KR101087378B1 - Piezoelectric Laminated Ceramic Device And Method of Manufacturing The Same - Google Patents

Abstract

A piezoelectric multilayer ceramic device is a piezoelectric multilayer ceramic device manufactured by stacking two or more ceramic green sheets. The piezoelectric multilayer ceramic device is formed between the internal electrodes formed on the two or more ceramic green sheets and between the internal electrodes to electrically connect the internal electrodes. A ceramic laminate comprising ceramic layers separated by the ceramic laminate, the ceramic laminate being formed from each of the one or both side surfaces in the center direction of the ceramic laminate, and extending from the top to the bottom of the piezoelectric ceramic laminate. Having a first recess and a second recess; And a first external electrode and a second external electrode respectively formed on the first concave portion and the second concave portion of the ceramic laminate, wherein the upper outer first electrode is an odd-numbered electrode among the plurality of internal electrodes. And the second external electrode electrically connects the even-numbered electrodes among the internal electrodes.

Piezoelectric, Ceramic, External Electrode, Internal Electrode, Metal

Description

Piezoelectric Laminated Ceramic Device and Method for Manufacturing the Same

The present invention relates to a piezoelectric multilayer ceramic element used as a piezoelectric actuator or a piezoelectric generator and a method of manufacturing the same.

1 is a view for explaining the principle of a piezoelectric actuator and a piezoelectric generator.

As shown in FIG. 1, a piezoelectric generator is a generator using a piezoelectric body that generates electricity directly by receiving external mechanical energy. In contrast, piezoelectric actuators receive electrical energy to generate mechanical forces. However, piezoelectric bodies of piezoelectric generators lack elasticity. Therefore, in order to prevent breakage when the piezoelectric material is deformed by external force or electricity, the piezoelectric material is used in conjunction with a polymer or metal substrate having good elasticity.

When manufacturing piezoelectric actuators or piezoelectric generators in unimorph type or bimorph type, piezoelectric laminated ceramics are bonded onto a metal substrate. At this time, the piezoelectric ceramic is mostly manufactured in a laminated structure for low voltage driving. Since the piezoelectric ceramic of such a laminated structure has to connect the electrodes inside thereof, as in the conventional MLCC (Multi-layer, Ceramic Capacitor), external electrodes are formed on the outside of the piezoelectric ceramic.

This is not a problem when the supporting substrate is an insulator such as a polymer when attaching the piezoelectric laminated ceramic and the supporting substrate. However, when metal is used as the supporting substrate, external electrodes, that is, both electrodes are shortened by the metal substrate. There is a problem. The support substrate should have a high elasticity property, and in particular, in the actuator requiring mechanical properties, most of the metal is used as the support substrate.

FIG. 2 is a perspective view of a piezoelectric multilayer ceramic 101 in which first and second external electrodes 102 and 103 are formed, and FIG. 3 is a cross-sectional view of the piezoelectric multilayer ceramic 101 shown in FIG. 4 is a cross-sectional view illustrating a state in which the piezoelectric multilayer ceramics 101 illustrated in FIGS. 1 and 2 are bonded to the metal substrate 105.

First, referring to FIGS. 2 to 4, the piezoelectric multilayer ceramic 101 has a plurality of internal electrodes 104 formed therein, and the plurality of internal electrodes 104 intersect the first and the first electrodes. 2 are electrically connected to the external electrodes 102 and 103 respectively. That is, odd-numbered internal electrodes are connected to the first external electrode 102, for example, and even-numbered internal electrodes are connected to the second external electrode 103. In addition, the piezoelectric multilayer ceramics 101 on which the first and second external electrodes 102 and 103 are formed are bonded to the metal substrate 105 as shown in FIG. 4.

However, there is a problem in that the first external electrode 102 and the second external electrode 103 of the piezoelectric multilayer ceramic described above are shorted by the metal substrate 105, and as illustrated in FIG. 5 to solve this problem. Likewise, when the first and second external electrodes 102 and 103 are formed on the piezoelectric multilayer ceramic 101, the first and second external electrodes 102 and 103 are formed on the piezoelectric multilayer ceramic 101. A method of forming the first and second external electrodes 102 and 103 is used such that the upper and lower ends of the first and second external electrodes are not formed. However, as described above, it is very difficult to manufacture the first and second external electrodes 102 and 103 such that the first and second external electrodes 102 and 103 are not formed to the upper and lower ends of the piezoelectric multilayer ceramics 101. Since the thickness of the ceramic between the inner electrodes 104 is approximately tens of micrometers, a high degree of care and technique is required to form the outer electrode leaving only tens of micrometers in the thickness of the entire hundreds of micrometers or several millimeters of the piezoelectric multilayer ceramic 101. Is required.

