JPH059079A - Production of piezoelectric device - Google Patents

Abstract

PURPOSE:To suppress the waving of the surface of a piezoelectric substrate and to simplify a process for removing bed powder when a piezoelectric device is produced. CONSTITUTION:When calcined starting material for piezoelectric ceramic is formed into a green sheet and this green sheet is blanked to a prescribed shape and fired to produce a piezoelectric device, the green sheet is coated with fine powder of the same material as the calcined starting material and the excess fine powder is removed with an air jet before blanking.

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 element used for a piezoelectric buzzer, a piezoelectric resonator, or the like.

[0002]

2. Description of the Related Art Conventionally, in order to form a piezoelectric element used for a piezoelectric buzzer, a piezoelectric resonator, etc., first, an organic binder, a plasticizer, etc. are kneaded with a calcination raw material of a piezoelectric ceramic, and this is doctor blade Green sheet is formed by using the extrusion method and extrusion method.

Next, the green sheets were punched according to the shape of the substrate of the piezoelectric element, a plurality of punched piezoelectric substrates were stacked, arranged on a firing setter and fired.

Here, conventionally, in order to stack and fire,
In order to prevent adjacent piezoelectric substrates from adhering to each other, the same fine powder (layout powder) as the calcination raw material was interposed therebetween.
After that, the bed dust adhering to the surface of the piezoelectric substrate was removed by ultrasonic cleaning, and the vibrating electrode was baked after drying (JP-A-63-134573).

According to the above-mentioned prior art, the particle size of the powder is 1
It was 50 μm or less, and when it was 30 μm or less, it was difficult to separate the sintered substrate from the spread powder.

[0006]

However, the particle size of the above-mentioned spread powder is 30.
It is as large as ˜150 μm, and depending on the coating method, it may be applied in a state where the piezoelectric substrate is deposited with a variation in the thickness direction. As a result, a large amount of swelling may occur on the surface of the piezoelectric substrate after firing, making it unusable as a substrate for a piezoelectric element.

Also, since the particle size is comparatively large and the firing adhesion is large, there is a problem that the piezoelectric substrate cannot be used as a piezoelectric substrate unless the piezoelectric powder is spread with a vibrator or the surface is smoothed by polishing. It was

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to manufacture a piezoelectric element in which swelling on the surface of the piezoelectric substrate is reduced and the step of removing the spread powder can be extremely simplified. It provides a method.

[0009]

According to the present invention, a step of forming a calcination raw material of a piezoelectric ceramic into a green sheet, a step of punching the green sheet into a predetermined shape, and a punching step In a method for manufacturing a piezoelectric element, which includes a step of firing a green sheet that has been subjected to, after the step of forming the green sheet, on the green sheet,
It is a method of manufacturing a piezoelectric element, characterized in that a step of applying the same fine powder as that of the calcination raw material and further removing excess fine powder by an air jet is performed.

[0010]

According to the present invention, the dried green sheet is coated with the same fine powder as the calcination raw material and the excess fine powder is removed by the air jet. The spread powder remaining on the substrate has a uniform deposition state and can be arranged in a fine particle size.

Therefore, since the spread powder that is thickly deposited in the thickness direction of the green sheet can be eliminated, a large swelling is not formed on the surface of the fired piezoelectric substrate. Further, only fine spread powder adheres to the surface of the fired piezoelectric substrate, but a conductive paste (containing a silver powder with a particle size of 3 to 10 μm as a conductive material) is used without the spread powder peeling step. To form a vibrating electrode.

Further, even when the spread powder that has adhered is peeled off, since the particle size is uniform and fine, the peeling work is easy, and for example, a substrate with a smooth surface can be obtained by only lightly wrapping. Obtainable.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
In describing the method for manufacturing a piezoelectric ceramic of the present invention, a piezoelectric buzzer, which is one of the piezoelectric elements, will be described as an example.

FIG. 1 is a sectional view of a piezoelectric element used in a piezoelectric buzzer, which is a flow chart for explaining the main steps of the method for producing a piezoelectric ceramic of the present invention, and FIG. 2 is a diagram of the main method of producing a piezoelectric ceramic of the present invention. It is a conceptual diagram of the manufacturing apparatus corresponding to a part.

