Patent ID: 8183737

Claim:
An elastic wave device comprising: a piezoelectric component including a plurality of grooves; at least one IDT electrode including a plurality of electrode fingers, a portion of each of the plurality of electrode fingers being located in at least one of the plurality of grooves; and a dielectric layer arranged on the piezoelectric component so as to cover the at least one IDT electrode, the dielectric layer having a temperature coefficient of frequency, and a sign of the temperature coefficient of frequency of the dielectric layer being opposite to that of the temperature coefficient of frequency of the piezoelectric component, or the sign of the temperature coefficient of frequency of the dielectric layer being the same as that of the temperature coefficient of frequency of the piezoelectric component, and an absolute value of the temperature coefficient of frequency of the dielectric layer being smaller than that of the temperature coefficient of frequency of the piezoelectric component; wherein each of the plurality of electrode fingers includes a first electrode layer and a second electrode layer, the first electrode layers being located in the grooves, and the second electrode layers being located on the first electrode layers and above tops of the grooves; and a one-half power of a product of a cube of a mean density (ρ a ) and a mean stiffness (C44 a ) of the first electrode layer, (ρ a 3 ×C44 a ) 1/2 , is larger than a one-half power of a product of a cube of a mean density (ρ b ) and a mean stiffness (C44 b ) of the second electrode layer, (ρ b 3 ×C44 b ) 1/2 .