Arlon CuClad 217: The Complete PCB Engineer’s Guide to Ultra-Low Dk PTFE Laminate

If you’ve been designing RF or microwave circuits for any length of time, you’ve probably run into the frustrating tradeoff between electrical performance and mechanical reliability. Arlon CuClad 217 sits at one end of that spectrum very intentionally — it prioritises the lowest possible dielectric constant and loss in a woven fiberglass-reinforced PTFE laminate, and it doesn’t apologise for it.

This guide is written from a working engineer’s perspective. Whether you’re evaluating the material for a new phased array radar programme, sizing up substrates for a 5G mmWave front-end, or just trying to understand why your fab house quoted you three times the price of FR-4, you’ll find the technical detail and practical context you need here.

What Is Arlon CuClad 217?

Arlon CuClad 217 is a PTFE-based laminate reinforced with woven fiberglass, originally developed by Arlon Materials for Electronics (MED) and now part of the Rogers Corporation portfolio following Rogers’ acquisition of Arlon. The “217” in the name directly references the target dielectric constant: Dk 2.17.

What differentiates CuClad 217 from other woven fiberglass PTFE laminates is its deliberately low fiberglass-to-PTFE ratio. Most PTFE-fiberglass composites use more glass to improve dimensional stability; CuClad 217 tips the balance the other way, maximising the proportion of PTFE to achieve the lowest achievable Dk and dissipation factor in its material class. The trade-off is a somewhat softer laminate compared to high-glass-content grades, but for RF and microwave applications — where you’re not primarily relying on the substrate for mechanical structure — the electrical payoff is well worth it.

The laminate uses a cross-plied construction, where alternating layers of PTFE-coated fiberglass cloth are oriented at 90° to each other. This sounds like a manufacturing detail, but it has a meaningful downstream effect: it delivers genuine electrical and mechanical isotropy in the XY plane. That isotropy is not something you can claim with non-woven or single-orientation woven fiberglass PTFE laminates, and for certain applications — particularly phased array antennas — it changes the design conversation entirely.

For a broader look at the Arlon PCB portfolio and how CuClad fits within it, that context helps when you’re comparing across the full range of Arlon laminate families.

Arlon CuClad 217 Key Electrical and Physical Specifications

Before getting into design and fabrication detail, here are the headline numbers that define this material. These are the figures that drive your design decisions:

Electrical Properties

Parameter	Value	Test Condition
Dielectric Constant (Dk)	2.17 / 2.20	10 GHz
Dissipation Factor (Df / tan δ)	0.0009	10 GHz
Dk Stability vs. Frequency	Very high (1 MHz to 20+ GHz)	—
Moisture Effect on Dk	Negligible	Low absorption

Physical and Mechanical Properties

Parameter	Value	Test Method
Density	2.23 g/cc (0.0806 lb/in³)	ASTM D792 Method A
Water Absorption	0.020%	IPC TM-650 2.6.2.2
Outgassing – Total Mass Loss	0.00%	NASA SP-R-0022A (125°C, vacuum)
Water Vapor Recovered	0.010%	NASA SP-R-0022A
Construction	Cross-plied woven fiberglass/PTFE	—
Reinforcement Orientation	Alternating plies at 90°	—

Available Configurations

Attribute	Options
Copper Cladding Weight	1/2 oz, 1 oz, 2 oz electrodeposited (ED)
Copper Type	Standard ED copper; rolled copper available
Available Thicknesses	0.015 in (0.38 mm) and others
Master Sheet Size	Up to 36″ × 36″ (standard); 36″ × 48″ available
Ground Plane Options	Aluminum, brass, or copper bonded plate
RoHS Compliance	Yes

That Df of 0.0009 at 10 GHz is the number most engineers focus on — and rightly so. In practical terms, it means insertion loss on a 10 GHz microstrip line on CuClad 217 is considerably lower than you’d see on CuClad 233 (Df ~0.0012) or PTFE-ceramic substrates with higher Dk values. When you’re designing a low-noise amplifier front-end where every 0.1 dB of insertion loss directly degrades noise figure, that difference matters.

Why the Cross-Plied Construction Matters for Your Design

The cross-plied construction is one of those specs that engineers sometimes skip past, but if you’re designing phased array antennas, it’s arguably more important than the Dk number itself.

