JP2003318457A - Multilayer piezoelectric oscillator and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer piezoelectric oscillator exhibiting an electromechanical coupling coefficient of 65% or above stably even in the form of array. <P>SOLUTION: The multilayer piezoelectric oscillator comprises two layers of piezoelectric, a single layer internal electrode laid alternately with the piezoelectric, one external electrode coupled with the internal electrode, a multilayer piezoelectric oscillator or an n-layer (n is a natural number of 3 or above) piezoelectric having the other external electrode formed at least on the upper or lower surface of the multilayer piezoelectric oscillator independently from the one external electrode, internal electrodes of n-1 layers laid alternately with the piezoelectric, and an external electrode group arranged to be connected in parallel with the internal electrode. The internal electrode is formed by interposing an adhesive layer between the electrodes constituting a two layer internal electrode, irregularity difference on the surface of the electrode constituting the internal electrode are set within 1.5 μm, thickness of the adhesive layer is set at 1 μm or less, and the resin of the adhesive layer has Shore D hardness of 80 or above. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric vibrator and a method for manufacturing the same, and more specifically, a high frequency resonator, a transducer, etc. that utilize resonance in the thickness direction of the piezoelectric vibrator (resonance of longitudinal vibration). In particular, the present invention relates to a laminated piezoelectric vibrator suitably used for an ultrasonic probe for ultrasonic diagnostic equipment and a method for manufacturing the same.

[0002]

2. Description of the Related Art An ultrasonic probe uses a built-in piezoelectric vibrator to convert an electric signal during transmission into an ultrasonic wave and an ultrasonic wave during reception with an electric signal. In the ultrasonic probe of the electronic scanning device which is most widely used at present, the piezoelectric vibrator is finely cut into an array (strip) shape by a dicing machine, etc. It is used as an element.

Regarding the performance of a piezoelectric vibrator required to increase the sensitivity of such an ultrasonic probe, the higher the piezoelectric constant d ₃₃ obtained by the following calculation formula, the more electrical energy becomes mechanical energy. It is convenient to convert.

[Chemical 1] k ₃₃ : Electromechanical coupling coefficient ε ₃₃ : Dielectric constant at constant stress S ₃₃ : Elastic compliance at constant electric field

In the case of a piezoelectric vibrator cut in an array, the electromechanical coupling coefficient k ₃₃ ′ (hereinafter, the electromechanical coupling coefficient in the array is represented by “k ₃₃ ′”) is large and the dielectric constant is large. Higher ε ₃₃ is more preferable, and it is further preferable that it is formed of a material having a high dielectric constant, which causes less loss due to a cable or device stray capacitance and is easy to match with a transmission / reception circuit.

For the above-mentioned reasons, the laminated piezoelectric vibrator is very useful because it has a structure in which a plurality of piezoelectric bodies are laminated and a high dielectric constant can be obtained.
By increasing the number of layers, 3 layers, ..., 1/4,
Since a lower resonance impedance of 1/9, ... Can be obtained, this is also useful.

[0006]

In producing the laminated piezoelectric vibrator as described above, a method of co-firing is adopted as a method of laminating the piezoelectric body. However, in this method, it is necessary to use a noble metal such as Pd or Pt as an electrode material for performing simultaneous firing, and therefore the cost increases as the number of stacked layers increases. Furthermore, it is difficult to obtain a large size due to problems such as warpage caused by co-firing. Also, in order to obtain a bonding strength that can withstand cutting, in order to improve the bondability between the ceramic and the electrode, glass frit However, the glass frit diffuses into the ceramics and causes the decrease of the above k ₃₃ ′ and the dielectric constant.

That is, in the above co-firing method,
If the bonding strength is high enough to withstand the cutting process for forming an array, the k ₃₃ 'and the dielectric constant will be low, and conversely, if the k ₃₃ ' and the dielectric constant are to be improved, the bonding strength will be low.
The electrodes peel off from the ceramic during the cutting process for cutting into an array.

As a method for laminating the piezoelectric body, in addition to the simultaneous firing method, there are a method for laminating the electrodes formed on the piezoelectric body by heat fusion and a method for laminating the piezoelectric body with an adhesive resin. However, in the method of laminating the electrodes by heat fusion, it is necessary to add a large amount of glass frit in order to increase the bonding strength between the ceramics and the electrodes. In addition, the glass frit diffuses into the ceramics, causing a decrease in k ₃₃ 'and a dielectric constant. In particular, the thinner the ceramic layer, the greater the damage to the characteristics.

[0009] In contrast, in the resin bonding method, the dielectric constant for the diffusion is not of the glass frit is not reduced, in the conventional resin bonding method, 'large variations in, k _33' k ₃₃ is less than 65% I can only get things.

Therefore, in the present situation, a laminated piezoelectric vibrator having a stable k ₃₃ ′ after being processed into an array and having a characteristic of 65% or more has not been put to practical use.

Therefore, the present invention solves the above-mentioned problems in the prior art and provides a laminated piezoelectric vibrator having a stable k ₃₃ ′ after processing into an array and having a characteristic of 65% or more. With the goal.

[0012]

According to the present invention, there are provided two layers of piezoelectric material, and one layer of internal electrodes alternately laminated with the piezoelectric material.
In a laminated piezoelectric vibrator having one external electrode connected to the internal electrode and the other external electrode independent of the one external electrode, the other external electrode is at least the laminated piezoelectric vibrator. Formed on the upper surface and the lower surface, the internal electrode is formed by interposing an adhesive layer between two layers of the internal electrode forming electrode, and the unevenness difference on the surface of the internal electrode forming electrode is 1.5 μm or less, Further, the above problem is solved by making the thickness of the adhesive layer 1 μm or less and using the resin of the adhesive layer having hardness of Shore D hardness of 80 or more to form the laminated piezoelectric vibrator.

