| 摘要 |
PROBLEM TO BE SOLVED: To provide a multilayer circuit board in which via holes for a signal line with small reflection are formed at high density and at low costs. SOLUTION: Insulating layers 100A to 100D are formed between a wiring layer 102 and a wiring layer 112 which are arranged so as to be faced. The wiring layers 102, 112 are connected by a connecting body 103 which is formed so as to pass the insulating layers 100A to 100D. The part on one end side and the part on the other end side of the connecting body 103 are connected by an intermediate connecting layer (a via land) 106 in the central position of the connecting body 103. A shielding layer (a grounding layer) 107 is arranged on a face nearly identical to the intermediate connecting layer 106 so as to be separated from the intermediate connecting layer 106. Then, the connecting distance between the wiring layer 102 and the wiring layer 112 via the connecting body 103 and the intermediate connecting layer 106 is designated as (h), the diameter of the connecting body 103 in the case the connecting body is regarded as a nearly cylindrical body is designated as R, the diameter of the intermediate connecting layer 106 in the case the intermediate connecting layer is regarded as a nearly cylindrical shape is designated as (r), and the separation distance between the intermediate connecting layer 106 and the shielding layer 107 is designated as L. Then, when a condition of (R.r)/(2.h)<=L<=(5.R.r)/h is satisfied, the characteristic impedance of a multilayer circuit board can be stabilized. |
