Arlon PCB Materials for 5G Applications: Best Choices in 2025

If you’re designing hardware for 5G infrastructure, one decision will shape everything else in your design process: the laminate. The Arlon PCB 5G laminate question comes up in nearly every infrastructure build because Arlon’s microwave material portfolio covers the full frequency range of 5G — from sub-6 GHz macro base stations all the way to 28 GHz and 39 GHz mmWave antenna arrays. Getting the material right from the start saves a respin, a failed compliance test, and months of frustration.

This guide is written from a working PCB engineer’s perspective. We’ll map each major Arlon laminate to specific 5G application scenarios, compare key electrical and thermal properties, and give you a clear selection framework based on what actually matters at these frequencies in 2025.

Why 5G Demands More from PCB Laminates Than Any Previous Generation

Standard FR-4 was adequate for 4G LTE hardware operating at 700 MHz to 2.6 GHz. At those frequencies, the Dk of 4.2–4.5 and Df of 0.015–0.025 were workable nuisances, not design killers. 5G changes the equation in two ways: the frequency bands are radically higher, and the antenna integration is physically tighter.

At 28 GHz, FR-4’s Df of 0.020 causes approximately 3× more signal loss per centimeter than a PTFE laminate with Df of 0.003. On a 10 cm transmission line — which is not even particularly long by base station standards — that difference is measurable in dB and directly reduces your effective isotropic radiated power (EIRP). For mmWave systems where link margins are already tight due to higher free-space path loss, that dielectric loss budget cannot be wasted on your substrate.

5G also drives a second material challenge: thermal load. Massive MIMO arrays for 5G NR integrate dozens to hundreds of antenna elements with active electronics on the same board. GaN power amplifiers operating at 25–30% efficiency at mmWave frequencies convert the majority of their input power to heat. Without a thermally capable laminate, junction temperatures rise, gain compresses, and MTBF drops. Arlon’s portfolio addresses both electrical performance and thermal management simultaneously, which is why it’s a recurring choice in 5G infrastructure hardware.

Understanding the Two 5G Frequency Regimes and What They Need

Before picking a laminate, you need to anchor your design to one of two fundamentally different frequency environments that define 5G in 2025.

Sub-6 GHz: Coverage-First 5G NR

Sub-6 GHz 5G (the n77 band at 3.3–4.2 GHz, n79 at 4.4–5.0 GHz, and C-band deployments at 3.5 GHz) handles the wide-area coverage layer of 5G networks. These are the frequencies that penetrate buildings, cover kilometers from a single site, and carry the majority of 5G traffic globally in 2025. PCB materials for sub-6 GHz work are less electrically demanding than mmWave — but they’re not a free pass to use FR-4.

At 3.5 GHz, insertion loss differences between materials become meaningful on long transmission lines, and the thermal requirements for 5G Massive MIMO at sub-6 GHz are significant. A 64T64R (64 transmit, 64 receive) active antenna unit (AAU) for sub-6 GHz runs dozens of PA chains simultaneously. Thermal management is a real constraint, not an afterthought.

mmWave: Capacity-First 5G at 24–39 GHz

The mmWave bands — primarily n257 (26.5–29.5 GHz), n258 (24.25–27.5 GHz), n260 (37–40 GHz), and n261 (27.5–28.35 GHz) — are where 5G delivers its headline capacity numbers: multi-gigabit downloads, sub-millisecond latency, and dense spatial multiplexing. These deployments are expanding rapidly in 2025 across urban dense networks, fixed wireless access (FWA), and enterprise private 5G.

At 28 GHz, the wavelength inside a typical Dk 3.0 laminate is approximately 6.2 mm. A quarter-wavelength structure measures just 1.55 mm. A standard through-hole via stub at 2–3 mm long is now a parasitic resonator that will crater your return loss. The skin depth of copper at 28 GHz is only 0.38 μm — meaning copper foil surface roughness of 2–4 μm (typical ED copper) is a dominant loss mechanism, not a secondary one. Everything tightens up at these frequencies, and the laminate you choose has to be specified with that reality in mind.

