Everything RF and microwave PCB engineers need to know about Arlon CuClad 233 — electrical specs, cross-plied construction explained, fabrication guidelines, LX testing grade, and comparison with CuClad 217 and 250.

If you’ve been designing RF and microwave circuits for any length of time, you’ve almost certainly run into a situation where material selection came down to a careful trade-off: do you push for the absolute lowest loss at the cost of mechanical reliability, or accept a small electrical compromise in exchange for a substrate that your fabricator can actually process without heartburn? Arlon CuClad 233 is one of those materials that was engineered specifically to live in that middle ground — and it does it well.

This guide covers everything you need to know about Arlon CuClad 233 as a working PCB design or manufacturing engineer: what it is, why the cross-plied construction matters, the full specification profile, fabrication considerations, typical applications, and how it compares to its siblings in the CuClad family.

What Is Arlon CuClad 233?

Arlon CuClad 233 is a cross-plied, woven fiberglass and PTFE composite laminate with a nominal dielectric constant (Dk) of 2.33. It was originally developed by Arlon Materials for Electronics and is now manufactured and marketed under Rogers Corporation, which acquired Arlon LLC. It sits as part of the broader CuClad series alongside CuClad 217 (Er 2.17–2.20) and CuClad 250 (Er 2.40–2.60).

The defining characteristic of CuClad 233 is its medium fiberglass-to-PTFE ratio. This is a deliberate engineering decision. CuClad 217 uses a very high PTFE content to achieve the lowest possible Dk and dissipation factor (Df), but that comes at the cost of mechanical softness and dimensional sensitivity. CuClad 250 swings the other way, adding more glass to bring mechanical properties closer to conventional substrates. CuClad 233 sits between them — maintaining a low Dk and low loss profile while providing noticeably better dimensional stability and handling characteristics than CuClad 217.

The cross-plied construction is worth its own discussion. In CuClad products, alternating plies of PTFE-coated fiberglass cloth are oriented at 90° to each other. This is not standard for PTFE-based laminates — DiClad products, for example, use parallel-plied construction. The cross-plied architecture of CuClad 233 delivers true electrical and mechanical isotropy in the X-Y plane, which is a property that cannot be claimed by most woven or non-woven fiberglass PTFE laminates. For engineers working on phased array antennas or precision microwave circuits where symmetry of electrical behavior in both axes matters, this is a genuinely important advantage.

Arlon CuClad 233 is currently handled and manufactured under the Rogers/Arlon brand. If you’re sourcing boards in this material or qualifying a fabricator, working with a manufacturer experienced in Arlon PCB processing is strongly recommended.

Arlon CuClad 233 Full Specification Table

The following table presents the typical electrical and mechanical properties for Arlon CuClad 233. These are typical values — not specification limits. Always consult the official Rogers/Arlon datasheet for your specific thickness and lot requirements.

Property	Value	Test Method
Dielectric Constant (Dk) @ 10 GHz	2.33	IPC TM-650 2.5.5.5
Dissipation Factor (Df) @ 10 GHz	0.0013	IPC TM-650 2.5.5.5
Dielectric Constant @ 1 MHz	2.33	IPC TM-650 2.5.5.3
Dissipation Factor @ 1 MHz	0.0010	IPC TM-650 2.5.5.3
Volume Resistivity	> 10^8 MΩ·cm	IPC TM-650 2.5.17
Surface Resistivity	> 10^7 MΩ	IPC TM-650 2.5.17
Moisture Absorption	< 0.10%	IPC TM-650 2.6.2
Peel Strength (1 oz Cu)	≥ 6 lbs/in	IPC TM-650 2.4.8
CTE (X-axis)	~16 ppm/°C	IPC TM-650 2.4.41
CTE (Y-axis)	~16 ppm/°C	IPC TM-650 2.4.41
CTE (Z-axis)	~200 ppm/°C	IPC TM-650 2.4.41
Tensile Strength (X-direction)	~28 MPa	ASTM D882
Thermal Conductivity	~0.26 W/m·K	ASTM E1461
Standard Panel Size (cross-plied)	36″ × 36″	—
Standard Panel Size (parallel-plied)	36″ × 48″	—

The Dk of 2.33 is extremely stable across frequency — a property inherent to PTFE-based materials. Rogers publishes curves showing minimal Dk drift from 1 MHz through well above 20 GHz, and this holds up in practice. For circuit designers, that stability translates directly to predictable impedance across the operating band of the design without frequency-dependent corrections.

