Patent ID: 7339304

Claim:
A surface acoustic wave device comprising: a piezoelectric substrate made of LiNbO 3 having an electromechanical coupling coefficient whose square (k 2 ) is at least about 0.025; at least one electrode made of one of a metal whose density is greater than that of Al, an alloy primarily including the metal or that is composed of laminated films made of a metal whose density is greater than that of Al or an alloy primarily including the metal and another metal, the at least one electrode being disposed on the piezoelectric substrate; a first insulating layer disposed in a region other than a region where said at least one electrode is disposed, a thickness of the first insulating layer being substantially equal to that of the at least one electrode; and a second insulating layer covering the at least one electrode and the first insulating layer; wherein a density of the at least one electrode is at least about 1.5 times greater than that of the first insulating layer.