Further, according to the present invention, n layers (where n is a natural number of 3 or more) of piezoelectric material, n-1 layers of internal electrodes alternately laminated with the piezoelectric material, and the internal electrodes are arranged in parallel. In a laminated piezoelectric vibrator including an external electrode group provided so as to be connected, the internal electrode is configured by interposing an adhesive layer between two layers of internal electrode constituting electrodes,
The unevenness on the surface of the internal electrode constituting electrode is 1.5
μm or less, and the thickness of the adhesive layer is 1 μm or less,
The above problem is solved by forming a laminated piezoelectric vibrator by using a resin having a Shore D hardness of 80 or more as the resin of the adhesive layer.

That is, according to the present invention, in the two-layer laminated piezoelectric vibrator or the n-layer laminated piezoelectric vibrator as described above, the unevenness of the surface of the internal electrode constituting electrode is set to 1.5 μm or less, and the adhesive layer By using a resin having a thickness of 1 μm or less and a hardness of 80 or more in Shore D hardness as a resin for the adhesive layer, k ₃₃ ′ is stable and 65% even in an array form.
The above laminated piezoelectric vibrator can be provided.

Further, in the present invention, the thickness of the internal electrode constituting electrode is preferably 1 μm or less, and further, the internal electrode constituting electrode is formed by a sputtering method, and the thickness of the internal electrode constituting electrode is A preferable mode is that the material has a thickness of 0.05 to 1 μm and the material is gold (Au).

[0016] Another subject matter of the present invention is a method for manufacturing the above-mentioned laminated piezoelectric vibrator, wherein ceramics are # 6.
000 or more abrasive wrapping first step, and the first step
The second step of forming the internal electrode constituting electrodes in a predetermined pattern on the surface of the ceramic obtained in the step, and the internal electrode constituting electrodes are adhered with an adhesive to provide a space between the two layers of internal electrode constituting electrodes. This is a method for manufacturing a laminated piezoelectric vibrator by way of a third step of forming internal electrodes with an adhesive layer interposed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated piezoelectric vibrator of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a two-layer laminated type laminated piezoelectric vibrator in which two piezoelectric layers are laminated in the present invention, and FIG. 2 is a three-layer laminated piezoelectric layer of n = 3 in the present invention. It is a figure which shows typically the laminated piezoelectric vibrator of a laminated type. Further, FIG. 3 is a diagram schematically showing a four-layer laminated piezoelectric vibrator in which four piezoelectric bodies of n = 4 are laminated in the present invention, and FIG. 4 is a piezoelectric body of n = 5 or more in the present invention. FIG. 3 is a diagram schematically showing an n-layer laminated type laminated piezoelectric vibrator in which n layers are laminated. FIG. 5 is a schematic enlarged view showing the internal electrodes and members in the vicinity thereof in the laminated piezoelectric vibrator of the present invention.

First, the two-layer laminated piezoelectric vibrator shown in FIG. 1 will be described. The laminated piezoelectric vibrator shown in FIG. 1 has two layers of piezoelectric bodies 1 and the piezoelectric bodies 1 alternately laminated. One layer of internal electrode 2, one external electrode 3 connected to the internal electrode 2, and the other external electrode 4 not connected to the internal electrode 2 (the other external electrode 4 is the one external electrode). 3 is not connected to the external electrode 3 and is independent of the one external electrode 3. And
The other external electrode 4 is formed on at least the upper surface and the lower surface of the laminated piezoelectric vibrator, and naturally, the upper surface portion and the lower surface portion are connected to each other.

The internal electrode 2 is, as shown in FIG.
It is constituted by interposing an adhesive layer 2b between the internal electrode constituting electrodes 2a of the layer, and in the present invention, the unevenness on the surface of the internal electrode constituting electrode 2a (see FIG. 5).
Is 1.5 μm or less, the thickness of the adhesive layer 2b is 1 μm or less, and the resin hardness of the adhesive layer 2b is 80 or more in Shore D hardness. There is.

In FIG. 1, the polarization direction of the piezoelectric body 1 is indicated by a thick arrow in the piezoelectric body 1. In the laminated piezoelectric vibrator shown in FIG. 1, the polarization directions of the two layers of the piezoelectric body 1 are shown. Are opposite to each other, but the polarization directions may be the same depending on the purpose. In addition, in FIG. 1, the boundary line of the portion where the electrodes such as the internal electrode 2 and the external electrodes 3 and 4 are formed is shown by a thick line regardless of the type of electrode, and the ridge line of the portion where the electrode of the piezoelectric body 1 is not formed is shown. Is indicated by a thin line. Then, dots are added to the surface on which the electrodes are formed. It should be noted that the contents illustrated by the thick lines, thin lines, dots, thick arrows, etc. are the same in other drawings showing the piezoelectric vibrator regardless of the laminated structure.

Next, the three-layer laminated piezoelectric vibrator of n = 3 shown in FIG. 2 will be described. The laminated piezoelectric vibrator shown in FIG. 2 is a laminated piezoelectric vibrator of a three-layer laminated type in which three piezoelectric bodies are laminated.
Two layers of internal electrodes 2 alternately laminated, and one external electrode 3 of the two layers of internal electrodes, which is connected to the internal electrode 2 of the first layer counted from the top surface of the laminated piezoelectric vibrator, Among the internal electrodes of the layer, the external electrode 4 is connected to the internal electrode 2 of the second layer counting from the upper surface of the laminated piezoelectric vibrator, and the external electrode 3 of the one side and the external electrode 4 of the other side are the above-mentioned. The two layers of internal electrodes 2 are provided so as to be connected in parallel,
The structure of the internal electrode 2 is similar to that of the two-layer laminated type laminated piezoelectric vibrator shown in FIG.

