Piezo Actuator in Multi-Layered Construction

• US 20120019107A1
• Filed: 02/09/2011
• Published: 01/26/2012
• Est. Priority Date: 08/18/2008
• Status: Active Grant

• Current Assignee: TDK Electronics AG (TDK Corporation)
• Original Assignee: Epcos AG (TDK Corporation)
• Inventors: Gabl, Reinhard, Rinner, Franz, Reszat, Jan-Thorsten, Laussermayer, Markus
• Granted Patent: US 8,638,025 B2
• Time in Patent Office: Days
• US Class Current: 310/363
• CPC Class Codes: H10N 30/063 Forming interconnections, e.g. connection electrodes of multilayered piezoelectric or electrostrictive parts
• CPC Class Codes: H10N 30/07 Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/508 adapted for alleviating internal stress, e.g. cracking control layers
• CPC Class Codes: H10N 30/872 Connection electrodes of multilayer piezoelectric or electrostrictive devices, e.g. external electrodes
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A multilayer piezo actuator is specified, in which piezoelectric layers and electrode layers are arranged to form a stack. Electrical contact is made with the electrode layers via two external electrodes which consist of wires which are woven with one another. The external electrodes are in this case connected over their entire area to the side surfaces of the stack. A method is also specified for fitting an external electrode.

Claims

1. A multilayer piezo actuator comprising:

a stack of piezoelectric layers and electrode layers located between the piezoelectric layers;

at least one external electrode electrically contacting electrode layers, the at least one external electrode being in the form of a wire mesh; and

a basic metallization on the outer face of the stack, wherein the external electrode is soldered over its entire area to the basic metallization on the outer face of the stack.

2. The piezo actuator according to claim 1, wherein the wire mesh comprises mesh nodes with a wire located at the top and a wire located at the bottom.

3. The piezo actuator according to claim 2, wherein the wire located at the bottom is attached to the outer face of the stack at the mesh node.

4. The piezo actuator according to claim 1, wherein the wire mesh comprises wires with a conductive carrier material.

5. The piezo actuator according to claim 4, wherein the carrier material includes a material selected from the group consisting of steel, copper and a copper alloy.

6. The piezo actuator according to claim 1, wherein the wire mesh comprises wires with an insulating carrier material.

7. The piezo actuator according to claim 6, wherein the carrier material is elastic.

8. The piezo actuator according to claim 1, wherein the wire mesh comprises wires that are provided with a conductive coating.

9. The piezo actuator according to claim 8, wherein the conductive coating contains at least one metal selected from the group consisting of copper and tin.

10. The piezo actuator according to claim 1, wherein the wire mesh comprises wires that are woven with one another at an angle of 90°

.

11. The piezo actuator according to claim 10, wherein the wires that are woven with one another include an angle of 45°

with a stacking direction of the stack.

12. The piezo actuator according to claim 1, wherein the basic metallization has at least one burnt-in metal paste.

13. The piezo actuator according to claim 1, wherein the basic metallization is surface-treated in order to improve the solderability.

14. The piezo actuator according to claim 1, wherein a continuous solder layer is located between the external electrode and the basic metallization.

15. The piezo actuator according to claim 1, wherein the wire mesh comprises a plurality of layers.

16. The piezo actuator according to claim 15, wherein the plurality of layers includes a bottom layer that is attached over its entire area to the outer face of the stack.

17. A method for fitting an external electrode to a piezo actuator, the method comprising:

providing a stack of piezoelectric layers and electrode layers located between the piezoelectric layers, a basic metallization being burnt in and applied to an outer face;

providing a wire mesh;

coating the wire mesh with solder material;

placing the wire mesh on the basic metallization; and

heating the wire mesh and, while the wire mesh is heated, soldering the wire mesh to the basic metallization, the wire mesh being pressed onto the basic metallization during the soldering.

18. The method according to claim 17, wherein providing the stack comprises forming the stack of piezoelectric layers and electrode layers, the basic metallization being burnt in and applied to an outer face.

19. The method according to claim 17, wherein the basic metallization is surface-treated in order to improve the solderability.