Method for producing a plurality of piezoelectric multilayer components

Abstract

A method for producing a plurality of piezoelectric multilayer components is disclosed. In an embodiment, a method for producing a plurality of piezoelectric multilayer components includes grinding the piezoelectric multilayer components without an addition of an abrasive by rubbing the piezoelectric multilayer components against one another so that a material abrasion of the piezoelectric multilayer components is carried out.

Claims

1. A method for producing a plurality of piezoelectric multilayer components, the method comprising: grinding the piezoelectric multilayer components without an addition of an abrasive by rubbing the piezoelectric multilayer components against one another so that a material abrasion of the piezoelectric multilayer components is carried out, wherein grinding the piezoelectric multilayer components is carried out in a drum loaded with the plurality of the piezoelectric multilayer components, and wherein the material abrasion is set by setting a number of piezoelectric multilayer components in the drum; and performing a heat treatment process in which the piezoelectric multilayer components are exposed to an elevated temperature before grinding the piezoelectric multilayer components, wherein, while performing the heat treatment process, a polymer of a binder is not decomposed, and wherein the heat treatment process is carried out under reduced pressure.

2. The method according to claim 1, wherein the piezoelectric multilayer components are ground as green bodies.

3. The method according to claim 1, further comprising sintering the piezoelectric multilayer components after grinding the piezoelectric multilayer components.

4. The method according to claim 1, wherein a hardness of the piezoelectric multilayer components is increased during the heat treatment process.

5. The method according to claim 1, further comprising at least partly removing a solvent and/or plasticizers of an organic binder from the piezoelectric multilayer components during the heat treatment process.

6. The method according to claim 1, wherein the elevated temperature is a temperature between 100° C. to 150° C. inclusive.

7. The method according to claim 1, wherein the material abrasion is further set by setting at least one of a running time of the grinding of the piezoelectric multilayer components or a rotational speed of the drum.

8. The method according to claim 1, wherein grinding the piezoelectric multilayer components comprises grinding the piezoelectric multilayer components by surrounding them with water.

9. The method according to claim 1, wherein the piezoelectric multilayer components are piezoelectric transformers.

10. The method according to claim 1, wherein the piezoelectric multilayer components are capacitors.

11. A method for producing a plurality of piezoelectric multilayer components, the method comprising: grinding the piezoelectric multilayer components without an addition of an abrasive by rubbing the piezoelectric multilayer components against one another so that a material abrasion of the piezoelectric multilayer components is carried out, wherein the grinding the piezoelectric multilayer components comprises grinding the piezoelectric multilayer components by surrounding them with water, and wherein soap is added to the water prior to the grinding; and performing a heat treatment process in which the piezoelectric multilayer components are exposed to an elevated temperature before grinding the piezoelectric multilayer components, wherein, while performing the heat treatment process, a polymer of a binder is not decomposed, and wherein the heat treatment process is carried out under reduced pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is described in greater detail below with reference to the figures.

(2) FIG. 1 shows a perspective view of a piezoelectric multilayer component;

(3) FIG. 2 shows a close-up image of a multilayer component which was produced by the method according to embodiments of the invention;

(4) FIG. 3 shows a close-up image of a comparative example of a multilayer component which was fabricated using the abrasive ZrO.sub.2; and

(5) FIG. 4 shows a further close-up image of a comparative example of a multilayer component which was fabricated using an abrasive.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(6) FIG. 1 shows a perspective view of a piezoelectric multilayer component 1 which was fabricated by the method according to embodiments of the invention. The piezoelectric multilayer component 1 is a piezoelectric transformer. The piezoelectric transformer can be used in particular in a device for generating non-thermal atmospheric pressure plasma.

(7) A piezoelectric transformer is a design of a resonance transformer which is based on piezoelectricity and constitutes an electromechanical system in contrast to the conventional magnetic transformers. The piezoelectric transformer is a Rosen-type transformer, for example.

(8) The piezoelectric multilayer component 1 comprises an input region 2 and an output region 3, wherein the output region 3 is adjacent to the input region 2 in a longitudinal direction z. In the input region 2, the piezoelectric multilayer component 1 comprises electrodes 4, to which an AC voltage can be applied. The electrodes 4 extend in the longitudinal direction z of the piezoelectric multilayer component 1. The electrodes 4 are stacked alternately with a piezoelectric material 5 in a stacking direction x, which is perpendicular to the longitudinal direction z. In this case, the piezoelectric material 5 is polarized in the stacking direction x.

(9) A y-direction y is in each case perpendicular to the stacking direction x and the longitudinal direction z.

(10) The electrodes 4 are arranged in the interior of the piezoelectric multilayer component 1 and are also referred to as internal electrodes. The piezoelectric multilayer component 1 comprises a first side surface 6 and a second side surface 7 opposite the first side surface 6. A first external electrode 8 is arranged on the first side surface 6. A second external electrode (not shown) is arranged on the second side surface 7. The internal electrodes 4 are electrically contacted alternately either with the first external electrode 8 or the second external electrode in the stacking direction x.