Unlike the piezoelectric multilayer ceramic device illustrated in FIG. 5, as shown in FIG. 6, internal electrodes may be connected through via holes 403 and 404 without forming electrodes on the outside of the piezoelectric multilayer ceramic. have. FIG. 7 is a plan view illustrating a piezoelectric multilayer ceramic in which internal electrodes are connected through the via holes illustrated in FIG. 6. When connecting the internal electrodes through the via holes 403 and 404, as shown in Figs. 8 and 9, two via holes are formed in every sheet before the lamination process, and in forming the internal electrodes, one is Connected to the internal electrode, the other being spaced apart from the internal electrode (405, 406). The sheets thus produced are stacked so that the isolated via holes are alternated every layer. However, when the via holes for the electrodes are formed on the inner surface of the sheet, there is a disadvantage in that the active region that generates the piezoelectric effect of the piezoelectric body is reduced (part where the vias are formed). In addition, when the filling of the via holes is insufficient or the interlayer alignment of the sheets is not accurate, there is a problem in that the connection through the via holes is not possible. In addition, the connection through the via hole is difficult to check, and there is an inefficient problem that can be confirmed only after evaluating its characteristics after completing the product.

Accordingly, the present invention has been made in view of the above-described circumstances, and an object of the present invention is to prevent the short circuit of electrodes when joining a piezoelectric laminated ceramic to a metal substrate, and to simplify the lamination process to improve productivity. It is to provide a piezoelectric multilayer ceramic device and a method of manufacturing the same.

A piezoelectric multilayer ceramic device according to the first aspect of the present invention for realizing the above object is a piezoelectric multilayer ceramic device manufactured by stacking two or more ceramic green sheets, the internal electrodes formed on the two or more ceramic green sheets, and A ceramic laminate comprising ceramic layers respectively formed between the internal electrodes and electrically separating the internal electrodes, the ceramic laminate being formed by digging in a direction toward the center of the ceramic laminate from each one or both side surfaces thereof; A first recess and a second recess extending from an upper portion to a lower portion of the piezoelectric ceramic laminate; And a first external electrode and a second external electrode respectively formed on the first concave portion and the second concave portion of the ceramic laminate, wherein the upper outer first electrode is an odd-numbered electrode among the plurality of internal electrodes. And the second external electrode electrically connects the even-numbered electrodes among the internal electrodes.

The first and second external electrodes have a substantially semicircular cross section.

The first external electrode and the second external electrode are respectively formed on the first side and the second side of the piezoelectric ceramic laminate, and the first side and the second side face to each other.

In some embodiments, the first and second external electrodes have a substantially fan shape in cross section.

According to another embodiment, the first external electrode and the second external electrode are formed at the first corner and the second corner of the piezoelectric ceramic laminate, respectively, and the first and second corners face each other.

A piezoelectric multilayer ceramic device manufacturing method according to a second aspect of the present invention includes the steps of: a) preparing a ceramic green sheet; b) forming a via hole on a predetermined cutting line to form an external electrode in the ceramic green sheet, and filling the formed via hole with a conductor material; c) forming an odd-numbered internal electrode on the ceramic green sheet on which the via holes are formed; d) forming even-numbered internal electrodes on the ceramic green sheet on which the via holes are formed; e) sequentially stacking the ceramic green sheets according to steps c) and d); f) cutting the ceramic green sheets laminated in step e) into product units along the cutting line; g) firing the ceramic laminate of the product unit to complete the piezoelectric multilayer ceramic device, wherein the cutting line corresponds to an end portion of the piezoelectric multilayer ceramic device to be manufactured.

In some embodiments, the via hole for forming the external electrode is formed on an intersection point of the cutting lines.

 According to the present invention, since the via hole is located at the center or the edge of the end of the product, there is an advantage in that the punching frequency is reduced in the via hole punching process than when the via hole is located inside. In addition, there is an effect that the piezoelectric active area of the device is widened. Since the degree of connection between the interlayer via holes can be confirmed by visual inspection through a microscope after the cutting process, there is an advantage of immediately finding a defect.

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

10 is a cross-sectional view illustrating a cross section of a piezoelectric multilayer ceramic device according to an exemplary embodiment.

FIG. 11 is a plan view of the piezoelectric multilayer ceramic element illustrated in FIG. 10.

10 and 11, a piezoelectric multilayer ceramic device according to an exemplary embodiment may include a plurality of internal electrodes 501 and a plurality of ceramic layers formed between the plurality of internal electrodes 501, respectively. Ceramic laminate 503 having 502, and first and second external electrodes 504 and 505 that electrically connect the plurality of internal electrodes 501.

