KR20220095659A - Piezoelectric Composite with Easy Transfer of Ultrasonic Energy and Method for Manufacturing the Same - Google Patents

Abstract

Disclosed are a piezoelectric composite capable of preventing a damage due to a difference in thermal expansion coefficient and suppressing transfer loss of ultrasonic energy due to a difference in acoustic impedance, and a method for manufacturing the same. In this case, an ultrasonic vibration generated from a piezoelectric material can be effectively transferred to a common electrode by using a metal mesh and an epoxy filled in the metal mesh to reduce the difference in acoustic impedance between the piezoelectric material and the common electrode. In addition, since stress concentration caused by a difference in thermal expansion coefficient can be alleviated by using the elastic characteristics of the metal mesh, it is possible to prevent damage to a conductor and the common electrode due to non-contact of them or a bending phenomenon on the surface of the common electrode due to a difference in the thermal expansion coefficient.

Description

Piezoelectric Composite with Easy Transfer of Ultrasonic Energy and Method for Manufacturing the Same

The present invention relates to a piezoelectric composite and a method for manufacturing the same, and more particularly, to a piezoelectric composite that can be used in an ultrasonic transducer and easily transmits ultrasound, and a method for manufacturing the same.

A piezoelectric composite is used to secure low acoustic impedance while maintaining excellent piezoelectric properties. As is known, a piezoelectric composite is manufactured by filling a piezoelectric element, for example, a polymer having a low acoustic impedance around a PZT (lead zirconate titanate) element.

According to the bonding structure of the piezoelectric element and the polymer, the piezoelectric composite can be divided into 10 types, such as 1-3 mode, 2-2 mode, and 3-3 mode. indicates. For example, the 1-3 mode piezoelectric composite has a form in which one linear piezoelectric fiber is planted in a three-member polymer matrix, and has been widely used in ultrasonic transducers in various fields due to its excellent piezoelectric properties.

Meanwhile, conventionally, a piezoelectric composite was manufactured using a powder injection molding manufacturing method. As is well known, the powder injection molding manufacturing method is a method of mass production by filling a cavity of a manufactured mold with a powder material. In the case of manufacturing an injection molded body for a piezoelectric composite (preform), it is possible to enlarge and mass-produce the injection molded body for a piezoelectric composite having a three-dimensional shape.

However, it is difficult and expensive to manufacture an injection molded body of a piezoelectric composite having a three-dimensional shape having piezoelectric columns having a small cross-sectional area. In addition, even when the injection molded body is manufactured, the injection molded body for the piezoelectric composite that is generated during the degreasing step of removing the organic binder from the injection molded body or during the sintering step of sintering at a high temperature for the degreasing body from which the organic binder is removed is distorted or collapsed. occurs

In addition, the heating temperature of the degreasing step of the injection molded body of the piezoelectric composite is about 600°C, and the heating temperature of the sintering step is about 900°C to 1300°C. Therefore, in the case of manufacturing the piezoelectric composite using the conventional powder injection molding manufacturing method, a relatively high temperature is required, and thus the manufacturing cost is relatively increased.

1 is an image showing a conventional piezoelectric composite having a 1-3 structure.

FIG. 2 is an image that is damaged due to a difference in coefficient of thermal expansion when a conventional piezoelectric composite is manufactured.

3 is an image showing the defects of the surface of the piezoelectric composite according to the difference in the coefficient of thermal expansion when the conventional piezoelectric composite is manufactured.

1 to 3, in the conventional piezoelectric composite having a 1-3 structure, electrodes 20 and 30 are respectively formed on the upper and lower portions of the piezoelectric body 10 through screen printing and heat treatment, and are made of aluminum. The formed common electrode 40 is disposed by being adhered to the upper and lower electrodes using thermosetting epoxy, respectively.

