US 11,744,156 B2
Multilayer piezoelectric element, piezoelectric vibration apparatus, and electronic device
Hiroshi Hamada, Takasaki (JP); Hiroyuki Shimizu, Takasaki (JP); Sumiaki Kishimoto, Takasaki (JP); Yukihiro Matsui, Takasaki (JP); Shigeo Ishii, Takasaki (JP); Tomohiro Harada, Takasaki (JP); and Yukihiro Konishi, Takasaki (JP)
Assigned to TAIYO YUDEN CO., LTD., Tokyo (JP)
Filed by TAIYO YUDEN CO., LTD., Tokyo (JP)
Filed on Jul. 30, 2018, as Appl. No. 16/49,348.
Claims priority of application No. 2017-152262 (JP), filed on Aug. 7, 2017; and application No. 2018-034063 (JP), filed on Feb. 28, 2018.
Prior Publication US 2019/0044053 A1, Feb. 7, 2019
Int. Cl. H01L 41/083 (2006.01); H01L 41/047 (2006.01); H01L 41/09 (2006.01); H01L 41/273 (2013.01); H01L 41/293 (2013.01); H01L 41/257 (2013.01); H01L 41/313 (2013.01); H10N 30/50 (2023.01); H10N 30/063 (2023.01); H10N 30/073 (2023.01); H10N 30/20 (2023.01); H10N 30/87 (2023.01); G06F 3/01 (2006.01); H10N 30/045 (2023.01); H10N 30/053 (2023.01)
CPC H10N 30/508 (2023.02) [H10N 30/063 (2023.02); H10N 30/073 (2023.02); H10N 30/206 (2023.02); H10N 30/872 (2023.02); G06F 3/016 (2013.01); H10N 30/045 (2023.02); H10N 30/053 (2023.02); H10N 30/871 (2023.02)] 9 Claims
OG exemplary drawing
 
1. A multilayer piezoelectric element, comprising:
a ceramic body formed by a piezoelectric ceramic and having first and second end faces facing a longitudinal direction, first and second principal faces facing a thickness direction perpendicular to the longitudinal direction, and a first pair of ridge parts connecting the first and second end faces, respectively, with the first principal face, and a second pair of ridge parts connecting the first and second end faces, respectively, with the second principal face, wherein the first pair and the second pair of ridge parts are constituted by curved faces as viewed in a direction perpendicular to the longitudinal direction and the thickness direction;
a pair of external electrodes covering the first and second end faces, and extending from the first and second end faces, respectively, onto the first principal face via the first pair of ridge parts, respectively, each one of the pair of external electrodes having a projecting portion projecting in the thickness direction in an area overlapping the first principal face as viewed in the thickness direction, where an apex point which is a thickest point of the projecting portion and thicker than all other parts of a portion of the each one of the pair of external electrodes, which is above a plane defined by the first principal face, as measured with respect to the plane defined by the first principal face, is present in the projecting portion at a location away from one of the first pair of ridge parts adjacent to the apex point in the longitudinal direction;
multiple internal electrodes stacked inside the ceramic body along the thickness direction and connected alternately to the pair of external electrodes along the thickness direction; and
a first surface electrode provided on the first principal face, said first surface electrode connected to one of the pair of external electrodes different from another of the pair of external electrodes to which one of the multiple internal electrodes immediately adjacent in the thickness direction is connected.