Learn how Arlon AD bondply bonds high-frequency PTFE laminates in multilayer PCBs — grades, stackup design, lamination parameters, and FAQs for RF engineers.

If you’ve ever tried to build a multilayer RF board using PTFE-based laminates, you already know the headache. PTFE doesn’t bond like FR-4. It flows differently, expands differently, and if you try to laminate it using standard epoxy prepreg, you end up with either mismatched dielectric properties or delamination failures down the road. That’s exactly where Arlon AD bondply enters the picture — and for engineers working on base station antennas, phased array radars, or 5G infrastructure boards, understanding this material properly can be the difference between a first-pass success and a very expensive stack of scrap.

This guide covers everything you need to know: what the AD Series actually is, how its bonding plies work, how to select the right grade for your stackup, and practical tips on multilayer lamination processing. Whether you’re designing a hybrid RF/digital board or an all-PTFE microwave structure, let’s dig in.

What Is the Arlon AD Series? Understanding the PTFE Composite Foundation

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The Arlon AD Series is a family of woven fiberglass-reinforced PTFE composite laminates engineered specifically for printed circuit board substrates in high-frequency applications. What makes it unique compared to traditional PTFE-only substrates is the deliberately higher fiberglass-to-PTFE ratio. This design choice trades a small amount of raw electrical performance for a significant improvement in dimensional stability — something that matters enormously when you’re trying to hold tight impedance tolerances across a multilayer panel.

Arlon’s Electronic Materials Division (EMD), based in Rancho Cucamonga, California, has been producing PTFE-based microwave laminates for over 50 years. The AD product line sits within their microwave materials portfolio alongside CuClad, DiClad, CLTE, and AD1000 series materials, covering dielectric constants from roughly 2.17 up to 10.2.

For the AD Series specifically, dielectric constants range from 2.5 to 3.5, available in dielectric thicknesses from 0.015″ to 0.062″, with custom thicker options available on request. The full lineup covers multiple Dk targets suited to different transmission line geometries and frequency bands.

Key Electrical Attributes of the AD Series

The core electrical appeal of the AD Series is the combination of low loss tangent and stable dielectric constant across a broad frequency range — two things that PTFE does exceptionally well compared to FR-4 or standard epoxy laminates.

Property	Typical Value	Test Method
Dielectric Constant (Dk)	2.5 – 3.5 (grade-dependent)	IPC-TM-650 2.5.5.5 / FSR
Loss Tangent (Df)	0.0014 – 0.003	IPC-TM-650 2.5.5.5
Z-axis CTE	Lower than standard PTFE	IPC-TM-650 2.4.24
Water Absorption	< 0.1%	IPC-TM-650 2.6.2
Copper Peel Strength	Standard ED / RTF foil	IPC-TM-650 2.4.8

These numbers put the AD Series comfortably ahead of FR-4 (Df typically 0.018–0.025) and broadly in line with competitive PTFE/glass materials from Rogers and Taconic — though specific loss tangent values vary significantly between AD grades.

The AD Series Lineup: Choosing the Right Grade

Not all AD grades are the same. Over the years Arlon has expanded and refined the lineup, introducing ceramic-filled variants (designated with the “A” suffix) that offer even better thermal stability and lower loss. Here’s a practical breakdown:

AD Series Grade Comparison

Grade	Dk (Nominal)	Key Feature	Best Use Case
AD250	2.50	PTFE/glass, cost-optimized	Antenna substrates, combiner boards
AD255A	2.55	Ceramic + PTFE + glass, very low Df (0.0014)	Base station, high-gain antenna
AD260A	2.60	Ceramic-filled, tight Dk tolerance, FSR tested	Telecom infrastructure, feed networks
AD300	3.00	Standard PTFE/glass, balanced Dk/cost	Stripline, general microwave
AD300A	3.00	Ceramic-loaded, improved CTE vs AD300	Hybrid multilayer stackups
AD320A	3.20 ± 0.04	Ceramic, stable to 40 GHz	mmWave, 5G, radar, medical imaging
AD350A	3.50	Ceramic-filled, higher Dk	Miniaturized circuits, filters
AD1000	10.2	Ultra-high Dk ceramic/PTFE	Miniaturization, patch antennas

The “A” designation — visible in AD255A, AD260A, AD300A, AD320A — signals the inclusion of micro-dispersed ceramic filler. This makes a real difference in practice. The ceramic loading reduces the coefficient of thermal expansion (CTE) in the Z-axis, bringing it closer to the expansion rate of copper. The result is improved plated through-hole (PTH) reliability, especially important in multilayer assemblies that see thermal cycling during assembly and field use.