In a single-direction or non-woven fiberglass PTFE composite, the fiberglass distribution across the laminate surface is not uniform in all directions. That creates subtle directional differences in dielectric constant — the material has a slightly different Dk depending on whether your trace runs north-south or east-west on the panel. For most microwave components, those differences are small enough to tolerate. For a large phased array where you have hundreds of identical radiating elements and feed network traces running in multiple directions, the variation becomes a systematic error source that degrades beam steering accuracy and array uniformity.

Arlon CuClad 217’s cross-plied structure eliminates this by ensuring that at any point on the laminate surface, the fiberglass content and PTFE content are statistically balanced in all in-plane directions. The result is genuine electrical and mechanical isotropy in the XY plane — something Rogers correctly notes no other woven or non-woven fiberglass PTFE laminate can claim.

The secondary benefit of cross-plied construction is better dielectric constant uniformity across the panel. You get tighter Dk tolerance part-to-part and panel-to-panel, which simplifies the work of achieving repeatable impedance control across a production run.

Arlon CuClad 217 vs. Other High-Frequency Laminates

Understanding where CuClad 217 fits relative to its alternatives will help you justify the material choice to your procurement team and identify which applications genuinely need it.

CuClad 217 vs. the CuClad Family

Material	Dk (10 GHz)	Df (10 GHz)	Glass/PTFE Ratio	Primary Use Case
CuClad 217	2.17 / 2.20	0.0009	Low (max PTFE)	Lowest loss, isotropy-critical
CuClad 233	2.33	~0.0012	Medium	Balanced loss/mechanical
CuClad 250	2.40–2.60	~0.0015–0.0018	Higher	Better dimensional stability

The CuClad family is designed around this deliberate trade-off: as you increase the glass content (moving from 217 to 233 to 250), you gain dimensional stability and mechanical robustness, but you give up some of the ultra-low loss and lowest Dk that makes 217 special.

CuClad 217 vs. Common Alternatives

Material	Dk	Df	Construction	Key Difference vs. CuClad 217
Arlon CuClad 217	2.17	0.0009	Woven glass/PTFE (cross-plied)	Baseline reference
Arlon DiClad 880	2.17	0.0009	Non-woven PTFE/glass	No XY isotropy; similar loss
Taconic TLY-5A	2.17	0.0009	Woven glass/PTFE	Similar spec; different fab ecosystem
Rogers RT/Duroid 5880	2.20	0.0009	PTFE/random glass fibre	Lower Dk control; very low loss
FR-4 (standard)	~4.5	~0.020	Woven glass/epoxy	Far higher loss; not suitable above ~1 GHz
Rogers RO4003C	3.55	0.0027	Ceramic/hydrocarbon	Better dimensional stability; higher Dk

The practical takeaway: if your application demands the absolute lowest dielectric constant in a fiberglass-reinforced PTFE laminate, combined with true XY isotropy, Arlon CuClad 217 is the correct choice. If dimensional stability or cost is the primary driver and you can tolerate higher Dk, look to CuClad 233 or 250, or the ceramic-filled hydrocarbon laminates like RO4003C.

Typical Applications for Arlon CuClad 217

The material’s electrical profile suits a well-defined set of applications. These are not arbitrary marketing categories — the specific combination of ultra-low Dk, near-zero loss tangent, XY isotropy, and low moisture absorption directly enables the following:

Military and Defence Electronics — Arlon CuClad 217 has a long history in radar system front-ends, electronic countermeasure (ECM) modules, and electronic support measures (ESM) receivers. These systems operate across wide frequency bands, often from S-band through Ka-band, and the material’s Dk stability across frequency is as important as its absolute loss value.

Phased Array Antenna Systems — The XY isotropy described earlier makes CuClad 217 the substrate of choice for phased array antenna feed networks where beam steering accuracy depends on matched electrical paths to each radiating element. Commercial 5G mmWave base stations and automotive radar (77 GHz FMCW) both benefit from this property.

Microwave Passive Components — Narrow-band bandpass filters, edge-coupled directional couplers, hybrid splitters, and power dividers all benefit from the tight Dk control and low loss. The dielectric uniformity directly translates to more predictable coupled-line behaviour and lower filter insertion loss.

Low Noise Amplifier (LNA) Input Networks — In receive chains where the LNA noise figure is critical, the input matching network substrate loss is directly additive to the system noise figure. CuClad 217’s 0.0009 Df minimises this contribution at X-band and above.

