Method for drilling a through hole in a laminar substrate and sheet used therein.

摘要

A high molecular weight sheet comprising a composite whose principal component is a special water soluble high molecular weight compound, or a multilayer sheet wherein a water soluble high molecular weight layer is piled on sheet material is prepared. Then, said sheet is layered on entry side of a laminated substrate comprising insulating material and metallic foil. In this state, through holes are formed in the laminated substrate through said sheet. When forming through holes, said water soluble high molecular weight compound serves as lubricant so as to extend drill life. In addition, it is possible to drill a lot of substrates, which are layered, at one time, resulting in the improvement of production efficiency.