Microdrills were deposited by Cr-N based and TiN coatings using a magnetron sputter technique. A flexible printed circuit board was used to evaluate the drilling lives. SEM observation was employed to reveal the wear and local welding. A special pin-on-disc tester was designed to assess the interaction between coatings and against materials. Drilling test indicated that the number of drilling holes increased significantly when the minidrill was coated Cr-N based film than TiN. Failure model of microdrill was studied for cutting this copper rich printed circuit board. Results demonstrated that welding produced between TiN coating and rich copper counter material, but welding did not occur between Cr-N based film and copper material.