Arlon DiClad 527 PCB Laminate: Properties, Uses & Design Guide

When you’re specifying a substrate for a high-frequency multilayer PCB — especially one where you need very thin cores between ground planes — the list of practical options gets short fast. Arlon DiClad 527 is one of the materials that consistently shows up on that short list, and it earns its place. It’s a woven fiberglass-reinforced PTFE laminate designed specifically for microwave and RF applications, and its standout characteristic is that it goes thinner than almost any comparable product in its class — down to 0.005″ (0.127 mm). If you’re an RF engineer evaluating substrate options or a PCB designer trying to understand what makes DiClad 527 tick, this guide covers everything you need: full electrical and mechanical specs, thickness availability, fabrication considerations, application guidance, and comparisons with competing materials.

What Is Arlon DiClad 527?

Arlon DiClad 527 is a woven fiberglass/PTFE composite laminate manufactured for use as a printed circuit board substrate in microwave and RF applications. It belongs to the DiClad family — a long-established line of PTFE-based PCB laminates that Arlon EMD has produced for over 50 years. DiClad 527 laminates use a higher ratio of fiberglass reinforcement relative to PTFE content than many competing PTFE laminates, which provides mechanical properties that approach those of conventional PCB substrates while retaining the exceptional low-loss electrical characteristics that make PTFE materials indispensable at high frequencies.

The DiClad series operates on a deliberate design philosophy: by precisely controlling the fiberglass-to-PTFE ratio, the product line spans from low Dk, ultra-low-loss laminates all the way to stiffer, more highly reinforced versions with better dimensional stability. DiClad 527 sits toward the high-reinforcement end of that spectrum. Its dielectric constant range of 2.40–2.65 reflects the fact that a higher fiberglass content naturally pulls the Dk up slightly compared to softer, more PTFE-rich compositions.

It is worth noting that while Arlon’s microwave laminate division (Arlon EMD) was acquired by Elite Material Co. (EMC) of Taiwan in January 2021, DiClad 527 continues to be manufactured at the Rancho Cucamonga, California facility. Specification sheets, part numbers, and material performance remain consistent with the original Arlon product.

Arlon DiClad 527 Full Electrical Specifications

These are the core electrical parameters from the published datasheet. Any field solver calculation, impedance stack-up, or simulation model should use these values as the starting point — and where possible, request the actual measured Dk for the specific batch from your fabricator.

Parameter	Value
Dielectric Constant (Dk) @ 10 GHz	2.40 – 2.65
Dissipation Factor (Df) @ 10 GHz	0.0018
Thermal Coefficient of Er (ppm/°C)	−153
Water Absorption (%)	0.03
Flammability Rating	UL94-V0

The dissipation factor of 0.0018 at 10 GHz is the number that keeps Arlon DiClad 527 competitive with other low-loss RF substrates. For context, standard FR-4 typically runs a Df of 0.02 or higher — that’s more than ten times worse. At microwave frequencies where even tenths of a dB in insertion loss matter, the difference between a substrate with Df = 0.0018 and one with Df = 0.02 is not marginal. It’s the difference between a functional amplifier chain and one that misses its noise figure budget.

The thermal coefficient of dielectric constant (–153 ppm/°C) means that the Dk decreases slightly as temperature rises. Over a typical operating range of –40°C to +85°C, this shift is predictable and manageable in most designs. For temperature-compensated oscillators or narrowband filters where Dk drift would shift the center frequency, this parameter needs to be included in your worst-case analysis.

Mechanical and Physical Properties of DiClad 527

Mechanical properties don’t get the same attention as electrical specs in RF design conversations, but they drive a lot of real-world reliability outcomes. CTE mismatch, peel strength, and dimensional stability under thermal cycling all affect whether your design survives qualification testing.

Parameter	Value
CTE — X axis (ppm/°C)	14
CTE — Y axis (ppm/°C)	21
CTE — Z axis (ppm/°C)	173
Typical Peel Strength (lbs/in)	14
Specific Gravity	2.31
Thermal Conductivity (W/mK)	0.254
Tensile Modulus (kpsi)	706

The Z-axis CTE of 173 ppm/°C is the figure most likely to cause issues in thick multilayer builds or boards with blind/buried vias. Under repeated thermal cycling, a high Z-axis CTE strains plated through-holes and barrel fills — PTFE-based substrates generally require careful via design and copper plating thickness to maintain long-term reliability. Consult IPC-6012 and your fabricator’s via reliability guidelines when designing high-aspect-ratio vias in DiClad 527 multilayer constructions.

