EP3465789A2

EP3465789A2 - Method for producing a plurality of piezoelectric multilayer components

Info

Publication number: EP3465789A2
Application number: EP17728135.9A
Authority: EP
Inventors: Bernhard Doellgast; Markus Puff
Original assignee: TDK Electronics AG
Current assignee: TDK Electronics AG
Priority date: 2016-06-02
Filing date: 2017-05-31
Publication date: 2019-04-10
Also published as: JP2019522381A; US20190252598A1; JP6735418B2; WO2017207654A3; US11024794B2; DE102016110216A1; WO2017207654A2; DE102016110216B4; CN109643753A

Abstract

The present invention relates to a method for producing a plurality of piezoelectric multilayer components (1), wherein the piezoelectric multilayer components (1) are ground without the addition of an abrasive, and wherein a material abrasion of the piezoelectric multilayer components (1) is carried out by rubbing the piezoelectric multilayer components (1) against each other.

Description

description

Process for producing a variety of

piezoelectric multilayer components

The present invention relates to a method for

Production of a variety of piezoelectric

Multilayer components. In the piezoelectric

Multilayer devices may be, for example, piezoelectric transformers suitable for producing a non-thermal atmospheric pressure plasma.

In the production of piezoelectric

In multilayer devices, the devices may be subjected to a process in which disordered loose grain devices are ground as an abrasive to achieve a smooth surface of the piezoelectric multilayer devices.

Disadvantages of this process are that the components produced in this way have a surface that often does not meet the requirements of smoothness.

Furthermore, the separation of the abrasive from the

Be very complex components.

The object of the present invention is now to provide an improved method for producing a plurality of piezoelectric multilayer components. This object is achieved by a method according to the present invention

Claim 1 solved. It is proposed a method for producing a plurality of piezoelectric multilayer devices, wherein the piezoelectric multilayer devices are ground without the addition of an abrasive, wherein a material abrasion of the piezoelectric

Multilayer components by rubbing the

piezoelectric multilayer components to each other.

In particular, the material abrasion can be done only by rubbing the piezoelectric multilayer components together. The method thus uses no abrasive.

An "abrasive" may be understood here to mean any abrasive that can be used to achieve a removal of material, an abrasive which is typically a fine-grained, hard and sharp-edged substance Known abrasives are, for example, sand or ZrO.sub.2 through the

Waiver of any abrasive. It has been shown that by rubbing the multilayer components together significantly smoother surfaces can be achieved than is possible with abrasives. Abrasives, for example sand with a grain size between 0.1 and 0.5 mm, cause severe scoring in the surface of the multilayer components in the scrubbing process. This can lead to local unevenness in the surface. These can be too local when using the multilayer components for plasma generation

Field overshoots, which can lead to local ignitions of plasma at undesirable points of the multilayer devices. This will on the one hand the efficiency

reduced and on the other hand the device may damaged, leading to premature failure of the

Component can come.

The absence of an abrasive, however, allows a smooth, rounded surface of the

To ensure multilayer components. Accordingly, the surface of a with the inventive

Process manufactured piezoelectric

Multilayer device no significant local

Bumps up. Therefore, the local field peak can be avoided by local peaks in the roughness of the surface. Also in the area of the edges of the

Multilayer device can be a smooth, rounded

Surface to be ensured.

Another advantage of the method in which no

Abrasive is used is that after

Completion of the grinding process on the step of separation of the multilayer components of the abrasive can be dispensed with. This step may be very

consuming. By doing without an additional

Abrasive can thus manufacture with less

Procedural steps are performed. That's why

Manufacturing process inexpensive and quickly feasible.

The material can be used in the process both by the

External surfaces are rubbed off as well as from the edges of the piezoelectric multilayer components. The outer surfaces may be four side surfaces whose surface normal in each case perpendicular to a longitudinal axis of the

Multi-layer components is, and two end faces whose surface normal is parallel to the longitudinal axis, respectively. Two adjacent external surfaces can do this always perpendicular to each other. In this case, two adjacent outer surfaces adjoin one edge in each case.