Arlon uses the IPC TM-650 2.5.5.6 (FSR) test method on every panel for the ceramic-filled grades to guarantee dielectric constant consistency — not just statistical sampling. For production PCBs where impedance tolerance is held to ±5% or tighter, that per-panel testing matters.

What Is Arlon AD Bondply and Why Does It Exist?

Here’s where many PCB engineers get tripped up. When you build a multilayer board using AD Series cores, you can’t just sandwich them together with standard FR-4 prepreg and call it a day. The mismatch in dielectric properties and CTE between an epoxy prepreg and a PTFE core would undermine your impedance calculations and create a mechanical weak point at the bond interface.

Arlon AD bondply refers to the bonding ply materials — low-density, resin-rich versions of the same PTFE-based material family — used to join AD Series cores in a multilayer stackup. Arlon supplies copper-clad laminates together with bonding plies and prepregs specifically formulated to maintain electrical continuity and mechanical integrity between layers.

The concept parallels what Rogers does with their 2929 bondply for RO3000 and RT/duroid series laminates: rather than using a dissimilar adhesive, you bond like-with-like. A bonding ply derived from the same PTFE composite system will have compatible Dk, Df, CTE, and thermal processing characteristics, preserving signal integrity across layer boundaries.

Three Bonding Methods for PTFE Multilayer PCBs

Understanding Arlon AD bondply requires understanding where it fits in the broader landscape of PTFE bonding approaches. There are fundamentally three methods used in industry:

Method	Material Used	Advantages	Limitations
Thermoplastic bonding films	FEP, CTFE, or PTFE films	Lowest electrical loss	High process temperature; not suited for sequential lamination
Thermoset prepreg / bondply	Arlon AD bondply, Rogers 2929	Sequential lamination capable; higher layer count	Slightly higher Df than thermoplastic films
Fusion (direct) bonding	No adhesive — direct PTFE-to-PTFE	Maximum electrical uniformity	Requires very high pressure (>1000 PSI), specialized press; challenging registration

The AD bondply approach falls into the thermoset/bondply category. It provides a middle path: better electrical properties than an epoxy prepreg, while being far more manufacturable than fusion bonding, which demands specialized induction heating press equipment and rigid process control.

For the majority of commercial wireless infrastructure boards — base station combiners, antenna feed networks, power dividers — the AD bondply approach offers the right compromise of performance, yield, and cost.

Multilayer Stackup Design with Arlon AD Bondply

Hybrid vs. All-PTFE Stackups

One of the most common real-world scenarios is the hybrid stackup: RF/microwave layers using AD Series cores, combined with lower-cost digital or power layers using FR-4 or mid-loss thermoset materials. This is economically attractive but introduces engineering challenges.

The primary concern is CTE mismatch. AD Series laminates, particularly the ceramic-filled “A” grades, have significantly lower CTE than standard FR-4. Under thermal cycling, differential expansion can stress the plated through-holes and cause barrel cracking or pad lifting. The AD bondply layer helps manage this transition, but the designer still needs to:

• Keep high-frequency signal layers together in the stackup (avoid crossing the PTFE/FR-4 boundary with critical RF signals)
• Size via drill diameters and aspect ratios conservatively for PTH zones that span both material types
• Discuss the stackup with the fabricator early — most shops that handle hybrid PTFE boards have proprietary lamination cycles optimized for specific material pairings

All-PTFE Stackup Considerations

For pure AD Series multilayers using AD bondply throughout:

• The bonding ply is a lower-density version of the core material, allowing it to flow into trace gaps under heat and pressure during lamination
• A general rule of thumb in the industry: use 5 mil bondply for every 1 oz of inner-layer copper to ensure adequate encapsulation around etched features
• Lamination pressure requirements are higher than standard FR-4 — typically exceeding 1000 PSI — and dwell time must be controlled carefully to bring the bondply to full cure without thermal overshoot
• PinLess lamination methods, commonly used for FR-4 multilayers, are problematic with PTFE because the standard spot-welding step requires very high local temperature and pressure that most welding machines can’t reliably deliver to PTFE. Pinned tooling or specialized induction welding equipment is typically required

Sample AD-Series Hybrid Stackup

Layer	Material	Role
L1	AD260A (0.020″)	RF signal layer — microstrip
Bond	AD bondply	Inter-layer adhesive
L2–L3	AD260A (0.031″)	Ground / power plane
Bond	AD bondply	Inter-layer adhesive
L4	AD260A (0.020″)	RF signal layer — stripline
Transition	Low-flow thermoset prepreg	CTE buffer toward FR-4
L5–L8	High-Tg FR-4	Digital / control layers

The key principle: keep RF signal layers grouped within the AD Series zone, and use a controlled-flow transition prepreg when moving to the FR-4 region.

