PIEZOELECTRIC DEVICE

• US 20140035440A1
• Filed: 07/31/2012
• Published: 02/06/2014
• Est. Priority Date: 07/31/2012
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: AIDA, Yasuhiro, KURACHI, Katsuyuki, SAKUMA, Hitoshi, MAEJIMA, Kazuhiko
• Granted Patent: US 9,136,820 B2
• Time in Patent Office: Days
• US Class Current: 310/365
• CPC Class Codes: G01C 19/5783 Mountings or housings not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: H03H 9/02133 of stress
• CPC Class Codes: H04R 17/02 Microphones
• CPC Class Codes: H10N 30/1051 based on piezoelectric or electrostrictive films or coatings
• CPC Class Codes: H10N 30/10516 Intermediate layers, e.g. barrier, adhesion or growth control buffer layers
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/886 Mechanical prestressing means, e.g. springs springs in general F16F1/00

Abstract

A piezoelectric device according to the present invention is provided with a pair of electrode films, a piezoelectric film sandwiched in between the pair of electrode films, and a stress control film which is in direct contact with a surface of at least one of the pair of electrode films, on the side where the electrode film is not in contact with the piezoelectric film, and which has a linear expansion coefficient larger than those of the relevant electrode film and the piezoelectric film.

Claims

1. A piezoelectric device comprising:

a first electrode film;

a piezoelectric film provided on the first electrode film;

a second electrode film provided on the piezoelectric film; and

a second stress control film provided on the second electrode film,

wherein the second stress control film is in direct contact with the second electrode film, and

wherein a linear expansion coefficient of the second stress control film is larger than linear expansion coefficients of the second electrode film and the piezoelectric film.

2. The piezoelectric device according to claim 1, wherein the second stress control film is a cured thermosetting resin.

3. The piezoelectric device according to claim 1, wherein the second stress control film is an inorganic oxide.

4. The piezoelectric device according to claim 1, wherein there is no substrate 10 μ

m or more thick on a top surface of the second stress control film and there is no substrate 10 μ

m or more thick on a bottom surface of the first electrode film, either.

5. The piezoelectric device according to claim 1, further comprising:

a first stress control film provided on a bottom surface of the first electrode film,

wherein the first stress control film is in direct contact with the first electrode film, and

wherein a linear expansion coefficient of the first stress control film is larger than linear expansion coefficients of the first electrode film and the piezoelectric film.

6. The piezoelectric device according to claim 5, wherein the first stress control film is a cured thermosetting resin.

7. The piezoelectric device according to claim 5, wherein the first stress control film is an inorganic oxide.

8. The piezoelectric device according to claim 5, wherein there is no substrate 10 μ

m or more thick on a top surface of the second stress control film and there is no substrate 10 μ

m or more thick on a bottom surface of the first stress control film, either.