TMM® laminates are thermoset, ceramic-filled polymer composites designed for high-frequency applications. They offer exceptional dimensional stability and thermal conductivity. Proper drilling techniques are essential to preserve the laminate’s integrity and maintain its high-performance characteristics.

Drilling Guidelines

1. Drill Bit Selection
   • Type: Use carbide or diamond-coated bits for optimal performance.
   • Tip Angle: 130°–140° point angle for enhanced cutting efficiency.
   • Helix Angle: Low helix angle to reduce material delamination.
   • Surface Coating: Diamond coating for improved wear resistance during extended drilling cycles.
2. Spindle Speed and Feed Rate
   • Spindle Speed: 20,000–30,000 RPM, depending on the board thickness and hole diameter.
   • Feed Rate: 2–5 inches per minute (IPM). Adjust based on laminate thickness and filler density.
3. Stack Height
   • Limit stack height to ensure accurate hole placement and avoid excessive drill wear.
   • Typical stack height: 2–4 panels for 0.062-inch thickness laminates.
4. Entry and Backer Materials
   • Entry Material: Use aluminum or rigid phenolic entry sheets to minimize surface burring.
   • Backer Material: Use phenolic or FR-4 backer boards to reduce breakout on the exit side.
5. Drilling Environment
   • Maintain a clean environment to avoid contamination of drill bits with ceramic particles.
   • Use vacuum systems for efficient debris removal during drilling.
6. Peck Drilling
   • Use peck drilling (intermittent withdrawal of the drill bit) for hole depths greater than 1.5 times the drill diameter.
   • This prevents material overheating and reduces clogging.
7. Cooling and Lubrication
   • Apply air cooling or mist lubrication to dissipate heat and extend tool life.
   • Avoid excessive lubrication, which may contaminate the laminate surface.
8. Post-Drill Cleaning
   • Clean drilled holes with compressed air or a vacuum to remove debris.
   • Use deionized water for cleaning if contamination is detected.

Additional Tips for High-Quality Drilled Holes

1. Bit Maintenance:
   • Inspect and replace drill bits after 500–1,000 holes, depending on wear and laminate hardness.
2. Hole Tolerance:
   • Design holes with a tolerance of ±0.001 inch to account for thermal expansion and mechanical stress.
3. Drill Reconditioning:
   • Recondition carbide bits periodically to maintain sharpness and cutting accuracy.
4. Pilot Holes:
   • For large diameter holes (>0.2 inches), drill pilot holes to improve accuracy and reduce stresses.

Common Drilling Challenges and Solutions

Issue	Cause	Solution
Delamination or Cracking	Excessive feed rate or dull bit	Reduce feed rate; use sharp bits.
Tool Wear	Abrasive ceramic filler content	Use diamond-coated drill bits.
Burr Formation	Incorrect entry material	Use aluminum entry sheets.
Hole Contamination	Inadequate debris removal	Increase vacuum power.

Following these guidelines ensures precise and clean drilling of TMM® laminates, preserving their electrical and mechanical properties. Adherence to proper techniques minimizes defects and maximizes the performance and reliability of high-frequency circuits.