The peel strength of 14 lbs/in is solid for a PTFE laminate. The woven glass reinforcement in DiClad 527 — compared to softer, more PTFE-rich compositions — contributes meaningfully to this value. That said, PTFE surfaces still require specific surface activation processes before plating, which we cover in the fabrication section below.

NASA Outgassing Data for DiClad 527

DiClad 527 qualifies for use in spacecraft and satellite applications based on the following NASA ASTM E595 outgassing results:

Parameter	Result	NASA Limit
Total Mass Loss (TML)	0.02%	< 1.00%
Collected Volatile Condensable Material (CVCM)	0.00%	< 0.10%

Both values are orders of magnitude below the NASA thresholds. For space-based programs, this data removes one potential qualification hurdle early in the material selection process.

DiClad 527 Thickness Options and Available Dielectric Constants

This is where Arlon DiClad 527 truly differentiates itself from DiClad 522 and from many competing RF laminates. The product goes all the way down to 0.005″ (0.127 mm) core thickness — thinner than most PTFE laminates can reliably achieve while maintaining dimensional stability. That makes it the natural choice when you’re designing a multilayer RF board and need thin dielectric cores to set the characteristic impedance of stripline structures without pushing trace widths below manufacturable limits.

Thickness (inches)	Thickness (mm)	Available Nominal Dk Options
0.005″	0.127	2.50, 2.55
0.010″	0.254	2.45, 2.50, 2.55, 2.60
0.015″	0.381	2.45, 2.50, 2.55
0.020″	0.508	2.50, 2.55
0.030″	0.762	2.50, 2.55
0.060″	1.524	2.50, 2.55

Master sheet sizes available are 36″×72″, 36″×48″, and 36″×36″. Copper foil options include electrodeposited (ED) copper foil in ½ oz (18 µm) and 1 oz (35 µm) weights, and rolled copper foil in ½ oz weight for the standard DiClad 527 product.

A note on the Dk options within each thickness: having multiple Dk values available at the same core thickness is a genuinely useful design tool. Rather than being locked into one Dk and reverse-engineering your trace width, you can fine-tune the dielectric constant to hit a target characteristic impedance with a more practical trace geometry. Always verify what Dk values are actually in stock at your fabricator before building this into your design — availability can vary.

Key Advantages of Arlon DiClad 527

DiClad 527 offers an extremely low loss tangent, excellent dimensional stability, and product performance uniformity. Breaking these down in practical terms for working engineers:

Thin Core Availability. The 0.005″ core option is the defining advantage of DiClad 527. When you’re designing stripline structures in a multilayer RF stackup and the math calls for a core under 0.010″, DiClad 527 is one of very few woven-glass PTFE materials that can deliver it with acceptable dimensional control.

Frequency-Stable Dielectric Constant. The electrical properties of DiClad 527 are tested at both 1 MHz and 10 GHz. The consistency between these test frequencies means the Dk you use in your 10 GHz impedance calculation is essentially the same Dk the material will present at 1 GHz — valuable for wideband or multi-band designs.

Better Dimensional Control Than Unreinforced PTFE. The woven fiberglass reinforcement in DiClad 527 provides greater dimensional stability than nonwoven fiberglass-reinforced PTFE-based laminates of similar dielectric constants. For tight-tolerance etched structures like coupled-line filters or Lange couplers, this dimensional stability directly affects your ability to hit the designed electrical response without manual trimming.

Dielectric Constant Uniformity. The consistency and control of the PTFE-coated fiberglass cloth allows for a greater variety of dielectric constants and produces a laminate with better Dk uniformity than comparable non-woven fiberglass-reinforced laminates. This matters enormously in phased-array designs where Dk variation across a large panel translates directly to beam-pointing error.

UL94-V0 Flammability. Required by many military, commercial avionics, and industrial programs. DiClad 527 carries the UL94-V0 rating.

Excellent Chemical Resistance. PTFE is inherently resistant to the wet chemistry used in PCB fabrication — solvents, acids, and etchants don’t degrade the substrate. The woven glass reinforcement doesn’t compromise this characteristic.

Primary Applications for Arlon DiClad 527

Typical applications include military radar feed networks, commercial phased array networks, low-loss base station antennas, missile guidance systems, digital radio antennas, filters, couplers, and low-noise amplifiers.