The piezoelectric element 1 used for the piezoelectric buzzer has a disk-shaped silver vibrating electrode 1 on both main surfaces of a disk-shaped piezoelectric substrate 10.
1, 12 are formed.

The piezoelectric substrate 10 is a piezoelectric ceramic such as lead zirconate titanate (PZT) or lead titanate (PT), and is a polarized substrate.

The vibrating electrodes 11 and 12 are formed by coating both principal surfaces of the piezoelectric substrate 10 by a thick film technique and baking. The specific conductive paste has an average particle size of 3 to 10
A mixture obtained by kneading μm silver particles, a low-melting-point glass frit and an organic vehicle is used. After applying the conductive base, the organic vehicle is burned off, and then baked at 600 to 800 ° C.

Next, the manufacturing method of the present invention will be described.

Step 21 is a step of manufacturing a calcination raw material of the piezoelectric ceramic.

Oxides, which are raw materials for piezoelectric ceramics such as PZT and PZ, are mixed in a predetermined ratio, and a calcined body is prepared in a calcining furnace.

Step 22 is a step of manufacturing the green sheet 31.

The calcined body is made into a particle size of 1 μm by vibromill or the like.
Dry pulverize to a certain degree. Then, the calcined powder and the organic binder are kneaded, and a sheet having a predetermined width is processed by extrusion molding and dried. Specifically, a mixture of the calcined powder and the organic binder is put into the extrusion molding machine 32, and the thickness of the extrusion molding machine 32 is 0.05 to
A sheet having a width of 0.5 mm and a width of 100 mm is formed. Next, the far-infrared dryer 33 dries at 150 to 180 ° C. for several minutes.

Step 23 is a step of applying the spread powder 34.

On the dried green sheet 31, a vibrating screen 35 is provided with a calcined powder (fine powder spread powder) pulverized by the above-mentioned vibro mill to a particle size of about 1 μm to 10 μm.
Apply by applying.

Specifically, as shown in FIG.
The powder 34, which is a fine powder, is put into the device 5, vibrated under a constant condition, and uniformly dropped and deposited on the green sheet 31 conveyed on the belt conveyor 36 at a constant speed.

Step 24 is a step of removing the surplus powder 39.

Spread powder 34 applied on the green sheet 31
Is left in a predetermined amount to remove the surplus powder. Specifically, as shown in FIG. 4, a gas having a constant flow velocity is supplied from the air jet nozzle 38 having a slit 37 provided so as to cross the width direction of the green sheet 31.
Spray on the surface of 1. The flow velocity of the blown gas is appropriately determined depending on the relationship between the gap between the green sheet 31 and the slit 37, but the flow velocity is, for example, 10 to 30 m / se.
c, the width of the nozzle is set to 1 mm, and the gap is set to 10 to 20 mm.

As a result, the powder 34 deposited on the green sheet 31 and the particles other than those directly attached to the green sheet 31 are removed. The remaining spread powder 34 seems to be adhered mainly due to the clonal force, and is firmly adhered even if the gas blowing speed is increased. Green sheet 3
The slits 37 crossing the width direction of 1 may be arranged obliquely with respect to the sheet conveying direction.

Next, the green sheet 31 coated with a predetermined amount of spread powder 34 is wound up by the winding machine 40 and conveyed to the next punching step for each reel body (not shown).

Step 25 is a punching process.

The above-mentioned green sheet 31 is cut into a rectangular shape in which predetermined work can be easily performed, or is further punched into a shape of a piezoelectric substrate of a piezoelectric buzzer by a press molding machine. In this step, the piezoelectric buzzer of this embodiment is directly punched into the same shape as the finished product.

Step 26 is a firing step.

A plurality of piezoelectric substrates punched into a predetermined shape are stacked and further housed in a firing setter (not shown) to carry out a sintering reaction in a firing furnace. At this time, the spread powder 34 exists between the overlapping piezoelectric substrates, and the surfaces of the adjacent piezoelectric substrates do not come into surface contact with each other.