Processing Guidelines for Arlon AD Bondply

If you’re working with a contract manufacturer, making sure they have hands-on experience with PTFE-based multilayers is non-negotiable. Here are the main process parameters to confirm:

Inner Layer Preparation

PTFE-based laminates require a sodium naphthalene (sodium etch) or similar chemical treatment, or a plasma activation process, on the bond surfaces before lamination. Standard oxide or micro-etch surface treatments used for FR-4 are insufficient — they won’t provide adequate adhesion to the bondply. Skipping this step is a common root cause of delamination failures in the field.

Lamination Cycle

Typical parameters for AD bondply lamination (confirm with Arlon’s process guidelines for your specific grade):

Parameter	Typical Range
Pressure	800 – 1200 PSI
Peak Temperature	350°C – 380°C (for PTFE-based bondply)
Vacuum Level	< 10 mbar
Temperature Ramp Rate	2–5°C/min to cure zone
Dwell Time at Peak	30–60 min

Note that these cycles are substantially more aggressive than standard FR-4 lamination (typically 175–185°C, 300–500 PSI). Make sure your press, caul plates, and tooling are rated for these conditions.

Drilling and Through-Hole Plating

PTFE is soft and gummy compared to FR-4. Dull drill bits will smear PTFE into the hole wall, creating a contaminated surface that resists copper adhesion in the plating step. Use sharp, fresh drill bits, reduce drill speed or feed rate per the laminate manufacturer’s guidelines, and consider plasma de-smear rather than permanganic de-smear for PTFE-rich stackups.

Applications: Where Arlon AD Bondply Earns Its Keep

Engineers reach for Arlon AD bondply when the application demands both high-frequency electrical performance and the structural integrity of a multilayer PCB. Typical use cases include:

• 5G base station antennas and feed networks — where low insertion loss and tight impedance control at 28 GHz and above are critical
• Phased array radar systems — where phase consistency across dozens of parallel signal paths demands a substrate with stable, predictable Dk over temperature
• Satellite communication transponders — operating at Ka-band and higher, where every 0.1 dB of loss matters
• Medical imaging systems (MRI, ultrasound electronics) — high-frequency signal integrity combined with reliability requirements
• Power amplifier boards for wireless infrastructure — where both RF performance and thermal management (enhanced by the ceramic filler’s higher thermal conductivity) are needed simultaneously

For Arlon PCB fabrication services that can handle these demanding stackups, partnering with a manufacturer who stocks Arlon materials and has established process qualification is strongly recommended.

Arlon AD Series vs. Competitive Materials

For context, here’s how the AD Series positions against other commonly specified high-frequency substrates:

Material	Dk	Df (@10 GHz)	CTE Z-axis	Processability
Arlon AD260A	2.60	~0.002	Low (ceramic-loaded)	Standard PTFE process
Arlon AD320A	3.20	0.0032	Low (ceramic-loaded)	Standard PTFE process
Rogers RT/duroid 5880	2.20	0.0009	Moderate	Requires careful handling
Rogers RO4350B	3.48	0.0037	Low	Near FR-4 processability
Taconic TLY-5	2.17	0.0009	Moderate	PTFE standard process
Standard FR-4	4.2–4.8	0.018–0.025	High	Easiest, lowest cost

The AD Series “A” grades occupy a compelling middle ground: better loss performance than RO4350B (which is a thermoset, not PTFE), and far better dimensional stability and PTH reliability than glass-only PTFE laminates like RT/duroid 5880.

Useful Resources for Engineers

Resource	Description	Link
Arlon AD Series Datasheet	Official electrical and mechanical properties for all AD grades	arlonemd.com
Arlon Microwave & RF Materials Guide	Comprehensive laminate selector covering all Arlon microwave products	Available via Arlon EMD or authorized distributors
IPC-4103	IPC standard for high-speed/high-frequency base materials	ipc.org
IPC-TM-650 Test Methods	Standard test methods for Dk, Df, CTE, peel strength	ipc.org/TM
Arlon Laminate Guide PDF	Technical guide covering dielectric selection, loss, and multilayer design	arlonemd.com/wp-content/uploads/2020/05/Laminate-Guide.pdf
AD Series PDF Datasheet	Arlon’s official AD Series product sheet with Dk vs. frequency curves	cirexx.com/wp-content/uploads/AD-Series.pdf
RayPCB Arlon PCB Resource	Fabrication guidance and Arlon material overview for PCB production	raypcb.com/arlon-pcb

Frequently Asked Questions (FAQs)

Q1: Can I use standard epoxy prepreg to bond Arlon AD Series cores in a multilayer?