Next, a four-layer laminated piezoelectric vibrator of n = 4 shown in FIG. 3 will be described. The laminated piezoelectric vibrator shown in FIG. 3 is a four-layer laminated piezoelectric vibrator in which four piezoelectric bodies 1 are laminated, and four layers of the piezoelectric body 1 and the piezoelectric body 1 are alternately laminated. The three-layer internal electrode 2 and one of the three-layer internal electrodes 2 connected to the first and third internal electrodes 2 counted from the top surface of the laminated piezoelectric vibrator.
And the other external electrode 4 connected to the internal electrode 2 of the second layer counting from the upper surface of the laminated piezoelectric vibrator among the internal electrodes 2 of the above three layers, and the external electrode 3 of the one side and the external electrode of the other side. The electrode 4 is provided so that the internal electrodes 2 of the above three layers are connected in parallel, and the configuration of the internal electrode 2 is the same as that of the two-layer laminated piezoelectric vibrator shown in FIG. is there.

Next, the laminated piezoelectric vibrator of n-layer laminated type with n = 5 or more shown in FIG. 4 will be described. The laminated piezoelectric vibrator shown in FIG. 4 is an n-layer laminated type laminated piezoelectric vibrator in which the piezoelectric bodies 1 are laminated in n layers (where n is an integer of 5 or more). The n-1 layer internal electrodes 2 and the n-1 layer internal electrodes 2 alternately stacked with the piezoelectric body 1
Of the external electrodes 3 connected to the odd-numbered internal electrodes 2 counted from the upper surface of the laminated piezoelectric vibrator and the even-numbered external electrodes 3 of the n-1 layer internal electrodes 2 counted from the upper surface of the laminated piezoelectric vibrator. The other outer electrode 4 connected to the inner electrode 2 is provided, and the one outer electrode 3 and the other outer electrode 4 are n-1.
The internal electrodes 2 of the layers are provided so as to be connected in parallel, and the configuration of the internal electrodes 2 is similar to that of the two-layer laminated type laminated piezoelectric vibrator shown in FIG. In the laminated piezoelectric vibrator of n-layer laminated type with n = 3 or more, the internal electrodes and the external electrodes are connected as described above as long as the internal electrodes of the n-1 layer are connected in parallel. It doesn't have to be.

In claim 2 and the like of the present specification, the expression "external electrode group" is used. This is composed of one external electrode and the other external electrode, and one external electrode and the other external electrode are formed. The external electrodes are independent from each other and are provided in such a manner that the n-1 layer internal electrodes can be connected in parallel.

In the present invention, the term "piezoelectric material" means a material obtained by subjecting a ceramic, a single crystal, or a composite of a ceramic or a single crystal and a polymer to a polarization treatment, and an internal electrode means a two-layer structure as shown in FIG. Internal electrode forming electrode 2a
The adhesive layer 2b is interposed between the two electrodes, and the internal electrode 2 is disposed between the two adjacent piezoelectric layers 1.

In the present invention, the internal electrodes are formed by forming electrodes for forming internal electrodes on one of the piezoelectric bodies, and forming electrodes for forming internal electrodes on the other piezoelectric body. Are bonded to each other with an adhesive so that an adhesive layer is interposed between the two layers of internal electrode constituting electrodes, and the n-1 layers of internal electrodes are connected in parallel between the internal electrodes. So that it is connected to the external electrode.

In the present invention, the above-mentioned internal electrode-constituting electrode
The unevenness difference of 1.5 μm or less on the surface of the
T shown in FIG. 5, that is, the internal electrode formed on the piezoelectric body 1.
Perpendicular to the bottom of the concave portion and the apex of the convex portion on the surface of the constituent electrode 2a
This means that the distance in the direction is 1.5 μm or less.
In the light, the recesses on the surface of this internal electrode constituent electrode
The convex difference is 1.5 or less because the uneven difference is 1.5 μm.
For larger, k ₃₃The variation of ’
₃₃'Is lower than 65%.

Further, in the present invention, it is preferable that the thickness of the internal electrode constituting electrode is 1 μm or less, which means that the thickness of the internal electrode constituting electrode is 1 μm or less.
This is because if it is thicker than μm, k ₃₃ ′ may be lower than 65%.

Further, in the present invention, in order to thin the above-mentioned internal electrode constituting electrode, the above-mentioned electrode is formed by sputtering.
It is preferable to form it as a u (gold) electrode, and the thickness of the internal electrode constituting electrode is preferably 0.05 μm to 1 μm. If the thickness of the internal electrode constituting electrode is greater than 1 μm, the cost will increase. Further, when the thickness of the electrode for the internal electrode structure is less than 0.05 μm,
Since some of the internal electrodes and the external electrodes cannot be electrically connected when cut into an array, the thickness of the internal electrode constituting electrode is preferably 0.05 to 1 μm as described above.

In the present invention, the electrode materials for the external electrodes and the electrodes for forming the internal electrodes are, for example, Ni, Cr,
A conductive metal such as Ti, Au, Pt, Pd, Ag, Cu, or Al is used, and it is preferable to use each of them according to the type of the piezoelectric body and the electrode forming method. The electrode may be formed by a conventional method, such as a sputtering method or a plating method.

