| 摘要 |
PROBLEM TO BE SOLVED: To suppress the change in a characteristic impedance even in the case of dispersion in the thickness of thin film formation itself concerning a coplanar line with which a signal conductor line and a ground layer are formed on the surface of a dielectric substrate by thin film formation. SOLUTION: This wiring board is provided with a ceramic dielectric substrate 1 and the coplanar line with which a signal conductor line 2 and ground layers 3 and 4 provided on both sides of the signal conductor line 2 are formed on the surface of the substrate 1 by thin film formation such as vaporing or metal plating. In this case, the thickness of signal conductor line 2 and ground layers 3 and 4 of the coplanar line is made more than 4 μm, the most outer surface of the signal conductor line 2 of the coplanar line at least is formed from the gold of thickness more than 1 μm, and further the ceramic dielectric layer 1 is formed from alumina ceramics containing alumina more than 98 wt.%. |
