KR20220089954A - Lead-free piezoelectric material and its manufacturing method - Google Patents

Abstract

The present invention provides a lead-free piezoelectric material comprising a lead-free piezoelectric material and a high-k material, wherein the lead-free piezoelectric material is interpolated in the form of a rod or bar in the high-k material layer, and a lead-free piezoelectric material and a method for manufacturing the same and, accordingly, characteristics such as permittivity and density of the lead-free piezoelectric body can be freely adjusted.

Description

Lead-free piezoelectric material and its manufacturing method

The present invention relates to a lead-free piezoelectric body and a method for manufacturing the same, and more particularly, to a lead-free piezoelectric body capable of freely controlling dielectric constant and density while avoiding the use of lead and the like, and a method for manufacturing the same.

Today, piezoelectric materials are used in very wide fields such as communication, medical care, sensors, precision measurement, display, and military industries. .

PZT-based piezoelectric materials are widely used as energy conversion devices due to their large piezoelectric coefficients and excellent electromechanical coupling coefficients.

In addition, regulations to exclude hazardous substances are being enforced all over the world, starting with the European Union, and accordingly, a lot of research and development has been conducted to create a new piezoelectric material that does not contain lead. However, a piezoelectric material with performance and productivity sufficient to replace the existing PZT series piezoelectric material has not yet been developed. The development of a non-associated piezoelectric body with electric current is required.

The present invention is to solve the above problems of the prior art, and by using a lead-free piezoelectric material and a high dielectric material at the same time to put a curing agent in the gap between the two materials to cure it, so that the dielectric constant and density can be freely adjusted while at the same time the use of lead, etc. It is to provide a lead-free piezoelectric body and a method for manufacturing the same.

In order to solve the above problems, the present invention provides a lead-free piezoelectric material including a lead-free piezoelectric material and a high-k material, wherein the lead-free piezoelectric material is spaced apart from the high-k material layer in the form of a rod or bar and is interpolated. It provides a lead-free pneumatic body that can be used.

In addition, the lead-free piezoelectric material rod or bar provides at least two or more lead-free piezoelectric body.

In addition, the lead-free piezoelectric material provides a lead-free piezoelectric body including lithium niobate (LN).

In addition, there is provided a lead-free piezoelectric material that is cured by penetration of a curing agent between the lead-free piezoelectric material rod or bar and the high dielectric material layer.

In addition, the dielectric constant or density of the lead-free piezoelectric material is determined according to at least one of the number and size of the lead-free piezoelectric material rods or bars, and the volume ratio of the lead-free piezoelectric material to the high-k material layer.

In addition, the present invention provides a method for manufacturing a lead-free piezoelectric material, comprising: etching a high-k material layer in a first direction to pattern it; etching and patterning a lead-free piezoelectric material layer to correspond to the high-k material layer etched in the first direction Step, manufacturing a first structure by inserting after penetrating a curing agent between the etched high-k material layer and the lead-free piezoelectric material layer, etching the first structure in a second direction perpendicular to the first direction and fitting another high-k material layer etched to correspond to the first structure etched in the second direction.

The present invention implements a lead-free piezoelectric material of a lead-free piezoelectric material and a high dielectric material, thereby improving the disadvantages of the lead-free piezoelectric material, and can replace the existing lead-based piezoelectric material, thereby providing an environmentally friendly lead-free piezoelectric material with excellent performance. , by adjusting the volume ratio of the lead-free piezoelectric material and the high-k material, it is possible to control the characteristics such as dielectric constant and density of the lead-free piezoelectric material.

1 is a view showing the structure of a lead-free piezoelectric body according to an embodiment of the present invention.
FIG. 2 is a view showing a cross section of a portion of FIG. 1A .
3 and 4 are a flowchart and a schematic diagram of a method of manufacturing a lead-free piezoelectric body according to an embodiment of the present invention, respectively.
5 is a view showing the result of measuring the dielectric constant according to the volume fraction of the lead-free piezoelectric body manufactured according to the present invention.
6 is a diagram showing the electrical impedance of the prepared lead-free piezoelectric body having 80% volume fraction and LN, BTO, and PZT samples having the same area and thickness.