Available Thickness and Copper Cladding Options

CuClad 233 is available in a range of standard thicknesses with electrodeposited (ED) copper on both sides.

Thickness (inches)	Thickness (mm)	Typical Copper Weights Available
0.010″	0.254	½ oz, 1 oz
0.020″	0.508	½ oz, 1 oz, 2 oz
0.031″	0.787	½ oz, 1 oz, 2 oz
0.062″	1.575	½ oz, 1 oz, 2 oz
0.125″	3.175	1 oz, 2 oz

CuClad laminates are also available bonded to a heavy metal ground plane. Aluminum, brass, or copper plates serve as both an integral heat sink and mechanical support structure, which is relevant for power module assemblies where thermal management and structural rigidity are both constraints. Rolled (RA) copper foil is also available on request and is preferred by some engineers for fine-line circuits because of its smoother surface profile.

When ordering, you must specify dielectric constant, thickness, copper cladding weight, panel size, and any special considerations such as the “LX” testing grade.

The LX Testing Grade: What It Means and When You Need It

This is a detail that trips up engineers who are new to the CuClad product line. For standard orders, Arlon/Rogers performs production testing on a sampling basis. For critical performance applications, CuClad products — including CuClad 233 — can be ordered with an “LX” designation. This means that every individual sheet is tested separately, and a dedicated test report is issued with the order.

In practice, this matters in two scenarios: military and defense electronics where lot traceability and individual sheet performance certification are required by contract, and precision microwave assemblies where Dk uniformity across the lot directly impacts yield in tuning-sensitive products like narrow-bandpass filters or phase-matched diplexers. The LX grade adds cost and lead time, but for the right application, it eliminates a major source of yield variance at the system assembly stage.

Cross-Plied Construction: The Key Differentiator of CuClad 233

It’s worth spending more time on why the cross-plied construction of CuClad 233 sets it apart from other woven PTFE laminates.

In a standard woven fiberglass PTFE laminate with parallel-ply construction (like DiClad products), all the PTFE-coated fiberglass cloth layers run in the same orientation. This means the material can exhibit slightly different electrical and mechanical behavior in the warp direction versus the fill direction of the weave. For many applications, this difference is small enough to ignore. But for applications that rely on symmetric electromagnetic behavior — phased array antennas, balanced mixers, precision coupler designs, and some radar front ends — that directional variance introduces errors that are difficult to compensate in design.

CuClad 233’s cross-plied construction, with alternating plies oriented 90° to each other, averages out these directional differences and delivers genuine electrical and mechanical isotropy in the X-Y plane. No other woven or non-woven fiberglass-reinforced PTFE laminate makes this claim, according to Arlon’s documentation. For phased array antenna engineers in particular, this isotropy eliminates one of the systematic error sources in beam-steering performance.

Why Dk 2.33 Positions CuClad 233 Uniquely in the Low-Loss Laminate Market

A Dk of 2.33 places CuClad 233 in the low-end of the dielectric constant range for woven glass PTFE laminates, just above pure PTFE (Dk ≈ 2.1) and well below standard ceramics or even ceramic-filled PTFE composites. To understand where this sits in practical design terms, the table below compares CuClad 233 against frequently used reference materials.

