| 摘要 |
PURPOSE: To improve the reliability by making a throughhole from an outer side face with sand blast and eliminating a processing alteration layer with chemical etching and conducting mirror surface polishment so as to make electric connection stable. CONSTITUTION: First and second covers 2, 3 made of a crystal plate whose thickness is 400μm are joined to a front side and a rear side of a diaphragm 1 made of a crystal plate whose thickness is 100μm. After making throughholes 16, 17 from the outside of the cover 3 by sand blast, an alteration layer 22 and a chipping 23 are eliminated by chemical etching. Furthermore, drooping by the alteration layer 22 and the chemical etching is eliminated by mirror surface polishment. Thus, a stable conductor 18 is obtained.
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