Rogers CuClad 233 PCB: Properties, Applications & Design Tips

If you’ve ever worked on RF or microwave circuit design, you know how critical material selection is. One wrong choice, and your carefully designed filter or LNA starts behaving like a different circuit entirely at high frequencies. That’s where CuClad 233 comes in—a PTFE-based laminate from Rogers Corporation that’s become a go-to substrate for engineers working on demanding high-frequency applications.

I’ve spent years specifying PCB materials for various RF projects, and CuClad 233 consistently delivers where it matters: predictable electrical performance, reasonable fabrication characteristics, and that crucial balance between cost and capability.

What is CuClad 233?

CuClad 233 is a woven fiberglass-reinforced PTFE (polytetrafluoroethylene) composite laminate manufactured by Rogers Corporation. The “233” designation refers to its nominal dielectric constant of 2.33, which places it in the sweet spot for many RF and microwave applications.

What sets CuClad 233 apart from other PTFE laminates is its cross-plied construction. The alternating glass fiber plies are oriented at 90° to each other, providing true electrical and mechanical isotropy in the X-Y plane. This is something you won’t find in many competing materials, and it matters significantly when you’re designing phased array antennas or other applications where consistent behavior across different orientations is essential.

The material uses a medium fiberglass-to-PTFE ratio, which Rogers engineered to strike a balance: you get a lower dielectric constant and improved dissipation factor without sacrificing the mechanical properties that make fabrication practical.

Key Properties and Specifications of CuClad 233

Understanding the technical specifications of CuClad 233 is essential for proper design integration. Here’s what you need to know:

Electrical Properties

Thermal and Mechanical Properties

The low dissipation factor of 0.0013 at 10 GHz is particularly noteworthy. This translates directly to reduced signal loss in your circuits—critical when you’re designing anything that operates in the X-band or above.

Why Engineers Choose CuClad 233: Key Benefits

Low Dielectric Constant for Better Performance

The Dk of 2.33 enables wider trace widths for a given impedance target. This isn’t just convenient—it directly impacts your yield rates and manufacturing costs. Wider traces mean better etching tolerances and reduced sensitivity to fabrication variations.

Excellent Dimensional Stability

The cross-plied woven glass construction provides significantly better dimensional stability compared to non-woven PTFE composites. When you’re designing multilayer boards or need tight registration between layers, this stability becomes essential.

CTE Matching with Aluminum

Here’s something many engineers overlook: the in-plane CTE of CuClad 233 closely matches aluminum. If you’re designing antenna systems that mount directly to aluminum aircraft skins or structures, this reduces thermal stress at the interface—a real consideration for aerospace applications.

Low Moisture Absorption

At 0.02% water absorption, CuClad 233 maintains its electrical properties even in humid environments. The low outgassing characteristics also make it suitable for certain space-adjacent applications where contamination is a concern.

Consistent Performance Across Frequency

The stable Dk over a wide frequency range means your impedance calculations remain valid as you move through different operating bands. This predictability simplifies the design process and reduces the need for empirical tuning.

CuClad 233 Applications in Industry

Military Radar and Electronic Warfare

CuClad 233 has established itself in defense applications, particularly in radar systems, electronic countermeasures (ECM), and electronic support measures (ESM). The material’s combination of low loss, dimensional stability, and reliable performance under varying environmental conditions makes it well-suited for military-grade equipment.

Phased Array Antenna Systems

The true isotropy in the X-Y plane is crucial for phased array applications. When you’re dealing with hundreds or thousands of antenna elements that need to behave identically regardless of their orientation, material consistency becomes non-negotiable. CuClad 233’s cross-plied construction delivers this consistency.

Microwave Components

Low-noise amplifiers (LNAs), filters, and couplers frequently specify CuClad 233 as the substrate material. These components demand:

• Predictable dielectric constant for accurate impedance matching
• Low loss to preserve signal integrity
• Stable performance across temperature variations

Satellite and Space Communications

For satellite communication systems operating in C-band and above, the low moisture absorption and stable electrical properties make CuClad 233 a practical choice. The material can handle the thermal cycling associated with space-adjacent environments.

5G Infrastructure

As 5G networks push into higher frequency bands, the demand for low-loss substrates continues to grow. CuClad 233’s performance characteristics align well with the requirements of 5G antenna systems and millimeter-wave circuits.

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CuClad 233 vs. Alternative Rogers Materials

Understanding where CuClad 233 fits in the broader landscape of high-frequency materials helps you make informed decisions.

Comparison Table

When to Choose CuClad 233 Over Alternatives

Choose CuClad 233 when you need:

• True X-Y isotropy (cross-plied construction)
• Better dimensional stability than non-woven alternatives
• A balance between electrical performance and processability
• Compatibility with aluminum structures (CTE matching)

Consider alternatives when:

• Absolute lowest loss is critical (CuClad 217 or RT/duroid 5880)
• Processing cost is the primary driver (RO4003C)
• Higher mechanical strength is required (CuClad 250)

Design Tips for CuClad 233 PCBs

Impedance Control Considerations

When designing with CuClad 233, use the design Dk value of 2.40 for impedance calculations rather than the process Dk of 2.33. This accounts for the glass weave effect and provides more realistic predictions for your actual circuit performance.

