Rogers 20mil RT/duroid 62022-layer ENIG High-Frequency Microwave PCB

Executive Summary

Thisarticle presents a 2-layer rigid PCB fabricated onRogers RT/duroid 6202 high-frequency laminate with ENIG surface finish. At 0.6 mm finished thickness built on a 20 mil (0.508 mm) dielectric core, theRogersboard measures 42.36 by 21.9 mm and is engineered for microwave and radar applications requiring low insertion loss and exceptional electrical stability. The following sections detail the PCB construction, stackup, design statistics, performance differentiation, and applications, followed by an in-depth technical review of theRT/duroid 6202 copper-clad laminate material.

Part I: PCB Product Description

1. Product Overview

The 20mil RT/duroid 6202 PCB is a 2-layer rigid high-frequency circuit board measuring 42.36 by 21.9 mm, yielding one piece per panel array. Built on Rogers' limited woven glass-reinforced PTFE composite, it carries 1 oz (35 um, approximately 1.4 mils) copper on both outer layers and an ENIG (Electroless Nickel Immersion Gold) surface finish. The finished board thickness is 0.6 mm, centered on a 20 mil (0.508 mm) RT/duroid 6202 dielectric core.

2. PCB Construction Details

The table below summarizes the complete construction specifications, covering base material, layer count, dimensional tolerances, copper weight, surface finish, and quality acceptance criteria.

3. PCB Stackup

A symmetric 2-layer stackup is centered on a 20 mil RT/duroid 6202 core with 35 um electrodeposited copper on both top and bottom layers, ensuring balanced thermal expansion and consistent impedance control.

4. PCB Statistics

The design comprises 13 components, 20 total pads (11 through-hole and 9 top-side SMT), 6 through-hole vias, and 2 electrical nets, reflecting a compact, high-density microwave circuit layout.

5. Key Performance and Differentiation

RT/duroid 6202 high frequency PCB is distinguished by its tightly controlled dielectric constant of 2.94 +/- 0.04 at 10 GHz and 23 degrees Celsius for laminate thicknesses of 0.020 inch and above, placing it among the lowest-Dk glass-reinforced high-frequency materials in the Rogers portfolio. This low Dk, combined with a dissipation factor of just 0.0015 at 10 GHz, minimizes phase velocity variation and insertion loss in microwave signal paths, making it particularly valuable for wideband antenna and radar feed networks. The thermal coefficient of dielectric constant is exceptionally low at +5 ppm/degree Celsius over the range of -50 to +150 degrees Celsius, ensuring that resonant frequencies, phase shifts, and characteristic impedance remain stable across extreme operating temperatures. This is a critical advantage for ground-based and airborne radar systems deployed in harsh thermal environments, where competing materials with higher TCDk values (typically 20 to 50 ppm/degree Celsius) would exhibit noticeable frequency drift.

Unlike pure PTFE laminates such as RT/duroid 5880, RT/duroid 6202 incorporates limited woven glass reinforcement, yielding dimensional stability of 0.05 to 0.07 mils per inch after etch and bake cycles. This often eliminates the need for double etching to achieve tight positional tolerances, improving manufacturing yield and reducing production cost. The in-plane coefficient of thermal expansion is 15 ppm/degree Celsius in both X and Y axes, closely matching copper's 17 ppm/degree Celsius and minimizing thermally induced shear stress on plated through holes and copper traces during assembly reflow and field operation. With a decomposition temperature (Td) of 500 degrees Celsius by TGA and thermal conductivity of 0.68 W/m/K at 80 degrees Celsius, the material withstands lead-free reflow profiles and dissipates heat effectively in power-dense circuits. Moisture absorption of only 0.04 percent ensures that electrical properties remain stable under humid conditions, and the UL 94 V-0 flammability rating meets stringent safety requirements for commercial and aerospace applications.

The ENIG surface finish further differentiates this board by offering a flat, coplanar contact surface with excellent shelf life and consistent contact resistance, avoiding the tin whisker risk and surface non-planarity associated with HASL finishes. The nickel layer under the immersion gold provides a robust barrier against copper diffusion, while the gold layer ensures solderability and oxidation resistance. At 9.1 lbs per inch (1.6 N/mm) copper peel strength, the laminate ensures robust copper-to-dielectric adhesion under thermal cycling and mechanical stress. The combination of low Dk, ultra-low Df, temperature-stable electrical properties, copper-matched CTE, and excellent dimensional stability positions RT/duroid 6202 as a premium choice for high-reliability microwave circuits where electrical performance and manufacturing consistency are equally critical.

6. Typical Applications

The 20mil RT/duroid 6202 PCB  ENIG finish is well suited for:

• Phased array antennas
• Ground-based
• Airborne radar systems
• Global Positioning System (GPS) antennas
• Power backplanes
• Commercial airline collision avoidance systems 
• Beam forming networks.

The low Dk and ultra-low Df make it particularly suited for wideband microwave components where signal integrity, phase accuracy, and low insertion loss govern overall system performance. Its compact 42.36 by 21.9 mm form factor and 2-layer construction also make it appropriate for size-constrained RF modules, satellite communication front-ends, and test and measurement fixtures requiring stable, repeatable high-frequency characteristics.