The ceramic laminate 503 includes a first recess 506 and a second recess 507 formed at both sides. The first concave portion 506 is formed by digging in the direction of the center of the ceramic laminate 503 from one side of the ceramic laminate 503. The first recess 506 extends from the top to the bottom of the ceramic laminate 503. In addition, the second concave portion 506 is formed on the other side of the ceramic laminate 503 at a position opposite to the first concave portion 506. Similarly, the second concave portion 506 is formed in the center direction from the other side of the ceramic laminate 503, and extends from the top to the bottom of the ceramic laminate 503.

The first and second external electrodes 504 and 505 are formed in the first concave portion 506 and the second concave portion 507 of the ceramic laminate 503, respectively.

The first external electrode 504 electrically connects odd-numbered electrodes (ie, negative or negative electrodes) of the plurality of internal electrodes 501. The second external electrode 505 electrically connects even-numbered electrodes of the plurality of internal electrodes 501.

The first and second external electrodes 504 and 505 have a substantially semicircular cross section. Thus, the first external electrode and the second external electrode 504 and 504 are approximately in the shape of a semicircular column.

12 is a cross-sectional view illustrating a piezoelectric multilayer ceramic device according to another exemplary embodiment, and FIG. 13 is a plan view illustrating a plane of the piezoelectric multilayer ceramic device illustrated in FIG. 12. In FIGS. 12 and 13, the same reference numerals are used for the same parts as FIGS. 10 and 11, and detailed descriptions thereof will be omitted.

12 and 13, a piezoelectric multilayer ceramic device according to another embodiment of the present invention may include the first external electrode 601 and the second external electrode 602 as the first layer of the ceramic laminate 503. It is formed at the edger and the second corner, respectively. The first and second corners face each other. The first external electrode and the second electrode 504 and 505 have a substantially fan-shaped cross section. Accordingly, the first external electrode 601 and the second external electrode 602 have a columnar shape of approximately 1/4 circle.

Hereinafter, a manufacturing process of the piezoelectric multilayer ceramic elements illustrated in FIGS. 10 to 13 will be described.

14 is a flowchart illustrating a manufacturing process of the piezoelectric multilayer ceramic device according to the present invention.

Referring to FIG. 14, material materials such as a ceramic ceramic powder, a binder, a solvent, and the like are prepared (S1).

Subsequently, a slurry and a slurry having a predetermined viscosity are prepared by adding a binder and a solvent, such as PVB (Polyvinyl Butyral), to the ceramic powder, followed by ball milling (S2).

The slurry prepared in step S2 is tape casted by a doctor blade method, cut into a predetermined size to make a ceramic green sheet, and then the ceramic green sheet is cut to an appropriate size. To prepare a ceramic green sheet (S3, S4).

Subsequently, via holes are formed on cut lines as shown in FIG. 15 to form external electrodes in the ceramic green sheets prepared by steps S3 and S4. In some embodiments, the via holes are formed at intersections where the cutting lines cross as shown in FIG. 17. Subsequently, the conductive material is filled in the via holes formed as shown in FIG. 15 or 17 (S5).

Next, as shown in FIG. 15, internal electrodes are formed in each of the ceramic green sheets on which external electrodes are formed by filling the via holes, for example, by screen printing, as shown in FIG. 16 (S6).

Subsequently, ceramic green sheets on which internal electrodes are formed are sequentially stacked to form bars as illustrated in FIG. 15 or 17 (S7).

Subsequently, the bar formed by step S7 is cut into product units according to the cutting line (S8).

Then, the individual components according to the cutting of step S8 are burned to remove the binder, and then co-fired with a metal substrate or ceramic at a temperature of about 800 to 1600 to complete the piezoelectric multilayer ceramic device.

According to an embodiment, unlike the internal electrode printing pattern illustrated in FIG. 16, as illustrated in FIG. 18, the internal electrode may be formed leaving one via hole of the green sheet. In this case, as shown in FIG. 17, even if a slight error occurs in the alignment, it is possible to reliably prevent the internal electrodes from shorting.

The present invention has been described above by way of example, but the present invention is not limited to the above-described embodiment, and those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Anyone can make a variety of variations.

1 is a view for explaining the principle of a piezoelectric actuator and a piezoelectric generator.

FIG. 2 is a perspective view illustrating a piezoelectric multilayer ceramic in which first and second external electrodes are formed.

3 is a cross-sectional view of the piezoelectric multilayer ceramic illustrated in FIG. 2.

4 is a cross-sectional view illustrating a state in which the piezoelectric multilayer ceramics illustrated in FIGS. 1 and 2 are bonded to a metal substrate.

