Circuit board production method, involves providing sounding pads connected to metallic edge of respective inside layer and sounding drilling in area of pads determining depth of inside layer

摘要

The method involves providing in unused areas of the circuit board inside layers (IL2,IL3,IL4,IL5) with sounding pads which are connected to the metallic edge of the respective inside layer. The metallic edge is drilled through and a conducting coat is provided on the through borings. Sounding drillings are carried out in the area of the pads for determining the depth of the inside layer and the distance between the layers is measured, stored and used for later circuit board drilling.