Material	Nominal Dk	Df @ 10 GHz	Primary Trade-off
Rogers RT/duroid 5880	2.20	0.0009	Very low loss, softer, less stable
Arlon CuClad 217	2.17	~0.0009	Lowest loss, softest mechanically
Arlon CuClad 233	2.33	~0.0013	Balance of loss + mechanical stability
Arlon CuClad 250GT	2.55	~0.0018	Better mechanical, slightly higher loss
Rogers RO4003C	3.55	0.0027	Thermoset, excellent stability, limited loss
Standard FR4	4.2–4.5	0.020+	Low cost, poor high-frequency performance

At a Df of 0.0013 at 10 GHz, CuClad 233 delivers insertion loss performance well below what any thermoset material (including Rogers RO4003) can achieve. The performance gap becomes more pronounced as frequency rises into Ka-band and above. For X-band radar components, satellite communications, and precision microwave passive components, this loss difference translates directly to system noise figure, filter insertion loss, and amplifier efficiency.

Typical RF and Microwave Applications for Arlon CuClad 233

The combination of low Dk, very low dissipation factor, X-Y plane isotropy, and better-than-CuClad-217 mechanical stability positions CuClad 233 well for a specific and important range of applications.

Application Category	Specific Use Cases
Military & Defense Electronics	Radar front ends (ECM, ESM, AESA arrays), electronic warfare systems, missile seekers
Precision Passive Microwave	Narrowband bandpass filters, directional couplers, hybrids, Wilkinson dividers
Low Noise Amplifier Boards	LNA input networks where insertion loss directly sets system noise figure
Phased Array Antennas	Applications requiring true XY isotropy for consistent beam steering
Satellite Communications	Uplink/downlink feed networks, VSAT terminal circuits
High-Speed Signal Interconnects	Applications leveraging low Dk for reduced propagation delay
Test & Measurement	Calibration substrates, microwave fixtures requiring stable and known Dk

The military electronics application domain is particularly well aligned with CuClad 233’s properties. Radar systems operating at S, C, X, or Ku band require extremely low insertion loss in their receive chains, tight phase matching in distributed components, and reliable long-term performance across wide temperature ranges. The PTFE base of CuClad 233 offers inherent chemical inertness and low moisture absorption, both of which contribute to stable performance in harsh field environments.

Arlon CuClad 233 vs. CuClad 217 vs. CuClad 250: Which One Should You Use?

Engineers regularly face the choice between the three main CuClad variants. Here’s a practical breakdown.

Parameter	CuClad 217	CuClad 233	CuClad 250GT/GX
Nominal Dk	2.17–2.20	2.33	2.55
Dissipation Factor @ 10 GHz	~0.0009	~0.0013	~0.0018
Fiberglass/PTFE Ratio	Low	Medium	High
Mechanical Robustness	Lower	Medium	Approaching conventional
Dimensional Stability	Lower	Better	Best in series
Construction	Cross-plied	Cross-plied	Cross-plied
XY Plane Isotropy	Yes	Yes	Yes
Best Fit	Lowest loss priority	Balanced performance	Mechanical stability priority

Choose CuClad 217 when insertion loss and dielectric constant are the dominant constraints and your fabricator has the capability to handle the softest substrate in the family. Choose CuClad 233 when you need very low loss but also need a substrate that handles better through fabrication, or when dimensional stability matters more than pushing Dk to the absolute minimum. Choose CuClad 250GT or 250GX when you need the mechanical behavior of CuClad to approach conventional PCB materials — the additional glass loading makes it more forgiving in high-volume production environments.

Fabrication Guidelines for Arlon CuClad 233

Processing PTFE-based laminates is materially different from FR4 fabrication. CuClad 233, while better behaved than CuClad 217 due to its higher glass content, still requires PTFE-specific process steps. Fabricators who approach it as if it were a standard FR4 or even a thermoset high-frequency material will have problems.

Storage and Handling Before Fabrication

PTFE laminates absorb very little moisture (CuClad 233 is rated below 0.10%), but they are sensitive to contamination. Store panels in a clean, controlled-humidity environment and process them promptly after opening packaging. Unlike FR4, PTFE does not benefit from a pre-bake to drive off absorbed moisture — the concern is surface contamination that affects plating adhesion.

