| 摘要 |
PROBLEM TO BE SOLVED: To allow a piezoelectric substrate to take a reliable contact as an electric contact and make an even and airtight contact possible by providing through-hole electrodes with projecting sections which project by a specified length from the surface of the piezoelectric substrate and specifying the surface roughness around the projecting sections. SOLUTION: A multilayer piezoelectric element has such a structure that a piezoelectric substrate 7 formed in one or more layers which is made of piezoelectric substance is stacked on a piezoelectric substrate 6 in the most outer layer, with a plurality of internal electrode patterns 3-2, 3-3, 3-4 being formed in respective layers of the piezoelectric substrate 7, and these internal electrode patterns 3-2, 3-3, 3-4 are brought in continuity with each other through an interlayer interconnection constituted of a plurality of through-hole electrodes 2-1, 2-2, 2-3, 2-4 formed in respective layers of the element. The through-hole electrodes 2-1-2-4 have projecting sections which project 1 μm or above from the surface of the piezoelectric substrate 6 and the surface roughness around the projecting sections is set to 2 μm or below to have a smooth surface. |