In the present invention, the adhesive used to form the internal electrodes is preferably such that the constituent resin is harder. Specifically, it is necessary to use an adhesive having a Shore D hardness of 80 or more. As a result, it is possible to obtain k ₃₃ ′ having an array shape of 65% or more. If the hardness of the resin of the adhesive layer is less than 80 in Shore D hardness, it is too soft, and therefore even if the unevenness of the surface of the internal electrode constituting electrode is within the above range, the longitudinal vibration of the piezoelectric body is caused by the adhesive layer. It is reduced, and k ₃₃ 'is lower than 65%, and in some cases, peeling occurs when the array is cut. In the present invention, the Shore D hardness, which indicates the hardness of the resin of the adhesive layer, is JIS-K-721.
It is measured according to the method specified in 5.

The above-mentioned adhesive may be, for example, an acrylic adhesive, a urethane adhesive, an epoxy adhesive, a polyimide adhesive or the like, but especially an epoxy adhesive or a polyimide adhesive. Is preferable because it has heat resistance required when producing an ultrasonic probe.

In the present invention, the thickness of the adhesive layer means the state before the internal electrode forming electrodes are adhered to form the internal electrodes, as shown in FIG. 6 points (see FIG. 6 so that the average value of the thickness of the adhesive layer can be obtained as accurately as possible).
As shown in FIG.
It is preferable to select a total of 5 places near the corner as the measurement position 11). Use a micrometer to measure the thickness, and use a single layer with a maximum thickness variation of ± 0.001 μm or less and use an adhesive. After the adhesion, in the same manner as described above, as shown in FIG. 6, the thickness at five points is measured with a micrometer,
The value obtained by subtracting the thickness of the piezoelectric body from the thickness,
It is calculated by dividing by the number of adhesive layers. In the present invention, the reason why the thickness of the adhesive layer is set to 1 μm or less is that by doing so, those having k ₃₃ ′ of 65% or more can be stably obtained, and when the thickness of the adhesive layer becomes larger than 1 μm. k ₃₃ 'is lower than 65%.

In the drawings attached to this specification, all of the laminated piezoelectric vibrators each having a square planar shape are illustrated.
The laminated piezoelectric vibrator of the present invention may be a planar body, and its planar shape is not limited to a quadrangular shape, and may be another shape such as a circular shape, a hexagonal shape, a polygonal shape, or a trapezoidal shape. Not only the upper surface and the lower surface have the same shape and the same size, but the upper surface and the lower surface may have different sizes such as a trapezoid.

In the present invention, as the piezoelectric material, for example, lead zirconate titanate (PZT) -based, barium titanate (BT) -based, lead titanate (PT) -based, bismuth titanate (BIT) -based ceramics and the like are used. Or a single crystal such as lead zirconate titanate niobate (PZNT) or lead magnesium titanate niobate titanate (PMNT), or ceramics or a composite of a single crystal and a polymer. The thing etc. can be used.

The laminated piezoelectric vibrator of the present invention is used, for example, for the first step of wrapping ceramics with a fine abrasive of # 6000 or more, and for forming internal electrodes in a predetermined pattern on the surface of the ceramics obtained in the first step. Via a second step of forming electrodes and a third step of adhering the internal electrode forming electrodes with an adhesive to form an internal electrode in which an adhesive layer is interposed between two layers of internal electrode forming electrodes Manufactured by the method characterized by the above, and various steps are added as necessary.

[0037]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples illustrated in the embodiments.

Example 1 A PZT-based piezoelectric material powder, a binder, a plasticizer, a solvent and a dispersant were mixed and kneaded and molded by an extrusion molding machine to obtain a green sheet having a thickness of 0.5 mm. It was The green sheet was cut into a predetermined size to obtain a ceramics forming compact, and the ceramics forming compact was degreased and then fired at 1200 ° C. for 2 hours to obtain a PZT-based ceramics. The surface of this ceramic was wrapped with abrasive grains of # 6000WA in a double-side polishing machine, and then cut into a predetermined size by a dicing machine.

PZT cut into a predetermined size as described above
After masking so that desired electrode patterns can be formed on both surfaces of the ceramics, Au (gold) with a thickness of 0.2
The Au electrode as an electrode for forming an internal electrode and the Au electrode as an external electrode were formed by sputtering so as to have a thickness of μm.

An ultra-depth shape measuring microscope (manufactured by KEYENCE Co., Ltd.) was used to observe three places on the surface of the Au electrode for forming the internal electrode of the ceramic on which the Au electrode was formed, with a visual field of 0.15 mm square.
As a result of observation using VK-8500), the maximum value of the unevenness difference on the surface of the Au electrode for forming the internal electrode is 1.2.
was μm. Further, as shown in FIG. 6, the thickness of five places was measured with a micrometer in a state where the electrodes for forming the internal electrodes were provided on the ceramics. The minimum thickness is 0.329
mm, maximum value is 0.331 mm, average thickness is 0.330
The thickness variation was within ± 0.001 mm at the maximum.

The ceramic on which the Au electrode is formed is
As shown in the structure of FIG. 1, two layers are laminated and press-cured in a state where a room temperature curing type epoxy adhesive is applied to the Au electrode surface for the internal electrode configuration, and Au for the internal electrode configuration is formed. By adhering the electrode surface with the above-mentioned epoxy adhesive, an internal electrode having an adhesive layer interposed between two layers of Au electrode for forming an internal electrode was formed. The hardness of the constituent resin of the epoxy adhesive used for adhering the Au electrode for forming the internal electrode was 88 in Shore D hardness. The area of the internal electrode obtained as described above is 10
It was mm × 31 mm.