Multilayer RF and Microwave Modules

The thin core capability of DiClad 527 makes it particularly well-suited for multilayer constructions where RF and digital layers need to coexist in a compact board. Embedding thin DiClad 527 cores between ground planes creates tightly coupled stripline environments that give designers control over impedance without excessively widening traces.

Phased Array Antenna Feed Networks

Large-format phased array panels demand exceptional Dk uniformity across the entire board footprint. Panel-to-panel and within-panel Dk variation translates to phase errors in the feed network that degrade beam efficiency. DiClad 527’s controlled Dk uniformity makes it a logical candidate for these systems.

Filters and Coupled-Line Couplers

DiClad laminates are frequently used in filter, coupler, and LNA applications where dielectric constant uniformity is critical. They are also used in power dividers and combiners where low loss is important. Tight Dk control means your coupled-line spacing calculations actually translate into the correct coupling coefficient on the fabricated board.

Base Station Antennas and Power Combiners

Low loss is everything in base station feed networks. Every tenth of a dB added in the combiner or feed path directly reduces radiated power and system efficiency. A Df of 0.0018 keeps those losses minimal even in long or complex feed network topologies.

Satellite and Aerospace Hardware

The NASA outgassing qualification, combined with the UL94-V0 rating and stable performance across wide temperature swings, opens DiClad 527 to space-borne and airborne electronic assemblies where material qualification is a significant up-front requirement.

Arlon DiClad 527 vs. DiClad 522: Knowing Which to Choose

The DiClad 527 and DiClad 522 are closely related materials, and the right choice depends almost entirely on your stack-up requirements.

Parameter	DiClad 527	DiClad 522
Dk @ 10 GHz	2.40 – 2.65	2.40 – 2.60
Df @ 10 GHz	0.0018	0.0018
Minimum Core Thickness	0.005″ (0.127 mm)	0.015″ (0.381 mm)
Maximum Core Thickness	0.060″ (1.524 mm)	0.250″ (6.350 mm)
Best Application	Thin-core multilayer RF modules	Standard and thick single-core RF boards
Dk Range	Slightly wider (to 2.65)	Slightly narrower (to 2.60)

The electrical performance is essentially identical between the two — same Df, similar Dk range, same CTE and peel strength data. The decision comes down to stack-up geometry. If your design needs a core thinner than 0.015″, DiClad 527 is the right answer. If your design works with cores 0.015″ and thicker, DiClad 522 gives you access to thicker stock options up to 0.250″ which DiClad 527 doesn’t cover.

DiClad 527 vs. Rogers RT/duroid 5880: A Practical Comparison

RT/duroid 5880 is perhaps the most common reference point when evaluating any low-loss PTFE laminate. Here’s how DiClad 527 compares:

Parameter	Arlon DiClad 527	Rogers RT/duroid 5880
Glass Reinforcement Type	Woven fiberglass	Random glass microfibers
Dk @ 10 GHz	2.40 – 2.65	2.20
Df @ 10 GHz	0.0018	0.0009
Minimum Thickness	0.005″ (0.127 mm)	0.005″ (0.127 mm)
Dimensional Stability	Excellent (woven glass)	Good
Mechanical Rigidity	Higher (more glass)	Lower (soft)
Ease of Fabrication	Better (stiffer)	Harder (soft material)

RT/duroid 5880 has a lower Dk (2.20 vs 2.40–2.65) and a lower Df (0.0009 vs 0.0018), so it offers both wider trace widths for a given impedance and marginally lower insertion loss. However, the random glass microfiber construction of RT/duroid 5880 makes it softer and harder to handle during fabrication. DiClad 527’s woven glass structure gives it an edge in dimensional stability and processability, particularly in multilayer constructions where registration accuracy matters. For designs where the extra mechanical rigidity of DiClad 527 simplifies fabrication and improves registration, the slight Df penalty over RT/duroid 5880 is an acceptable trade.

DiClad 527 vs. Rogers RO4350B

RO4350B is a popular thermoset (non-PTFE) laminate and is worth mentioning because engineers sometimes ask whether it can substitute for DiClad 527.