At this time, when the common electrode 40 is heat-treated with a thermosetting epoxy, as shown in FIG. 2 , the common electrode 40 cannot adhere to the piezoelectric body 10 due to a difference in coefficient of thermal expansion and is damaged. In addition, in order to prevent damage due to the difference in the coefficient of thermal expansion, when a stainless (STS) thin plate having a relatively small difference in the coefficient of thermal expansion compared to aluminum is used and heat treatment is performed, the piezoelectric body 10 is formed on the surface of the common electrode 40 as shown in FIG. 3 . Bending occurs due to the column shape of That is, when stainless steel is used as the common electrode 40 , the difference in the coefficient of thermal expansion is small and the adhesion is maintained, but the surface of the common electrode 40 is not flat and curved, so there is a problem in that scattering occurs during ultrasonic transmission. Such scattering is a factor that may cause breakage during ultrasonic vibration.

Korean Patent Publication 10-2019-0092705

The problem to be solved by the present invention is to prevent the piezoelectric composite from being damaged by the difference in the coefficient of thermal expansion and to suppress the transmission loss of ultrasonic energy due to the difference in acoustic impedance. is in providing.

In order to solve the above problems, the piezoelectric composite of the present invention is a piezoelectric body that vibrates by an applied voltage, a conductor disposed above and below the piezoelectric body, respectively disposed on the conductor, and a voltage is applied and a common electrode to which a conductive wire is connected, a connection layer surrounding the piezoelectric body and the conductor, and an adhesive means disposed between the conductor and the common electrode and having a mesh shape.

The bonding means may include a metal net having a plurality of meshes and an adhesive member disposed in the plurality of meshes and bonding the conductor and the common electrode.

The metal mesh may include stainless steel or aluminum.

The metal mesh may have a diameter of 0.1 mm to 0.5 mm.

The mesh may have a size of 0.1mm ² to 0.7mm ² .

The adhesive member may be a composite in which a polymer resin and a metal powder are mixed.

The polymer resin may include thermosetting epoxy, the metal powder may include aluminum powder, and the adhesive member may be formed so that the polymer resin and the metal powder have a volume ratio of 80:20 vol%.

The acoustic impedance of the bonding means may be determined by the acoustic impedance of the piezoelectric body and the acoustic impedance of the common electrode.

The acoustic impedance of the bonding means may have an acoustic impedance obtained by adding an acoustic impedance according to an area of the metal mesh and an acoustic impedance according to an area of the bonding member filled in the metal mesh.

In order to solve the above problems, the method for manufacturing a piezoelectric composite of the present invention includes the steps of preparing a piezoelectric body in which a conductor is disposed on the upper part and the lower part, respectively, disposing an adhesive means having a mesh shape on the conductor, and on the adhesive means and adhering the conductor to the common electrode by disposing a common electrode there.

The disposing of the bonding means may include determining the acoustic impedance of the bonding means using the acoustic impedance of the piezoelectric body and the acoustic impedance of the common electrode.

The determining of the acoustic impedance of the bonding means may include preparing a metal mesh having a plurality of meshes and filling the plurality of meshes with an adhesive member bonding the conductor and the common electrode. .

The determining of the acoustic impedance of the bonding means may further include determining the acoustic impedance of the metal mesh and the acoustic impedance of the bonding member.

Filling the adhesive member may include mixing a polymer resin and a metal powder.

The polymer resin may include thermosetting epoxy, the metal powder may include aluminum powder, and the adhesive member may be formed so that the polymer resin and the metal powder have a volume ratio of 80:20 vol%.

According to the present invention, the ultrasonic vibration generated from the piezoelectric body can be effectively transmitted to the common electrode by manufacturing the metal mesh and the epoxy filled in the metal mesh to reduce the difference in acoustic impedance between the piezoelectric body and the common electrode. Therefore, it is possible to improve the durability of the piezoelectric composite and reduce heat generation.

