| 摘要 |
PROBLEM TO BE SOLVED: To accurately adjust the frequency while preventing deterioration in membrane property and the production of foreign matter by selectively etching areas of a common electrode, formed on the opposite surface from the main surface of a piezoelectric substrate where an input electrode, an output electrode, and an earth electrode are present, opposite to the input electrode, output electrode, and earth electrode. SOLUTION: On one main surface S1 of the piezoelectric substrate 1, the input electrode 2, output electrode 3, and earth electrode 4 are formed by vacuum vapor-deposition, etc., and on the other main surface S2, a common electrode 5 is formed. Then while frequency characteristics are monitored, a desirable areas of the common electrode 5 is selectively etched. For example, when balance adjustment is made, adjustment is so made that the input electrode 2 and common electrode 5, and output electrode 3 and common electrode 5 have matching frequency characteristics. The area of the common electrode 5 which faces the input electrode 2 is covered with a mask 6 and etched by an ion gun 7. Otherwise, the area facing the output electrode 3 is covered with the mask 6 and etched by the ion gun 7. |
