Arlon DiClad 522 is a PTFE/woven glass laminate with Dk 2.40–2.60 and Df 0.0018 at 10 GHz. Full specs, DiClad 522 vs 527 comparison, fabrication tips, applications & FAQs for RF/microwave PCB design.

When you’re designing RF circuits that demand low loss, tight Dk uniformity, and mechanical behavior closer to FR-4 than typical soft PTFE laminates, Arlon DiClad 522 consistently earns a place on the shortlist. It sits in a practical sweet spot within the DiClad family — higher fiberglass content than the ultra-low-Dk members, which translates into better dimensional stability, more predictable multilayer registration, and a handling experience that doesn’t make your fabrication shop groan.

This guide breaks down everything a working PCB engineer needs to know about Arlon DiClad 522: the material structure, the full specification set, where it performs best, how it compares to close alternatives, and the fabrication realities that determine whether your prototype matches your simulation.

What Is Arlon DiClad 522? Product Family Context

Arlon DiClad 522 belongs to the DiClad series — a family of woven fiberglass/PTFE composite laminates originally developed and manufactured by Arlon Electronic Materials, now part of Rogers Corporation following the 2015 acquisition. The DiClad series covers a range of Dk values by precisely controlling the fiberglass-to-PTFE ratio in the laminate construction.

The DiClad family currently includes four main products: DiClad 880 (Dk 2.17–2.20), DiClad 870 (Dk 2.33), DiClad 522 (Dk 2.40–2.60, tested at 1 MHz), and DiClad 527 (Dk 2.40–2.65, tested at 10 GHz). DiClad 522 and DiClad 527 share the same fundamental construction — a higher fiberglass-to-PTFE ratio than other DiClad members — but differ in how the dielectric constant is characterized and verified. This is a practical distinction that matters when you’re specifying for a microwave application: DiClad 522’s Dk is characterized at 1 MHz, while DiClad 527’s is measured at 10 GHz. For designs where the operating frequency is in the microwave range, DiClad 527’s 10 GHz characterization provides directly relevant data. DiClad 522 remains widely specified and sourced in practice, and the two materials have nearly identical physical construction.

One architectural distinction that sets all DiClad laminates apart from Arlon’s CuClad series is that DiClad materials use a parallel-plied construction — the coated fiberglass plies are aligned in the same direction. This contrasts with CuClad’s cross-plied 90° alternating ply arrangement. The implication is that DiClad 522 does not provide the true XY-plane electrical isotropy that CuClad products offer. For most filter, coupler, power divider, and base station antenna applications, this makes no practical difference. For phased array designs with strict inter-element phase matching requirements, it’s worth factoring in.

For engineers working with an Arlon PCB manufacturer, DiClad 522 is a well-supported, long-established material with broad fabricator familiarity.

Arlon DiClad 522 Material Composition

The properties of DiClad 522 trace directly to its two-component construction.

High Fiberglass-to-PTFE Ratio: The Defining Design Choice

The fundamental design lever in the DiClad series is the ratio of woven fiberglass reinforcement to PTFE matrix. DiClad 522 uses a higher fiberglass-to-PTFE ratio compared to DiClad 880 and DiClad 870. This choice deliberately trades some of the ultra-low-loss performance of pure PTFE composites for mechanical properties that approach conventional substrates.

In practice, this means DiClad 522 is stiffer, dimensionally more stable during lamination and drilling, and exhibits lower CTE in the x and y directions compared to lower-fiberglass-content PTFE laminates. The dimensional stability improvement directly benefits multilayer registration — a persistent challenge with highly compliant PTFE-rich materials.

PTFE Composite Base

Despite its higher glass content, DiClad 522 remains fundamentally PTFE-based. PTFE’s non-polar molecular structure produces inherently low dielectric loss across a wide frequency range. This is the property that makes the DiClad series worth specifying over hydrocarbon or epoxy alternatives in loss-budget-constrained designs. The combination of PTFE’s intrinsic low-loss nature and the woven glass reinforcement’s dimensional stability is what makes DiClad 522 a practical material rather than just a high-performance one.

Woven Fiberglass Reinforcement

The woven glass in DiClad 522 uses PTFE-coated fiberglass cloth, with the plies aligned in the same direction (parallel plied). The consistency and control of this PTFE-coated cloth is a key manufacturing process point — it’s what allows Arlon/Rogers to produce DiClad 522 with better Dk uniformity than comparable non-woven fiberglass reinforced PTFE laminates. Dk uniformity matters enormously in filter and coupler designs, where the resonant frequency and coupling coefficient of each circuit element depend directly on the local dielectric constant the element experiences.

