| 摘要 |
PROBLEM TO BE SOLVED: To improve the efficiency of high frequency transmission by forming a dielectric film by chemical vacuum evaporation so as to keep the existent impedance even when a micro strip line width is increased so as to suppress disconnection or a cross talk in a wiring substrate for high frequency. SOLUTION: In a high frequency wiring substrate having a wiring layer capable of transmitting a signal of high-frequencies equal to or higher than 1 GHz, a dielectric film is formed by chemical vacuum evaporation on a ground electrode formed directly on an insulting substrate or previously formed on the insulated substrate at need. The ground electrode is formed desirably on the whole surface of the insulated substrate by baking a silver electrode, copper plating, etc. The dielectric film is formed on the ground electrode always by chemical vacuum evaporation. Material to be used for this dielectric film is not restricted in particular as long as it can be subjected to chemical vacuum evaporation processing, but a matter having a low dielectric constant such as a fluorine-containing aromatic compound is desirably used. |