The Arlon 5G Laminate Portfolio: What’s Available and Why It Matters

Arlon PCB materials for 5G work span four distinct product families, each addressing a different point on the frequency-thermal-cost curve. Here’s how they map to 5G applications in 2025.

Arlon 25N / 25FR — Sub-6 GHz Backbone

The 25N is a ceramic-filled PTFE composite reinforced with woven glass. Its Dk of 3.38 at 10 GHz and Df of approximately 0.0025 make it a natural step up from FR-4 for sub-6 GHz 5G infrastructure. It processes on standard lamination equipment with modifications to the temperature ramp — no specialized PTFE presses required, which keeps your fabricator options wide and your lead time manageable.

The 25FR variant adds a UL94 V-0 flame retardant, which matters for commercial 5G equipment requiring CE marking and UL certification. For small cell products, RRU enclosures, and consumer CPE hardware where regulatory certification is mandatory, 25FR is the version to specify.

At 3.5 GHz, the 25N’s Df of 0.0025 delivers a meaningful improvement over FR-4 without the processing complexity or cost of the higher-performance CLTE series. For sub-6 GHz filter boards, power dividers, and combiner networks, the 25N/25FR is the right entry point into the Arlon 5G laminate family.

Arlon CLTE — The Workhorse for 5G Wireless Infrastructure

CLTE (Ceramic Laminate Thermoset Epoxy) is Arlon’s ceramic-filled PTFE composite with a nominal Dk of approximately 2.94–3.0. It directly competes with Rogers RO4003C in terms of electrical performance and application fit, and it’s been used in base station antenna and combiner board designs for the better part of two decades.

For 5G infrastructure in 2025, CLTE covers the sub-6 GHz range comfortably and extends into the lower mmWave bands with reasonable performance. Its Df of approximately 0.0025 at 10 GHz translates to manageable insertion loss for transmission lines in the 5–18 GHz range. The CLTE series also offers better multilayer reliability than unloaded PTFE — its CTE is closer to copper, which reduces the Z-axis expansion stress on plated through holes in high-layer-count antenna feed networks.

CLTE is specifically called out by Arlon as suitable for base station antennas and phased array radars — the same category of hardware that 5G massive MIMO systems fall into. In 2025, this positions CLTE as the most widely applicable Arlon 5G laminate for the sub-10 GHz range, balancing performance, multilayer capability, and production availability.

Arlon CLTE-XT — Built for 5G mmWave

CLTE-XT is the premium variant of the CLTE family, and in 2025 it is Arlon’s most relevant material for mmWave 5G work. Its specifications address every major challenge that 28 GHz and 39 GHz 5G design throws at a PCB engineer:

Df of 0.0009–0.0012 at 10 GHz — the lowest in Arlon’s entire microwave portfolio, and among the lowest of any commercially available laminate in its class. At 28 GHz, where dielectric loss scales significantly with frequency, that ultra-low Df translates to the best possible signal budget.

Near-zero thermal coefficient of Dk (TCDk) — critical for phased array antenna systems where beam pointing accuracy depends on consistent electrical length across all antenna elements over the operating temperature range. A CLTE-XT-based antenna array covering -40°C to +85°C (typical outdoor 5G hardware specification) maintains its phase relationships where a material with poor TCDk would introduce beam squint at temperature extremes.

Lowest moisture absorption in its class (< 0.02%) — outdoor 5G hardware faces condensation, rain, and humidity. Moisture changes the effective Dk, shifting impedances and resonant frequencies. CLTE-XT’s near-zero moisture uptake removes this variable from your design sensitivity analysis.

Lowest thermal expansion — designed to closely match copper’s CTE, CLTE-XT improves via reliability in the large-panel multilayer boards used in 5G massive MIMO feed networks. With 64 or 128 antenna elements feeding into a single board, via reliability is a life-limited failure mode that material choice directly influences.

