| 摘要 |
PURPOSE:To keep surely a bonding layer at a prescribed thickness, by providing a recess or a projection controlled to a prescribed interval on a ground plane of a package on which a substrate is bonded. CONSTITUTION:An input electrode 2 and an output electrode 3 are provided on the surface of the piezoelectric substrate 1 respectively. The recess 8 to control the thickness of the bonding layer 4 is provided on the ground plane 4 of the packaging on which this piezoelectric substrate 1 is bonded. Thus, the thickness of the bonding layer 5 is kept to a thickness more than the wavelength of an unnecessary bulk wave. On the other hand, the thickness of the bonding layer 5 is kept at a specified value by providing projections 9-1, 9-2 on the ground plane of the package. |
