| 摘要 |
PROBLEM TO BE SOLVED: To form a groove for breaking in a proper depth without disconnection or without being affected by the thickness wiring layer for electric plating. SOLUTION: A cylindrical metallic layer 125 having an axis in the thickness direction of an unburned ceramic large substrate is provided at a site crossing a boundary K in a conductor wiring layer 121, while the boundary K is allowed to pass inside this. The cylindrical metallic layer 125 and the conductor wiring layer 121 maintain electric conduction. Break grooves 103 are formed from each surface and back face 101a and 101b side through the boundary K in the state of the unburned ceramic large substrate. The conductor wiring layer 121 is made cylindrical at the site where the break grooves 103 are formed so that disconnection can be hardly generated at the time of forming the grooves. |