Arlon TC350 — For 5G Power Amplifier Boards

TC350 is a ceramic-filled PTFE composite with a specific property that no other Arlon material matches: thermal conductivity of approximately 1.0 W/mK, combined with RF-grade dielectric performance (Dk ~3.5, Df ~0.004 at 10 GHz). For 5G GaN power amplifier boards, this combination is not available from most competing materials.

In a 5G base station PA module, the GaN HEMT devices operate at 28V supply and 30–40% PAE (power-added efficiency) at sub-6 GHz. For a 40W output PA, that’s approximately 60–80W of heat generation from a chip that occupies a few square millimeters of die area. Conventional low-loss PTFE laminates handle the RF performance but conduct heat poorly (~0.2 W/mK typical). TC350’s 1.0 W/mK allows thermal energy to spread laterally through the board and conduct to heatsink structures more effectively, reducing the thermal vias and copper fill density needed to hit junction temperature targets.

Arlon specifically positions TC350 for tower-mounted amplifiers and outdoor PA designs — exactly the category that 5G NR remote radio units (RRUs) fall into. The material also handles wide temperature cycling without the Dk drift that would cause gain variation and VSWR changes across the PA’s operating temperature range.

Arlon AD1000 — mmWave Antenna Beyond 40 GHz

The AD1000 is engineered for RF circuits operating above 40 GHz, including emerging 5G applications at n260 (37–40 GHz) and future mmWave expansions into the 60 GHz and 77 GHz ranges. It achieves a Dk under 3.5 even above 40 GHz — an important capability since most laminates show Dk drift as frequency increases into Ka band — combined with ultra-low insertion loss.

In 2025, AD1000 is relevant for frontier 5G hardware: 5G Fixed Wireless Access (FWA) CPE targeting the 37–40 GHz band, Next-generation AAU designs integrating sub-THz sensing alongside 5G communications, and 5G-linked automotive radar systems where the same hardware platform must serve both functions.

Arlon 5G Laminate Comparison: Core Properties at a Glance

Material	Dk @ 10 GHz	Df @ 10 GHz	Thermal Conductivity	Primary 5G Application
Arlon 25N / 25FR	3.38	0.0025	~0.25 W/mK	Sub-6 GHz infrastructure
Arlon CLTE	2.94–3.0	0.0025	~0.42 W/mK	Sub-6 GHz to 18 GHz
Arlon CLTE-XT	2.94	0.0009–0.0012	~0.42 W/mK	mmWave 5G (24–40 GHz)
Arlon TC350	3.5	0.004	~1.0 W/mK	5G PA boards, RRU
Arlon AD1000	< 3.5 @ 40+ GHz	< 0.003	~0.5 W/mK	Ka-band, 37–40 GHz 5G
Standard FR-4 (reference)	4.2–4.5	0.015–0.025	~0.3 W/mK	Not suitable above 2 GHz

Mapping Arlon Laminates to 5G Hardware Categories

5G Massive MIMO Active Antenna Units (AAU)

Modern 5G AAUs integrate the antenna array and radio unit into a single assembly. At sub-6 GHz, 64T64R configurations are now standard deployments. The PCB inside an AAU handles multiple functions simultaneously: patch antenna elements, feed network distribution, PA bias lines, and digital control routing.

For the RF layers of a sub-6 GHz 5G AAU, Arlon CLTE is a strong match — it offers adequate electrical performance at 3.5 GHz and 4.9 GHz, supports large-panel multilayer construction, and handles the thermal cycling that outdoor antenna hardware experiences across seasons.

For mmWave AAU designs targeting 28 GHz deployments, Arlon CLTE-XT is the correct choice. Phase consistency across all antenna elements is critical for beamforming accuracy, and CLTE-XT’s near-zero TCDk means beam pointing does not drift with temperature. This is not a marginal improvement — it is the difference between an antenna that maintains its beam pattern specification over the full operating temperature range and one that does not.

