| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve a connection pad in connection strength by a method wherein the connection pad is partially depressed from the surface of a ceramic board so as to form a recess with a prescribed depth. SOLUTION: Part-mounting through-holes 2 are provided by a punching machine to mullite green sheets corresponding to the number of wiring layers to serve as part mounting connection pads. Tungsten paste comparatively low in viscosity is filled into the through-hole 2 of the surface mullite green sheet. Tungsten paste comparatively high in viscosity is filled into the through-holes provided to the other green sheets. A recess depressed as deep as 10 to 80μm from the surface is formed on the through-hole 2 provided to the surface mullite green sheet. A wiring layer is formed on the green sheets with tungsten paste respectively, and the mullite green sheets are laminated in a prescribed layer configuration, bonded together by a press, and burned into a multilayer ceramic board 1. Then, Ni plating 5 and Au plating are provided to the surface of the ceramic board 1. By this setup, Ni plating and tungsten filled in the through- hole 2 are enhanced in connection strength between them.</p> |