(11) Furthermore, the piezoelectric multilayer component 1 comprises a third side surface 20 and a fourth side surface 21, which are opposite one another and which are arranged perpendicular to the first side surface 6 and the second side surface 7. The surface normals of the third and fourth side surfaces 20, 21 point in each case in the stacking direction x.

(12) The input region 2 can be driven with a low AC voltage that is applied between the electrodes 4. On account of the piezoelectric effect, the AC voltage applied on the input side is firstly converted into a mechanical oscillation. In this case, the frequency of the mechanical oscillation is essentially dependent on the geometry and the mechanical construction of the piezoelectric multilayer component 1.

(13) The output region 3 comprises piezoelectric material 9 and is free of internal electrodes. The piezoelectric material 9 in the output region is polarized in the longitudinal direction z. The piezoelectric material 9 of the output region 3 can be the same material as the piezoelectric material 5 of the input region 2, wherein the piezoelectric materials 5 and 9 can differ in their polarization direction. In the output region 3, the piezoelectric material 9 is shaped to form a single monolithic layer polarized completely in the longitudinal direction z. In this case, the piezoelectric material 9 in the output region 3 has only a single polarization direction.

(14) If an AC voltage is applied to the electrodes 4 in the input region 2, then a mechanical wave forms within the piezoelectric material 5, 9, which mechanical wave generates an output voltage as a result of the piezoelectric effect in the output region 3. The output region 3 has an output-side end surface 10. In the output region 3, an electrical voltage is thus generated between the end surface 10 and the end of the electrodes 4 of the input region 2. In this case, a high voltage is generated at the output-side end surface 10. In this case, a high potential difference also arises between the output-side end surface and an environment of the piezoelectric multilayer component, which potential difference suffices to generate a strong electric field that ionizes a process gas.

(15) In this way, the piezoelectric multilayer component 1 generates high electric fields that are able to ionize gases or liquids by electrical excitation. In this case, atoms or molecules of the respective gas or of the respective liquid are ionized and form a plasma. An ionization occurs whenever the electric field strength at the surface of the piezoelectric multilayer component 1 exceeds the ignition field strength of the plasma. In this case, ignition field strength of a plasma denotes the field strength required for the ionization of the atoms or molecules.

(16) The piezoelectric multilayer component 1 furthermore comprises an input-side end surface 22 opposite the output-side end surface 10. Furthermore, the piezoelectric multilayer component 1 comprises edges 23. The edges 23 can be rounded.

(17) During its production the piezoelectric multilayer component 1 is subjected to a grinding process in which no abrasive is used and in which a material abrasion of the piezoelectric multilayer component 1 is carried out by rubbing the piezoelectric multilayer component 1 against further piezoelectric multilayer components.

(18) FIG. 2 shows a close-up image of a segment of a piezoelectric multilayer component 1 which was fabricated by the method described here, wherein a material abrasion from the side surfaces 6, 7, 20, 21, the end surfaces 21, 22 and the edges 23 of the piezoelectric multilayer component 1 is carried out by rubbing the components against one another. In this case, the multilayer components are arranged in a loose state in a drum.

(19) In comparison therewith, FIG. 3 shows a close-up image of a comparative example of a multilayer component which was subjected to an abrading process in which ZrO.sub.2 was used as abrasive.

(20) A comparison of FIGS. 2 and 3 shows that by dispensing with an abrasive, it is possible to remove the material from the side surfaces and edges of the multilayer components in a manner that leads to less rough side surfaces and more smoothly rounded edges. In this way, the arising of local unevenness at the outer surfaces of the multilayer component can be avoided. Accordingly, the undesired plasma ignition at such local unevenness can be avoided.

(21) FIG. 4 shows a close-up image of a comparative example of a piezoelectric multilayer component which was ground without a heat treatment process having been carried out previously and using an abrasive comprising abrasive grains. FIG. 4 shows that an abrasive grain 24 was pressed into the piezoelectric multilayer component during the grinding process and has remained in the component after the grinding process. The abrasive grain 24 has an adverse effect in the multilayer component 1. It leads, for example, to a considerable unevenness of the surface.

(22) By comparison with grinding the piezoelectric multilayer components without an abrasive, the use of an abrasive merely has the advantage that the surface can be removed more rapidly. However, this is outweighed by the disadvantage that, with the use of an abrasive, the surface becomes significantly rougher, as shown in FIG. 3, and that it is even possible for grains of the abrasive to penetrate into the surface.

(23) Alternatively, it is also conceivable to grind the piezoelectric multilayer components jointly with ceramic cones and without the addition of an abrasive. In this case, it is possible to achieve a smoothness of the surfaces which is comparable with the result of the material abrasion by rubbing the piezoelectric multilayer components 1 against one another. However, an additional step for separating the piezoelectric multilayer components and the ceramic cones after grinding is then required as well.

(24) If the piezoelectric multilayer components 1 are rubbed against one another, a smooth surface can be obtained. If the grinding process is performed for two hours, the edges of the piezoelectric multilayer components 1 can be rounded in a desired manner.