5G Small Cell and Tower-Mounted Amplifiers

Small cells (street furniture, indoor distributed antenna systems, enterprise picocells) run at lower power than macro base stations but face more constrained thermal environments. Many small cell designs use Arlon TC350 for the PA stage, where its thermal conductivity advantage over standard PTFE laminates reduces junction temperature enough to extend device lifetime to the target service life of 7–10 years.

Tower-mounted amplifiers (TMAs) operating at 3.5 GHz benefit from Arlon CLTE for the RF circuitry combined with TC350 if the PA chain is integrated into the same module. Hybrid stack-up approaches — where CLTE or 25N handles the antenna feed layers and TC350 handles the PA board — are increasingly common in 2025 as integration density increases.

5G Fixed Wireless Access (FWA) Customer Premises Equipment

FWA CPE is one of the fastest-growing 5G deployment categories in 2025, particularly for mmWave-based broadband replacement services. These indoor/outdoor units must operate across wide temperature ranges, resist moisture ingress, and maintain calibrated beam direction over their service life.

For FWA hardware targeting 28 GHz, Arlon CLTE-XT is the premium choice for the antenna board layer. Its moisture absorption below 0.02% and stable Dk across temperature directly protect beam accuracy without requiring active calibration loops to compensate for material-driven drift.

5G Backhaul and Fronthaul Links

The 5G network architecture requires high-capacity microwave and mmWave backhaul links connecting base stations to the core network. These point-to-point and point-to-multipoint links operate at 18 GHz, 28 GHz, 38 GHz, and emerging E-band (60–90 GHz) frequencies.

At 18–28 GHz, Arlon CLTE covers the loss requirements for most backhaul PCB assemblies. For links targeting E-band or the upper mmWave range, Arlon AD1000 or CLTE-XT is required to keep insertion loss within link budget.

5G-Specific Design Considerations When Using Arlon Laminates

Copper Foil Specification at mmWave

This is the design detail that separates engineers with mmWave experience from those without. At 28 GHz, the skin depth of copper is approximately 0.38 μm. Standard electrodeposited (ED) copper has surface roughness of 2–5 μm — roughly 5–13× the skin depth. The result is that current-carrying surface is not smooth copper but an irregular, high-resistance landscape that significantly increases conductor loss above what the ideal skin-effect formula predicts.

When specifying Arlon CLTE-XT or AD1000 for mmWave 5G boards, always specify low-profile (LP), very-low-profile (VLP), or HVLP copper foil on RF signal layers. The Arlon microwave-grade copper options for these materials are specifically selected to match the ultra-low dielectric loss of the substrate — there is no point achieving Df = 0.001 in the dielectric if standard ED copper causes 3–4× more conductor loss than the theoretical minimum.

Hybrid Stack-Up Strategy for 5G Mixed-Signal Boards

The 5G AAU and small cell designs that dominate 2025 hardware development are mixed-signal boards. RF antenna elements, mmWave routing, sub-6 GHz feed networks, digital baseband interfaces, and power electronics all share the same panel. Specifying Arlon CLTE-XT for every layer in a 20-layer mixed-signal board is both unnecessary and expensive.

The practical approach is a hybrid stack-up:

Layer Zone	Function	Recommended Material
Outer 2 layers	mmWave antenna / RF routing	Arlon CLTE-XT
Mid-stack RF layers	Feed network distribution	Arlon CLTE
Digital control layers	Baseband, control signals	High-Tg FR-4 or 45N
Power layers	DC distribution	High-Tg FR-4 or 45N

This approach concentrates premium laminate cost where it has measurable impact on performance and uses cost-appropriate materials for layers where FR-4-equivalent electrical performance is sufficient.

Dielectric Thickness Tolerance and Impedance Control

At 28 GHz, a 1% change in dielectric thickness shifts the characteristic impedance of a microstrip line by approximately 0.5–0.8 Ω. For a 50 Ω transmission line in an antenna feed network, a ±3 Ω impedance variation introduces measurable return loss degradation. Arlon’s RF laminate grades offer tighter dielectric thickness tolerances than commodity FR-4, which directly improves impedance control in production.