In addition, since the stress concentration caused by the difference in the coefficient of thermal expansion can be alleviated by using the elastic properties of the metal mesh, the conductor and the common electrode cannot adhere to each other due to the difference in the coefficient of thermal expansion, and the conductor and the common electrode cannot be bonded to each other and are damaged or the surface of the common electrode is bent. can be prevented from becoming

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is an image showing a conventional piezoelectric composite having a 1-3 structure.
FIG. 2 is an image that is damaged due to a difference in coefficient of thermal expansion when a conventional piezoelectric composite is manufactured.
3 is an image showing a defect due to a difference in thermal expansion coefficient when manufacturing a conventional piezoelectric composite.
4 is a view showing the piezoelectric composite of the present invention.
5 is a view for explaining a matching layer for reducing a difference in acoustic impedance between the piezoelectric body and the common electrode.
6 is a view showing the bonding means of the present invention.
7 is an image showing the piezoelectric composite manufactured by the present invention.
8 is an image showing the experimental results of the piezoelectric composite shown in FIG.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and variations, specific embodiments thereof are illustrated and illustrated in the drawings and will be described in detail hereinafter. However, it is not intended to limit the invention to the particular form disclosed, but rather the invention includes all modifications, equivalents and substitutions consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element, such as a layer, region, or substrate, is referred to as being “on” another component, it may be directly on the other element or intervening elements in between. .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, such elements, components, regions, layers and/or regions are not It will be understood that they should not be limited by these terms.

4 is a view showing the piezoelectric composite of the present invention.

Referring to FIG. 4 , the piezoelectric composite according to the present invention includes a piezoelectric body 110 that vibrates by an applied voltage, a conductor 120 disposed above and below the piezoelectric body 110 , and a conductor 120 , respectively. The common electrode 130 , the conductive wire to which a voltage is applied, and the connecting layer 140 surrounding the piezoelectric body 110 and the conductor 120 are respectively disposed on each other, and between the conductor 120 and the common electrode 130 . It is disposed and includes an adhesive means 150 having a mesh shape.

The piezoelectric body 110 may vibrate by an electric field generated by an applied voltage. The piezoelectric material 110 may be made of a piezoelectric material, for example, the piezoelectric material may include lead zirconate titanate (PZT), lead magnesium niobate-lead titanate (PMN-PT), lead zinc niobate-lead titanate (PZN-PT), Formed with at least one material selected from lead indium niobate-lead titanate (PINPT), lead ytterbium niobate-lead titanate (PYN-PT), BaNiTiO ₃ (BNT), and barium zirconate titanate-barium calcium titanate (BZT-BCT). may be, but is not limited thereto.

The conductor 120 may be disposed above and below the piezoelectric body 110 , respectively. That is, the conductors 120 are spaced apart from each other with the piezoelectric body 110 interposed therebetween, and at least some of them may overlap each other. The conductor 120 is electrically connected to a common electrode 130 , which will be described later, to which a voltage is applied, and may function as an upper electrode and a lower electrode of the piezoelectric body 110 . In addition, the conductor 120 may be made of a metal material having low resistance and excellent heat dissipation characteristics. For example, the conductor 120 may include silver (Ag), magnesium (Mg), aluminum (Al), copper (Cu), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), and neodymium. It may be formed of any one of (Nd), iridium (Ir), and chromium (Cr), and may preferably be an upper electrode and a lower electrode formed of silver (Ag).

The common electrode 130 may be respectively disposed on the conductor 120 . The common electrode 130 may be formed of a conductive material, and may include aluminum (Al), stainless steel (STS), or the like. An electric wire to which an external electric signal is applied may be connected to one side and the other side of the common electrode 130 . The wires may be electrically connected to the common electrode 130 through soldering, etc., and may be coated with thermosetting epoxy or the like to reinforce soldering.

It has a structure in which the piezoelectric body 110 is disposed between the common electrodes 130 , and may be a piezoelectric composite of mode 1-3 in which a plurality of piezoelectric bodies 110 are disposed in an array form between the common electrodes 130 . That is, the plurality of piezoelectric bodies 110 may have a structure in which the conductors 120 respectively disposed on the upper and lower portions of the piezoelectric body 110 are commonly attached to the common electrode 130 .

The connection layer 140 may be formed to surround the piezoelectric body 110 . That is, the connection layer 140 may fill a space between the piezoelectric bodies 110 disposed in an array form. For example, the connection layer 140 may fill the space between the piezoelectric bodies 110 with a polymer having a low acoustic impedance, air, or the like. For example, it may be in the form of a 1-3 mode piezoelectric composite in which the array-shaped piezoelectric bodies 110 are planted in a polymer matrix.