For controlled impedance traces:

• Calculate trace widths based on the design Dk
• Verify with your fabricator’s impedance modeling tools
• Request test coupons for critical applications

Stackup Design

CuClad 233 works well in both single-layer and multilayer constructions. For hybrid stackups combining CuClad 233 with FR-4 or other materials:

• Match CTE values where possible to minimize warpage
• Consider using Rogers CuClad 6250 or 6700 bonding films for multilayer PTFE constructions
• Position the CuClad 233 layer at the critical RF interfaces

Trace Width and Spacing

The low Dk of 2.33 allows for wider traces at standard impedances:

These wider traces improve manufacturing yield and reduce sensitivity to etching variations.

Thermal Management

While CuClad 233’s thermal conductivity (0.26 W/m/K) is adequate for most applications, high-power designs may require additional thermal management. Consider:

• Metal backing (aluminum, brass, or copper plates)
• Thermal vias in ground planes
• Heat spreader integration

Fabrication Guidelines for CuClad 233

Drilling Considerations

PTFE-based laminates like CuClad 233 require attention during drilling:

• Use sharp carbide drill bits with 130° point geometry
• Reduce surface speed to prevent PTFE smearing (100 SFM or less recommended)
• Use hard phenolic entry material (10–25 mil) to clean debris from drill bits
• Implement peck drilling for high aspect ratio holes to prevent bird-nesting

Plated Through-Hole Preparation

The PTFE surface requires treatment before electroless copper plating:

• Sodium naphthalene etch is the traditional approach—effective but requires careful handling
• Plasma treatment using hydrogen/nitrogen gas mixtures (30–70% H₂, 70–30% N₂) is an alternative

Both methods prepare the PTFE surface for reliable copper adhesion.

Lamination Process

For multilayer boards:

• Clean surfaces thoroughly before lamination (chemical cleaning preferred over mechanical scrubbing)
• Use vacuum lamination at 370–390°F (190–200°C) under 200–300 psi
• Implement gradual ramp-up and cool-down to avoid trapped air and warpage

Solder Mask Application

Apply solder mask within 12 hours of etching. For improved adhesion:

• Process through a sodium etch cycle or plasma treatment
• Pre-bake to remove residual moisture from the laminate

Available Configurations and Ordering

CuClad 233 is available in the following standard configurations:

Copper Cladding Options

• ½ oz (17.5 µm)
• 1 oz (35 µm)
• 2 oz (70 µm) electrodeposited copper

Rolled copper foil is available for applications requiring reduced surface roughness.

Panel Sizes

Maximum available size: 36″ × 48″ (914 mm × 1219 mm)

Thickness Options

Multiple dielectric thicknesses are available. Contact Rogers Corporation or authorized distributors for specific thickness availability.

Special Testing

For critical applications, specify “LX” testing grade. This ensures each sheet is individually tested with a test report included with the order.

Useful Resources for CuClad 233

Frequently Asked Questions About CuClad 233

Is CuClad 233 compatible with lead-free soldering processes?

Yes. CuClad 233 is fully compatible with lead-free assembly processes. The material maintains its structural integrity through the higher temperatures required for lead-free reflow (typically 260°C peak).

What frequency range is CuClad 233 suitable for?

CuClad 233 performs well from DC through millimeter-wave frequencies. The stable dielectric constant and low loss tangent make it suitable for applications up to 30 GHz and beyond, depending on circuit design and manufacturing precision.

How does CuClad 233 compare to FR-4 for high-frequency applications?

FR-4 is inadequate for most high-frequency applications above a few GHz. Compared to FR-4, CuClad 233 offers significantly lower dielectric loss (0.0013 vs. ~0.020), more stable Dk with frequency and temperature, and better controlled electrical properties. The tradeoff is higher material cost and more specialized fabrication requirements.

Can CuClad 233 be used in hybrid constructions with FR-4?

Yes, hybrid stackups are common. Position the CuClad 233 at the critical RF layers (typically outer layers for microstrip designs) while using FR-4 for inner layers where high-frequency performance isn’t required. Pay attention to CTE differences during lamination to prevent warpage.

What’s the difference between CuClad 233 and DiClad 870?

Both have similar Dk values (~2.33), but CuClad 233 features cross-plied construction while DiClad 870 uses aligned plies. The cross-plied construction of CuClad 233 provides true isotropy in the X-Y plane, making it better suited for phased array antennas and applications requiring consistent performance regardless of trace orientation.

Simulation and Modeling Considerations

When designing circuits on CuClad 233, proper material characterization in your simulation tools is essential. Most commercial EM simulators support Rogers materials natively:

• Ansys HFSS and SIwave — 3D planar EM simulation for signal integrity and EMI analysis up to 40+ GHz
• Keysight ADS — Integrated 2D/3D EM simulation with circuit co-simulation
• Cadence Allegro — Signal integrity analysis with controlled impedance support

When setting up simulations, always use Rogers’ published data for the operating frequency range. The design Dk value (2.40) accounts for manufacturing tolerances and glass weave effects that purely theoretical calculations might miss.

For critical applications, request material characterization data from Rogers or perform your own measurements using resonant cavity or transmission line methods.

Final Thoughts

CuClad 233 remains a solid choice for RF and microwave applications that demand consistent electrical performance without the extreme cost of pure PTFE laminates. Its cross-plied construction, stable dielectric properties, and reasonable fabrication characteristics make it particularly valuable for antenna systems, military electronics, and communication equipment.

The key to success with CuClad 233—like any high-frequency material—lies in understanding its properties and designing accordingly. Use the design Dk value for impedance calculations, work with a fabricator experienced in PTFE processing, and don’t underestimate the importance of proper hole preparation and surface treatment.

For engineers working on critical RF applications, CuClad 233 provides the predictable foundation your designs need to perform as intended when they leave the simulation environment and enter the real world.