| 摘要 |
PROBLEM TO BE SOLVED: To make the connection of a via conductor of a ceramic board with its surface conductor favorable, by providing further on an internal via conductor formed in the ceramic board a surface layer via conductor with a porosity not smaller than a specific value to be joined to the surface conductor. SOLUTION: Into a via hole 5 formed in a ceramic board 1, an internal via conductor 4a is filled. Further, a surface layer via conductor 4b with a porosity not smaller than 5% is filled into the existing portion of the via hole 5 on the internal via conductor 4a. Then, on the surface of the surface layer via conductor 4b, a surface conductor 2 containing a glass frit is formed in a joining way. Thereby, the melts of the glass frit in the surface conductor 2 can so penetrate into the existing voids not smaller than 5% in the surface vicinity of the surface layer via conductor 4b that the melts are not maldistributed on its joining plane to the surface conductor 2. Therefore, the connection of the surface layer via conductor 4b with the surface conductor 2 can be made favorable. |