The bonding means 150 may be disposed between the conductor 120 and the common electrode 130 . That is, the conductor 120 and the common electrode 130 may be bonded to each other by the bonding means 150 .

In general, in order to bond the piezoelectric body 110 and the common electrode 130 to each other, a thermosetting epoxy is used between the piezoelectric body 110 and the common electrode 130 to perform adhesion through heat treatment. However, due to the difference in the coefficient of thermal expansion between the piezoelectric body 110 and the common electrode 130 , there is a problem in that the adhesive is not properly adhered during heat treatment and is damaged or the surface of the common electrode 130 is curved. In addition, effective ultrasonic waves cannot be transmitted due to a difference in acoustic impedance between the piezoelectric body 110 and the common electrode 130 . Accordingly, the matching layer 102 is used to reduce the difference in acoustic impedance between the piezoelectric body 110 and the common electrode 130 .

5 is a view for explaining a matching layer for reducing a difference in acoustic impedance between the piezoelectric body and the common electrode.

Referring to FIG. 5 , a matching layer 102 for matching the acoustic impedance between the piezoelectric body 101 and the medium is disposed in order to reduce a difference between the acoustic impedance of the piezoelectric body 101 and the acoustic impedance of a medium through which ultrasonic waves are transmitted. In addition, a backing layer 103 for absorbing or suppressing vibrations generated from the piezoelectric body is formed on the opposite surface of the matching layer 102 . Here, when the acoustic impedance of the piezoelectric body 101 is Z _piezo and the acoustic impedance of the medium is Z _medium , the acoustic impedance Z _matching of the matching layer 102 for matching the acoustic impedance between the piezoelectric body 101 and the medium is below It can be obtained using Equation 1 of

Here, the piezoelectric body 101 and the medium may correspond to the piezoelectric body 110 and the common electrode 130 of the present invention, respectively, and the matching layer 102 for reducing the acoustic impedance corresponds to the bonding means 150 of the present invention. can be That is, if the acoustic impedance of the piezoelectric body 110 and the acoustic impedance of the common electrode 130 are known, the acoustic impedance of the bonding means 150 functioning as the matching layer 102 can be determined by reducing the acoustic impedance difference between the two.

As an example, the acoustic impedance according to each material may be represented as shown in Table 1 below.

density (g/cc) velocity (m/s) Acoustic impedance (1.0E6 ralls) Aluminum 2.7 6422 17.33 PZT 7.9 4630 34 stainless steel 8 6000 45.45 epoxy 1.17 2554 3

As shown in Table 1, when PZT is used as the piezoelectric material 110, the acoustic impedance is 34 Mryl, when aluminum is used as the common electrode 130, the acoustic impedance is 17.33 Mryl, and when stainless steel is used, the acoustic impedance is 45.45 Mryl. It can have an impedance. That is, as the common electrode 130 , both aluminum and stainless steel have a large difference from the acoustic impedance of the piezoelectric body 110 . Ultrasonic waves are not effectively transmitted due to the difference in acoustic impedance.

Moreover, since the acoustic impedance of the thermosetting epoxy generally used as the bonding means 150 for bonding the piezoelectric body 110 and the common electrode 130 is 3 Mray, the thermosetting epoxy has the piezoelectric body 110 and the common electrode 130. It does not play a role as the matching layer 102 for reducing the acoustic impedance, but only performs a role of bonding the.

Therefore, in order for the bonding means 150 to function as the matching layer 102 , it is necessary to determine the acoustic impedance for matching the acoustic impedance between the piezoelectric body 110 and the common electrode 130 using Equation 1 . For example, when PZT is used as the piezoelectric body 110 and aluminum is used as the common electrode 130, the acoustic impedance of 24 Maryl can be obtained by substituting each acoustic impedance into Equation 1 to obtain the acoustic impedance for matching. have.

That is, when the bonding means 150 is formed to have an acoustic impedance of 24 Mrayl, it can serve as the matching layer 102 to effectively transmit the ultrasonic waves generated from the piezoelectric body 110 to the medium. In addition, since ultrasonic waves can be effectively transmitted, energy loss can be reduced, and heat generated from the piezoelectric body 110 can be significantly reduced. This may lead to the effect of improving the durability of the piezoelectric composite.

