| 摘要 |
PURPOSE:To improve mechanical strength and heat shock resistance by connecting the plane part and circular conical part of a ceramic chip cover of which the cylindrical part having a large diameter and the small diameter plane part at the top end are connected by the circular conical part by a curved surface having a specific radius of curvature or above. CONSTITUTION:The boundary part between the plane part 3 and circular conical part 4 of a chip cover for welding which consists of a cylindrical part 1 having a large diameter, the plane part 3 at the tip having a small diameter and having a guide hole 2 for a welding material 5 and the convergent circular conical part 4 and is formed of a ceramics consisting essentially of silicon nitride is formed to a curved surface having >=0.5mm. radius R of curvature. The ceramics consisting essentially of silicon nitride is constituted of 70-97wt% silicon nitride of an alpha layer, 0.1-10wt% of >=1 kind among molybdenum, niobium, halfnium, tantalum, tungsten and the carbide, silicide and boride thereof and 2-20wt% a grain boundary layer consisting of Si-Y-Al-O-N. |
