JPH08288607A - Manufacture of piezoelectric material and paste for forming conductor of piezoelectric material - Google Patents

Abstract

PURPOSE: To suppress the growth and densification of particles by adding niobium oxide and/or antimony oxide to paste for forming conductor composed mainly of silver and palladium or palladium. CONSTITUTION: Paste for forming conductor is prepared by adding 70 pts.wt. ethyl cellulose, DBP, and α-terpineol and 20 pts.wt. PZT powder having the same composition as that a piezoelectric ceramic sheet has. Then Nb2 O5 and/or Sb2 O3 is added to the paste at a rate of 10-100μg/cm<2> and the paste is printed on the piezoelectric ceramic sheet. A plurality of printed ceramic sheet are laminated, pressed, and sintered. The growth and densification of particles can be suppressed by lowering the driving force of sintering by lowering the surface energy of the PZT particles or lowering the sintering speed by hindering the diffusion of the ions constituting the PZT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric body formed by coating a lead zirconate titanate-based ceramic sheet with a conductor-forming paste and firing them at the same time. More specifically, it is suitable for forming the piezoelectric body. Palladium-based or silver-palladium-based conductor forming paste.

[0002]

2. Description of the Related Art A lead zirconate titanate (hereinafter abbreviated as PZT) -based laminated piezoelectric material is a piezoelectric material in which each layer is formed of a conductor-forming paste containing palladium (Pd) or silver-palladium (Ag-Pd) as a main component. It is made by printing on a body ceramics sheet (green sheet), performing lamination, hot pressing, etc., and then firing. Conventionally, a conductor-forming paste mainly containing Pd having a high melting point has been used, but low-temperature firing has been achieved due to improvements in the piezoelectric ceramic sheet, and recently, an inexpensive Ag-Pd-based conductor forming paste has been used. It has come to be used.

The above-mentioned conductor-forming paste includes conductor-forming powder mainly containing Pd and Ag-Pd, and lead (P
b), Zr (zirconium), Ti (titanium) oxide as a main material for conductor adhesion, and organic materials such as a binder, a dispersant, and a plasticizer. Pd and A
As its name suggests, the conductor-forming powder mainly containing g-Pd forms a Pd or Ag-Pd film by firing and forms a conductor inside and / or on the surface of the laminated piezoelectric material. Pd, Z
The conductor adhering material powder mainly containing oxides of r and Ti is basically made of the same powder material as that of the piezoelectric body to be laminated, and has the function of improving the adherence of the piezoelectric body after firing to the conductor film. However, in some cases, the conductor adhering material powder may not be contained. Organic materials such as binders, dispersants, and plasticizers are powder dispersibility during paste formation, workability during printing, leveling during paste drying, shape retention of dried conductor film, and adhesion to green sheet before firing. It is used to improve sex, and its types and amounts vary widely.

[0004]

Recently, as the applications of the laminated piezoelectric material have expanded, there has been a demand for utilizing the laminated piezoelectric material in a resonance state in a direction perpendicular to the laminating direction. However,
The conventional laminated piezoelectric material that uses a conductor-forming paste has the drawback of being easily broken in the resonance state. That is, in the past, the conductor forming paste as described above was sufficient because it was used only to apply a DC voltage in the stacking direction and simply expand and contract in the stacking direction, but the resonance state in the direction perpendicular to the stacking direction was sufficient. However, the adhesion between the conductor and the piezoelectric substrate was still insufficient for use in.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a piezoelectric body which can be used for a long time at a resonance frequency.

[0006]

As a result of investigating the cause of the above-mentioned problems, the inventors have found that Pd and Ag have a function of lowering the contraction start temperature of the PZT-based ceramic sheet.
It was found that only the ceramic sheet base material near the conductor started to sinter faster than other parts, and the strain remained at the interface part to reduce the strength. Therefore, we have conducted repeated research on how to eliminate this cause, and
_{It was found that 2} O ₅ ) and / or antimony oxide (Sb ₂ O ₃ ) have an effect of suppressing grain growth and densification, and the present invention has been completed.