The bonding means 150 of the present invention for performing such a role as the matching layer 102 is filled in a metal net 151 having a plurality of meshes and a plurality of meshes, and a conductor 120 and a common electrode 130 are provided. It may include an adhesive member 152 for bonding the.

6 is a view showing the bonding means of the present invention.

4 and 6 , the metal mesh 151 is disposed between the piezoelectric body 110 and the common electrode 130 , and in more detail, the conductor 120 disposed above and below the piezoelectric body 110 , respectively. ) and the common electrode 130 disposed on the upper and lower conductors 120 , respectively. In this case, the metal mesh 151 may be formed to be in contact with the conductor 120 and the common electrode 130 .

The metal mesh 151 has an acoustic impedance matching function for reducing the acoustic impedance difference between the piezoelectric body 110 and the common electrode 130 , as well as the conductor 120 and the common electrode disposed above and below the piezoelectric body 110 . 130 may serve to reduce the resistance between. That is, by reducing the resistance between the conductor 120 and the common electrode 130 , an effective ohmic contact between the conductor 120 and the common electrode 130 may function.

In addition, it is possible to prevent damage due to a difference in the coefficient of thermal expansion between the piezoelectric body 110 and the common electrode 130 during thermal curing. That is, the stress concentration phenomenon that causes damage of the piezoelectric composite due to the difference in the coefficient of thermal expansion can be alleviated by using the elastic properties of the metal mesh 151 . Accordingly, a phenomenon in which the conductor 120 and the common electrode 130 are not adhered to each other and are damaged due to the difference in the coefficient of thermal expansion can be prevented.

The size of the mesh formed on the metal mesh 151 and the diameter of the metal mesh 151 are determined according to the material selected for acoustic impedance matching, and the size of the mesh has a size of 0.1mm ² to 0.7mm ² , the metal mesh The diameter of 151 is preferably formed to have 0.1mm to 0.5mm. For example, if the size of the mesh is smaller than 0.1 mm ² , the amount of the adhesive member 152 filled in the mesh may be small, and the adhesive properties may deteriorate, and if it is larger than 0.7 mm ² , the conductor 120 and the common electrode per unit area Since the area of the metal mesh 151 in contact with 130 is reduced, elastic properties of the metal mesh 151 for preventing damage due to a difference in thermal expansion coefficient may be lowered. In addition, when the diameter of the metal mesh 151 is smaller than 0.1 mm, the elastic properties of the aforementioned metal mesh 151 are deteriorated, and when the diameter is larger than 0.5 mm, the distance between the piezoelectric body 110 and the common electrode 130 is increased. The efficiency of ultrasonic waves generated from the piezoelectric body 110 may be reduced.

For example, when stainless steel is used as the metal mesh 151, it is preferable to form a diameter of the metal mesh 151 with a diameter of 0.2 mm and a size of the mesh with a size of 0.36 mm ² .

The adhesive member 152 may be filled in the mesh of the metal net 151 , and may function to adhere the conductor 120 and the common electrode 130 to each other. In addition to the function of bonding the conductor 120 and the common electrode 130 , the adhesive member 152 is a matching layer 102 for reducing the acoustic impedance between the piezoelectric body 110 and the common electrode 130 together with the metal mesh 151 . ) can function as

In addition, the adhesive member 152 may be in the form of a composite in which a polymer resin and a metal powder are mixed. For example, the polymer resin is a thermosetting resin, and is an epoxy resin, unsaturated polyester resin, polyurethane, bakelite, duroplast, urea-formaldehyde, diallyl-phthalate, epoxy vinyl ester, polyimide, polycyanurate. of cyanate ester, dicyclopentadiene, phenolic, benzoxazine, copolymers thereof, or mixtures thereof. Preferably, the polymer resin used for the adhesive member 152 may be a thermosetting epoxy. The metal powder may include aluminum or stainless steel.