Arlon DiClad 522 Full Specifications

Here is a comprehensive view of DiClad 522’s key properties, drawn from the Arlon Microwave Materials Guide and published datasheet data.

Electrical Properties

Property	Value	Test Condition
Dielectric Constant (Dk)	2.40–2.60	1 MHz
Dissipation Factor (Df)	0.0018	10 GHz
Thermal Coefficient of Dk	–153 ppm/°C	—
Dk Stability vs. Frequency	Stable, characterization curve available	MHz to >10 GHz

Thermal and Environmental Properties

Property	Value	Test Method
Water Absorption	0.03%	ASTM D792 / IPC
Thermal Conductivity	0.254 W/(m·K)	—
NASA Outgassing – Total Mass Loss	0.02%	NASA SP-R-0022A
NASA Outgassing – CVCM	0.00%	NASA SP-R-0022A
Flammability Rating	UL94 V-0	UL

Mechanical and Physical Properties

Property	Value
Density	2.31 g/cc
CTE – X axis	14 ppm/°C
CTE – Y axis	21 ppm/°C
CTE – Z axis	173 ppm/°C
Typical Peel Strength	14 lbs
Tensile Modulus	~706 kpsi

Available Configurations

Parameter	Options
Dielectric Constant Range	2.40–2.60 (selectable in increments)
Standard Copper Weights	½ oz, 1 oz, 2 oz electrodeposited
Alternative Copper	Rolled copper foil (on request)
Metal-Backed Options	Aluminum, brass, or copper ground plane
Panel Sizes	Up to 36″ × 48″ (parallel plied)

Translating the Key Numbers to Real Design Impact

Dissipation factor of 0.0018 at 10 GHz is roughly half that of RO4350B (0.0037) and nearly one order of magnitude better than FR-4 (0.020+). For a base station antenna feed network with 15 inches of transmission line at 5.8 GHz, that difference in Df translates to meaningfully lower insertion loss — directly affecting antenna gain and system noise figure in receive paths.

Thermal coefficient of Dk at –153 ppm/°C is a specification that many engineers overlook until it bites them in production. A negative TCDk means the dielectric constant decreases as temperature rises. For a filter centered at 5.8 GHz, a significant operating temperature swing will shift the resonant frequency proportionally to the Dk change. This needs to be budgeted in the design, especially for outdoor infrastructure equipment cycling between –40°C and +85°C. DiClad 522 has better TCDk than pure PTFE-dominated laminates, but it’s a parameter that deserves simulation attention in temperature-sensitive designs.

X-axis CTE of 14 ppm/°C and Y-axis CTE of 21 ppm/°C are notably lower than typical pure PTFE-rich laminates, which is the direct result of the higher fiberglass content. Copper’s CTE is approximately 17 ppm/°C. The x-axis CTE essentially matches copper, which is why DiClad 522 shows better in-plane dimensional stability than lower-glass alternatives. The anisotropy between X (14 ppm/°C) and Y (21 ppm/°C) reflects the parallel-plied construction — the glass fabric’s warp and fill directions have different reinforcement densities.

Z-axis CTE of 173 ppm/°C is substantially higher than the x and y axes — this is typical for PTFE-based laminates and requires attention in through-hole design. Compared to FR-4’s z-axis CTE of 60–80 ppm/°C, DiClad 522 imposes more stress on plated through-hole barrel walls during thermal cycling. Good PTH design practices (conservative aspect ratios, adequate annular rings, proper through-hole activation before plating) are essential.

Water absorption of 0.03% is excellent for any PCB material. For RF circuits installed in outdoor base station cabinets or military equipment exposed to humidity cycling, moisture uptake is a direct threat to impedance stability. DiClad 522’s 0.03% absorption effectively removes moisture as a variable in deployed system performance.

Arlon DiClad 522 vs. Competing Materials

DiClad 522 vs. DiClad 527

Parameter	DiClad 522	DiClad 527
Dk Range	2.40–2.60	2.40–2.65
Dk Test Frequency	1 MHz	10 GHz
Construction	Parallel plied	Parallel plied
Dimensional Stability	Good	Better
Typical Use Case	Filter/coupler design	Microwave circuits, multilayer

DiClad 527 is specified when the application is explicitly in the microwave range and you want Dk data that corresponds directly to your operating frequency. Its slightly higher fiberglass content (reflected in the extended Dk range to 2.65) gives it better dimensional stability and registration in multilayer lamination. For single and double-sided filter designs where Dk at 1 MHz is an adequate specification anchor, DiClad 522 is an equivalent and widely available option.

