Arlon CuClad 6700: The PTFE Bondply That Makes Microwave Multilayer PCBs Actually Work

Anyone who has tried to build a true multilayer PTFE microwave PCB knows the fundamental problem: how do you bond layers of PTFE-based laminate — a material engineered specifically to not stick to anything — into a solid, reliable multilayer stack? PTFE’s chemical inertness is precisely what makes it so good for RF applications, and precisely what makes multilayer construction such a headache.

Arlon CuClad 6700 is one of the most established answers to that problem. It’s a CTFE (chloro-trifluoroethylene) thermoplastic co-polymer bonding film designed to laminate PTFE-based substrates in microwave stripline packages and multilayer RF circuits — with electrical properties that closely match the low-Dk PTFE laminates it’s bonding. For engineers designing microwave multilayers, knowing this material inside out is not optional.

This guide covers everything: what CuClad 6700 is, why its chemistry matters, the full specifications, how to process it correctly, where it fits in your stackup choices, and how it compares to the competing bondply options on the market today.

What Is Arlon CuClad 6700 and Why Was It Developed?

The Arlon CuClad 6700 bondply was originally developed by Arlon Materials for Electronics (now operating under Rogers Corporation after Rogers acquired Arlon LLC). The CuClad name refers to the broader product family of woven fiberglass/PTFE composite laminates that Arlon produced for RF and microwave PCB substrates — CuClad 217, 233, and 250 being the core laminates, with the 6250 and 6700 series serving as the companion bonding films for multilayer construction using those substrates.

The material is classified as a thermoplastic bonding film, not a thermoset prepreg. That distinction is critical to understanding how it behaves during lamination and in service. Thermoplastic films melt and flow at the bonding temperature, wet the PTFE surfaces, and re-solidify on cooling. They don’t undergo irreversible chemical cross-linking the way thermoset prepregs do. This means they can theoretically be remelted — which carries important implications for both assembly processes and end-use temperature limits that every designer needs to understand before specifying CuClad 6700 in a build.

For Arlon PCB designs that use PTFE-based core materials — whether CuClad 233, CuClad 250, or other PTFE composite substrates — the 6700 bonding film is the production-proven joining method that maintains the electrical character of the PTFE substrate stack without introducing a high-Dk, high-loss adhesive layer into the critical signal region.

Arlon CuClad 6700 Key Properties and Specifications

The complete specifications table below is drawn from the official Rogers/Arlon datasheet and corroborated by published test data. Always download the current datasheet directly from Rogers Corporation before finalizing stackup parameters — particularly for space-grade or defense-grade builds.

Table 1: Arlon CuClad 6700 Electrical Properties

Property	Value	Test Condition / Method
Dielectric Constant (Dk)	2.30–2.35	10 GHz
Dissipation Factor (Df)	0.0025	10 GHz
Dielectric Strength	>40 kV/mm	ASTM D149
Volume Resistivity	High	Standard conditions
Dk Match With	CuClad 217, 233, 250; DiClad series	Midrange of product line

Table 2: Arlon CuClad 6700 Physical and Thermal Properties

Property	Value	Notes
Material Chemistry	CTFE (Chloro-trifluoroethylene) thermoplastic co-polymer	Fluoropolymer family
Available Thicknesses	0.0015″ (0.038 mm) / 0.003″ (0.076 mm)	Two standard options
Available Format	24″ (610 mm) roll or sheet	Standard width
Thermoplastic Melt Temperature	~397°F (203°C)	Film melting point
Recommended Bond Temperature	400–475°F (204–246°C)	Press set point 450°F suggested
Hold Time at Bonding Temp	15 minutes minimum	Critical — insufficient time = failed bond
Recommended Pressure	~100 psi (up to 200 psi for complex circuits)	Uniform pressure required
Cool-Down Rate (max)	10°F/min (5.5°C/min)	Under pressure
Cool-Down Exit Temperature	Below 200°F before press opening	Prevents delamination
Remelt Temperature	~350°F (177°C)	Lower than initial melt — solder exposure risk
Water Absorption	Very low	Fluoropolymer-class
Outgassing	Low	RoHS/ESA compliant
Shelf Life	No limitation (sealed, <25°C, 70% RH)	Stored correctly
Space Certification	NASA/ESA compliant	Satellite applications
Flammability	Flame retardant	Fluoropolymer-inherent

Two numbers from that table deserve direct attention: the Dk of 2.30–2.35 and the Df of 0.0025. Those figures put CuClad 6700 squarely in the middle of the CuClad substrate family’s dielectric range, which is exactly the point — the bonding layer doesn’t create a significant dielectric discontinuity between substrate layers. For precision microwave stripline circuits where buried transmission lines must maintain consistent characteristic impedance, that Dk matching is the whole game.