For example, the adhesive member 152 may be a composite in which a polymer resin is used as an epoxy, a metal powder is used as an aluminum powder, and the epoxy and aluminum powder are mixed in a volume ratio of 80:20 vol%. The mixing ratio of the polymer resin and the metal powder may be adjusted according to the acoustic impedance value of the bonding means 150 determined through Equation 1 above. The adhesive member 152 in which the polymer resin and metal powder are mixed may be filled in a plurality of meshes formed in the metal mesh 151 .

Accordingly, the total acoustic impedance of the bonding means 150 formed of the metal mesh 151 and the bonding member 152 can be obtained through Equation 2 below.

For example, when PZT is used as the piezoelectric body 110 and stainless steel having a smaller difference in coefficient of thermal expansion than aluminum is used as the common electrode 130, the acoustic impedance of PZT 34 Mryl and the acoustic impedance 45.45 Mryl of stainless steel are expressed in Equation 1 When applied, the acoustic impedance of the bonding means 150 for reducing the difference in acoustic impedance between the piezoelectric body 110 and the common electrode 130 can be obtained by 24 Maryl.

That is, when the overall acoustic impedance of the bonding means 150 according to the metal mesh 151 and the bonding member 152 filled in the mesh of the metal mesh 151 is matched with the acoustic impedance obtained through Equation 1, the piezoelectric body 110 and A difference in acoustic impedance of the common electrode 130 may be minimized.

In an embodiment, the diameter of the metal mesh 151 made of stainless steel is 0.2 mm, and the size of the mesh is 0.36 mm ² , so that the area of the metal mesh 151 made of stainless steel and the total area ratio of the mesh are 44:56, and , when the mesh is filled with the adhesive member 152 mixed with the epoxy and aluminum powder in a volume ratio of 80:20 vol%, the total acoustic impedance of the bonding means 150 can be calculated as follows.

Z _{Adhesive means} = (area ratio of metal mesh × 45.45 Maryl) + (area ratio of adhesive member × 6.09 Maryl) = 23.4 Maryl

That is, the total acoustic impedance of the bonding means 150 may be manufactured to have an acoustic impedance value of 23.4 Mray, which is close to the acoustic impedance value of 24 Mray calculated through Equation (1).

Therefore, the piezoelectric body 110 by manufacturing to include the bonding means 150 of 23.4 Mryl as the matching layer 102 between the piezoelectric body 110 having an acoustic impedance of 34 Mryl and the common electrode 130 having an acoustic impedance of 45.45 Mryl. ) and the transmission loss of ultrasonic energy generated due to a difference in impedance between the common electrode 130 can be suppressed. That is, when ultrasonic vibration is generated by the piezoelectric composite, the ultrasonic wave can be effectively transmitted through the medium.

In addition, by forming the bonding means 150 with the metal mesh 151 filled with the bonding member 152 in a plurality of meshes, damage caused by the difference in the coefficient of thermal expansion between the piezoelectric body 110 and the common electrode 130 during thermal curing is prevented. can do. That is, the stress concentration generated by the difference in the coefficient of thermal expansion can be alleviated by using the elastic properties of the metal mesh 151 . Accordingly, it is possible to prevent the conductor 120 and the common electrode 130 from failing to adhere to each other due to the difference in thermal expansion coefficient and from being damaged or from being bent on the surface of the common electrode 130 .

7 is an image showing the piezoelectric composite manufactured by the present invention.

First, referring to FIG. 7, in the piezoelectric composite of mode 1-3 manufactured in FIG. 7, a plurality of piezoelectric bodies (PZT) and a common electrode (stainless) arranged in an array form are included in a metal mesh (stainless) and an adhesive member included in the metal mesh. (Composite in which thermosetting epoxy and aluminum powder are mixed) shows the thermosetting state.

As in FIG. 7 , even after thermal curing, damage to the piezoelectric composite due to thermal expansion is prevented by the metal mesh disposed between the piezoelectric body 110 and the common electrode 130, and it can be confirmed that the surface of the common electrode is also flat. can

8 is an image showing the experimental results of the piezoelectric composite shown in FIG.

Here, Figure 8 (a) is an image showing the state of water disposed on the surface of the piezoelectric composite before the operation of the piezoelectric composite of the present invention, Figure 8 (b) is the piezoelectric composite of Figure 8 (a) after operation It is an image showing the state of water disposed on the surface of the complex.