Step 27 is an electrode baking step.

This electrode is formed on both main surfaces of the piezoelectric substrate 10, and is used as an electrode when a high DC voltage is applied in the polarization process of the piezoelectric substrate 10, or the vibrating electrode 11 of the completed piezoelectric element 1 as it is. , 12 may also be used.

Specifically, one side of the main surface of the piezoelectric substrate is coated with a conductive paste by a thick film method and dried, and then the other side of the main surface is similarly coated with a conductive paste by a thick film method. , Dry, and finally the conductive film on both main surfaces is 600-80
Bake at 0 ° C.

As a result, the piezoelectric element 1 used for the piezoelectric buzzer is completed.

In the above-mentioned manufacturing method, a fine spread powder of a calcined material having an average particle size of about 1 to 10 μm is applied on a dried green sheet, and thereafter, excess spread powder is removed by an air jet. Become. As a result, only the required amount of fine spread powder with large adhesive force on the green sheet,
It will remain evenly.

Therefore, it is possible to prevent the adhesion between the adjacent piezoelectric substrates caused by the repeated firing as in the prior art, and further, the swelling due to the adhesion of the spread powder on the surface of the piezoelectric substrate after firing becomes extremely small and adheres to the piezoelectric substrate. The electrode can be formed without the step of removing the spread powder.

Further, since the spread powder before the punching process has a fine particle size and is the minimum required amount, even if the spread powder is lost during the conveyance to the punching process, the surface of the piezoelectric substrate after firing will not have swelling. It becomes minute and has no effect.

Further, in the above manufacturing method, as compared with the conventional manufacturing method, only the air jet device is added,
It is a low-cost manufacturing method that does not require a large change in the manufacturing process.

Even if it is necessary to peel off the spread powder that has adhered, since the particle size is uniform and fine, the work of peeling is easy, and for example, a substrate with a smooth surface can be obtained by lightly wrapping. be able to.

In the above-mentioned embodiment, the method of manufacturing a piezoelectric element as a piezoelectric buzzer has been described, and the detailed description of the polarization process is omitted. However, a polarization processing electrode is formed on a fired piezoelectric substrate, and polarization is performed. After performing the treatment, the electrodes for polarization treatment may be peeled off, individual vibrating electrodes may be formed again, and the piezoelectric substrate may be cut into the shape of a predetermined element. In short, the present invention is to remove the excess portion of the fine powder spread powder deposited on the dried green sheet by air jet before the firing step, and omit the punching step and the like during that period. Is the purpose of use of the piezoelectric element, for example, for piezoelectric filter, for piezoelectric resonator, for ladder type filter, for surface wave resonator, for surface wave filter, etc.
The manufacturing process can be changed or replaced as appropriate according to the suitable process sequence.

[0044]

According to the present invention, it is possible to prevent the piezoelectric substrates from adhering to each other during firing, to reduce the swelling on the surface of the piezoelectric element, and to further simplify the step of removing the spread powder. Become.

[Brief description of drawings]

FIG. 1 is a sectional view of a piezoelectric element according to a manufacturing method of the present invention.

FIG. 2 is a conceptual diagram showing the main steps of the manufacturing method of the present invention.

FIG. 3 is a conceptual diagram of a manufacturing apparatus used for a part of the manufacturing method of the present invention.

FIG. 4 is a partial enlarged view of a manufacturing apparatus used for a part of the manufacturing method of the present invention.

[Explanation of symbols]

 1-Piezoelectric element 10-Piezoelectric substrate 11, 12-Electrode 31-Green sheet 34-Spreading powder 35-・ Vibration sieve 38 ・ ・ ・ ・ ・ ・ Air jet nozzle

Claims (1)

Claim: What is claimed is: 1. A step of forming a calcination raw material of a piezoelectric ceramic into a green sheet, a step of punching the green sheet into a predetermined shape, and a firing of the punched green sheet. In a method of manufacturing a piezoelectric element including a step, after the step of forming a green sheet, a step of applying the same fine powder as the calcination raw material on the green sheet and further removing excess fine powder by an air jet may be performed. A method for manufacturing a characteristic piezoelectric element.