Surface acoustic wave element

Abstract

A surface acoustic wave element has a small energy loss and when it is used in a filter device, suppresses a spurious component occurring near the resonant frequency of a principal response and improves the frequency characteristic near the pass band of the filter device. The surface acoustic wave element includes a piezoelectric substrate, a comb-shaped electrode, and an insulating film. The comb-shaped electrode is disposed on the piezoelectric substrate. The insulating film is disposed so as to cover the piezoelectric substrate and the comb-shaped electrode. Where λ is the wavelength of an elastic wave that propagates in the piezoelectric substrate and h is the difference between the maximum and minimum values of a thickness dimension from the top surface of the piezoelectric substrate to the top surface of the insulating film, 0.01≦h/λ≦0.03 is satisfied.

Dependencies are inferred from the claim text.