Patent ID: 7382217
Filing Date: 2008-06-03
Classification: H03H

Abstract:
1. A surface acoustic wave device comprising a piezoelectric substrate, an IDT which is formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, and grating reflectors on both sides of the IDT that reflect a surface acoustic wave, the surface acoustic wave device using an SH wave as an excitation wave, wherein the piezoelectric substrate is a rotated Y-cut quartz plate having a cut angle θ set to a range of −64.0°<θ<−49.3° rotated counterclockwise from a Z crystalline axis and a propagation direction of a surface acoustic wave set to a direction of 90°±5° with respect to an X crystalline axis, wherein, when a wavelength of an excited surface acoustic wave is denoted by λ, an electrode film thickness H/λ normalized with wavelength of the IDT is set to a range of 0.04<H/λ<0.12, and wherein, when a line occupancy rate mr of electrode fingers constituting the IDT is defined to be electrode finger width/(electrode finger width+electrode finger spacing), the line occupancy rate mr is set to a range of 0.53≦mr ≦0.65.