Patent ID: 7463119

Claim:
A surface acoustic wave device having a piezoelectric substrate and an IDT formed on the piezoelectric substrate and using an excited wave as an SH wave, wherein the piezoelectric substrate is a rotation Y-cut substrate made from a quartz flat substrate, where a cut angle θ of the piezoelectric substrate is a rotation angle of a crystal Z-axis when the piezoelectric substrate is rotated around a crystal X-axis, a direction in which the piezoelectric substrate is rotated from a positive Z-axis side to a positive Y-axis side is a direction in which the cut angle θ is negative, and the cut angle θ is set in the range of −65°≦θ≦−61°, and a propagation direction of a surface acoustic wave is set in the range (90°±5°) with respect to the crystal X-axis, and the IDT is made of Ta or an alloyed metal containing Ta as the main component.