Referring to FIGS. 8(a) and 8(b), when the piezoelectric composite manufactured according to the present invention is driven at a resonant frequency, it can be confirmed that the ultrasonic energy is effectively transferred to the water on the surface.

As described above, the piezoelectric composite according to the present invention uses the metal mesh 151 and the epoxy filled in the metal mesh 151 to reduce the difference in acoustic impedance between the piezoelectric body 110 and the common electrode 130, thereby reducing the piezoelectric body. The ultrasonic vibration generated at 110 may be effectively transmitted to the common electrode 130 . Therefore, it is possible to improve the durability of the piezoelectric composite and reduce heat generation.

In addition, since the stress concentration generated by the difference in the coefficient of thermal expansion can be alleviated by using the elastic properties of the metal mesh 151 , the conductor 120 and the common electrode 130 cannot adhere to each other and are damaged due to the difference in the coefficient of thermal expansion. Otherwise, it is possible to prevent a bending phenomenon from occurring on the surface of the common electrode 130 .

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

110: piezoelectric body 120: conductor
130: common electrode 140: connection layer
150: bonding means 151: metal mesh
152: adhesive member

Claims (15)

a piezoelectric body that vibrates by an applied voltage;
conductors respectively disposed above and below the piezoelectric body;
a common electrode disposed on the conductor and connected to a conductor to which a voltage is applied;
a connection layer surrounding the piezoelectric body and the conductor; and
and an adhesive means disposed between the conductor and the common electrode and having a mesh shape. According to claim 1, wherein the bonding means,
a metal mesh having a plurality of meshes; and
and an adhesive member disposed in the plurality of meshes and bonding the conductor and the common electrode. 3. The method of claim 2,
The metal mesh is a piezoelectric composite including stainless or aluminum. 3. The method of claim 2,
The metal mesh is a piezoelectric composite having a diameter of 0.1mm to 0.5mm. 3. The method of claim 2,
The mesh has a size of 0.1mm ² to 0.7mm ² A piezoelectric composite having a size. 3. The method of claim 2,
The adhesive member is a piezoelectric composite that is a composite in which a polymer resin and a metal powder are mixed. 7. The method of claim 6,
The polymer resin includes a thermosetting epoxy, and the metal powder includes an aluminum powder,
The adhesive member is a piezoelectric composite which is formed so that the polymer resin and the metal powder have a volume ratio of 80:20 vol%. 3. The method of claim 2,
The acoustic impedance of the bonding means is determined by the acoustic impedance of the piezoelectric body and the acoustic impedance of the common electrode. 3. The method of claim 2,
The acoustic impedance of the bonding means is a piezoelectric composite having an acoustic impedance obtained by adding the acoustic impedance according to the area of the metal mesh and the acoustic impedance according to the area of the bonding member filled in the metal mesh. preparing a piezoelectric body in which conductors are respectively disposed on the upper part and the lower part;
disposing an adhesive means having a mesh shape on the conductor; and
and disposing a common electrode on the bonding means to bond the conductor and the common electrode. 11. The method of claim 10, wherein the step of disposing the bonding means,
and determining the acoustic impedance of the bonding means by using the acoustic impedance of the piezoelectric body and the acoustic impedance of the common electrode. The method of claim 11, wherein the determining of the acoustic impedance of the bonding means comprises:
Preparing a metal mesh having a plurality of meshes; and
and filling an adhesive member for bonding the conductor and the common electrode in the plurality of meshes. The method of claim 12, wherein the determining of the acoustic impedance of the bonding means comprises:
The method further comprising the step of determining the acoustic impedance of the metal mesh and the acoustic impedance of the adhesive member. The method of claim 12, wherein the filling of the adhesive member comprises:
A method for manufacturing a piezoelectric composite comprising mixing a polymer resin and a metal powder. 15. The method of claim 14,
The polymer resin includes a thermosetting epoxy, and the metal powder includes an aluminum powder,
The adhesive member is a piezoelectric composite manufacturing method in which the polymer resin and the metal powder are formed to have a volume ratio of 80:20 vol%

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