| 摘要 |
PURPOSE:To improve the reliability of equipment by eliminating the occurrence of discharge by increasing the hole diameter of a crack after etching the surface of a piezoelectric crystal plate and by vapor-depositing a metallic film on its internal wall. CONSTITUTION:The surface of a piezoelectric plate, such as an LiNbO3 and LiTaO3 crystal plate, is polished with chemicals to be made smooth and the reverse surface, on the other hand, is roughened. Then, at least the reverse surface of the crystal plate is immersed in an etching solution, such as a mixed solution of an aqueous NH4F solution and HF or that of an aqueous nitric acid solution and HF, to etch a worked layer away. Respective transducers are formed on the surface and then a metallic film 42, etc., are adhered by vapor deposition. In this case hole diameters of cracks 51a-51c are increased and the metallic film 42 are adhered to their internal walls. Thus, the occurrence of discharge based upon pyroelectricity is eliminated completely and the reliability of equipment is improved remarkably. |