The piezoelectric multilayer component can in

Be substantially cuboid. However, the method is also suitable for differently shaped multilayer components,

for example, for cylindrical components.

By the abrasion of material from the outer surfaces, the outer surfaces can be smoother, d. H. the roughness of the

External surfaces may decrease as a result of material abrasion.

Due to the material abrasion from the edges of the

Multilayer components, the edges can be rounded. Accordingly, by the method, a formerly sharp edge can be formed into a rounded edge, wherein the

Radius of the rounded edge is greater, the more material has been removed. Rounded edges add

piezoelectric transformers have the advantage over sharp edges that there is no local field increase at a rounded edge. Accordingly, it may not be undesirable on a rounded edge

Plasma ignition come.

The method described here is for the production

various piezoelectric multilayer components suitable, for example for the production of transformers, actuators or capacitors.

In the grinding, the piezoelectric

Multilayer devices are present in a loose state.

For example, the components may be arranged in a loose state in a drum. As a loose state can be called a state in which the Multilayer devices are not mechanically connected to each other.

The grinding of the piezoelectric

Multi-layer devices should serve to remove a surface of the piezoelectric multilayer devices themselves. The intention is not to free the surface of the piezoelectric multilayer components from contamination. In the manufacturing process there is usually no contamination on the surface that would have to be removed.

The piezoelectric multilayer components can be used as

Green body are ground, wherein the piezoelectric multilayer devices are sintered after grinding.

A green body is an unfired blank. A green body is a body in the green state, that is, a ceramic body before performing a burning or

Sintering process. In the green state, material from the

Multi-layer devices are removed in a simple manner, since the hardness of the multilayer components is significantly lower before sintering than after performing a

Sintering process. Since the material abrasion after sintering would be considerably more expensive, the grinding process

preferably performed before sintering.

A green body has a hardness which is significantly lower than the hardness of a typical hard bulk material, such as a screw, a nail or a steel spring. Of the

Green body is softer and more elastic than such

Metal parts. The green body often contains an organic binder needed for the previous molding. The organic binder typically has plasticizers. These can be removed by a temperature treatment, wherein the device is harder.

Before the grinding of the piezoelectric components, a tempering process can be performed. In the annealing process, the piezoelectric device may be exposed to elevated temperatures of 100 ° C to 150 ° C. The plasticizers of the organic binder can be at least partially removed. By removing the plasticizer, the hardness of the

Component increases. Accordingly, by the

Annealing process, the hardness of the device can be adjusted as desired. In particular, the tempering process may allow the hardness of the piezoelectric components to be adjusted such that they are not undesirably deformed during the grinding.

The temperature selected during the annealing process depends on the plasticizer used. The tempering process can be carried out under reduced pressure.

The tempering process can serve to evaporate solvents and / or plasticizers from an organic binder and thus from the piezoelectric multilayer component. The multilayer components are hardened by the annealing process. In one embodiment, the piezoelectric

Multilayer device after the implementation of the

Annealing process to a hardness, which grinding without

Abrasive allows. In the annealing process, the binder or a polymer of the binder is not decomposed. The binder is not expelled in gaseous form from a ceramic of the piezoelectric multilayer component. Thus, the annealing process is not debinding. The temperature range of 100 ° C to 150 ° C, which occurs during the annealing process, is not sufficient for debindering. The polymer is during the

Tempering process rather left intact. The component can be hardened by the at least partial removal of the solvent and / or the plasticizer, but it remains a green compact. The step of debinding can only after the step of grinding without the addition of abrasive

be performed.

A hardness of the piezoelectric multilayer component can be increased during the annealing process.

In the annealing process, a solvent and / or

Plasticizer of an organic binder are at least partially removed from the piezoelectric multilayer component.

