By Nanofilm Technologies International Limited
NTI Nanofilm applied Rainbow-TAC, its FCVA-deposited tetrahedral amorphous carbon coating, to the carbide micro-drills. Rainbow-TAC forms an ultra-dense,smooth and low-friction protective layer over the cutting surface. Unlike conventional unfiltered arc coatings, the FCVA process minimises macro-droplets and surface irregularities that can create weak points along the cutting edge. This is particularly important for micro-drills, end mills and other precision tools, where the coating must protect the cutting edge without altering the geometry that controls machining accuracy. The coating’s low-friction surface also helps reduce heat generation and material adhesion during high-speed machining, allowing the cutting edge to retain its condition for longer. Under the same drilling parameters, Rainbow-TAC increased total micro-drill life from approximately 1,500 holes to more than 5,000 holes. The first signs of burring were delayed from around 500 holes to at least 1,500 holes. Visual inspection showed that the Rainbow-TAC-coated micro-drill remained clean and sharp at the point when the standard-coated tool had already reached the end of its useful operating life. Performance Comparison by Drilling Stage 500 holes: Unfiltered Arc Coating - Visible burring began. The first visible signs of cutting-edge deterioration appeared at approximately 500 holes. Rainbow-TAC (FCVA) - No visible burring. The coated cutting edge remained clean, with burring delayed beyond this stage. 1,500 holes: Unfiltered Arc Coating - End of useful drill life. Severe edge degradation had developed and the micro-drill required replacement. Rainbow-TAC (FCVA) - Cutting edge remained serviceable. The drill remained clean and sharp, with the first signs of burring delayed to at least this stage. 3,000 holes: Unfiltered Arc Coating - Useful life already reached. The benchmark drill had reached the end of its operating life at around 1,500 holes. Rainbow-TAC (FCVA) - Minor wear became visible. Only minor cutting-edge wear began to appear after approximately 3,000 holes. 5,000+ holes: Unfiltered Arc Coating - Useful life already reached. The benchmark drill had required replacement well before this stage. Rainbow-TAC (FCVA) - Coating remained intact. The Rainbow-TAC coating remained intact beyond 5,000 holes. Rainbow-TAC’s dense, smooth and low-friction coating architecture provides a platform that can be adapted to precision tools used in semiconductor-related production, including tooling for packaging materials, leadframes, connectors, test components and electronic housings. NTI Nanofilm can adjust the Rainbow-TAC coating architecture and process parameters according to tool geometry, substrate material and machining conditions. This enables semiconductor manufacturers and precision-tooling partners to evaluate longer tool life and more stable machining performance against the wear mechanisms and production requirements most relevant to their applications. Performance figures are based on a controlled drilling study using 0.4 mm carbide micro-drills on an FR4 High-Tg material stack under defined operating conditions. The benchmark demonstrates micro-tooling performance under the stated test conditions and does not represent direct validation across all semiconductor manufacturing applications. Actual results may vary with tool geometry, workpiece material, stack configuration and machining parameters.