When ordering Arlon CLTE-XT or AD1000 for mmWave 5G boards, specify dielectric thickness tolerance explicitly in the purchase order and confirm your fabricator’s capability to hold ±10% or better on laminate thickness. Tighter than ±5% may require sorted incoming material — discuss this with both your Arlon distributor and your PCB fabricator before locking the stack-up.

Arlon 5G Laminate vs. Competing Materials

Engineers evaluating Arlon for 5G work inevitably compare it to the Rogers RO4000 series, which is the most widely specified RF laminate family in infrastructure hardware. The comparison is relevant because design engineers often inherit or reference Rogers-based designs.

Property	Arlon CLTE	Arlon CLTE-XT	Rogers RO4350B	Rogers RO3003
Dk @ 10 GHz	2.94–3.0	2.94	3.48	3.00
Df @ 10 GHz	0.0025	0.0009–0.0012	0.0037	0.0013
Thermal Cond. (W/mK)	~0.42	~0.42	0.69	0.50
TCDk	Very low	Near zero	Low	Low
Multilayer Capability	Good	Good	Excellent	Good
FR-4 Processability	Yes (modified)	Yes (modified)	Yes	No (PTFE)

The CLTE-XT’s Df of 0.0009–0.0012 is significantly lower than RO4350B’s 0.0037 — a genuine performance advantage for long mmWave transmission lines. For applications where insertion loss budget is extremely tight, CLTE-XT outperforms RO4350B at frequencies above 20 GHz. For designs where FR-4-compatible processing and readily available fabrication are the priority, RO4350B’s higher Df is often an acceptable trade-off.

Useful Resources for 5G Arlon Laminate Design

These references belong in your bookmarks before you finalize any 5G PCB stack-up:

• Arlon EMD Datasheet Library — arlonemd.com/resources/#data-sheets — Download current datasheets for CLTE, CLTE-XT, TC350, AD1000, and all 5G-relevant Arlon materials. Always use the latest version — properties have been refined over time.
• Arlon Microwave and RF Materials Guide (PDF) — Available at arlonemd.com/resources — Full product comparison and application mapping for Arlon’s microwave portfolio.
• Rogers 5G Material Selection White Paper — rogerscorp.com — Even if Rogers isn’t your final choice, this document’s methodology for 5G material evaluation is excellent and directly applicable to Arlon laminate selection.
• IPC-4101 Slash Sheet Database — ipc.org — Qualification standard for base materials. Confirm which slash sheet each Arlon material qualifies under before writing your BOM specification.
• PCB Directory Laminate Database — pcbdirectory.com — Searchable by Dk, Df, Tg, and CTE across manufacturers. Useful for cross-referencing CLTE against RO4350B and other materials in a single table.
• Sierra Circuits 5G PCB Design Guide — protoexpress.com — Practical reference covering copper foil selection, thermal management, and CTE considerations for 5G hardware.
• Arlon PCB Overview at PCBSync — pcbsync.com/arlon-pcb/ — Comprehensive material family overview with practical application guidance across Arlon’s entire product line.

5 FAQs on Arlon PCB 5G Laminate Selection

Q1: Is Arlon CLTE-XT really necessary for 28 GHz 5G, or can I use standard CLTE and save cost?

For short transmission lines (under 5 cm) at 28 GHz, standard CLTE’s Df of 0.0025 may be acceptable depending on your link budget. Run the math: at 28 GHz, the difference between Df = 0.0025 and Df = 0.001 over a 10 cm transmission line is approximately 1.2–1.5 dB of additional insertion loss with standard CLTE. If your design has that margin available, standard CLTE works. If you’re already fighting for every 0.5 dB in your EIRP budget — which most mmWave 5G hardware teams are — CLTE-XT’s lower loss directly contributes to real-world performance. Phase stability over temperature is the other differentiator; if your design requires consistent beam pointing over -40°C to +85°C, CLTE-XT’s near-zero TCDk is not optional.

