Rogers IsoClad 933: Properties, Datasheet Specs & High-Frequency PCB Design Guide

If you’ve ever designed RF circuits for conformal antennas, missile guidance systems, or radar applications, you know how frustrating it can be to find a laminate that offers both conformability and rock-solid electrical performance. That’s exactly where IsoClad 933 shines. This Rogers Corporation laminate has become my go-to material when projects demand the flexibility to wrap around curved surfaces without sacrificing the low-loss characteristics essential for high-frequency operation.

In this guide, I’ll walk you through everything you need to know about IsoClad 933—from its core properties and technical specifications to practical design tips I’ve picked up over years of working with PTFE-based materials.

What Is IsoClad 933? Understanding the Material Composition

IsoClad 933 is a non-woven fiberglass/PTFE composite laminate manufactured by Rogers Corporation. Unlike traditional woven glass reinforced laminates, IsoClad 933 uses longer random fibers and a proprietary manufacturing process that creates a unique material structure.

Why Non-Woven Reinforcement Matters

The non-woven construction is what sets this material apart from competitors. In a typical woven fiberglass laminate, the glass fibers create a regular pattern that can cause anisotropic behavior—meaning electrical properties vary depending on signal direction. With IsoClad 933’s random fiber orientation, you get highly isotropic performance in the X, Y, and Z axes.

This matters when you’re designing microstrip lines or patch antennas where consistent impedance is critical. I’ve seen too many designs fail because engineers didn’t account for the Dk variation that woven materials can introduce at different trace orientations.

IsoClad 933 vs. IsoClad 917: Key Differences

Rogers offers two main variants in the IsoClad series:

IsoClad 917 uses a lower ratio of fiberglass to PTFE, achieving the lowest Dk and dissipation factor in its class. IsoClad 933, on the other hand, uses a higher fiberglass/PTFE ratio for better dimensional stability and mechanical strength—making it more suitable for applications where the board will experience mechanical stress or thermal cycling.

IsoClad 933 Technical Specifications and Properties

Here’s where the rubber meets the road. Let me break down the specifications you’ll need for your design calculations and material selection.

Electrical Properties

The low dielectric constant of 2.33 allows for wider traces at a given impedance, which can improve manufacturability and reduce conductor losses. The dissipation factor of 0.0016 at 10 GHz is excellent for minimizing signal attenuation in microwave applications.

Thermal and Mechanical Properties

The Z-axis CTE of 203 ppm/°C is worth noting—it’s significantly higher than the X and Y values. This is typical for PTFE-based materials and something you’ll need to account for in via reliability calculations, especially in multilayer designs with significant thermal cycling.

Why Choose IsoClad 933? Key Benefits for RF Engineers

Conformability for Curved Applications

This is the killer feature of IsoClad 933. The non-woven reinforcement makes the material less rigid than woven fiberglass laminates, allowing it to conform to curved surfaces. If you’re designing conformal antennas for aircraft fuselages, missile radomes, or vehicle-mounted systems, this flexibility is essential.

I worked on a project several years ago where we needed to wrap an antenna array around a cylindrical radar housing. Standard rigid laminates simply wouldn’t work without cracking or delaminating. IsoClad 933 handled the curve radius beautifully while maintaining consistent RF performance across the entire surface.

Isotropic Electrical Performance

The random fiber orientation delivers consistent dielectric properties regardless of signal direction. For antenna designs where radiation patterns matter, this isotropy translates to predictable behavior that matches your simulations.

Stable Dk Across Frequencies

The dielectric constant remains remarkably stable across a wide frequency range, which simplifies impedance matching networks and makes your designs more robust against frequency drift.

Low Moisture Absorption

At just 0.05% water absorption, IsoClad 933 maintains its electrical properties even in humid environments—crucial for outdoor or aerospace applications.

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IsoClad 933 Applications: Where This Material Excels

Conformal Antennas

This is the primary application for IsoClad 933. Conformal antennas integrated into aircraft wings, missile bodies, or vehicle surfaces require materials that can bend without compromising performance. The ability to electronically steer beams while maintaining consistent impedance makes IsoClad 933 ideal for phased array systems.