You can, but it’s generally not recommended for RF-critical layers. Standard epoxy prepreg has a much higher loss tangent (Df ~0.018–0.025 vs. ~0.002 for AD bondply) and a higher, mismatched CTE. For hybrid boards where only some layers are RF-sensitive, low-flow thermoset prepregs can be used as a transition layer between the PTFE zone and the FR-4 zone, but they should not sit directly adjacent to a critical RF signal layer if performance matters.

Q2: What’s the difference between Arlon AD bondply and Rogers 2929 bondply?

Both serve the same function — bonding PTFE-based multilayer laminates — but they’re chemically different systems from competing manufacturers. Rogers 2929 is a non-reinforced hydrocarbon-based thin-film adhesive (Dk ~2.9, Df <0.003), optimized for bonding RT/duroid and RO3000 series laminates. Arlon AD bondply is matched to the AD Series PTFE/ceramic composite family. While cross-manufacturer use is sometimes done in hybrid situations, best practice is to use the bondply from the same material family as your cores to ensure consistent Dk and CTE throughout the stackup.

Q3: What pressing equipment is required for AD bondply lamination?

AD bondply lamination requires a press capable of achieving 800–1200 PSI at temperatures up to 380°C under vacuum (<10 mbar). Conventional hydraulic flat presses equipped with high-temperature platens and a suitable vacuum system are commonly used. More recently, induction heating press systems (such as InduBond X-Press) have shown advantages for PTFE multilayers because they deliver uniform heat through stainless steel separators, reducing thermal gradients across the lamination book. For pin registration during layup, a pinned fixture system is recommended since spot-welding PTFE with standard PinLess welding machines is unreliable.

Q4: How does the ceramic filler in AD “A” grades affect bonding performance?

The micro-dispersed ceramic in grades like AD260A and AD320A serves two roles relevant to bonding. First, it reduces the Z-axis CTE to a value closer to copper’s expansion coefficient, which directly improves PTH barrel reliability during the thermal cycles of assembly and field use. Second, the ceramic loading improves dimensional stability in X-Y, reducing registration errors in high layer count builds. From a bondply perspective, the ceramic-filled core and the matching ceramic-filled bondply create a more uniform, homogeneous lamination that behaves predictably during repeated thermal cycling.

Q5: Is Arlon AD Series compatible with lead-free (Pb-free) assembly processes?

Yes, the AD Series and its bonding plies are compatible with lead-free soldering profiles. The ceramic-filled grades have decomposition temperatures well above the peak reflow temperatures required for SAC305 solder (typically 260°C peak). However, because PTFE-based substrates have lower CTE than FR-4, the cumulative strain on PTH barrels during lead-free reflow (which reaches higher peak temperatures than SnPb reflow) should be evaluated carefully, particularly for high-aspect-ratio vias. Using the ceramic-filled “A” grades, which have lower Z-axis CTE, mitigates this risk significantly compared to non-ceramic PTFE laminates.

Summary: When to Specify Arlon AD Bondply

As a PCB engineer, the decision to use Arlon AD bondply comes down to a few key questions: Is your board operating above 3 GHz where FR-4 loss becomes significant? Are you building a multilayer stackup where at least some layers need to be PTFE-based? Do you need the multilayer to survive assembly and thermal cycling without delamination or PTH failures?

If the answer to all three is yes, the AD Series — and specifically the ceramic-filled “A” grades — paired with their matched bonding plies, gives you a well-supported, industrially proven path to a high-performance, manufacturable multilayer. The material is backed by 50+ years of Arlon’s microwave laminate expertise, broad industry familiarity among RF PCB fabricators, and a solid documentation ecosystem that makes qualifying a new process straightforward.

The engineering tradeoff is real: PTFE processing is more demanding and more expensive than FR-4. But for anything running at microwave frequencies where insertion loss, phase stability, and impedance precision matter, the AD Series is a genuine workhorse material — and the bondply is what makes multilayer construction with it actually practical.