The piezoelectric multilayer components can be exposed to temperatures of 100 ° C to 150 ° C during the annealing process.

After grinding, the components can optionally be dried.

After grinding and optionally after drying, thermal processes are carried out, for example

Debinding and / or sintering. The grinding can be carried out in a drum equipped with a variety of piezoelectric

Multilayer components is loaded, the material abrasion by adjusting at least one of running time of

Abrasive process, the number of piezoelectric

Multilayer components in the drum and the

Rotation speed of the drum is set in the desired manner. The three parameters mentioned here

each affect the material abrasion during the

Grinding process.

By increasing the transit time, ie the time in which the drum rotates, the removal of the material from the multilayer components is increased. Running time and material abrasion are almost linear to each other.

The rotational speed of the drum, that is the

The speed with which the drum rotates also influences the material abrasion of the multilayer components. The exact influence of the rotational speed on the

Material abrasion depends on the geometry and the size as well as the exact structure of the multilayer components. The

Rotation speed should be chosen so that the highest possible material abrasion per second is achieved, in order to increase the duration of the grinding process

minimize.

The number of piezoelectric multilayer components in the drum, that is to say the loading of the drum, should also be set to an optimum value for material abrasion. Be too many per unit volume

Multi-layer devices loaded into the drum, so the multilayer devices can wedge each other and it Hardly comes to a rubbing of the components together. As a result, the material abrasion is greatly inhibited. Even if too few multilayer components are loaded into the drum, only a few rubbing processes of the components occur

to each other, whereby also the achievable friction

would be reduced.

The multilayer components may be surrounded by the medium of water in the grinding. Water does not act as an abrasive because the water does not cause any material abrasion from the surface of the multilayer components.

In particular, in the drum during the

Grinding the piezoelectric multilayer components next to the multilayer components only water and air are. Alternatively or in addition to water, another liquid can also be used.

Water or another liquid serves to make that

hold abraded material in suspension. If no liquid is used as a medium, the abraded material may be deposited as dust on the surfaces of the

Set down components and glue them together. As a result, further removal could be prevented or at least made more difficult. In addition, by the use of water or other liquid as the medium, an attenuation of the movements of the piezoelectric components, whereby it comes to more uniform movements, so that the material is removed more uniformly from the piezoelectric multilayer components.

The water can also serve to influence a surface tension. For this purpose soap may be added to the water. The piezoelectric multilayer components may be piezoelectric transformers.

In particular, these may be transformers suitable for use in a plasma generator for producing non-thermal atmospheric pressure plasma. In these components, it is particularly important to achieve a smooth, rounded surface, since otherwise by local field peaks plasma ignitions in

would arise undesirably, by which the

Component could be damaged.

In the following, the present invention is based on the

Figures described in more detail.

FIG. 1 shows a perspective view of a

piezoelectric multilayer component,

FIG. 2 shows a detail of a

Multilayer device that with the

process according to the invention was produced,

FIG. 3 shows a detail of a comparative example of a multilayer component which was produced using the scrubber Zr0 ₂ .

FIG. 4 shows a further detail of a

Comparative example of a multilayer component, which was manufactured using a scouring agent.

FIG. 1 shows a perspective view of a

piezoelectric multilayer component 1, which with the inventive method was made. In which

Piezoelectric multilayer component 1 is a piezoelectric transformer. The piezoelectric transformer can be used in particular in a device for generating non-atmospheric atmospheric pressure plasma.

A piezoelectric transformer is a type of resonant transformer based on piezoelectricity and unlike the conventional magnetic ones

Transformers represents an electromechanical system. The piezoelectric transformer is, for example, a

Roses type transformer. The piezoelectric multilayer component 1 has a

Entrance area 2 and an output area 3, wherein the output area 3 is connected in a longitudinal direction z to the input area 2. In the input area 2, the piezoelectric multilayer component 1 has electrodes 4, to which an alternating voltage can be applied. The

Electrodes 4 extend in the longitudinal direction z of the piezoelectric multilayer component 1

Electrodes 4 are stacked alternately with a piezoelectric material 5 in a stacking direction x which is perpendicular to the longitudinal direction z. The piezoelectric material 5 is polarized in the stacking direction x.