Parameter	Arlon DiClad 527	Rogers RO4350B
Base Chemistry	PTFE / Woven glass	Hydrocarbon ceramic thermoset
Dk @ 10 GHz	2.40 – 2.65	3.48
Df @ 10 GHz	0.0018	0.0037
Processability	Requires PTFE-specific fab	FR-4-like processing
Cost	Higher	Lower
Lead-Free Assembly	Compatible	Compatible

RO4350B processes like FR-4, which is its biggest advantage — lower cost, more fabricators can handle it, and tighter process control from a larger installed base. But with a Dk of 3.48 vs DiClad 527’s range starting at 2.40, your trace widths will be significantly narrower for the same impedance, and the Df of 0.0037 is roughly double that of DiClad 527. For designs above 15 GHz or where insertion loss is a primary concern, DiClad 527 is the stronger performer.

PCB Fabrication Guide for Arlon DiClad 527

Working with PTFE-based laminates requires process adjustments that go well beyond what most FR-4 shops do routinely. Here’s what to know before your design goes to fab.

Drilling PTFE Laminates

PTFE is soft and viscous when cut. Standard FR-4 drill parameters will smear and tear the material rather than produce clean hole walls. Use sharp, new carbide drill bits, reduce spindle speed and feed rate relative to FR-4 parameters, and use entry and exit materials (phenolic backup is common) to support the laminate and reduce burring. Hit count per drill bit should be dramatically lower than FR-4 — consult your fabricator’s PTFE-specific drill parameter tables.

Surface Activation Before Plating

This is the most critical process difference between PTFE and conventional FR-4 fabrication. Raw PTFE surfaces are essentially non-bondable — they have almost no surface energy, and copper won’t adhere without treatment. Fabricators use either a sodium naphthalene chemical etch or a plasma etch to activate the PTFE surface before electroless copper deposition. Inadequate activation leads to solder pad lifting and via barrel delamination — failures that often don’t show up until thermal cycling in the field. Make sure your fabricator has documented, validated procedures for PTFE surface activation.

Pre-Bake Before Reflow

Even though DiClad 527 has water absorption of just 0.03%, pre-baking assembled boards at 105°C for two to four hours before reflow is standard practice for PTFE laminates. Any residual moisture creates steam during the rapid temperature rise of a reflow profile, which can generate micro-voids in the dielectric or cause delamination at the copper-PTFE interface.

Impedance Control and Dk Verification

Because DiClad 527 is available in multiple Dk values within the same thickness, your impedance-controlled traces must be calculated using the specific Dk of the laminate batch being used — not just the nominal range. Request the actual measured Dk certificate from your material supplier or fabricator, and input that value into your field solver. A difference of 0.05 in Dk at a core thickness of 0.010″ will shift a 50-ohm microstrip design by more than 1 ohm — significant for matching-sensitive RF circuits.

Multilayer Bonding and Hybrid Stackups

For DiClad-to-DiClad multilayer construction, use Arlon’s compatible PTFE bonding plies. Mixing DiClad 527 with FR-4 or other thermoset prepregs in a hybrid stackup is possible but requires careful CTE matching and thermal cycle planning — the very different Z-axis CTEs of PTFE and epoxy-glass materials can stress interface bonds and vias under thermal cycling. Work with a fabricator that has demonstrated experience in mixed-dielectric RF stackups.

For expert fabrication support with DiClad 527 and the full range of Arlon laminates, experienced Arlon PCB manufacturers can help you navigate stackup design, material sourcing, and process qualification.

A Real-World DiClad 527 Stackup Example

Here’s a practical 4-layer RF board stackup using DiClad 527 as the signal core:

Layer	Material	Thickness	Purpose
Top Copper (L1)	1 oz ED Copper	35 µm	RF signal / microstrip
Core 1	DiClad 527 (2.50 Dk)	0.020″ (0.508 mm)	Primary RF dielectric
L2 Copper	1 oz ED Copper	35 µm	Ground plane
Bonding Ply	PTFE compatible	~0.003″	Layer bonding
L3 Copper	1 oz ED Copper	35 µm	Ground plane
Core 2	DiClad 527 (2.50 Dk)	0.010″ (0.254 mm)	Thin stripline core
Bottom Copper (L4)	1 oz ED Copper	35 µm	RF signal / stripline

In this construction, L1 operates as a microstrip reference layer using the 0.020″ core to set trace width for 50-ohm impedance, while the thin 0.010″ core provides a tightly coupled ground reference for stripline structures on L4. DiClad 527’s availability of both thicknesses in the same material is what makes this clean symmetric stackup possible.