 5 is a cross-sectional view of a piezoelectric multilayer ceramic device in which a conventional external electrode is partially formed.

6 is a cross-sectional view of a conventional piezoelectric multilayer ceramic device in which internal electrodes are connected using via holes.

FIG. 7 is a plan view of the piezoelectric multilayer ceramic device illustrated in FIG. 6.

8 and 9 are plan views illustrating a state of charge of a via hole formed in the piezoelectric multilayer ceramic device illustrated in FIG. 6.

10 is a cross-sectional view illustrating a piezoelectric multilayer ceramic device according to an exemplary embodiment of the present disclosure, where 501 is an internal electrode, 502 is a ceramic layer, 503 is a ceramic laminate, 504 is a first external electrode, and 505 is a second 506 shows an external electrode, 506 a first recess, and 507 a second recess.

FIG. 11 is a plan view of the piezoelectric multilayer ceramic element illustrated in FIG. 10.

12 is a cross-sectional view illustrating a piezoelectric multilayer ceramic device according to another embodiment of the present invention, where 501 is an internal electrode, 502 is a ceramic layer, 503 is a ceramic laminate, 601 is a first external electrode, and 602 is a second Figure shows an external electrode.

FIG. 13 is a plan view of the piezoelectric multilayer ceramic device illustrated in FIG. 12.

14 is a process flowchart illustrating an example of a manufacturing process of a piezoelectric multilayer ceramic device according to the present invention.

15 is a plan view illustrating a plane of a manufactured bar after the lamination process of FIG. 14 is completed.

FIG. 16 is a view showing a plane and a cross-section of internal electrodes formed in each layer of each individual product after completion of the cutting process of FIG. 14.

17 is a plan view illustrating an example in which a via hole is formed at an edge of a cutting line.

18 is a plan view and a cross-sectional view of internal electrodes formed on each layer of each individual product according to another embodiment of the present invention.

FIG. 19 is a cross-sectional view of the piezoelectric multilayer ceramic device having the internal electrodes shown in FIG. 18.

Claims (11)

A piezoelectric multilayer ceramic device manufactured by stacking two or more ceramic green sheets, A ceramic laminate including internal electrodes formed on the two or more ceramic green sheets, and ceramic layers formed between the internal electrodes to electrically separate the internal electrodes, respectively, wherein the ceramic laminate is one Or a first concave portion and a second concave portion which are formed by digging in the direction of the center of the ceramic laminate from both side surfaces and extending from the top to the bottom of the piezoelectric ceramic laminate; And A first external electrode and a second external electrode formed on the first concave portion and the second concave portion of the ceramic laminate; The upper external electrode electrically connects odd-numbered electrodes of the plurality of internal electrodes, and the second external electrode electrically connects even-numbered electrodes of the internal electrodes. The piezoelectric multilayer ceramic device of claim 1, wherein the first external electrode has a substantially semicircular cross section. 3. The piezoelectric multilayer ceramic device of claim 2, wherein the second external electrode has a substantially semicircular cross section. The piezoelectric multilayer ceramic according to any one of claims 1 to 3, wherein the first external electrode and the second external electrode are formed on the first side and the second side of the piezoelectric ceramic laminate, respectively. device. The piezoelectric multilayer ceramic device of claim 4, wherein the first side surface and the second side surface face each other. The piezoelectric multilayer ceramic device of claim 1, wherein the first external electrode has a substantially fan shape in cross section. 7. The piezoelectric multilayer ceramic device of claim 6, wherein the second external electrode has a substantially fan shape in cross section. The method of claim 1, wherein the first external electrode and the second external electrode are formed at first corners and second corners of the piezoelectric ceramic laminate, respectively. Piezoelectric multilayer ceramic elements. 9. The piezoelectric multilayer ceramic device of claim 8, wherein the first and second edges face each other. a) preparing a ceramic green sheet; b) forming a via hole on a predetermined cutting line to form an external electrode in the ceramic green sheet, and filling the formed via hole with a conductor material; c) forming an odd-numbered internal electrode on the ceramic green sheet on which the via holes are formed; d) forming even-numbered internal electrodes on the ceramic green sheet on which the via holes are formed; e) sequentially stacking the ceramic green sheets according to steps c) and d); f) cutting the ceramic green sheets laminated in step e) into product units along the cutting line; g) firing the ceramic laminate of the product unit to complete the piezoelectric multilayer ceramic device, The cut line corresponds to an end portion of the piezoelectric multilayer ceramic device to be manufactured. The method of claim 10, wherein the via hole formed on a predetermined cutting line for forming the external electrode is formed on an intersection point of the cutting lines.

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