That is, according to the present invention, (1) a lead zirconate titanate-based piezoelectric ceramic sheet is coated with a conductor-forming paste mainly containing silver and palladium or palladium,
A method for producing a piezoelectric body, which is formed by co-firing them, wherein niobium oxide and / or antimony oxide is added to the conductor-forming paste, and (2) the piezoelectric ceramic sheet. A method for producing a piezoelectric body, which comprises applying a conductor-forming paste such that niobium oxide and / or antimony oxide are present at a rate of 10 to 100 μg per 1 cm 2, and (3) lead zirconate titanate-based piezoelectric A conductor-forming paste which is applied to a body ceramics sheet and simultaneously fired to form a piezoelectric body, wherein niobium oxide and / or antimony oxide is added to a conductor-forming paste mainly containing silver and palladium or palladium. A gist of the present invention is a piezoelectric conductor forming paste.

The present invention will be described in more detail below.

As the conductor-forming material powder mainly containing Ag and Pd or Pd, the same powders as in the conventional one can be used. Rather, these should be decided depending on the material of the piezoelectric ceramic sheet to be applied. That is, when co-firing with a piezoelectric ceramics sheet whose firing temperature exceeds 1300 ° C., Ag—Pd is melted and thus it is difficult to use it as a conductor.
Will be mainly used. When the piezoelectric ceramic sheet is fired at a lower temperature, for example, 12
At 50 ° C, Ag 50 parts-Pd 50 parts, 1150
At ° C, it is possible to use a mixture or alloy of Ag 70 parts-Pd 30 parts as a conductor.
It is effective regardless of the Pd ratio.

In order to match the contraction timing of the conductor material with the contraction timing of the piezoelectric ceramic sheet base material, it is common to use an average particle diameter or particle shape suitable for the piezoelectric ceramic sheet base material. The adjustment of the contraction timing is performed for the purpose of preventing warpage due to the difference in contraction timing when the conductor forming paste is printed on the piezoelectric ceramic sheet, laminated and fired. The particle size and the particle shape are not limited.

It is an ambiguous expression to mainly include, but for various reasons, as a conductor forming component other than Ag and Pd, gold (Au), Pt (platinum) and rhodium (Rh) are used.
Ruthenium oxide (Ru
This is because a small amount of conductive oxide such as O ₂ ) may be added. In the present invention, it is effective to mainly contain Pd or Ag and Pd regardless of the presence or absence of these components. Therefore, it is difficult to limit the content, but Ag
And / or when the total amount of Pd is larger than the other inorganic components, it is surely effective.

As the binder, ethyl cellulose or nitrocellulose is often used. As the dispersant, Prysurf A210G (registered trademark) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. is used. DB as plasticizer and solvent
A high boiling point and relatively high viscosity such as P (dibutyl phthalate), α-terpineol, and octanol alcohol are often used. In the present invention, there is no interaction with an organic material such as a binder, a dispersant, a plasticizer, and a solvent, so there is no particular limitation.

It is difficult to limit the content of Nb ₂ O ₅ and / or Sb ₂ O ₃ even with the same paste because the amount existing per unit area changes depending on the printing thickness (printing amount). Is. However, when the paste is printed, it is 10 to 100 per square centimeter.
Since it is most effective when the amount of μg is present, if it is difficult to change the printing thickness (printing amount), change the content of Nb ₂ O ₅ and / or Sb ₂ O _{3 in} the paste by printing. If it is adjusted so as to fall within the above range, the effect will be enhanced.

On the contrary, when a paste having a predetermined amount of Nb ₂ O ₅ and / or Sb ₂ O ₃ is used as it is without adjustment, for example, Nb ₂ O ₅ and / or Sb ₂ O ₃ In the case of a paste with a small content, increase the printing thickness of the paste so that Nb ₂ O ₅ and / or Sb
₂ O ₃ is 10 to 100 μg per square centimeter
The print thickness may be adjusted so that the amount of There are many methods for adjusting the print thickness (print amount), and any method may be adopted. For example, the print thickness can be greatly changed by adjusting the emulsion thickness of the pattern mask for printing, and a small amount of thickness can be adjusted by changing the squeegee angle, the squeegee pushing pressure, the squeegee moving speed, and the like. .