When the thickness of the two-layer laminated ceramics obtained as described above was measured by a micrometer at five points as shown in FIG. 6, the minimum value was 0.659 mm,
Maximum value is 0.661 mm, average thickness is 0.660 mm
Met. Since the average thickness of each of the PZT ceramics used was 0.330 mm, the thickness of the adhesive layer was calculated to be 0 μm. As described above, the calculated thickness of the adhesive layer is 0 μm because the distance between the convex portion and the convex portion on the opposite surface of the micrometer is different in spite of the unevenness of the surface of the internal electrode constituting electrode. Since the thickness is measured, in the adhesive layer portion, the uneven portions of the internal electrode constituting electrodes may overlap with each other, and the thickness of the adhesive layer may be 0 or less. However, there is no doubt that the adhesive layer has a thickness of 1 μm or less.

The laminated ceramics obtained as described above is used at room temperature for 1 kV / mm with respect to the thickness of one piezoelectric layer.
The structure shown in Fig. 1 is used for the polarization process, and the area is 10mm x
A two-layer laminated piezoelectric vibrator having a 31 mm internal electrode 2 interposed between two layers of the piezoelectric body 1 was obtained. In addition, a two-layer laminated type, a two-layered three-layered type, a four-layered laminated type described later, or three
The numbers of layers and 4 layers indicate the number of piezoelectric layers.

This two-layer laminated type laminated piezoelectric vibrator has a length x
It had a rectangular and flat rectangular parallelepiped shape with a size of width × thickness of 11 mm × 32 mm × 660 mm, and the average thickness of the piezoelectric body of each layer was 0.330 mm.

Further, the above-mentioned two-layer laminated type laminated piezoelectric vibrator has a CW / ET (cut width / thickness of laminated piezoelectric vibrator) of 0.5.
So that the size is 11mm × 0.330mm ×
Cut into an array of 0.660 mm and
Frequency-impedance characteristics were measured using an impedance analyzer 4194A manufactured by HP (Hewlett Packard) Co., Inc. with respect to ten laminated piezoelectric vibrators of a layer laminated type, and resonance frequency (fr) in the thickness direction of the fundamental wave and anti-resonance were measured. Frequency (fa) and resonance impedance (Zr)
I asked. Then, from the resonance frequency (fr) and the anti-resonance frequency (fa), the electromechanical coupling coefficient (k ₃₃ ') in the thickness direction was calculated according to the test method of the piezoelectric ceramics vibrator of the Japanese electronic material industry. In addition, the capacitance (C) was measured with an LCR meter, and the average value was calculated. The main configuration of the two-layer laminated type laminated piezoelectric vibrator of Example 1 is shown in Table 1 below, and its characteristics are shown in Table 2 below. Table 2 also shows the maximum and minimum values of k ₃₃ ′.

Example 2 As in Example 1, a ceramic having a predetermined Au electrode formed thereon was coated with the same epoxy adhesive as in Example 1 on the surface of the Au electrode for forming the internal electrode. By laminating three layers so as to have the structure shown in Fig. 3 and press-curing, the Au electrodes for internal electrode configuration are adhered with an adhesive to bond between two layers of Au electrodes for internal electrode configuration with an area of 10 mm x 31 mm. The internal electrodes interposing the layers are formed and subjected to a predetermined polarization treatment, and in the structure shown in FIG. 2, three layers of piezoelectric bodies 1 and 2 are formed.
A three-layer laminated piezoelectric vibrator in which the internal electrodes 2 of the layers were alternately laminated was obtained.

The three-layer laminated piezoelectric vibrator thus obtained is
The size of length x width x thickness is 11 mm x 32 mm x 0.99
It had a flat rectangular parallelepiped shape of 2 mm, and the average thickness of the piezoelectric body of each layer was 0.330 mm.

With respect to the laminated piezoelectric vibrator of the three-layer laminated type of the second embodiment, the piezoelectric characteristic and the electric characteristic were measured as in the first embodiment. The main configuration of the three-layer laminated piezoelectric vibrator of Example 2 is shown in Table 1 below, and its characteristics are shown in Table 2 below.

Example 3 A ceramic having a predetermined Au electrode formed thereon as in Example 1 is shown in FIG. 3 in a state in which the same epoxy adhesive as in Example 1 is applied to the Au electrode for forming the internal electrodes. In order to form a structure, four layers are laminated and press-cured to bond the internal electrode forming Au electrodes with an adhesive to form an adhesive layer between the two internal electrode forming Au electrodes having an area of 10 mm × 31 mm. A laminated piezoelectric body of a four-layer laminated type in which four layers of piezoelectric bodies 1 and three layers of internal electrodes are alternately laminated in the structure shown in FIG. The oscillator was obtained.

The obtained four-layer laminated piezoelectric vibrator is
The size of length x width x thickness is 11 mm x 32 mm x 1.32
It had a flat rectangular parallelepiped shape of 0 mm, and the average thickness of the piezoelectric body of each layer was 0.330 mm.

The piezoelectric and electrical characteristics of the four-layer laminated piezoelectric vibrator of Example 3 were measured in the same manner as in Example 1. The main structure of the four-layer laminated piezoelectric vibrator of Example 3 is shown in Table 1 below, and its characteristics are shown in Table 2 below.

Example 4 A PZT-based piezoelectric substance-forming powder, a binder, a plasticizer, a solvent and a dispersant were mixed and kneaded and molded by an extrusion molding machine to obtain a green sheet having a thickness of 0.5 mm. It was The obtained green sheet is cut into a predetermined size to obtain a ceramic structure compact, and the ceramic structure compact is degreased and then fired at 1200 ° C. for 2 hours to obtain PZ.
A T-based ceramic was obtained. The surface of the obtained PZT ceramics was wrapped with # 6000WA using a double-sided polishing machine, and then cut into a predetermined size with a dicing machine.

