| 摘要 |
PURPOSE:To prevent the reduction in pattern accuracy through the purification of a substrate surface, by applying the plasma etching to the substrate after the forming of an electrode pattern. CONSTITUTION:An input transducer 1, an output transducer 4, and a multistrip coupler 3 are formed on a piezoelectric crystal substrate. The generation of a tripple transient echo is prevented by coating a sound absorbing member at the end of the input transducer 1. Further, sound absorbing films 7 and 8 to absorb unnecessary waves propagated to opposite direction from the input and output transducers are provided. To regulate the propagation between the transducers and to absorb unnecessary waves, a sound absorbing film 9 is provided. The absorbing films are formed in the thickness of several tens of mum through the screen printing. Through the provision of flashing to the substrate before the screen printing by means of the plasma etching, the reduction in the pattern accuracy due to flap of the sound absorbing films can be prevented. |