Hereinafter, preferred embodiments of the present invention will be described in detail. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present invention, the terms include or have is intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features, number, step , it should be understood that it does not preclude the possibility of the existence or addition of , operation, components, parts, or combinations thereof.

1 is a view showing the structure of a lead-free piezoelectric body according to an embodiment of the present invention.

Referring to FIG. 1 , the present invention includes a lead-free piezoelectric material and a high-k material in order to solve the above-described problem, and the lead-free piezoelectric material is formed in the form of a rod or a bar on the high-k material layer. To provide a lead-free piezoelectric body spaced apart and interpolated.

The lead-free piezoelectric material refers to any material that generates a piezoelectric phenomenon and does not contain a lead component. In particular, in the embodiment of the present invention, Lithium Niobate (hereinafter, LN) is an example, but is not limited thereto.

The lead-free piezoelectric material has excellent piezoelectric properties, high Curie temperature, high mechanical quality factor, and low elastic loss, while the dielectric constant is very low and the electrical impedance is very high, so moldability is limited in miniaturization. .

Accordingly, the lead-free piezoelectric material according to the embodiment of the present invention includes a lead-free piezoelectric material and a high dielectric material having a high dielectric constant and good flexibility so as to improve the above disadvantages while maintaining excellent characteristics of the lead-free piezoelectric material.

The high dielectric material refers to a material having a higher dielectric constant than that of a lead-free piezoelectric material, and Barium Titanate, Potassium Sodium Niobate, Calcium Copper Titanate, etc. may be used, and in particular, in an embodiment of the present invention, Barium Titanate (BaTiO ₃ ) One example, but not limited thereto.

Here, the lead-free piezoelectric material and the high-k material have a rod or bar-shaped cut groove formed to be bonded to each other by being etched and patterned, respectively, and the lead-free piezoelectric material is applied to the high-k material layer as a rod. Alternatively, the two materials are interdigital joined by being spaced apart in the form of a bar and interpolated.

In addition, in the lead-free piezoelectric body according to an embodiment of the present invention, by adjusting the volume ratio according to the method in which the lead-free piezoelectric material and the high dielectric material are etched and patterned, the physical and electrical properties such as the dielectric constant and density of the lead-free piezoelectric body to be implemented can be freely adjusted. can

In addition, the dielectric constant and density of the lead-free piezoelectric material may be determined according to the number and size of the lead-free piezoelectric material rods or bars, and the volume ratio of the lead-free piezoelectric material to the high-k material layer. For example, at least two rods or bars of the lead-free piezoelectric material may exist, and the number of rods or bars may vary depending on the dielectric constant and density of the lead-free piezoelectric body to be implemented.

FIG. 2 is a view showing a cross section of a portion of FIG. 1A .

Referring to FIG. 2 , in the embodiment of the present invention, the lead-free piezoelectric body includes a curing agent between the lead-free piezoelectric material and the high-k material, and the curing agent penetrates and hardens between the lead-free piezoelectric material rod or bar and the high-k material layer, so that the Two materials can be connected and fixed.

Hereinafter, a method for manufacturing a lead-free piezoelectric body according to the present invention will be described with reference to FIGS. 3 and 4 .

Currently, as a method for manufacturing a piezoelectric composite, a die and fill method in which a polymer is filled in a space created by cutting a piezoelectric ceramic several times is used. However, if you want to fill the space formed by cutting piezoceramics by making a high-k material as a fluid and filling it with the die-and-fill method, the viscosity of the fluid is high, so it is difficult to fill uniformly, and in order to obtain high dielectric constant, high-temperature and high-pressure In order to obtain a uniform high dielectric constant of the piezoelectric composite, a method of interdigital bonding with the already cut piezoelectric ceramic after cutting a solid high dielectric material is required.