A y-direction y is perpendicular to the respective

Stacking direction x and the longitudinal direction z.

The electrodes 4 are inside the piezoelectric

Multilayer component 1 is arranged and also called

Internal electrodes. The piezoelectric Multilayer component 1 has a first side surface 6 and a second side surface 7, which lies opposite the first side surface 6. On the first side surface 6, a first outer electrode 8 is arranged. On the second

Side surface 7, a second outer electrode (not shown) is arranged. The internal electrodes 4 are in

Stacking direction x alternately with either the first

Outer electrode 8 or the second outer electrode electrically contacted.

Further, the piezoelectric multilayer component 1 has a third side surface 20 and a fourth side surface 21 facing each other and perpendicular to the first side surface 6 and the second side surface 7

are arranged. The surface normals of the third and fourth side surfaces 20, 21 each point in the stacking direction x.

The input region 2 can be driven with a low alternating voltage, which is applied between the electrodes 4. Due to the piezoelectric effect, the

The input side applied AC voltage is first converted into a mechanical vibration. The frequency of

mechanical vibration is essential of the

Geometry and the mechanical structure of the piezoelectric multilayer component 1 dependent.

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. In which

Piezoelectric material 9 of the output region 3 may be the same material as the piezoelectric material Material 5 of the input area 2 act, with the piezoelectric materials 5 and 9 in their

Can distinguish polarization direction. in the

Output area 3, the piezoelectric material 9 is formed into a single monolithic layer, the

is completely polarized in the longitudinal direction z. In this case, the piezoelectric material 9 in

Output area 3 only a single polarization direction.

Is the electrodes 4 in the input area 2 a

Applied AC voltage, so formed within the piezoelectric material 5, 9, a mechanical wave, which generates an output voltage by the piezoelectric effect in the output region 3. The exit area 3 has an exit-side end face 10. In the output region 3, an electrical voltage is thus generated between the end face 10 and the end of the electrodes 4 of the input region 2. At the output-side end face 10, a high voltage is generated. It also arises between the output side face and an environment of

piezoelectric multilayer component a high

Potential difference that is enough to make a strong

generate electric field that ionizes a process gas. In this way, the piezoelectric generates

Multilayer Device 1 high electric fields capable of ionizing gases or liquids by electrical excitation. In this case, atoms or molecules of the

ionize respective gas and the respective liquid and form a plasma. It always comes to one

Ionization when the electric field strength at the surface of the piezoelectric multilayer component 1 the

Ignition field strength of the plasma exceeds. As ignition field strength of a plasma is the field strength that is required for the ionization of the atoms or molecules.

The piezoelectric multilayer component 1 further has an input-side end face 22, which is the

Output side end face 10 is opposite. Furthermore, the piezoelectric multilayer component 1 has edges 23. The edges 23 may be rounded. The piezoelectric multilayer component 1 is subjected during its manufacture to a grinding process in which no abrasive is used and in which

Material abrasion of the piezoelectric

Multilayer component 1 by rubbing the

piezoelectric multilayer component 1 takes place on further piezoelectric multilayer components.

Figure 2 shows a detailed view of a section of a piezoelectric multilayer component 1, which was manufactured by the method described here, wherein a

Material abrasion from the side surfaces 6, 7, 20, 21, the

End faces 21, 22 and the edges 23 of the piezoelectric multilayer component 1 by rubbing of the components together. In this case, the multilayer components are arranged in a loose state in a drum.

In comparison, FIG. 3 shows a detail of a comparative example of a multilayer component which has been subjected to a scrubbing process using ZrÜ ₂ as an abrasive.

