| 摘要 |
PURPOSE:To improve vibration characteristic by selecting and using the composition of synthetic resin to make characteristic of sheath material complementary to that of a piezo-electric substrate. CONSTITUTION:A piezo-electric substrate 1 is a thin plate of piezo-electric ceramic, and electrodes 3, 3 are formed at the center of both faces facing each other and makes thickness vibration of energy confining type. Electrodes 3, 3 are connected respectively to leads 4, 4 through leader electrodes. Sheath material 2 is protective member made by molding epoxy resin and covers whole piezo-electric substrate projecting only leads 4, 4. As periphery of electrodes 3, 3 on both sides of the piezo-electric substrate 1 becomes an area for thickness vibration of energy confining type, the sheath material 2 is excluded and hollows 5, 5 are formed. The sheath material is formed to a thickness complementary to temperature characteristic of the piezo-electric substrate 1 by selecting the composition of the epoxy resin and controlling viscosity and thixotropy etc.
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