Satellite and Space Electronics — The near-zero outgassing performance (0.00% total mass loss per NASA SP-R-0022A at 125°C in vacuum) makes CuClad 217 suitable for space-qualified hardware. The low water absorption (0.020%) also means dielectric constant stays stable in varying humidity environments.

Test and Measurement Substrates — Precision RF calibration standards, fixture substrates, and probe tip assemblies benefit from the material’s predictable, stable Dk.

Designing with Arlon CuClad 217: Practical Considerations

Impedance Control and Trace Geometry

The low Dk of 2.17 means that for a given substrate thickness and target impedance (typically 50 Ω), your microstrip trace will be wider than on higher-Dk materials. On a 0.015″ (0.38 mm) substrate, a 50 Ω microstrip in CuClad 217 runs to approximately 1.1–1.2 mm wide. This is actually advantageous — wider traces have lower resistive loss, which compounds the benefit of the low dissipation factor to further reduce total insertion loss.

Use a reliable microstrip/stripline calculator that accounts for dispersion at your frequency of interest. Rogers’ online impedance calculator (MWI-2010) supports CuClad material properties directly.

Copper Foil Selection

For circuits operating above 10 GHz, specify smooth copper foil (1/2 oz or 1 oz electrodeposited copper). Rougher foil profiles increase conductor loss at high frequencies because the skin depth at 10 GHz is approximately 0.66 μm — comparable to the surface roughness of standard ED copper. Rolled (RA) copper is also available on special order if your application demands the smoothest possible conductor surface.

Dielectric Constant Frequency Stability

One of the practical advantages of CuClad 217 that doesn’t always make headlines: the Dk is remarkably stable from 1 MHz through well beyond 20 GHz. The PTFE matrix contributes to this stability because PTFE itself has very low dispersion. This means you can design a circuit at one frequency and scale it with confidence — you don’t need to model frequency-dependent Dk shifts in your EM simulator beyond the normal numerical precision of the simulation.

Fabricating Arlon CuClad 217 PCBs: What Your Fab House Needs to Know

PTFE-based laminates like Arlon CuClad 217 require fabrication procedures that differ substantially from FR-4. Not every PCB shop has the right tooling and chemical processes. Before committing a design to manufacture, verify that your fab house has documented PTFE laminate experience. Here’s what the process demands:

Drilling

PTFE is a soft, somewhat slippery material. Standard carbide drill bits designed for FR-4 will tend to smear the PTFE rather than cut cleanly. Your fab house should be using carbide or diamond-coated drill bits specifically rated for PTFE composites, with controlled feed rates and spindle speeds to prevent bore wall smearing. Stack heights in a drill pack should also be lower than FR-4 practice to maintain hole quality.

Through-Hole Preparation (Desmear / Etchback)

PTFE’s non-stick surface chemistry — the same property that makes Teflon cookware useful — creates adhesion challenges for plated through-holes. Standard permanganate desmear processes used on FR-4 don’t bond well to PTFE. Two effective approaches exist:

• Sodium etching (chemical): Solutions like Poly-Etch or FluoroEtch chemically strip fluorine atoms from the PTFE surface and create reactive carbon sites. This is the most common approach for production volumes.
• Plasma treatment: An oxygen/argon plasma desmear activates the PTFE surface without chemicals. It’s cleaner and produces excellent adhesion but requires the right plasma equipment.

Skipping this step or using the wrong process is a common cause of barrel cracking and PTH reliability failures in PTFE laminate boards.

Etching and Surface Finish

Chemical etching of the copper layer follows standard wet etching practice. The copper adhesion to CuClad 217 is well-established because the laminate is manufactured with the copper bonded during pressing. ENIG (Electroless Nickel Immersion Gold) is the most common surface finish for microwave boards — it provides a flat, solderable, wire-bondable surface. HASL is generally avoided for precision RF work because the solder surface is too topographically rough for consistent RF performance at high frequencies.

