RT-duroid® 6002 laminates are widely used in high-frequency and microwave applications due to their excellent electrical and mechanical properties. Drilling is a critical step in fabricating bonded assemblies and multilayer boards with RT-duroid materials. Following the proper guidelines ensures clean vias, prevents delamination, and maintains structural integrity.

Drilling Challenges with RT-duroid 6002

1. PTFE Composition:
   • PTFE-based materials are softer and more prone to deformation than FR-4 laminates.
   • Requires specialized tooling and optimized parameters.
2. Glass Fiber Content:
   • Abrasive glass fibers in RT-duroid 6002 can wear down drill bits quickly.
3. Thermal Sensitivity:
   • Excessive heat during drilling can cause smearing and damage to the laminate.

Drilling Tools and Equipment

1. Drill Bits:
   • Use carbide or diamond-coated drill bits for durability and precision.
   • Ensure sharp bits for optimal performance and clean hole walls.
2. Backing and Entry Materials:
   • Use phenolic entry materials to prevent drill bit deflection.
   • Place aluminum backing sheets to minimize burrs and improve hole quality.
3. Drilling Machine:
   • Ensure high-speed drilling equipment with minimal vibration.
   • Incorporate vacuum systems for effective 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 inches (0.05–0.1 mm) per revolution
Peck Drilling	Use for holes deeper than 4x the diameter.

Hole Preparation and Cleaning

1. Desmear Process:
   • For PTFE materials, use a plasma etching or sodium treatment process to remove any smear from the hole walls.
   • Plasma settings: Oxygen-based plasma with optimized dwell time.
2. Deburring:
   • Use a soft nylon brush for light deburring without damaging the laminate.

Thermal Management During Drilling

1. Coolant Use:
   • Air blast or mist coolant is recommended to reduce heat build-up.
   • Avoid water-based coolants as they may impact laminate integrity.
2. Heat Control:
   • Maintain controlled drilling speeds to avoid excessive heat, which can smear PTFE and compromise hole quality.

Best Practices for Multilayer Boards

1. Stack Drilling:
   • Limit the number of layers in a stack to minimize deflection.
   • Use separator sheets between layers for better accuracy.
2. Registration and Alignment:
   • Align drill stacks using pins to ensure precise hole placement.
3. Inspection:
   • Perform visual and dimensional inspection of drilled holes using optical or X-ray systems.

Post-Drilling Considerations

1. Plating Preparation:
   • Ensure clean, smooth vias to promote reliable copper plating adhesion.
   • Conduct quality checks for any residual debris or defects.
2. Stress Relief:
   • Perform thermal stress relief by baking drilled laminates at 150–200°C (300–392°F) for 1–2 hours.

By adhering to these drilling guidelines, manufacturers can achieve high-quality vias and maintain the structural integrity of RT-duroid 6002 bonded assemblies and multilayer boards. These practices ensure reliable performance in high-frequency applications and extend the lifespan of fabrication tools.