Cutting and Routing

CuClad 233 can be cut with standard shearing equipment, but PTFE’s softness means clean tooling is essential. Dull router bits cause smearing rather than cutting, which leads to ragged edges and potential delamination. Use sharp carbide tools, maintain appropriate feed rates for PTFE-based material, and ensure adequate chip evacuation to prevent heat buildup.

Drilling

Keep stack heights low — one to two panels per drill stack is the standard recommendation for PTFE materials. Use appropriate entry material (thin aluminum) and backup material to support clean hole entry and exit. Inspect hole walls before plating. PTFE smear inside holes is the most common cause of PTH reliability failures in PTFE laminates.

PTFE Surface Activation (Critical Step)

PTFE is chemically inert — that’s one of the reasons it’s electrically excellent, but it means electroless copper will not adhere to raw PTFE hole walls. Before electroless copper deposition, the hole walls must be activated using either a sodium naphthalate etchant or a plasma etch process. This step is non-negotiable. Inadequate activation is the leading cause of PTH barrel failure and delamination at via interfaces in PTFE multilayer boards.

If your fabricator cannot confirm they perform this step — and specify which activation chemistry they use — consider that a disqualifying gap in their process qualification.

Etching and Line Definition

Standard cupric chloride or ammoniacal etchants work well with CuClad 233’s electrodeposited copper. Peel strength is typically above 6 lbs/inch for 1 oz copper, which is adequate for fine-line work. Handle panels with care, as PTFE-based boards are more sensitive to edge delamination from rough handling than thermoset materials.

Soldering and Assembly

CuClad 233’s low moisture absorption is an asset during reflow assembly — there’s minimal risk of moisture-induced delamination during the thermal excursion. The material is compatible with standard SMT reflow profiles. However, PTFE has low thermal conductivity (~0.26 W/m·K), so heat does not spread as quickly as in ceramic or higher-conductivity substrates. Profile your oven based on actual thermal measurements on the populated board, not assumed FR4 behavior.

Common Design Mistakes When Using CuClad 233

From a practical design standpoint, a few errors come up repeatedly with this material.

Not accounting for Dk variation with thickness. The nominal Dk of 2.33 is measured at specific laminate thicknesses. Very thin laminates can show slightly different effective Dk values. If you’re designing for precise impedance targets — particularly for 50-ohm lines on thin substrates — verify the effective Dk from the Rogers/Arlon Laminate Properties Tool or request actual measured data for your specific thickness.

Using FR4-based transmission line calculators. A 50-ohm microstrip on CuClad 233 is geometrically very different from one on FR4. The lower Dk requires wider traces for the same impedance on the same substrate thickness, which also changes the EM coupling behavior around corners and gaps. Always use accurate Dk and substrate thickness in your line width calculations.

Ignoring Z-axis CTE in multilayer designs. At approximately 200 ppm/°C, the Z-axis CTE of CuClad 233 is high compared to copper (~17 ppm/°C). This mismatch drives barrel fatigue in through-hole vias and plated holes during thermal cycling. For multilayer designs in high-thermal-cycle environments, carefully evaluate your via aspect ratios and consider whether micro-via or blind via constructions can reduce the at-risk barrel length.

Specifying standard grade when LX is needed. If your product has mil-spec traceability requirements or if you’re producing a lot-sensitive circuit like a narrowband filter bank, standard sampling-grade test certification may not be sufficient. Specify LX grade at the time of ordering.