After masking both surfaces of the obtained PZT ceramics of a predetermined size so that a desired electrode pattern can be formed, Au (gold) is sputtered to a thickness of 0.2 μm to form an internal electrode structure. An Au electrode as an electrode and an Au electrode as an external electrode were formed.

As a result of observing three places on the surface of the Au electrode for forming the internal electrode of the ceramics on which the Au electrode was formed with an ultra deep shape measuring microscope in the same field of view as 0.15 mm square as in Example 1, The maximum value of the unevenness on the surface of the Au electrode for electrode configuration was 1.3 μm. Thereafter, the structure shown in FIG. 1 was used and the area was 10 m in the same manner as in Example 1 except that the ceramics on which the Au electrode was formed was used.
A two-layer laminated piezoelectric vibrator having m × 31 mm internal electrodes was obtained.

The obtained two-layer laminated type laminated piezoelectric vibrator is
The size of length x width x thickness is 11 mm x 32 mm x 0.46
It had a flat rectangular parallelepiped shape of 1 mm, and the average thickness of the piezoelectric body of each layer was 0.230 mm.

With respect to the two-layer laminated type laminated piezoelectric vibrator of Example 4, the piezoelectric characteristics and the electric characteristics were measured in the same manner as in Example 1. The main structure of the two-layer laminated type laminated piezoelectric vibrator of Example 4 is shown in Table 1 below, and its characteristics are shown in Table 2 below.

Comparative Example 1 The surface of the PZT ceramics obtained in the same manner as in Example 4 was replaced with #.
A two-layer laminated piezoelectric vibrator was manufactured in the same manner as in Example 4, except that the laminated piezoelectric vibrator was wrapped with 2000 WA of abrasive grains.

The maximum value of the unevenness on the surface of the Au electrode for forming the internal electrodes, which was measured during the production of the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 1, was 2.3 μm. Further, with respect to the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 1, the piezoelectric characteristics and the electric characteristics were measured in the same manner as in Example 1. The main configuration of the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 1 is shown in Table 1 below, and its characteristics are shown in Table 2 below.

Comparative Example 2 The surface of the PZT ceramics obtained in the same manner as in Example 4 was replaced with #.
A two-layer laminated piezoelectric vibrator was manufactured in the same manner as in Example 4 except that it was wrapped with 800 WA of abrasive grains.

The maximum value of the unevenness on the surface of the Au electrode for forming the internal electrode measured during the manufacture of the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 2 was 4.3 μm. The piezoelectric characteristics and the electrical characteristics of the two-layer laminated piezoelectric vibrator of Comparative Example 2 were measured in the same manner as in Example 1. The main structure of the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 2 is shown in Table 1 below, and its characteristics are shown in Table 2 below.

As described above, in Table 1, the main constitutions of the laminated piezoelectric vibrators of Examples 1 to 4 and Comparative Examples 1 and 2, that is,
Number of stacked piezoelectric bodies, unevenness on the surface of the electrode for forming the internal electrode, hardness of the resin of the adhesive layer (Shore D hardness), thickness of the adhesive layer in the internal electrode, type of electrode for forming the internal electrode (metal of the constituent material) The thickness of the internal electrode forming electrode is shown in Table 1. In Table 1, “the number of stacked piezoelectric bodies” is defined as “the number of stacked layers” and “the unevenness difference on the surface of the internal electrode forming electrode” is shown in Table 1 in terms of space. "," Difference in surface unevenness, "" hardness of resin of adhesive layer "
"Adhesive layer resin hardness", "Adhesive layer thickness in internal electrode""Adhesive layer thickness", "Internal electrode configuration electrode type", "Electrode type", "Internal electrode configuration electrode""Thickness" is abbreviated as "electrode thickness". The same simplified description as to the main configuration of such a laminated piezoelectric vibrator applies to subsequent tables showing the main structure of the laminated piezoelectric vibrator.

Table 2 also shows Examples 1 to 4 and Comparative Example 1
The characteristics of the laminated piezoelectric vibrators, that is, the electromechanical coupling coefficient (average value, maximum value, minimum value) in the thickness direction, the resonance frequency in the thickness direction of the fundamental wave, the antiresonance frequency, the resonance impedance, and the capacitance. In Table 2, the “electromechanical coupling coefficient” is “k ₃₃ ′”, the “resonance frequency” is “fr”, the “anti-resonance frequency” is “fa” because of space limitations.
"Resonance impedance" is abbreviated as "Zr", and "electrostatic capacitance" is abbreviated as "C". The simplified display regarding the characteristics of the laminated piezoelectric vibrator is the same in the following tables showing the characteristics of the laminated piezoelectric vibrator.

[0063]

[Table 1]

[0064]

[Table 2]

As is clear from the results shown in Table 2, in the laminated piezoelectric vibrators of Examples 1 to 4, k ₃₃ ′ showing the electromechanical coupling coefficient in the longitudinal array was 65% or more, and the comparison was made. Compared with the laminated piezoelectric vibrators of Examples 1 and 2, k ₃₃ 'is larger,
Moreover, the variation was small.

Example 5 A two-layer laminated piezoelectric vibrator having the structure shown in FIG. 1 was manufactured in the same manner as in Example 1 except that the thickness of the adhesive layer was 0.5 μm.

The piezoelectric and electrical characteristics of the two-layer laminated piezoelectric vibrator of Example 5 were measured in the same manner as in Example 1. The main configuration of the two-layer laminated type laminated piezoelectric vibrator of Example 5 is shown in Table 3 below, and its characteristics are shown in Table 4 below.

Example 6 A two-layer laminated type laminated piezoelectric vibrator having the structure shown in FIG. 1 was produced in the same manner as in Example 5 except that the thickness of the adhesive layer was set to 1 μm.