Useful Resources for DiClad 527 Engineers

Resource	Description	Link
Arlon Microwave Materials Guide (PDF)	Full guide covering DiClad, CuClad, CLTE, and all Arlon RF laminates	integratedtest.com (PDF)
DiClad 522/527 RS Components Datasheet (PDF)	Official RS-sourced technical data sheet for DiClad 522 and 527	docs.rs-online.com (PDF)
MatWeb Material Database	Searchable material property database entry for DiClad 522/527	matweb.com
LookPolymers Datasheet	Aggregated material data and property overview for DiClad 527	lookpolymers.com
Arlon EMD Official Site	Manufacturer’s official product documentation and technical resources	arlonemd.com
Arlon Laminate Guide (PDF)	Comprehensive Arlon laminate selection guide with full comparison tables	arlonemd.com (PDF)
Rogers DiClad 527 Product Page	Product overview and laminate properties tool access	rogerscorp.com

Frequently Asked Questions About Arlon DiClad 527

1. Why would I choose DiClad 527 over DiClad 522?

The single most important reason is core thickness. DiClad 527 starts at 0.005″ (0.127 mm), while DiClad 522 starts at 0.015″ (0.381 mm). If your stack-up requires a thin RF core — for tightly coupled stripline structures or for multilayer RF modules where the overall board thickness is constrained — DiClad 527 is the only DiClad option that can deliver it. Electrically, both materials have the same Df (0.0018) and overlapping Dk ranges, so there’s no meaningful RF performance difference between them. The decision is almost purely a stack-up geometry call.

2. Can Arlon DiClad 527 be used in lead-free assembly processes?

Yes. DiClad 527 is compatible with lead-free soldering processes. PTFE has a very high continuous use temperature, well above the peak temperatures seen in standard lead-free reflow profiles. The primary risk in lead-free assembly is moisture-induced delamination during the faster, higher-peak-temperature profiles — pre-baking boards before reflow addresses this directly. Confirm lead-free process compatibility with your specific assembly house and their particular thermal profile.

3. What surface finish works best with DiClad 527?

ENIG (Electroless Nickel Immersion Gold) is the most common surface finish used with DiClad 527 and RF laminates generally. ENIG provides a flat, solderable, and corrosion-resistant surface without the co-planarity issues of HASL. Immersion silver is also used in some RF applications where signal loss at the surface finish matters — at very high frequencies, the skin effect concentrates current at the conductor surface, and ENIG’s nickel layer adds some conductor loss. For applications above 20 GHz, direct immersion silver or OSP over rolled copper may be worth evaluating.

4. How does DiClad 527 handle at frequencies above 20 GHz?

DiClad 527 remains a viable substrate into millimeter-wave frequencies, though a few factors become more important as frequency rises. Conductor loss (driven by copper surface roughness and skin depth) becomes the dominant loss mechanism over dielectric loss above roughly 20 GHz — specifying low-profile or rolled copper foil reduces this. Glass fiber weave effects, where the periodic structure of the woven glass creates local Dk variations that scatter signals, also become more significant at mmWave frequencies. For the most demanding mmWave applications, materials with random or non-woven glass structures (like RT/duroid 5880) or ceramic-filled PTFE without glass reinforcement may offer lower overall loss. For most applications up to Ka-band (26.5–40 GHz), DiClad 527 performs well with appropriate copper foil selection.

5. Is DiClad 527 available as prepreg or bonding ply for multilayer use?

DiClad 527 itself is a core laminate, not a prepreg. For multilayer constructions using DiClad 527 cores, you need compatible PTFE-based bonding plies (also called bonding films or prepregs). Arlon supplies compatible bonding plies for DiClad multilayer constructions — always specify these through the same channel as your core material to ensure lot-to-lot compatibility. Do not attempt to bond DiClad 527 cores using standard FR-4 prepreg; the lamination temperatures and bonding chemistry are incompatible and will produce unreliable interlayer adhesion.

Conclusion

Arlon DiClad 527 earns its place in the RF and microwave designer’s toolkit through a combination of factors that no single competing product fully replicates: the extremely low dissipation factor of 0.0018 at 10 GHz, the availability of thin cores starting at 0.005″ for demanding multilayer stack-up geometries, good dimensional stability from the woven fiberglass reinforcement, multiple Dk options within each thickness for impedance design flexibility, and qualification data that covers everything from commercial wireless infrastructure to NASA-certified space hardware.

For engineers designing multilayer phased arrays, radar feed networks, or compact RF modules where thin cores are a hard constraint, DiClad 527 is frequently the best answer. The fabrication requirements are real and require a capable PTFE-experienced shop — but for the right application, the performance justifies the process complexity.