Useful Resources for CuClad 233 Engineers

Resource	Description	Link
Rogers CuClad Series Datasheet	Official spec sheet covering CuClad 217, 233, and 250	rogerscorp.com
Rogers Laminate Properties Tool	Interactive tool for filtering and comparing laminate properties	Rogers PCB Tools
MatWeb CuClad 233 Entry	Third-party material database with converted property units	MatWeb
IPC TM-650 Test Methods	Standard test procedures referenced in the datasheet	IPC.org
Arlon/Rogers PCB Fabrication Resources	Manufacturing guidelines for CuClad and other PTFE laminates	RayPCB Arlon PCB
Midwest PCB CuClad Datasheet PDF	Mirror of the CuClad series datasheet with all three variants	midwestpcb.com

5 Frequently Asked Questions About Arlon CuClad 233

1. What is the difference between CuClad 233 and DiClad 233?

Both are Arlon/Rogers PTFE-fiberglass laminates targeting a similar Dk range, but the construction differs fundamentally. CuClad products use cross-plied construction (alternating plies at 90° to each other), which delivers electrical and mechanical isotropy in the X-Y plane. DiClad products use parallel-plied construction, where all fiberglass plies run in the same direction. The cross-plied CuClad 233 is preferred for applications where XY isotropy matters — phased arrays, balanced circuits, and directional couplers. DiClad variants are sometimes preferred for specific single-axis applications or where cost is a stronger driver.

2. Can Arlon CuClad 233 be used in multilayer PCB designs?

Yes, but multilayer construction with PTFE-based laminates requires compatible bonding materials. You cannot use standard FR4 prepregs as bonding plies between CuClad 233 cores — the mismatch in CTE, glass transition temperature, and resin chemistry leads to delamination and reliability failures. Use Rogers-specified bondply or bonding films designed for PTFE-based multilayer construction, and confirm your fabricator’s multilayer process for PTFE materials before committing to a design.

3. Is CuClad 233 appropriate for commercial wireless infrastructure, or is it mainly a military substrate?

The original application focus for CuClad 233 was military and high-performance microwave electronics, given its very low loss and cross-plied isotropy. That said, the material is applicable wherever Df below 0.0015 is needed and mechanical robustness is more important than the absolute lowest Dk. Commercial satellite terminal circuits, precision test fixtures, LNA boards for base station receivers, and high-performance VSAT equipment are all valid commercial applications for CuClad 233.

4. How does CuClad 233 handle at millimeter-wave frequencies (above 30 GHz)?

PTFE-based materials, including CuClad 233, generally maintain good dielectric properties well into the millimeter-wave frequency range. Dk stability across frequency is one of PTFE’s intrinsic advantages. However, at millimeter-wave frequencies, surface roughness of the copper foil becomes a significant loss mechanism — often dominant over the dielectric loss. For mmWave designs on CuClad 233, specify low-profile or rolled annealed copper foil to minimize conductor roughness losses, and account for the copper roughness contribution in your insertion loss budget.

5. What is the best way to confirm the actual Dk of a CuClad 233 lot before fabrication?

Rogers/Arlon provides a standard test report with each order for the LX testing grade, with lot-specific Dk and Df measurements. For standard-grade material, you can request test data from your distributor’s incoming inspection records. If you need to verify independently, the IPC TM-650 2.5.5.5 test method (full-sheet resonator or stripline resonator method at 10 GHz) is the standard approach used in the datasheet and can be repeated in-house or at a qualified test lab. Some engineers also use time-domain reflectometry (TDR) on characterization coupons included in the production panel, which provides real-time Dk confirmation based on the actual processed board.

Final Thoughts on Arlon CuClad 233

Arlon CuClad 233 has maintained a strong position in the high-frequency laminate market precisely because it occupies a genuinely useful operating point: low enough dissipation factor to compete with the best PTFE materials in its class, combined with dimensional stability and mechanical handling characteristics that make it a realistic production substrate rather than a laboratory curiosity.

For military radar, ECM, and ESM systems where performance is non-negotiable and the LX grade provides the individual-sheet traceability these programs require, CuClad 233 remains a first-choice substrate. For precision microwave passive components where the cross-plied XY isotropy eliminates a systematic error source, it provides a competitive advantage that is genuinely hard to replicate with standard parallel-plied materials.

If you’re working with this material for the first time, the most important thing to get right is the fabrication process — specifically the PTFE activation step for plated holes and drilling parameters. Get those right with a qualified fabricator, and CuClad 233 will deliver exactly the performance its datasheet promises.