Patent ID: 7397327
Filing Date: 2008-07-08
Classification: H01L,H03H

Abstract:
1. A surface acoustic wave filter comprising: a mount board including a land; a device chip in which a wiring pattern including an IDT and a pad electrically connected to the IDT is provided on one of a pair of parallel and opposing principal surfaces of a piezoelectric substrate, the pad being disposed so as to oppose the land of the mount board, the pad and the land being electrically connected through a bump; and a resin film covering the other principal surface of the piezoelectric substrate and sealing the device chip; wherein an area of the one of the principal surfaces of the piezoelectric substrate is greater than an area of the other principal surface of the piezoelectric substrate; each peripheral surface of the piezoelectric substrate extending between the pair of principal surfaces includes a parallel planar portion which is substantially parallel to the pair of principal surfaces of the piezoelectric substrate and a vertical planar portion which is substantially perpendicular to the pair of principal surfaces of the piezoelectric substrate, such that each of the peripheral surfaces of the piezoelectric substrate includes a stepped portion including at least one step; and a thickness of the at least one step is substantially 50%±15% of a thickness of the piezoelectric substrate.