RT-duroid® 5870 and 5880 materials are widely used for high-frequency and microwave circuit designs due to their excellent dielectric properties and low loss. However, their PTFE-based composition and unique mechanical characteristics require specific handling and fabrication processes to maintain performance and reliability.

1. Material Overview

Key Properties:

• RT-duroid 5870:
  • Dielectric constant (ϵr\epsilon_rϵr​): 2.33 ± 0.02.
  • Dissipation factor (tan⁡δ\tan \deltatanδ): 0.0012.
• RT-duroid 5880:
  • Dielectric constant (ϵr\epsilon_rϵr​): 2.20 ± 0.02.
  • Dissipation factor (tan⁡δ\tan \deltatanδ): 0.0009.

Both materials feature low moisture absorption, excellent thermal stability, and compatibility with high-frequency applications.

2. Storage and Handling

• Store in a clean, dry environment at room temperature to prevent contamination and moisture absorption.
• Use gloves to handle laminates, avoiding fingerprints or surface oils.
• Avoid bending the material, as the PTFE base is prone to deformation.

3. Cutting and Machining

3.1 Cutting:

• Use carbide or diamond-coated tools for precision.
• Shearing is not recommended due to potential delamination.

3.2 Drilling:

• Use sharp, carbide-tipped drill bits with high speed and low feed rates.
• Maintain low pressure to avoid burr formation and delamination.
• For plated through-holes (PTH), clean drilled holes with plasma or chemical etching to remove debris.

4. Copper Cladding and Etching

4.1 Copper Cladding:

• RT-duroid materials typically come with rolled or electro-deposited copper foil.
• Avoid excessive mechanical stress during processing, as the adhesion between PTFE and copper is sensitive.

4.2 Etching:

• Use standard etching solutions (e.g., ferric chloride or ammonium persulfate).
• Maintain precise temperature and agitation during etching to ensure uniform copper removal.
• Post-etch, clean thoroughly to remove chemical residues.

5. Lamination and Bonding

• Bonding Films: For multilayer applications, use Rogers 3001 or compatible bonding films designed for PTFE materials.
• Pressing: Maintain uniform pressure and temperature (typically 250°C to 350°C) during lamination.
• Release Films: Use non-stick release films to prevent damage during pressing.

6. Metallization and Plating

• PTFE surfaces require surface roughening for proper metallization.
• Use plasma treatment or sodium etching to enhance adhesion.
• Follow with electroless copper plating before electroplating to ensure uniform coverage and strong bonding.

7. Soldering and Thermal Management

7.1 Soldering:

• Use lead-free or low-temperature solders to minimize thermal stress.
• Keep soldering temperatures below 260°C to prevent PTFE degradation.
• Limit dwell time during reflow soldering to reduce warping and adhesion loss.

7.2 Thermal Relief:

• After soldering, implement stress-relief cycles (e.g., 200°C for 1 hour) to mitigate residual thermal stress.

8. Inspection and Testing

• Visual Inspection: Check for surface defects, delamination, and debris.
• Peel Strength Testing: Evaluate copper adhesion to ensure durability.
• Electrical Testing: Verify impedance and dielectric performance using a network analyzer.

9. Common Challenges and Solutions

Challenge	Solution
Poor copper adhesion	Use plasma treatment or sodium etching before metallization.
Burr formation during drilling	Use sharp carbide tools and clean drilled holes with plasma etching.
Warping after soldering	Implement thermal stress relief after soldering.
Impedance mismatches	Use precise etching and tightly control dielectric constant tolerances.

10. Safety and Environmental Considerations

• Ensure proper ventilation during plasma treatment and soldering.
• Dispose of etching chemicals and debris following environmental regulations.