Radar and Electronic Warfare Systems

Modern radar systems operating at X-band and above demand low-loss substrates. IsoClad 933’s combination of low Dk and low Df supports the high-frequency performance these systems require. I’ve seen it used extensively in military applications where reliability under extreme conditions is non-negotiable.

Missile Guidance Systems

Guidance systems need substrates that can handle the mechanical shock and thermal extremes of missile flight while maintaining RF performance. The enhanced mechanical strength of IsoClad 933 compared to IsoClad 917 makes it better suited for these demanding environments.

Stripline and Microstrip Circuits

For general high-frequency circuit design above 10 GHz, IsoClad 933 offers excellent signal integrity with minimal loss.

5G Millimeter Wave Systems

As 5G networks push into mmWave frequencies, the demand for low-loss substrates continues to grow. IsoClad 933’s stable properties up to 100 GHz make it viable for next-generation wireless infrastructure.

Satellite Communication Antennas

Satcom systems operating at Ku-band and Ka-band benefit from the material’s low loss and stable dielectric properties. The low moisture absorption is particularly important for ground stations exposed to weather.

PCB Design Guidelines for IsoClad 933

Stackup Considerations

When designing multilayer boards with IsoClad 933, keep these points in mind:

Place IsoClad 933 layers closest to high-frequency components. Since these layers have the lowest loss, positioning them near RF ICs and antenna feeds minimizes the path length through lossy materials.

Use thicker cores for shielding. Thicker dielectric layers between signal traces help reduce crosstalk and electromagnetic interference between critical RF paths.

Pair signal layers with ground planes. This is standard practice, but it’s especially important with PTFE-based materials to maintain controlled impedance.

Minimize layer transitions. Every via transition introduces inductance and potential impedance discontinuities. Keep high-frequency signals on dedicated layers where possible.

Impedance Calculations

With a Dk of 2.33, you can use standard microstrip and stripline formulas. For a 50Ω microstrip on 15 mil (0.381mm) IsoClad 933 with 1 oz copper, expect a trace width around 45 mils (1.14mm). Always verify with your fabricator’s impedance calculator and request test coupons.

Thermal Management

The thermal conductivity of 0.26 W/m/K is modest compared to ceramic-filled materials like RO4000 series. For high-power applications, consider:

• Adding thermal vias under power devices
• Using thicker copper weights
• Implementing metal-backed designs for heat spreading

IsoClad 933 Fabrication and Processing Guidelines

PTFE-based materials require specific handling that differs from standard FR-4 processing. Here’s what you need to know—and what to communicate to your fabricator.

Drilling Considerations

Use carbide drills with 130° included lip angle. Standard FR-4 drill parameters won’t work here. PTFE tends to accumulate on drill bits, causing smear and poor hole wall quality.

Keep stack heights conservative. For most applications, limit stack height to 0.240 inches (6.1mm) or 75% of the drill’s flute length.

Phenolic entry and exit materials are essential. Use 16-25 mil phenolic for standard boards, thicker for boards over 250 mils. The phenolic essentially cleans debris from the drill bit.

Conservative hit counts. Unlike FR-4 where you might get 3,000+ hits per drill, PTFE materials typically require new drills after 150-300 hits depending on hole quality requirements.

Hole Wall Treatment

This is critical—skip this step and your plated holes will fail.

Sodium treatment (preferred): Uses sodium naphthalene complex in glycol ether solution to strip fluorine atoms from PTFE molecules, making the surface wettable. Products like W.L. Gore Tetra-Etch are commonly used.

Plasma treatment (alternative): Can work with direct metallization processes but requires careful process control. Panels should be baked at 110-125°C for at least one hour before plasma treatment.

Handling Precautions

PTFE-based materials are softer than standard laminates and more susceptible to damage:

• Always wear non-absorbent gloves (nylon knit)
• Store panels vertically to prevent creasing
• Avoid stacking panels without interleaving material
• Never allow copper surfaces to contact bare hands—fingerprints cause corrosion

Multilayer Bonding

IsoClad 933 is compatible with various adhesive systems including thermoset prepregs and thermoplastic bonding films. Work with your fabricator to select the appropriate system based on your electrical and thermal requirements.