7. PCB Conclusion

This 20mil Rogers 6202 PCB with ENIG finish is a purpose-engineered high-frequency microwave solution. A low-loss PTFE-glass composite substrate, 4/7 mil trace geometry, 1 oz copper construction, 20 um via plating, 100 percent electrical testing, and IPC-Class-2 quality assurance combine to deliver reliable electrical performance in a compact 42.36 by 21.9 mm form factor.

The material's copper-matched CTE, exceptional dimensional stability, temperature-stable Dk of 2.94 +/- 0.04, and ultra-low dissipation factor of 0.0015 ensure long-term reliability and consistent performance in demanding radar, phased array, and beam-forming environments. With worldwide availability and proven lead-free process compatibility, this PCB represents a high-value, high-performance solution for engineers seeking a balance of electrical excellence and manufacturing robustness.

Part II: RT/duroid 6202 CCL Material Knowledge

1. Introduction to RT/duroid 6202

Rogers RT/duroid 6202 laminate is a high-frequency circuit material engineered as a low-loss, low-dielectric-constant laminate with limited woven glass reinforcement. It is designed to provide the electrical and mechanical properties essential for designing complex microwave structures that are both mechanically reliable and electrically stable. 

The material is part of Rogers RT/duroid family, which has been a benchmark in the high-frequency PCB industry for decades. RT/duroid 6202 occupies a unique position in the portfolio: it offers a Dk of 2.94 for standard thicknesses of 0.020 inch and above, lower than many glass-reinforced competitors but with superior dimensional stability compared to unreinforced PTFE laminates, making it ideal for designs that balance electrical performance with manufacturability and registration accuracy.

2. Material Composition and Technology

RT/duroid 6202 is a PTFE (polytetrafluoroethylene) composite reinforced with a limited amount of woven glass fiber. The PTFE matrix provides inherently low dielectric loss, excellent chemical resistance, and high thermal stability. The woven glass reinforcement, deliberately limited in quantity to avoid elevating the dielectric constant, improves dimensional stability, mechanical handling, and registration accuracy during PCB fabrication. This hybrid construction addresses a key limitation of unreinforced PTFE laminates, which tend to exhibit greater etch shrinkage and dimensional movement during processing.

The result is a material that retains the electrical benefits of PTFE while approaching the dimensional stability of glass-reinforced epoxy laminates. Excellent dimensional stability of 0.05 to 0.07 mils per inch is achieved through this limited woven glass reinforcement, which often eliminates the need for double etching to achieve tight positional tolerances. The copper cladding is available in both electrodeposited (ED) and rolled foil formats, with standard weights of half oz (18 um) and 1 oz (35 um), providing flexibility for different current-carrying and conductor-loss requirements. The material is fully compatible with lead-free assembly processes and carries a UL 94 V-0 flammability rating.

3. Complete Standard Properties Datasheet

The full datasheet below covers electrical, thermal, mechanical, and physical properties. All values are typical at 23 degrees Celsius unless otherwise noted; SI units are given first with other frequently used units in parentheses. Dielectric constant varies by laminate thickness due to construction limitations.

[a] Due to construction limitations, the dielectric constant of 0.005 inch laminates is 3.06 +/- 0.04; 0.010 inch and 0.015 inch laminates are 3.02 +/- 0.04; and laminates of 0.020 inch and greater are 2.94 +/- 0.04, all measured at 10 GHz and 23 degrees Celsius.

4. Standard Offerings

Three standard dielectric thicknesses are available with matching panel sizes and copper cladding options. Additional non-standard thicknesses from 0.005 to 0.060 inch, alternate panel sizes, and special claddings such as resistive foil and reverse-treated ED copper are available upon request.

5. CCL Product Image

Figure 1: RT/duroid 6202 copper-clad laminate showing electrodeposited copper foil and PTFE-glass dielectric layers.

6. CCL Conclusion

Rogers RT/duroid 6202 is a purpose-engineered high-frequency laminate that combines the ultra-low loss of PTFE with the dimensional stability and handling robustness of limited woven glass reinforcement. Its tightly controlled dielectric constant of 2.94 +/- 0.04 at 10 GHz for thicknesses of 0.020 inch and above, ultra-low dissipation factor of 0.0015, exceptional temperature stability of +5 ppm/degree Celsius TCDk, and copper-matched in-plane CTE of 15 ppm/degree Celsius make it an excellent substrate for phased array antennas, ground-based and airborne radar systems, GPS antennas, beam forming networks, and commercial airline collision avoidance systems.

With a comprehensive property set spanning electrical, thermal, mechanical, and physical domains, three standard thicknesses, multiple panel sizes, both ED and rolled copper cladding options, and proven lead-free process compatibility with UL 94 V-0 certification, RT/duroid 6202 offers designers a reliable, high-performance, and manufacturable substrate for the most demanding microwave and millimeter-wave applications.