DiClad 522 vs. Rogers RO4350B

Parameter	Arlon DiClad 522	Rogers RO4350B
Dk (10 GHz)	2.40–2.60	3.48
Df (10 GHz)	0.0018	0.0037
CTE – Z axis	173 ppm/°C	32 ppm/°C
Processing	PTFE-specialized	FR-4 compatible
Moisture Absorption	0.03%	0.06%
Peel Strength	14 lbs	Higher (thermoset adhesion)

RO4350B is the default choice for cost-driven commercial RF designs because it processes like FR-4 — no PTFE-specific through-hole activation, no specialized lamination procedures. It’s also a hydrocarbon/ceramic thermoset, meaning the z-axis CTE (32 ppm/°C) is far more favorable for PTH reliability than DiClad 522’s 173 ppm/°C. For production volumes where fabrication cost and yield matter, RO4350B’s processing advantages are real. DiClad 522 wins on loss (roughly 2× lower Df) and moisture performance, but these advantages only justify the added fabrication complexity where the design genuinely needs them.

DiClad 522 vs. Arlon DiClad 880 (Dk 2.17–2.20)

Parameter	Arlon DiClad 522	Arlon DiClad 880
Dk (10 GHz)	2.40–2.60	2.17–2.20
Df (10 GHz)	0.0018	~0.0009
Glass Content	Higher	Lower
Dimensional Stability	Better	Softer, more compliant
Circuit Size at Dk	Smaller than DiClad 880	Larger circuits at same freq.

DiClad 880 offers lower Dk and lower Df — the best electrical performance in the DiClad family. But the lower glass content makes it softer, more difficult to handle in a production fab environment, and more prone to dimensional variation during multilayer lamination. DiClad 522’s higher glass content is a genuine practical advantage when designing multilayer circuits or working in a volume production context. For designs where trace widths and circuit size are constrained, DiClad 522’s higher Dk allows somewhat more compact geometries than DiClad 880 at the same operating frequency.

DiClad 522 vs. Arlon CuClad 250

Parameter	Arlon DiClad 522	Arlon CuClad 250
Dk Range	2.40–2.60	2.40–2.60
Df (X-band)	0.0018	0.0018
Construction	Parallel plied	Cross-plied
XY Isotropy	No	Yes
Best For	Filters, couplers, power dividers	Phased arrays, isotropic designs

DiClad 522 and CuClad 250 cover essentially the same Dk and Df territory. The key differentiation is construction: CuClad 250’s cross-plied layers provide verified XY-plane electrical and mechanical isotropy. For designs where circuit orientation relative to the fiber direction is a concern — particularly phased array antennas — CuClad 250’s isotropy is the right choice. For most planar filter, coupler, and combiner designs, the orientation doesn’t matter and DiClad 522 is a straightforward, equivalent option.

Application Areas Where Arlon DiClad 522 Delivers

Military Radar Feed Networks

Radar feed networks route transmit and receive signals between the transceiver and the antenna elements. They require low insertion loss (to maximize effective radiated power and receiver sensitivity), predictable impedance (to minimize reflections that degrade radar resolution), and stable performance over military temperature ranges. DiClad 522’s combination of low Df, good Dk uniformity, and UL94 V-0 flammability rating suits these requirements. The NASA-compliant outgassing data (Total Mass Loss 0.02%, CVCM 0.00%) also makes it viable for airborne applications where outgassing can contaminate optics and sensitive sensors.

Commercial Phased Array Networks

Large commercial phased arrays — for 5G base stations, point-to-multipoint links, and satellite terminal antennas — need low-loss feed networks connecting multiple radiating elements. DiClad 522’s stable Dk across frequency keeps impedance consistent as the operating band changes, and the 0.0018 Df at 10 GHz provides acceptable insertion loss performance for commercial system budgets. At frequencies below 10 GHz where most commercial phased arrays operate, this material is well-matched to the application.

Low Loss Base Station Antennas

Base station antenna companies have been using Arlon DiClad materials for decades for this reason: the Dk range of 2.40–2.60 allows reasonably compact transmission line and coupler geometries, the low Df keeps insertion loss within system budgets at 1.7–5.9 GHz, and the long-term outdoor environmental performance — aided by 0.03% moisture absorption — supports 10–20 year service life requirements. DiClad 522 is explicitly named by Arlon as a target application, and it has the track record to support this use.

Filters, Couplers, and Power Dividers

These passive microwave components live and die by Dk uniformity — a shift in local dielectric constant shifts the electrical length of resonators, changes coupling coefficients, and moves passband edges. DiClad 522’s better-than-nonwoven Dk uniformity, produced by the precise PTFE-coated woven glass cloth, directly supports predictable filter and coupler performance. For Ku-band and X-band bandpass filters targeting precise passbands with low group delay ripple, DiClad 522’s uniformity makes the design-to-hardware correlation more reliable.