Accordingly, the present invention prepares a lead-free piezoelectric material and a high-k material etched so as to be able to bond to each other, and then permeates and bonds a curing agent between the two materials to produce a lead-free piezoelectric body, which can be generated in the process-filling method. It is possible to provide a lead-free piezoelectric body having uniform piezoelectric properties and high dielectric constant by solving possible problems.

3 and 4 are a flowchart and a schematic diagram of a method for manufacturing a lead-free piezoelectric body according to an embodiment of the present invention, respectively.

3 and 4, the method of manufacturing a lead-free piezoelectric material according to an embodiment of the present invention includes the steps of patterning a high-k material layer by etching in a first direction (S10), and the high-k material etched in the first direction. A step of etching and patterning the lead-free piezoelectric material layer to correspond to the layer (S20), impregnating the curing agent between the etched high-k material layer and the lead-free piezoelectric material layer, and then fitting the first structure (S30), Removing certain portions on both sides of the first structure through lapping (S40), etching the first structure in a second direction perpendicular to the first direction (S50), and etching in the second direction and fitting another high-k material layer etched to correspond to the first structure (S60).

First, the high-k material layer is etched in the first direction to form grooves (S10), and then the lead-free piezoelectric material layer is etched so that the grooves are formed to correspond to the high-k material layer etched in the first direction. It is patterned to occur (S20).

Here, the volume ratio of the dielectric material can be adjusted according to the etching method of the high-dielectric material layer and the lead-free piezoelectric material layer, and properties such as dielectric constant and density of the lead-free piezoelectric material can be freely adjusted through this.

In addition, the grooves patterned on the high-k material layer and the lead-free piezoelectric material layer may be in the form of rods or bars, but are not limited thereto. Considering the dielectric constant, density, etc. of the lead-free piezoelectric material to be manufactured It may be etched in various forms.

Next, a curing agent is penetrated between the etched high-k material layer and the lead-free piezoelectric material layer, and then fitted to prepare a first structure (S30), and as curing is progressed by the infiltrated curing agent, the two material layers are connected and fixed on the first structure.

Next, after manufacturing the first structure and before etching the first structure, a certain portion on both sides of the first structure is removed through lapping (S40), and through this, the density, volume, etc. are adjusted and the first structure is etched. Unnecessary parts on both sides of the structure can be removed. Bar-shaped patterning is possible through the lapping, and lapping may be appropriately performed depending on the density, volume, and the like of the lead-free piezoelectric body to be manufactured, and the degree of unnecessary parts.

Next, the first structure is etched in a second direction perpendicular to the first direction (S50), which is different only in the etching direction, and proceeds in the same manner as in etching the lead-free piezoelectric material layer, and thus another unique A groove is formed so that it can be fitted in correspondence with the entire material layer.

Next, another high-k material layer etched to correspond to the first structure etched in the second direction is fitted (S60) to manufacture a lead-free piezoelectric body.

Here, the other high-k material layer means a high-k material layer etched in the second direction, and the etching direction is different from that of the high-k material layer etched in the first direction, and the other high-k material layer is The high-k material layer etched in the first direction may be made of the same or different high-k material, and rod-shaped patterning is possible through the above process.

Hereinafter, the present invention will be described in more detail based on preferred embodiments of the present invention. However, it goes without saying that the technical spirit of the present invention is not limited thereto and may be variously implemented by those skilled in the art.

production example

LN (Lithium niobate 36° rotated Y-cut, Boston Piezo-Optics, Inc., Bellingham, MA, USA), BTO (Barium titanate, RNDKOREA, Inc., Seoul, South Korea) and Epoxy (Epo-Tek 301, Epoxy) Technology, Inc., Billerica, MA, USA) was used to design and manufacture 2-2 lead-free piezoelectric bodies having various volume fractions (50%, 60%, 70,%, 80%), where the volume fraction is LN It is the ratio of the volume occupied by this to the volume occupied by all materials.

