Introduction

RT/duroid 5870 and 5880 are high-frequency laminates manufactured by Rogers Corporation, widely used in the electronics industry for microwave and RF applications. These materials are known for their excellent electrical and mechanical properties, making them ideal for high-performance circuit boards, antennas, and other RF components. This comprehensive analysis of the RT/duroid 5870 – 5880 Data Sheet will delve into the material properties, applications, and key considerations for engineers and designers working with these laminates.

Material Composition and Properties

Chemical Composition

RT/duroid 5870 and 5880 are composed of a unique blend of polytetrafluoroethylene (PTFE) composite reinforced with glass microfibers. This composition results in a material with exceptional electrical and mechanical characteristics:

1. Low dielectric constant
2. Low loss tangent
3. Excellent dimensional stability
4. Consistent electrical properties over a wide frequency range

Dielectric Properties

One of the most critical aspects of RT/duroid 5870 and 5880 is their dielectric properties:

• Dielectric Constant (εr):
  • RT/duroid 5870: 2.33 ± 0.02 (10 GHz)
  • RT/duroid 5880: 2.20 ± 0.02 (10 GHz)
• Dissipation Factor (tan δ):
  • Both materials: 0.0005 to 0.0009 (10 GHz)

These low dielectric constants and dissipation factors contribute to:

• Reduced signal losses
• Improved signal integrity
• Enhanced overall system performance in high-frequency applications

Thermal Properties

RT/duroid 5870 and 5880 exhibit excellent thermal stability:

• Coefficient of Thermal Expansion (CTE):
  • X-axis: 31 ppm/°C
  • Y-axis: 48 ppm/°C
  • Z-axis: 237 ppm/°C
• Thermal Conductivity: 0.22 W/m/K

These properties ensure dimensional stability across a wide temperature range, crucial for maintaining consistent electrical performance in varying environmental conditions.

Mechanical Properties

The mechanical robustness of RT/duroid 5870 and 5880 is noteworthy:

• Tensile Strength:
  • X-axis: 450 psi (3.1 MPa)
  • Y-axis: 317 psi (2.2 MPa)
• Compressive Modulus: 86,000 psi (593 MPa)
• Flexural Strength:
  • X-axis: 13,900 psi (95.8 MPa)
  • Y-axis: 11,500 psi (79.3 MPa)

These mechanical properties contribute to the material’s durability and reliability in various applications.

Applications

RT/duroid 5870 and 5880 find extensive use in numerous high-frequency applications:

1. Microstrip and Stripline Circuits: The low dielectric constant allows for wider lines, reducing conductor losses in microstrip and stripline configurations.
2. Antennas: Ideal for patch antennas, phased array antennas, and other antenna designs requiring low loss and consistent performance.
3. Aerospace and Defense: Used in radar systems, satellite communications, and military electronics due to their reliability and performance in harsh environments.
4. Test and Measurement Equipment: Employed in high-precision RF and microwave test fixtures and calibration standards.
5. Medical Devices: Utilized in medical imaging equipment and diagnostic tools operating at high frequencies.
6. 5G and mmWave Applications: Suitable for next-generation wireless communication systems operating at millimeter-wave frequencies.

Fabrication and Processing

Working with RT/duroid 5870 and 5880 requires specific considerations during fabrication and processing:

Machining and Drilling

• Use sharp, carbide-tipped tools to minimize burring and ensure clean edges.
• Maintain high spindle speeds and slow feed rates to prevent material delamination.
• Cooling fluids are generally not required but can be used if needed.

Metallization

• Both materials can be plated using standard electroless copper or direct metallization processes.
• Careful surface preparation is crucial for ensuring good adhesion of the metallic layers.

Bonding and Lamination

• RT/duroid 5870 and 5880 can be bonded to themselves or other materials using specialized adhesive systems.
• Thermoplastic films or thermoset prepregs are commonly used for multilayer constructions.

Etching

• Standard etchants used for copper can be employed.
• Plasma etching techniques can be used for fine-line geometries and improved edge definition.

Read more about:

• Rogers 4350B
• Rogers 4003C
• Rogers 3003
• RF PCB

Environmental Considerations

RT/duroid 5870 and 5880 exhibit excellent resistance to various environmental factors:

• Chemical Resistance: Highly resistant to a wide range of chemicals, solvents, and corrosive agents.
• Moisture Absorption: < 0.02%, ensuring stable electrical properties in humid environments.
• Fungus Resistance: Non-nutrient to fungal growth, ideal for tropical and high-humidity applications.
• Outgassing: Low outgassing characteristics, suitable for space and vacuum applications.

Comparison: RT/duroid 5870 vs. 5880

While RT/duroid 5870 and 5880 share many similarities, there are some key differences:

1. Dielectric Constant:
   • RT/duroid 5870: 2.33 ± 0.02
   • RT/duroid 5880: 2.20 ± 0.02
2. Glass Microfiber Density:
   • RT/duroid 5870: Higher density
   • RT/duroid 5880: Lower density
3. Mechanical Strength:
   • RT/duroid 5870: Slightly higher mechanical strength
   • RT/duroid 5880: More isotropic properties
4. Typical Applications:
   • RT/duroid 5870: Often preferred for antenna applications
   • RT/duroid 5880: Commonly used in mmWave and high-frequency circuits

Design Considerations

When working with RT/duroid 5870 and 5880, designers should consider the following:

1. Impedance Control: The low dielectric constant allows for wider traces, which can be advantageous for power handling but may require careful impedance matching.
2. Thermal Management: While these materials have low thermal conductivity, proper heat dissipation strategies should be implemented for high-power applications.
3. Dimensional Stability: Account for the CTE in designs that may experience significant temperature variations.
4. Copper Foil Selection: Choose appropriate copper foil type and weight based on the specific application requirements and frequency of operation.
5. Multilayer Designs: When creating multilayer structures, consider the potential for misalignment due to the material’s low dielectric constant and plan accordingly.

Conclusion

RT/duroid 5870 and 5880 are premium high-frequency laminates that offer exceptional electrical and mechanical properties for demanding RF and microwave applications. Their low dielectric constants, low loss tangents, and excellent dimensional stability make them ideal choices for high-performance circuits, antennas, and other critical components in the electronics industry.

Understanding the unique characteristics and processing requirements of these materials is essential for engineers and designers to fully leverage their capabilities. As the demand for high-frequency and high-speed applications continues to grow, RT/duroid 5870 and 5880 remain at the forefront of material solutions, enabling innovation in telecommunications, aerospace, defense, and beyond.

By carefully considering the properties and applications outlined in this analysis of the RT/duroid 5870 – 5880 Data Sheet, designers can make informed decisions to optimize their high-frequency designs and push the boundaries of RF and microwave technology.