NTI Rainbow-TAC Extends Micro-Drill Life and Delays Burring by at Least 3×

In high-volume precision manufacturing, micro-tool performance has a direct influence on production economics. 

The usable life of each micro-drill or end mill determines how frequently machines must stop for tool replacement, how much tooling is consumed and how consistently machining quality can be maintained over a production run. As component geometries become smaller and machining requirements become more demanding, early cutting-edge wear can quickly translate into higher operating costs and greater quality risk. 

A controlled drilling study demonstrated how surface engineering could materially improve this production equation. 

The Production Challenge 

The study evaluated 0.4 mm carbide micro-drills machining an FR4 High-Tg material stack under identical operating conditions. 

With a standard arc-evaporated coating, visible burring began at approximately 500 holes. By around 1,500 holes, the micro-drill showed severe edge degradation and had reached the end of its useful operating life. 

Replacing micro-drills early helped protect machining quality but increased tool consumption and machine stoppages, while continuing to use a worn tool increased the risk of burr formation, rough machined surfaces and inconsistent downstream processing. 

The requirement was therefore to extend useful micro-tool life while delaying the point at which cutting quality began to deteriorate. 

The NTI Surface Engineering Approach 

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. 

Measured Performance 

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 

Drilling Stage	Unfiltered Arc Coating	Rainbow-TAC (FCVA)
500 holes	Visible burring began The first visible signs of cutting-edge deterioration appeared at approximately 500 holes.	No visible burring The coated cutting edge remained clean, with burring delayed beyond this stage.
1,500 holes	End of useful drill life Severe edge degradation had developed and the micro-drill required replacement.	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	Useful life already reached The benchmark drill had reached the end of its operating life at around 1,500 holes.	Minor wear became visible Only minor cutting-edge wear began to appear after approximately 3,000 holes.
5,000+ holes	Useful life already reached The benchmark drill had required replacement well before this stage.	Coating remained intact The Rainbow-TAC coating remained intact beyond 5,000 holes.

Business Impact

Extending micro-drill life from approximately 1,500 to more than 5,000 holes substantially reduces the number of tools required to complete the same machining volume.

At an annual production volume of one million holes, the benchmark performance would reduce the calculated number of micro-drill changeovers by up to 70%.

Standard Tool	Rainbow-TAC
667 Approximate changeovers	200 Approximate changeovers

For manufacturers, this means less machine time lost to tool replacement, lower micro-tool consumption and a longer period of consistent cutting performance before quality begins to decline.

Delayed burring also provides process teams with greater confidence in replacement planning. Instead of reacting to premature cutting-edge degradation, tool changes can be scheduled around a wider and more predictable operating interval.

The value therefore extends beyond the micro-drill itself. It supports improved uptime, better tooling efficiency and greater control over machining cost per hole.

From Micro-Drill Performance to Semiconductor Precision Manufacturing

While the controlled benchmark focused on micro-drilling, the underlying challenges of cutting-edge wear, friction, heat and material adhesion are also relevant to precision tooling used across the semiconductor manufacturing value chain.

As semiconductor components and packaging structures become smaller and more complex, micro-drills, end mills and other precision tools must retain their cutting geometry while machining materials such as technical ceramics, copper alloys, mould compounds and advanced composites.

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 Disclaimer

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.