Zero-Taper Microholes: Precision Drilling for High-End Components by MONO

As femtosecond lasers gain popularity in precision manufacturing, their "cold processing" characteristics—no heat-affected zone (HAZ) and sub-micron level precision—have become the core technology for industries such as automotive, medical, and semiconductor. However, the inherent Gaussian energy distribution inevitably leads to a **"top-wide, bottom-narrow" taper** in microholes during traditional vertical drilling. This taper has become a **major barrier** to performance upgrades. Leveraging its profound expertise, **Mono** has broken this physical limitation to achieve zero-taper (vertical) microhole drilling, opening up new possibilities.

1. Why Is "Zero-Taper" So Critical?

A "zero-taper hole" refers to a hole where the sidewall is perfectly perpendicular to the surface, with identical inlet and outlet diameters. As a precise channel for fluid or gas transmission, the taper directly affects fluid flow characteristics, which is a rigid requirement in critical applications:

• Automotive Industry (GDI Injectors): Zero-taper ensures uniform and stable fuel atomization for complete combustion, improved efficiency, and reduced emissions.
• Medical Devices (Microfluidics): Vertical hole walls are the foundation for accurate metering of liquid samples and flow rate control—taper would cause dosage inaccuracies.
• Semiconductor Testing (Probe Cards): Zero-taper ensures probe perpendicularity and contact stability for accurate and reliable test results on tens of thousands of microholes.
• High-End Textiles (Spinnerets): Perpendicularity of microholes determines the cross-sectional morphology and final performance of high-performance fibers.

2. MONO’s Femtosecond Laser Drilling: Solving the Taper Challenge

The root cause of taper is that femtosecond laser energy is most concentrated at the focal point, causing the hole diameter to gradually decrease with depth. High-quality drilling requires more than just a laser.

Mono Technology’s solution integrates **advanced optics, precision mechanics, and intelligent algorithms** to achieve dynamic and accurate control of beam posture, enabling high-quality processing of non-tapered straight holes.

How Processing Technology Impacts Microhole Quality:

• Advanced Beam Control Technology: ML-VORTEX femtosecond laser precision processing center adopts a 5-axis linkage system, enabling high-speed rotation and tilting of the laser beam during processing. By precisely controlling the laser beam’s incident angle, the system "trims" the hole wall from the side to actively compensate for the natural taper caused by Gaussian beams.  
  
• Adaptive Parameter Strategy: Developed for different materials and hole depths, this strategy gradually reduces the scanning diameter with processing depth and real-time matches the optimal laser power, ensuring consistent hole diameter throughout the hole and achieving near-zero taper (taper angle < 0.5°).
• Multispectral Confocal Ranging + 3D Visual Modeling: These technologies construct a **micron-level digital twin** of the workpiece, dynamically compensating for clamping errors and material deformation to ensure zero-taper accuracy on complex surfaces (e.g., curved nozzles).

3. Technical Advantages: Redefining the Standard for Precision Drilling

3.1 Extreme Precision: Breaking Through Tolerance and Surface Finish Limits

Semiconductor:

Microhole arrays on probe boards, with ±1μm positioning accuracy, high perpendicularity, and excellent roundness & surface finish.

Medical Devices:

Tantalum metal microhole arrays, with inlet (left) and outlet (right) diameters of only 25μm ± 1μm and a taper angle < 0.5°.

3.2 Extreme Structures: High Aspect Ratios and High-Density Arrays

Aerospace Curved Filter Screens:

3,500 non-tapered microhole arrays on curved surfaces, with $\text{Ra} \le 0.4\mu\text{m}$.

Aerospace Tungsten Sheets:

Non-tapered microhole arrays with an **aspect ratio of 10:1** and high roundness.

3.3 Versatile Material Adaptability: From Metals to Ceramics

Semiconductor Ceramics:

50 microholes drilled in ceramics, with an aspect ratio of 10:1 and high roundness.

Medical Devices (PI Catheters):

Zero-taper microhole processing on PI (Polyimide) catheters, with no burrs.

3.4 Customizable Shapes: From Perfect Circles to Complex Special Shapes

Textile Industry (Spinnerets):

Processing of special-shaped holes with zero-taper, clear contours, and one-step forming.

4. Femtosecond Laser Solutions