vibration, S
〒. is the elastic compliance associated with thickness-beam vibration. Further, in order to obtain a resonator with low loss in a high frequency region, it is necessary that the mechanical quality factor QM is 20 degrees or more. With the conventional firing method, only a mechanically weak material can be obtained, and only a thickness of about 200 μm can be obtained, so it has been difficult to obtain a resonator with a diameter of about 10 MH 2 even by vertical vibration.

Furthermore, until now there have been few examples of measurement of σ, and the composition range with σ of 113 or more has not been clarified.

Until now, no material has been obtained that has a QM of 20 degrees or more, a σ of 113 or more, and which can be processed into a thin plate of 200 μm or less. The present invention includes 1
It relates to a method of obtaining a piezoelectric ceramic material for high frequency use that has a σ of 13 or more and a QM of 200 degrees, and a large coupling coefficient Kt that can be processed into a thin plate of about 30 μm.
1-w)(PbTll-ZZrzO3)+WMnO2(
However, 0.48≦z≦0.64, 0.004≦w≦0
．． This is based on the discovery that it can be obtained by heat-pressing sintering of composition 06) under limited conditions.

Examples will be described below. PbO, TiO2, Z
Raw materials for rO2 and MnO2 were weighed to have the compositions shown in the table below, and wet mixed in a ball mill for 17 hours.

The slurry was filtered, dried, calcined at about 850'C for 2 hours, and wet milled again using a ball mill. After drying the crushed material, diameter 30W$L1 thickness 17
A disk of garlic was molded at a pressure of 500 k9/d, and then sintered under heat and pressure under the conditions shown in the table below. Thereafter, annealing treatment was performed at 900'C for 4 hours. For comparison, powder made under the same conditions was molded and fired normally. Disks of 6 diameters were cut from these fired samples and polished to a minimum thickness of 30 μm. 30 μm for mechanically weak samples
The thin plate element was cracked by the time it reached a thickness of 100 mm, making it impossible to obtain the desired thin plate element. In addition, the piezoelectric property is determined by the thickness of 0.3
A gold electrode was provided on the disk sample of TgfL, and it was
Measurements were made on a sample in which a DC electric field of 5 KV/TWL was applied in silicone oil of C. K33 is 1x1x5Tr
Measured using a $13 sample. Table 1 shows the relationship between firing conditions and polishing limits.

In normal firing, porcelain with the maximum density was obtained under the firing conditions shown in the table, but it was not possible to polish it to a thickness of 200 pm or less. However, due to the heat and pressure sintering of the present invention,
An extremely thin porcelain body can be obtained. When the heating and pressure sintering temperature was 1050 to 1300°C, polishing up to 30 pm was possible. During sintering. The pressing force is 100k
If it was smaller than g/Clt, the sample would be non-uniform due to insufficient sintering, and it would be difficult to polish the porcelain to a thickness of 200 pm or less. By heating and pressurizing sintering at a pressure in the range of 100 to 500 k9/c, porcelain that can be polished to a thickness of 30 μm can be obtained! Ta. Regarding heating time, 0.
If the sintering time is shorter than that, the sintering will be non-uniform and it will not be possible to obtain a material that can withstand polishing into a thin plate of 100 μm or less. Further, sintering of 2 or more diameters is not preferable because it greatly reduces the strength of the porcelain and the productivity. Therefore, the range of conditions for heating and pressure sintering in the method of the present invention is a temperature of 1050°C.
-1300°C, pressure 100-500 kg/Cltl time range between 0.5-24TII. 1250 in Figure 1
The figure shows how σ changes with respect to z for a ceramic sample (w=0.008) that was heat-pressure sintered at ℃, 200 kg/Clt, and 4 hours.

As is clear from FIG. 1, σ was maximum when the value of z was 0.55. In that case, Kt and K33 are each 0
．． It showed large values at 54 and 0.68. The tendency of the change in σ due to the change in z hardly changes depending on the value of w and the heating and pressurizing conditions. The range that satisfies the energy confinement condition of the fundamental wave of the thickness vertical vibration, that is, the condition of σ〉113, is 0.48≦z≦ when w=0.008.
The composition range is 0.64. In addition, w is 0.004 to 0
．． In the case of 06 as well, the condition of σ>113 was satisfied within the above range of z. Figure 2 shows a temperature of 1250℃ and a pressure of 20℃.
Sample sintered under heat and pressure at 0 kg/Clt for 4 hours (z=0
．． 60) shows the change in Q9 due to w.

QM is maximum when w is 0.02. This tendency is
It does not change depending on the value of and the heating and pressure sintering conditions. As is clear from the figure, the range of w in which QM is 200 or more is 0.004 to 0.06.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the relationship between the composition and Poisson's ratio σ of a sample made by the method according to the present invention, and FIG. 2 is a diagram showing an example of the relationship between the composition and the mechanical quality factor QM. be.

Claims (1)

[Claims] 1 (1-w) [PbTi_1_-_zZr_zO_3+
In the composition represented by wMnO_2, 0.48≦z
≦0.64, 0.004≦w≦0.006 at a temperature of 1050 to 1300°C and a pressure of 100°C.
A method for producing piezoelectric ceramics, characterized by heating and pressurizing sintering at ~500 kg/cm^2 for 0.5 to 24 hours.