Missile Guidance Systems and Digital Radio Antennas

DiClad 522 is explicitly listed in Arlon’s application guidance for missile guidance systems. The combination of NASA-compliant outgassing, low loss, excellent chemical resistance, and dimensional stability under vibration all contribute. Digital radio antennas — whether for military UHF/VHF communications or commercial microwave backhaul — benefit from the same low-loss, low-moisture-absorption properties.

Fabrication Guidelines for Arlon DiClad 522

DiClad 522 requires PTFE-appropriate fabrication processes. Its higher glass content relative to other DiClad members makes it somewhat easier to handle than ultra-PTFE-rich laminates, but PTFE-specific steps are still mandatory.

Through-Hole Surface Activation

PTFE is chemically inert — excellent for dielectric performance, terrible for copper adhesion without surface treatment. Drilled holes through DiClad 522 must be activated before electroless copper deposition. Accepted methods are sodium etch (chemical activation using sodium/naphthalene) or plasma etch (oxygen plasma). Shops without one of these processes in place should not be processing DiClad 522. Failure to activate leads to zero copper adhesion in the barrel, producing open PTHs or intermittent connections that may not fail immediately but will fail in thermal cycling.

Drilling Parameters

DiClad 522’s higher fiberglass content makes it harder and more abrasive than lower-glass PTFE laminates. Use drill bit specifications appropriate for glass-PTFE composites, including appropriate entry and backup materials. Expect shorter drill bit life than for pure PTFE laminates. Adjust feed rates to minimize PTFE smear on hole walls, which would reduce the effectiveness of subsequent sodium or plasma etch activation.

Lamination for Multilayer Designs

For multilayer DiClad 522 designs, use compatible PTFE bonding materials — Rogers 2929 or equivalent. Standard FR-4 prepregs are not appropriate for bonding PTFE-based core layers. The higher glass content in DiClad 522 compared to DiClad 880 or CuClad 217 provides better dimensional predictability during lamination, but PTFE-specific lamination profiles (temperature, pressure, and vacuum schedule) must still be followed. Pre-bake the laminate cores to remove moisture before lamination.

Copper Foil and Surface Finish

DiClad 522 is supplied with ½ oz, 1 oz, or 2 oz electrodeposited copper as standard; rolled copper is available on request. For designs at 5.8 GHz and above, rolled or smooth copper foil reduces conductor loss compared to standard electrodeposited copper. At these frequencies, the skin depth becomes comparable to surface roughness. ENIG and immersion silver are the recommended surface finishes. HASL is generally not appropriate for high-frequency PTFE-based boards due to surface irregularity.

Metal-Backed Configurations

DiClad 522 is available bonded to aluminum, brass, or copper ground plane plates. These metal-backed configurations provide integral heat sinking and mechanical rigidity, making them valuable for power amplifier substrates and antenna panels where thermal management and structural stiffness are required alongside the RF performance.

Material Selection Decision Framework

Design Requirement	DiClad 522 Fit
Low loss at 1–18 GHz	✅ Excellent
Low moisture / outdoor environment	✅ Excellent
Tight Dk uniformity for filters	✅ Excellent
UL94 V-0 compliance needed	✅ Excellent
NASA outgassing compliance needed	✅ Excellent
PTFE-capable fabricator available	Required
FR-4 processing preferred	⚠️ Consider RO4350B
XY-plane isotropy needed (phased arrays)	⚠️ Consider CuClad 250
Absolute lowest loss required	⚠️ Consider DiClad 880
Above 20 GHz operation	⚠️ Evaluate mmWave-specific materials

Useful Resources for Arlon DiClad 522 Design and Procurement

• Rogers DiClad Series Product Page — rogerscorp.com/diclad-series-laminates — Current product information, Laminate Properties Tool, and Dk/Df vs. frequency curves
• Rogers DiClad Datasheet (PDF) — Available from Rogers’ website and authorized distributors; includes DiClad 522 and 527 physical and electrical data
• Arlon DiClad/CuClad/IsoClad Fabrication Guidelines (PDF) — Available via RF Global Net and Rogers’ technical library; essential for fabricators new to DiClad processing
• Matweb DiClad 522/527 Database Entry — matweb.com — Property data for mechanical modeling and thermal simulation
• Arlon Microwave Materials Guide (PDF) — Full Arlon laminate comparison table including DiClad 522 data; available from Rogers’ authorized distributors
• Rogers Laminate Properties Tool — Interactive tool for comparing DiClad 522 against other Rogers/Arlon laminates on specific properties
• Saturn PCB Toolkit — Free PCB impedance calculator with PTFE laminate support; useful for microstrip and stripline trace width calculations on DiClad 522

Frequently Asked Questions About Arlon DiClad 522

Q1: What is the practical difference between DiClad 522 and DiClad 527, and which should I specify?

