Patent ID: 11476829

Abstract:
A substrate for a surface acoustic wave device is constituted of a piezoelectric material and includes a first surface on which a surface acoustic wave propagates, and a second surface located opposite to the first surface. The second surface has an arithmetic mean roughness (Ra) of 0.2 μm to 0.4 μm, and there is satisfied either of the relationship between the arithmetic mean roughness (Ra) and mean spacing (S) of local peaks of Ra/S≥11, and the relationship between the arithmetic mean roughness (Ra) and mean spacing (Sm) of irregularities of Ra/Sm≥6.7. Further, the second surface has a maximum height (Rmax) of 2.5 μm to 4.5 μm, and there is satisfied either of the relationship between the maximum height (Rmax) and mean spacing (S) of local peaks of Rmax/S≥130, and the relationship between the maximum height (Rmax) and mean spacing (Sm) of irregularities of Rmax/Sm≥80.