[0015]

Although [action] Ag and Pd is not clear why reducing the shrinkage starting temperature of the PZT-based piezoelectric ceramic sheet base material _{of, Pb (Zr 0. 5 2} Ti 0. 4 8) outer percentage to 0 ₃ consisting of the composition PZT When 1 part by weight of Ag or Pd was added and calcined, it was observed that the densification start temperature and the densification end temperature were lowered by 100 ° C. or more as compared with the case of no addition.

On the other hand, when Nb ₂ O ₅ and Sb ₂ O ₃ are similarly added to the PZT-based piezoelectric ceramic sheet base material and fired, densification and grain growth are suppressed. The reason for this is also not clear, but it has the function of lowering the surface energy of the PZT particles to lower the driving force for sintering, and / or impeding the diffusion of the ions constituting PZT to lower the sintering rate. It is thought to cause it. Although not actually confirmed, it is considered that it also functions to slow down the diffusion rate of Ag and Pd.

[0017]

【Example】

-Examples 1-7, Comparative Examples 1-4-Pb ₀ . _{9 5} Sr ₀ . ₀₅ (Zr _{0 .53} Ti ₀ .4 ₇ ) O
_A PZT-based piezoelectric ceramic sheet (green sheet) having a composition of ₃ and a firing thickness of 100 μm was prepared.
A total of 70 parts by weight of ethyl cellulose as a binder, dibutyl phthalate (DBP) as a plasticizer, and α-terpineol as a solvent with respect to 100 parts by weight of Pd or Ag-Pd.
Parts by weight, PZT having the same composition as the piezoelectric ceramic sheet
20 parts by weight of powder was added to Pd or Ag-Pd, and Nb ₂ O ₅ and / or Sb ₂ O ₃ was added in an amount shown in Table 1 to prepare a paste having a printing thickness of 10 μm.
Then, a plurality of piezoelectric ceramic sheets were printed so as to have the same shape, a plurality of sheets were laminated and pressed, and then die cut to φ20 mm and fired to form a laminated piezoelectric body. After that 3000V at 100 ° C
It was polarized for 30 minutes with an electric field strength of / mm. The firing temperature is A
An appropriate temperature was set according to g / Pd.

A voltage of 50 Vp-p per layer was applied to the thus-prepared laminated piezoelectric material at a resonance frequency (around 130 kHz) in a direction perpendicular to the laminating direction, and the time until destruction was measured. . The results are shown in Table 1. In addition,
If it did not break even after 5000 hours, it was cut off there and it was not broken. In addition, it was described that, for those that were not densified, the breaking time was not measured, and sintering was not performed.

[0019]

[Table 1]

-Examples 8 to 10-In the above example, Nb ₂ O ₅ and // at a printing thickness of 10 μm.
Alternatively, the pastes of Comparative Examples 2 to 4 in which the amount of Sb ₂ O ₃ present deviated from the region of 10 to 100 μg / cm ² were used as Nb ₂
The amount of O ₅ and / or Sb ₂ O ₃ present is 10 to 100 μg
Printing was performed by adjusting the printing thickness so that it became / cm ² , and the same test was performed. The results are shown in Table 2. When the same pastes in Table 1 are compared with each other, it is clear that the breaking time is extended.

[0021]

[Table 2]

[0022]

EFFECTS OF THE INVENTION Since the laminated piezoelectric material according to the present invention maintains its reliability even if it is used at a resonance frequency for a long time, even when it is used for an actuator or the like, the replacement period is extended and the management is improved. There are merits.

Claims (3)

[Claims] 1. A method for manufacturing a piezoelectric body, which comprises applying a conductor forming paste mainly containing silver and palladium or palladium to a lead zirconate titanate-based piezoelectric ceramics sheet and simultaneously firing them to form the conductor. A method for manufacturing a piezoelectric body, comprising adding niobium oxide and / or antimony oxide to a paste for use in a piezoelectric material. 2. The piezoelectric material according to claim 1, wherein the conductor forming paste is applied such that niobium oxide and / or antimony oxide are present at a rate of 10 to 100 μg per 1 cm 2 of the piezoelectric ceramic sheet. Body manufacturing method. 3. A conductor-forming paste for applying a lead zirconate titanate-based piezoelectric ceramic sheet and simultaneously firing them to form a piezoelectric body, which is used for forming a conductor mainly containing silver and palladium or palladium. A paste for forming a conductor of a piezoelectric body, comprising niobium oxide and / or antimony oxide added to the paste.