| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve the electrical properties of an inductor built in a board using a threaded hole, and to enable to mass-produce the board with a built-in inductor with a high yield. <P>SOLUTION: The threaded hole 15 is bored in the insulating board 11, a conductor film 16 is formed on the inner wall of the threaded hole 15 by, for instance, plating, and the spiral ridge 15b of the threaded hole 15 is removed (e.g. cut off by a drill) while the spiral thread groove 15a of the threaded hole 15 is left unremoved. The threaded hole 15 where the spiral ridge 15b is removed is filled up with composite material 18 composed of resin and functional material (inorganic filler) mixed into it. After the spiral ridge 15b has been removed, the conductor film 16 left in the adjacent spiral thread grooves 15b is preferably removed by soft etching performed on the threaded hole 15 to surely form a spiral conductor in the threaded hole, even if misalignment occurs somewhat when the spiral ridge is removed. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