With respect to the two-layer laminated type laminated piezoelectric vibrator of Example 6, the piezoelectric characteristic and the electric characteristic were measured in the same manner as in Example 1. The main configuration of the two-layer laminated type laminated piezoelectric vibrator of Example 6 is shown in Table 3 below, and its characteristics are shown in Table 4 below.

Comparative Example 3 A two-layer laminated piezoelectric vibrator having the structure shown in FIG. 1 was prepared in the same manner as in Example 5 except that the thickness of the adhesive layer was 2 μm.

With respect to the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 3, the piezoelectric characteristics and electric characteristics were measured in the same manner as in Example 1. The main configuration of the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 3 is shown in Table 3 below, and its characteristics are shown in Table 4 below.

Comparative Example 4 A two-layer laminated piezoelectric vibrator having the structure shown in FIG. 1 was manufactured in the same manner as in Example 5 except that the thickness of the adhesive layer was 3 μm.

The piezoelectric and electrical characteristics of the two-layer laminated piezoelectric vibrator of Comparative Example 4 were measured in the same manner as in Example 1. Table 3 shows the main constitution of the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 4, and Table 4 shows its characteristics.

[0074]

[Table 3]

[0075]

[Table 4]

As is clear from the results shown in Table 4, in the laminated piezoelectric vibrators of Examples 5 to 6, k ₃₃ ′ showing the electromechanical coupling coefficient of the array was 65% or more, and Comparative Examples 3 to Four
The k ₃₃ 'is larger than that of the laminated piezoelectric vibrator of
The variation was small.

Example 7 A powder for forming a PZT-based piezoelectric material, a binder, a plasticizer, a solvent and a dispersant were mixed and kneaded and molded by an extrusion molding machine to obtain a green sheet having a thickness of 0.5 mm. It was The obtained green sheet was cut into a predetermined size to obtain a ceramic structure molded body. After degreasing the molded body for ceramics composition, it is fired at 1200 ° C. for 2 hours to obtain PZ.
A T-based ceramic was obtained. The surface of the obtained PZT ceramics was wrapped with # 2000WA abrasive grains by a double-side polishing machine, and then cut into a predetermined size by a dicing machine.

A plating resist material having a predetermined shape is printed on both surfaces of the obtained ceramic of a predetermined size by a screen printing machine to cure the resist, and then a Cu layer is formed by electroless plating of Cu, and thereafter, a Cu layer is formed. The resist material was removed to obtain a PZT-based ceramic having an electrode having a predetermined shape and a Cu thickness of 2.0 μm.

The surface of the PZT-based ceramics having the Cu electrodes formed thereon was mirror-polished with a double-sided polishing machine so that the thickness of Cu was 1 μm. 0.15m as in Example 1
When observed using an ultra-depth shape measuring microscope in the m-angle field of view, the maximum value of the unevenness difference on the surface of the Cu electrode for forming the internal electrode was 1.0 μm.

Further, as shown in FIG. 6, when the thickness of five points on the polished surface of the ceramic was measured with a micrometer, the minimum value of the thickness was 0.330 mm and the maximum value was 0.
The thickness was 332 mm, the average thickness was 0.331 mm, and the variation in thickness was ± 0.001 mm at the maximum.

The same procedure as in Example 1 except that the above ceramics was used and an epoxy adhesive having a resin hardness of 85 as Shore D hardness was used as an adhesive for adhering the Cu electrode for forming the internal electrode. A layer laminated ceramics was produced.

When the thickness of the obtained two-layer laminated ceramics was measured with a micrometer at five places as shown in FIG. 6, the minimum value of the thickness was 0.661 mm and the maximum value was 0.6.
It was 63 mm and the average thickness was 0.662 mm.
The average thickness of each of the PZT ceramics used was 0.
Since it was 331 mm, the thickness of the adhesive layer was calculated to be 0.
was μm.

The two-layer laminated ceramics obtained as described above are used at room temperature to obtain a thickness of one piezoelectric layer of 1 kV /
The structure shown in Fig. 2 has a surface area of 10 mm after polarization processing
A two-layer laminated piezoelectric vibrator having an internal electrode of 31 mm was obtained.

The obtained two-layer laminated piezoelectric vibrator is
The size of length x width x thickness is 11 mm x 32 mm x 0.66
It had a flat rectangular parallelepiped shape of 2 mm, and the average thickness of the piezoelectric body of each layer was 0.331 mm.

The above-mentioned two-layer laminated piezoelectric vibrator is
/ ET (cutting width / element thickness) to be 0.5, 1
It was cut into an array of 1 mm × 0.331 mm × 0.662 mm. The frequency-impedance characteristics of 10 of the two-layer laminated piezoelectric vibrators in the form of an array were measured using an HP impedance analyzer 4194A, and the resonance frequency (fr) in the thickness direction of the fundamental wave and anti-resonance were measured. The frequency (fa) and the resonance impedance (Zr) were obtained. Further, the electromechanical coupling coefficient k ₃₃ ′ in the thickness direction was calculated from the above resonance frequency (fr) and antiresonance frequency (fa) according to the test method of the piezoelectric ceramic vibrator of the Japanese electronic material industry. Further, the electrostatic capacity (C) was measured with an LCR meter. Table 5 shows the main components of the two-layer laminated piezoelectric vibrator of Example 7, and Table 6 shows the characteristics thereof.
Shown in.

Comparative Example 5 A two-layer laminated type laminated piezoelectric vibrator was manufactured in the same manner as in Example 7 except that the room temperature curing type epoxy adhesive whose constituent resin hardness was 78 in Shore D hardness was used.

