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1. (WO2018159596) SUBSTRATE FOR SURFACE ACOUSTIC WAVE DEVICE, AND PSEUDO SURFACE ACOUSTIC WAVE ELEMENT

Pub. No.:    WO/2018/159596    International Application No.:    PCT/JP2018/007205
Publication Date: Sat Sep 08 01:59:59 CEST 2018 International Filing Date: Wed Feb 28 00:59:59 CET 2018
IPC: H03H 9/25
Applicants: KYOCERA CORPORATION
京セラ株式会社
Inventors: UTO, Takashi
宇都 隆司
Title: SUBSTRATE FOR SURFACE ACOUSTIC WAVE DEVICE, AND PSEUDO SURFACE ACOUSTIC WAVE ELEMENT
Abstract:
The present invention is formed of a piezoelectric material and is provided with: a first surface through which a surface acoustic wave propagates; and a second surface that is positioned oppositely to the first surface. The second surface has an arithmetic average roughness (Ra) of 0.2-0.4 µm. The relationship between the arithmetic average roughness (Ra) and the average interval (S) of local peaks satisfies Ra/S≥11, or the relationship between the arithmetic average roughness (Ra) and the average interval (Sm) of recessed and projected parts satisfies Ra/Sm≥6.7. In addition, the second surface has a maximum height (Rmax) of 2.5-4.5 µm. The relationship between the maximum height (Rmax) and the average interval (S) of the local peaks satisfies Rmax/S≥130, or the relationship between the maximum height (Rmax) and the average interval (Sm) of the recessed and projected parts satisfies Rmax/Sm≥80.