Overview
RT-Duroid® 6002 laminates are high-performance PTFE-based materials widely used in microwave and high-frequency applications. Due to their unique PTFE composition, glass fiber content, and thermal sensitivity, drilling is a critical fabrication step. Following proper drilling guidelines ensures clean vias, prevents delamination, and maintains structural integrity for multilayer and bonded PCB assemblies.
Drilling Challenges
1. PTFE Composition
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PTFE is softer and more prone to deformation than conventional FR-4 laminates.
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Requires specialized tooling and optimized drilling parameters to prevent smearing.
2. Glass Fiber Content
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Abrasive glass fibers can accelerate drill bit wear.
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Drill bit maintenance and selection are critical.
3. Thermal Sensitivity
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Excessive heat can cause smearing, deformation, or damage to the laminate.
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Cooling strategies are essential during drilling.
Recommended Drilling Tools and Equipment
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Drill Bits: Carbide or diamond-coated bits for durability and precision. Maintain sharpness for clean hole walls.
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Backing and Entry Materials:
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Phenolic entry sheets prevent drill bit deflection.
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Aluminum backing sheets reduce burrs and improve hole quality.
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Drilling Machine: High-speed equipment with minimal vibration. Use vacuum systems for debris removal.
Drilling Parameters
| Parameter | Recommended Range |
|---|---|
| Spindle Speed | 50,000–80,000 RPM |
| Feed Rate | 50–100 IPM (1.27–2.54 m/min) |
| Retract Rate | 500–1,000 IPM (12.7–25.4 m/min) |
| Chip Load | 0.002–0.004 in (0.05–0.1 mm) per revolution |
| Peck Drilling | Recommended for holes deeper than 4× diameter |
Hole Preparation and Cleaning
Desmear Process:
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Use plasma etching or sodium treatment to remove smear from PTFE hole walls.
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Oxygen-based plasma with optimized dwell time ensures effective cleaning.
Deburring:
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Use a soft nylon brush to lightly deburr without damaging the laminate.
Thermal Management During Drilling
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Coolant: Air blast or mist coolant recommended. Avoid water-based coolants to protect PTFE integrity.
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Heat Control: Maintain controlled drilling speeds to minimize heat buildup and prevent smearing.
Best Practices for Multilayer Boards
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Stack Drilling: Limit the number of layers per stack to reduce deflection.
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Separator Sheets: Use between layers for better alignment and accuracy.
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Registration and Alignment: Align stacks with pins for precise hole placement.
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Inspection: Use optical or X-ray inspection to verify hole quality and dimensional accuracy.
Post-Drilling Considerations
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Plating Preparation: Ensure vias are clean and smooth for reliable copper adhesion.
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Quality Checks: Inspect for residual debris or defects before plating.
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Stress Relief: Bake drilled laminates at 150–200°C (300–392°F) for 1–2 hours to relieve thermal stress.
Conclusion
By adhering to these drilling guidelines for RT-Duroid® 6002, manufacturers can achieve:
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High-quality, precise vias
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Reduced delamination risk
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Structural integrity for bonded and multilayer assemblies
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Extended tool life and fabrication efficiency
These best practices are essential for high-frequency, microwave, and multilayer PCB applications, ensuring long-term reliability and performance in demanding environments such as aerospace, defense, and telecommunications.