Both materials share the same high-fiberglass PTFE composite construction and Dk range (2.40–2.65), but differ in how Dk is characterized: DiClad 522 at 1 MHz, DiClad 527 at 10 GHz. For microwave applications from 1–18 GHz, DiClad 527’s 10 GHz Dk data is more directly relevant to your design. DiClad 527 also has slightly better dimensional stability. In practice, many engineers and fabricators treat these as interchangeable for design purposes. If your application is above 1 GHz, specify DiClad 527 for more accurate datasheet-to-simulation correlation; use DiClad 522 when it’s the available stock option and you verify Dk at your operating frequency.

Q2: Can I use DiClad 522 in a hybrid stackup with RO4350B or FR-4 layers?

Yes, hybrid stackups are commonly used to reduce cost by confining DiClad 522 to the RF-critical signal layers while using less expensive materials for power and ground planes or digital signal layers. The key challenge is managing CTE mismatch between PTFE-based and epoxy/hydrocarbon layers. Use a PTFE-compatible bonding film at all material interfaces, and verify your hybrid stackup design with the fabricator before production. Perform thermal cycling qualification testing — especially if the board will see wide temperature excursions in service. A fabricator with prior hybrid stackup experience is important here.

Q3: Why is DiClad 522 preferred over CuClad 250 for filter and combiner applications?

For planar filter and combiner designs, the dielectric constant uniformity that DiClad 522 offers is the primary driver — both materials cover similar Dk and Df territory. CuClad 250 adds cross-plied XY isotropy, which is valuable for phased array applications but irrelevant for most filter and combiner designs where circuit orientation is fixed. DiClad 522’s parallel-plied construction is simpler to produce and can offer slightly better Dk uniformity in specific configurations. Both are valid choices; for filters and combiners, the choice often comes down to which material your preferred fabricator holds in stock.

Q4: Does DiClad 522 need any special handling before fabrication?

Yes. Like all PTFE-based laminates, DiClad 522 should be pre-baked before lamination and drilling to remove absorbed moisture (typically 150–180°C for 1–2 hours). The material should be handled with clean gloves to avoid surface contamination. Store in a dry environment when not being processed. The higher glass content in DiClad 522 makes it mechanically stiffer than lower-glass PTFE laminates like DiClad 880, which reduces but does not eliminate the risk of panel warpage during handling. Standard PTFE laminate precautions apply throughout the fabrication process.

Q5: Is Arlon DiClad 522 suitable for commercial 5G base station antenna designs at 3.5 GHz?

Absolutely — this is one of the application areas where DiClad 522 delivers excellent value. At 3.5 GHz, the loss advantage over RO4350B (Df 0.0018 vs. 0.0037) is meaningful for long signal path feed networks, and the moisture absorption of 0.03% versus RO4350B’s 0.06% helps maintain consistent antenna performance over years of outdoor humidity cycling. The material’s track record in base station antenna applications is long and well-established. Work with a fabricator experienced in PTFE materials, specify ENIG or immersion silver surface finish, and you’ll find DiClad 522’s performance-to-cost ratio attractive for commercial antenna production volumes.

Summary: Where Arlon DiClad 522 Belongs in Your Material Selection

Arlon DiClad 522 delivers a specific and well-proven combination of properties: low RF loss (Df 0.0018 at 10 GHz), excellent Dk uniformity across frequency, outstanding moisture resistance (0.03% absorption), NASA-compliant outgassing, and mechanical properties that approach conventional substrates — all in a woven glass PTFE composite with decades of field-proven reliability.

It’s not the right material for every application. If you need FR-4-style processing without PTFE-specific fabrication steps, RO4350B belongs on your shortlist. If you need the absolute lowest loss and don’t mind a softer, more compliant material, look at DiClad 880 or CuClad 217. If XY-plane isotropy is non-negotiable for a phased array, use CuClad 250 instead.

But for military radar feed networks, base station antenna panels, microwave filters and couplers, missile guidance electronics, and any design where low loss, Dk uniformity, and long-term moisture stability matter — Arlon DiClad 522 has earned its reputation as a dependable, well-characterized workhorse material that bridges the gap between the extreme performance of pure PTFE composites and the manufacturing convenience of standard substrates.