With respect to the two-layer laminated type laminated piezoelectric vibrator of Comparative Example 5, the piezoelectric characteristic and the electric characteristic were measured in the same manner as in Example 1. Table 5 shows the main structure of the two-layer laminated piezoelectric vibrator of Comparative Example 5, and Table 6 shows its characteristics.

[0088]

[Table 5]

[0089]

[Table 6]

As is clear from the results shown in Table 6, in the laminated piezoelectric vibrator of Example 7, k ₃₃ ′ showing the electromechanical coupling coefficient of the array was 65% or more, and the laminated piezoelectric element of Comparative Example 5 was Compared to the oscillator, k ₃₃ 'was large and the variation was small.

Example 8 A PZT-based piezoelectric material powder, a binder, a plasticizer, a solvent and a dispersant were mixed and kneaded, and molded by an extrusion molding machine to obtain a green sheet having a thickness of 0.5 mm. It was The obtained green sheet is cut into a predetermined size to obtain a ceramics forming compact, which is then degreased and fired at 1200 ° C. for 2 hours to obtain PZ.
A T-based ceramic was obtained. The surface of the obtained PZT ceramics was wrapped with # 6000WA abrasive grains by a double-sided polishing machine, and then cut into a predetermined size by a dicing machine.

A plating resist material having a predetermined shape is printed on both surfaces of the obtained ceramics of a predetermined size by a screen printing machine to cure the resist, and then a Ni layer is formed by electroless plating of Ni. Then, the resist material was removed to obtain a PZT-based ceramics having an internal electrode-forming electrode having a predetermined shape and a Ni thickness of 1.0 μm.

The unevenness on the surface of the Ni electrode for forming the internal electrode was measured in the same manner as in Example 1, and the thickness of the ceramic was measured.

Then, the PZT on which this Ni electrode is formed
The thickness of the adhesive layer of the internal electrodes was determined in the same manner as in Example 1 except that the system ceramics was used, and a two-layer laminated piezoelectric vibrator was manufactured, and the piezoelectric characteristics and the electrical characteristics were measured.
Table 7 shows the main constitution of the two-layer laminated type laminated piezoelectric vibrator of Example 8, and Table 8 shows its characteristics.

[0095]

[Table 7]

[0096]

[Table 8]

As is clear from the results shown in Table 8, in the laminated piezoelectric vibrator of Example 8, k ₃₃ ′ showing the electromechanical coupling coefficient of the array was as large as 65% or more, and the variation was small. .

[0098]

As described above, according to the present invention, it is possible to provide a laminated piezoelectric vibrator having a stable electromechanical coupling coefficient of 65% or more even in an array form.

[Brief description of drawings]

FIG. 1 is a view schematically showing an example of a two-layer laminated type laminated piezoelectric vibrator of the present invention.

FIG. 2 is a diagram schematically showing an example of an n-layer (three-layer) laminated type laminated piezoelectric vibrator in the case of n = 3 in the present invention.

FIG. 3 is a diagram schematically showing an example of an n-layer (four-layer) laminated type laminated piezoelectric vibrator in the case of n = 4 in the present invention.

FIG. 4 is a diagram schematically showing an example of an n-layer laminated type laminated piezoelectric vibrator when n = 5 or more in the present invention.

FIG. 5 is a schematic enlarged view showing an example of the internal electrodes of the laminated piezoelectric vibrator of the present invention and the vicinity thereof.

FIG. 6 is a diagram schematically showing an example of measurement positions of the thickness of ceramics in the present invention.

[Explanation of symbols]

1 Piezoelectric body 2 internal electrodes 2a Internal electrode configuration electrode 2b adhesive layer 3 One external electrode 4 Other external electrode

Claims (5)

[Claims] 1. A two-layer piezoelectric body, a one-layer internal electrode alternately laminated with the piezoelectric body, one external electrode connected to the internal electrode, and one external electrode independent of each other. A laminated piezoelectric vibrator having the other external electrode,
The other external electrode is formed on at least an upper surface and a lower surface of the laminated piezoelectric vibrator, and the internal electrode is formed by interposing an adhesive layer between two layers of internal electrode forming electrodes. The laminated piezoelectric vibrator, wherein the unevenness on the surface of the adhesive layer is 1.5 μm or less, the thickness of the adhesive layer is 1 μm or less, and the hardness of the resin of the adhesive layer is 80 or more in Shore D hardness. 2. An n-layer (where n is a natural number of 3 or more) piezoelectric body, an n-1 layer internal electrode alternately laminated with the piezoelectric body, and the internal electrode are connected in parallel. And a group of external electrodes provided on the internal electrode structure, wherein the internal electrodes are formed by interposing an adhesive layer between two layers of the internal electrode structure electrodes. The unevenness of the surface of the working electrode is 1.5 μm or less, the thickness of the adhesive layer is 1 μm or less, and the hardness of the resin of the adhesive layer is 80 or more in Shore D hardness. . 3. The laminated piezoelectric vibrator according to claim 1, wherein the internal electrode constituting electrode has a thickness of 1 μm or less. 4. The internal electrode forming electrode is formed by a sputtering method, and the internal electrode forming electrode has a thickness of 0.05 to 1 μm.
The laminated piezoelectric vibrator according to any one of claims 1 to 3, wherein m is the material of the internal electrode constituting electrode and is gold. 5. A first step of lapping ceramics with an abrasive of # 6000 or more, and a second step of forming internal electrode constituting electrodes in a predetermined pattern on the surface of the ceramic obtained in the first step, The third step of forming an internal electrode in which the internal electrode forming electrode is adhered with an adhesive to form an internal electrode with an adhesive layer interposed between the two layers of internal electrode forming electrodes. 5. The method for manufacturing a laminated piezoelectric vibrator according to any one of 4 above.