IsoClad 933 vs. Other High-Frequency Laminates

How does IsoClad 933 stack up against other common RF materials? Here’s a practical comparison:

Choose IsoClad 933 when conformability is a requirement. If you’re building flat boards and want easier processing, the RO4000 series offers a good balance of performance and manufacturability. For absolute minimum loss in flat designs, RT/duroid 5880 remains the gold standard—but it’s more expensive and harder to process.

Useful Resources and Downloads

Official Rogers Corporation Resources

• IsoClad 933 Datasheet (PDF): rogerscorp.com/documents/isoclad-laminates-data-sheet.pdf
• IsoClad Fabrication Guide (PDF): rogerscorp.com/documents/fabrication-guidelines-isoclad-laminates.pdf
• Product Safety Information Sheet (PSIS): Available on Rogers website
• Laminate Properties Tool: tools.rogerscorp.com/acs/properties/laminates
• Rogers Technology Support Hub: rogerstechub.com
• Sample Request: rogerscorp.my.salesforce-sites.com/samples

Material Database References

• MatWeb Material Data: matweb.com – IsoClad 933
• EverythingRF Product Listing: everythingrf.com/products/laminates/rogers-corporation/isoclad-933

Frequently Asked Questions About IsoClad 933

What is the dielectric constant of IsoClad 933?

IsoClad 933 has a dielectric constant (Dk) of 2.33 ±0.04 at 10 GHz. This value remains stable across a wide frequency range and temperature span (-50°C to 150°C), with a thermal coefficient of -132 ppm/°C. For design calculations, use 2.33 as your target value.

Is IsoClad 933 suitable for multilayer PCB construction?

Yes, IsoClad 933 works well in multilayer constructions. It’s compatible with various bonding systems including thermoset prepregs and thermoplastic films. However, be aware of the Z-axis CTE (203 ppm/°C) when designing vias for applications with significant thermal cycling. Many designers use IsoClad 933 in hybrid stackups combined with FR-4 for cost optimization—placing IsoClad on RF-critical layers and FR-4 on power distribution layers.

How does IsoClad 933 compare to FR-4 for high-frequency applications?

IsoClad 933 significantly outperforms FR-4 above 1 GHz. Standard FR-4 has a Dk around 4.5 and Df of 0.02—over 10× higher loss than IsoClad 933’s 0.0016. This means substantially lower signal attenuation, more predictable impedance, and better overall RF performance. The trade-off is cost (IsoClad 933 is more expensive) and processing complexity (PTFE requires specialized fabrication steps).

What frequencies is IsoClad 933 best suited for?

IsoClad 933 performs excellently from UHF through millimeter wave frequencies. Its properties remain stable up to 100 GHz, making it suitable for 5G mmWave, automotive radar (77 GHz), and satellite communication applications. The material sees the most use in X-band (8-12 GHz), Ku-band (12-18 GHz), and Ka-band (26-40 GHz) applications.

Does IsoClad 933 require special PCB fabrication processes?

Yes. Key differences from standard FR-4 processing include:

• Hole wall treatment: Sodium etching or plasma treatment is mandatory before plating
• Drilling: Requires carbide drills, phenolic entry/exit materials, and conservative hit counts
• Handling: Material is softer and more susceptible to damage
• Bonding: Specialized adhesive systems for multilayer construction

Work with a fabricator experienced in PTFE-based materials. Not all PCB shops have the equipment and expertise to process IsoClad 933 correctly.

Final Thoughts: When to Specify IsoClad 933

After working with various RF laminates over the years, I’ve found IsoClad 933 occupies a specific niche that it fills extremely well. Choose it when:

• Your design requires conforming to a curved surface
• You need isotropic electrical properties for antenna applications
• Operating frequencies are above 10 GHz
• Dimensional stability and mechanical strength are important
• The application demands low moisture absorption

For flat-panel designs where conformability isn’t required, the RO4000 series often makes more sense due to easier processing and lower cost. For absolute minimum loss requirements in space or military applications, RT/duroid 5880 might be worth the extra cost and complexity.

Whatever you decide, get samples early, work with an experienced fabricator, and always build test coupons to verify your impedance calculations. RF materials rarely behave exactly as the datasheets suggest—real-world validation is always necessary.