| 摘要 |
[Problems] To provide a multi-layer printed wiring board without decrease in connection reliability by using a via hole of a small diameter. [Means of Solving the Problems] Stress applied during a heat cycle is smaller in via holes 60A and 60B that are formed on cover plated layers 36a and 36d and whose bottoms are formed inside a region of ((R) + (r)/3) where (R) is the radius of a throughhole and (r) is the radius of a lower via hole, as compared with a via hole 160 formed on the second interlayer resin insulation layer 150. Accordingly, the radii of the bottoms of the via holes 60A and 60B are made smaller than that of the via hole 160. |
