Nanolayer CrNx/WNy coatings used on micro drills for machining of printed circuit boards

A series of CrNx/WNy nanolayer coatings were synthesized using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™), employing one W target and three Cr targets. For comparison, a monolayer CrN coating was also grown on the same deposition system. Characterization was conducted using EDX, SEM, TEM, AFM, XRD, nanohardness indentation tester, and scratch tester. Performance of cutting tools with the nanolayer coatings was carried out via machining tests using the coated micro drills to continuously make through-thickness holes on printed circuit boards. The results showed that nanolayer CrNx/WNy coatings with various modulation period (λ) could be obtained on an industrial-size deposition machine by means of control in the current applied to the W target. Of the studied nanolayer CrNx/WNy coatings, the one with λ = 27 nm showed the highest nanohardness and best micro drilling performance. This nanolayer coating showed significant improvements in cutting performance as compared with the referred monolayer CrN coating.