Q2: Can I use Arlon 25N for a 5G massive MIMO antenna board at 3.5 GHz?

Yes, the 25N is a reasonable choice for 3.5 GHz antenna board layers in terms of electrical performance — its Dk of 3.38 and Df of 0.0025 are appropriate for that frequency. The constraint is thermal. In a 64T64R massive MIMO array, if PA or LNA stages are integrated onto the same board, TC350’s thermal conductivity advantage becomes relevant. If the antenna feed network is electrically separate from the PA board (as in a distributed architecture), 25N handles the antenna layers well. Confirm with your fabricator that they have prior experience handling 25N, as its softness compared to FR-4 requires operator attention during panel handling.

Q3: How does Arlon TC350 compare to Rogers RO4350B for a 5G GaN power amplifier design?

Both materials are used in PA board applications, but they have different primary strengths. RO4350B has lower Df (0.0037 vs. TC350’s 0.004 at 10 GHz) and slightly tighter Dk tolerance, making it the preference for narrow-band amplifier matching network designs where impedance precision is critical. TC350’s thermal conductivity (1.0 W/mK vs. RO4350B’s 0.69 W/mK) is a clear advantage for high-power applications where junction temperature is the life-limiting constraint. For 5G GaN PA designs at 3.5 GHz running 40W+ output, TC350’s thermal advantage often outweighs the marginal Df difference. Above 18 GHz, reconsider — TC350’s higher Df becomes more significant and RO4350B or CLTE becomes the better choice if the thermal load is manageable.

Q4: What fabricators in 2025 are reliably processing Arlon CLTE-XT for mmWave 5G production?

This is the most practical question and the one least covered in marketing materials. CLTE-XT, like all PTFE-based laminates, requires specific lamination parameter control — temperature ramp rates, press pressure profile, inner layer preparation — that not all shops execute consistently. As of 2025, fabricators with demonstrated Arlon PTFE processing capability include Cirexx International (specifically Arlon-certified), Hughes Circuits, and several larger Asian shops that have qualified Arlon materials for 5G production runs. Before committing to production quantities, request an impedance coupon measurement report and TDR characterization from any new fabricator. A shop that has run CLTE-XT before will proactively offer these — one that hasn’t may not even know to ask.

Q5: Is there an Arlon material suitable for 5G smartphone antenna-in-package (AiP) modules?

Smartphone AiP designs are primarily built on modified polyimide or LCP (Liquid Crystal Polymer) substrates rather than PTFE-based laminates, primarily because of the extreme thinness requirements and the flex/semi-flex integration with the phone’s main board. Arlon’s 55NT (aramid-reinforced epoxy, low CTE, excellent dimensional stability) is used in some compact, thin multilayer designs adjacent to AiP architectures. For the RF performance layer of an AiP targeting 28 GHz in a handset, Arlon’s PTFE materials are typically too thick and mechanically constrained for that integration. The Arlon 5G laminate portfolio is most applicable to infrastructure and CPE hardware rather than handset-level AiP integration, where specialized substrate suppliers dominate.

Final Thoughts: Choosing Your Arlon 5G Laminate in 2025

The 5G material selection decision in 2025 is more nuanced than it was three years ago, because 5G hardware now spans a much wider range of form factors and frequency bands — from ruggedized outdoor macro-cell AAUs to compact indoor small cells to FWA CPE with integrated antennas.

For sub-6 GHz deployments, Arlon 25N/25FR and CLTE cover the material requirements at a cost that works for high-volume infrastructure production. For mmWave, CLTE-XT is the material to evaluate first — its ultra-low Df and near-zero TCDk directly address the two technical requirements that make 28 GHz 5G difficult. For PA-dominated designs where thermal resistance is a first-order constraint, TC350 fills a unique role that nothing else in Arlon’s portfolio matches.

The choice between these materials comes down to three numbers in your design: the operating frequency, the insertion loss budget, and the junction temperature target. Get those defined early, run the loss calculations with each material’s Df at your operating frequency, and the right Arlon PCB 5G laminate will identify itself.