Ordering Arlon CuClad 217: Specifying Your Material

When ordering CuClad 217, you’ll need to specify several parameters to get the right material. A complete material call-out should include:

• Dielectric constant variant: Er = 2.17 or Er = 2.20
• Dielectric thickness: e.g., 0.015″ (0.38 mm), 0.020″, 0.031″, etc.
• Copper cladding weight: 1/2 oz, 1 oz, or 2 oz
• Cladding type: Double-sided (standard) or single-sided
• Panel size: e.g., 12″ × 18″ cut sheet or 36″ × 36″ master sheet
• Test level: Standard or “LX” (lot acceptance testing with individual test report per piece)
• Special options: Metal-backed (ground plane bonded) if required

The “LX” test level option is worth noting for defence and space programmes — it means each piece of laminate is individually tested and ships with its own test report, giving you material traceability at the unit level rather than the batch level.

Useful Resources for Arlon CuClad 217

The following references are directly useful when working with this material:

Resource	Description	Link
Rogers CuClad 217 Product Page	Official datasheet, Dk/Df curves, laminate properties tool	rogerscorp.com
CuClad Series Datasheet (PDF)	Full material data for CuClad 217/233/250	rogerscorp.com/documents
Rogers MWI Impedance Calculator	Online tool for microstrip/stripline design with CuClad materials	rogerscorp.com/resources
MatWeb CuClad 217 Data	Material property database entry with SI/imperial values	matweb.com
IPC-4103 Standard	Specification for High-Frequency (Microwave) Base Materials	ipc.org
Midwest PCB CuClad Datasheet (PDF)	Legacy Arlon-era CuClad series datasheet	midwestpcb.com
RF-Microwave.com CuClad 217 Listing	Distributor specification and stock information	rf-microwave.com

5 FAQs About Arlon CuClad 217

Q1: Is Arlon CuClad 217 the same as Rogers CuClad 217?

Yes. Arlon CuClad 217 and Rogers CuClad 217 refer to the same material. Rogers Corporation acquired Arlon’s electronics materials division, so the CuClad product line transferred to Rogers ownership. You’ll still see both names used interchangeably in datasheets, distributor listings, and legacy documentation — “Arlon CuClad 217” is common in material databases and engineering references predating the acquisition, while Rogers now manufactures and sells the product under its own branding.

Q2: What is the difference between CuClad 217 with Er 2.17 and Er 2.20?

Both values represent the same material family, but the Er 2.17 and 2.20 variants reflect slightly different fiberglass loading levels. The Er 2.17 grade has the absolute minimum glass content and therefore the lowest Dk, while the 2.20 grade has marginally more glass, giving slightly better dimensional stability. For most RF designs, either grade works; select based on whether you need the absolute lowest Dk or slightly more mechanical robustness in your stackup.

Q3: Can I use CuClad 217 in a multilayer stackup with FR-4?

Technically possible, but not recommended for high-frequency designs. The CTE (coefficient of thermal expansion) mismatch between PTFE-based and epoxy-based laminates creates reliability concerns at the bond interface, particularly after thermal cycling. If you need a multilayer design combining CuClad 217 signal layers with a lower-cost dielectric for power and ground planes, consult with your fabricator about compatible bonding films and verify the CTE compatibility in your thermal profile.

Q4: How does CuClad 217 perform at mmWave frequencies (above 30 GHz)?

Exceptionally well. The dielectric constant remains stable and the low dissipation factor means insertion loss scales predictably with frequency. The main consideration at mmWave is surface roughness of the copper foil — conductor loss becomes dominant and scales with the square root of frequency. Specify smooth or very smooth copper foil grades for Ka-band (26.5–40 GHz) designs.

Q5: Is CuClad 217 suitable for lead-free soldering processes?

Yes, but with care. The material has no glass transition temperature in the conventional epoxy sense (PTFE doesn’t have a Tg like thermoset resins), so it handles high temperatures differently. Lead-free solder reflow at 260°C is generally manageable, but thermal excursions above 260°C should be minimised. Confirm the maximum process temperature with your fabricator for the specific thickness and copper weight you’re using.

Summary: When to Choose Arlon CuClad 217

Arlon CuClad 217 is a specialist material that earns its place on a BOM when the design genuinely needs what it offers. It’s not the cheapest option, it requires a fabricator with PTFE experience, and it demands more careful design practice than FR-4. But when you’re running signals at X-band or above, designing a precision filter where every 0.1 dB of insertion loss matters, or laying out a phased array where XY dielectric uniformity is non-negotiable, the performance gap over any alternative justifies the complexity and cost.

If your application sits in military radar, satellite communications, 5G mmWave infrastructure, or precision microwave test equipment, Arlon CuClad 217 is the substrate you’ve been designing toward — whether you knew it by that name or not.