DRILLING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an entry sheet for drilling which assures superior hole profile and high positioning accuracy even for drilling with a drill bit of a diameter of 0.3 mmϕor less, and a high quality drilling method with the entry sheet for drilling. SOLUTION: The drilling method is applied to the material of printed circuit boards. An entry sheet for drilling the material of printed circuit boards is made by forming a coat of thermosetting resin of average thickness 1 to 10μm on one side of an aluminum foil of thickness 20 to 200μm. The entry sheet for drilling is placed on the material of printed circuit boards with the aluminum foil side attached, and drilling is performed from the resin side.