A comparison of Figures 2 and 3 shows that through the

Abandoning an abrasive material from the Side surfaces and edges of the multilayer components m can be removed in a way that less rough

Side surfaces and smooth rounded edges leads. In this way, the formation of local unevennesses on the outer surfaces of the multilayer component can be avoided. Accordingly, the undesirable plasma ignition at such local bumps can be avoided.

FIG. 4 shows a detailed view of a comparative example of a multilayer piezoelectric component which has been ground without the prior use of an annealing process and with the use of an abrasive substance which has abrasive grains. FIG. 4 shows that an abrasive grain 24 is in the piezoelectric process during the grinding process

Multilayer component was pressed and remained in this after the grinding process. The abrasive grain 24 has a negative effect in the multilayer component 1. It leads

For example, a significant unevenness of the

Surface .

The use of an abrasive has over the

Grinding the piezoelectric multilayer components without abrasive only the advantage that a removal of the surface can be made faster. However, the disadvantage is that when using an abrasive, the surface becomes significantly rougher, as shown in Figure 3, and even grains of the abrasive can penetrate into the surface. Alternatively, it is also conceivable, the piezoelectric

Multi-layer components to be ground together with ceramic cones and without the addition of an abrasive. In this case, a smoothness of the surfaces can be achieved, the is comparable to the result of the material abrasion by rubbing the piezoelectric multilayer components 1 together. However, then an additional step for the separation of the piezoelectric multilayer components and the ceramic cone after grinding is still required.

If the piezoelectric multilayer components 1 rubbed against each other, a smooth surface can be achieved. If the grinding process is carried out for two hours, the edges of the piezoelectric

Multi-layer components 1 are rounded in the desired manner.

Reference sign list

1 piezoelectric multilayer component

2 entrance area

3 output area

4 electrode

5 piezoelectric material

6 first side surface

7 second side surface

8 first outer electrode

9 piezoelectric material

10 output side face

20 third side surface

21 fourth side surface

22 input-side end face

23 edges

24 abrasive grain

X stacking direction

y y direction

z longitudinal direction

Claims

claims

1. A process for producing a variety of

piezoelectric multilayer components (1),

wherein the piezoelectric multilayer components (1) are ground without the addition of an abrasive, wherein a material abrasion of the piezoelectric multilayer components (1) by rubbing the

Piezoelectric multilayer components (1) to each other.

2. Method according to the previous claim,

wherein the piezoelectric multilayer components (1) are ground as a green body and wherein the

piezoelectric multilayer components (1) according to the

Sanding be sintered.

3. Method according to one of the preceding claims,

being before grinding the piezoelectric

Multilayer components (1) an annealing process

is performed, in which the piezoelectric

Multi-layer devices (1) are exposed to an elevated temperature. 4. Method according to the preceding claim,

being a hardness of the piezoelectric

Multilayer component (1) is increased during the annealing process. 5. The method according to any one of claims 3 or 4,

wherein in the annealing process, a solvent and / or plasticizer of an organic binder, at least partly from the piezoelectric

Removed multilayer component (1)

6. The method according to any one of claims 3 to 5,

wherein the piezoelectric multilayer components (1) in the annealing process temperatures of 100 ° C to 150 ° C are exposed.

Method according to one of the preceding claims,

wherein the grinding is performed in a drum having the plurality of piezoelectric ones

Multilayer components (1) is loaded,

wherein the material abrasion is adjusted as desired by adjusting at least one of the running time of the grinding operation, the number of piezoelectric multilayer components (1) in the drum and the rotational speed of the drum.

8. Method according to one of the preceding claims,

wherein the piezoelectric multilayer components (1) are surrounded by the medium of water in the grinding.

Method according to one of the preceding claims,

where it is the piezoelectric

Multilayer components (1) to piezoelectric

Transformers acts.