First, pre-etched LN and BTO were prepared, and then the epoxy was filled to fill the gap between the posts and cured. After that, both sides were wrapped to the design thickness through a precision lapping system, chromium and gold electrodes were deposited on both sides, and the finished lead-free piezoelectric body was cut to the final size and manufactured. x 0.38 mm.

Example 1

5 is a view showing the result of measuring the dielectric constant according to the volume fraction of the lead-free piezoelectric body manufactured according to the present invention.

The dielectric constant was measured using an impedance analyzer (Keysight Inc. E4990A), and the dielectric constants of PZT, BTO, and LN were compared with lead-free piezoelectric materials having various volume fractions.

Referring to FIG. 5 , the dielectric constant of the manufactured lead-free piezoelectric body is different depending on the volume fraction of the piezoelectric material, and is determined from a value between the dielectric constants of BTO and LN. Through this, by adjusting the volume ratio of the lead-free piezoelectric material and the high dielectric material according to the manufacturing method of the present invention, characteristics such as dielectric constant and density of the lead-free piezoelectric body can be variously controlled, and furthermore, by using a material having a higher dielectric constant than BTO, It could be expected that the dielectric constant of the lead-free piezoelectric body could be improved.

Example 2

6 is a diagram showing the electrical impedance of the prepared lead-free piezoelectric body having 80% volume fraction and LN, BTO, and PZT samples having the same area and thickness.

The electrical impedance was measured using an impedance analyzer (Keysight Inc. E4990A) as in Example 1, and the electrical impedance (a) of the produced lead-free piezoelectric body having 80% volume fraction and it were compared with the electrical impedance of PZT, BTO, and LN and (b).

Referring to FIG. 6 , the electrical impedance of the prepared lead-free piezoelectric body having an 80% volume fraction was significantly reduced compared to that of LN. Therefore, it was confirmed that the electrical impedance matching can be easily performed by solving the disadvantage of the high electrical impedance of LN while maintaining the performance of the piezoelectric material through the LN-BTO lead-free piezoelectric body.

As described above, according to the lead-free piezoelectric body and its manufacturing method according to the present invention, it does not use lead, which is a hazardous material, so there is no regulation and is eco-friendly. It can compensate for the shortcomings, and since the dielectric constant and density of the lead-free piezoelectric body can be freely adjusted, it can be applied in various fields.

Claims (6)

A lead-free piezoelectric material comprising a lead-free piezoelectric material and a high dielectric material, comprising:
The lead-free piezoelectric material is a lead-free piezoelectric material, characterized in that the interpolation spaced apart in the form of a rod (rod) or bar (bar) in the high dielectric material layer. The method of claim 1,
The lead-free piezoelectric material, characterized in that at least two or more rods or bars. The method of claim 1,
The lead-free piezoelectric material is lead-free piezoelectric body, characterized in that it comprises lithium niobate (LN). According to claim 1, wherein the lead-free piezoelectric body,
A lead-free piezoelectric material, characterized in that the curing agent is penetrated between the lead-free piezoelectric material rod or bar and the high dielectric material layer to be cured. The method of claim 1,
The dielectric constant or density of the lead-free piezoelectric material is determined according to at least one of the number and size of the lead-free piezoelectric material rods or bars, and the volume ratio of the lead-free piezoelectric material to the high-k material layer. A method for manufacturing a lead-free piezoelectric body according to any one of claims 1 to 5,
patterning the high-k material layer by etching in a first direction;
etching and patterning the lead-free piezoelectric material layer to correspond to the high-k material layer etched in the first direction;
manufacturing a first structure by impregnating and fitting a curing agent between the etched high-k material layer and the lead-free piezoelectric material layer;
removing certain portions on both sides of the first structure through lapping;
etching the first structure in a second direction perpendicular to the first direction; and
and fitting another high-k material layer etched to correspond to the first structure etched in the second direction.

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