Understanding the CTFE Chemistry: Why It Matters for Your Design

Standard PTFE (polytetrafluoroethylene) is extremely difficult to bond adhesively because of its non-polar molecular structure. Almost nothing wants to stick to it without aggressive surface treatment. CuClad 6700 addresses this by using CTFE — chloro-trifluoroethylene — a close fluoropolymer relative to PTFE that retains most of PTFE’s excellent electrical properties while having a lower melt viscosity and better surface adhesion characteristics.

The thermoplastic nature of CTFE also means the bonding film flows under heat and pressure during lamination, physically encapsulating copper trace features on inner layers and wetting the PTFE substrate surfaces. This mechanical interlocking, combined with the chemical compatibility between the CTFE and PTFE base materials, creates the inter-layer bond.

The important trade-off vs. thermoset bonding materials is the remelt behavior. At ~350°F (177°C), the CuClad 6700 bond can begin to soften. That’s comfortably above normal PCB operating temperatures, but it’s a meaningful constraint if your assembly process involves wave soldering or reflow with peak temperatures approaching or exceeding 260°C (500°F). For applications where the PCB will be soldered post-lamination, you need to either use DuPont Teflon FEP bondply (which has a higher remelt point), or manage assembly temperatures very carefully.

CuClad 6700 vs. Competing PTFE Bonding Films

Several bonding materials compete for the same multilayer PTFE application space. Here’s how they compare:

Table 3: Arlon CuClad 6700 vs. Competing PTFE Bondply Materials

Property	CuClad 6700	CuClad 6250	Rogers 3001	DuPont Teflon FEP	Rogers 2929
Chemistry	CTFE thermoplastic	EAA thermoplastic	CTFE thermoplastic	FEP thermoplastic	Thermoset
Dk	2.30–2.35	2.32	~2.3	2.1	2.9
Df	0.0025	~0.002	~0.003	0.001	0.003
Melt Temp	397°F (203°C)	213°F (101°C)	425°F (218°C)	565°F (296°C)	N/A (thermoset)
Remelt Temp	~350°F	~180°F	~350°F	~520°F	No remelt (thermoset)
Bond Pressure	~100 psi	Lower (foam-compatible)	~100 psi	Higher	~100 psi
NASA/ESA OK	Yes	No (low temp limit)	No	Yes	No
Solder-Safe Post-Bond	Borderline	No	Borderline	Yes (if below 520°F)	Yes (thermoset, stable)
Thickness Options	0.0015″ / 0.003″	0.0015″	0.0015″	Various	1.5 / 2 / 3 mil
Typical Application	PTFE multilayers, stripline, space	Pressure-sensitive foam assemblies	PTFE multilayers	High-temp PTFE multilayers	High-reliability RF multilayers

Reading this table, the CuClad 6700’s niche becomes clear. It delivers better Dk matching and lower Df than Rogers 2929 (which has a Dk of 2.9 — meaningfully higher than any CuClad substrate). It handles higher process temperatures than CuClad 6250, making it suitable for the standard PTFE lamination conditions. And it carries NASA/ESA compliance that DuPont Teflon FEP also supports but Rogers 3001 and 2929 do not.

If your build will see solder exposure post-lamination at high temperatures, FEP or thermoset 2929 is a more robust choice. For pure microwave stripline packages — sealed multilayers that don’t see further solder processing — CuClad 6700 is the field-proven standard.

Target Applications for Arlon CuClad 6700

Microwave Stripline Multilayer Packages

This is the core application the material was designed for. In a typical microwave stripline construction, you have signal layers buried between ground planes, with controlled trace geometry defining characteristic impedance. Using CuClad 6700 between CuClad 233 or CuClad 250 laminate layers gives you a true all-PTFE-family stackup with consistent Dk throughout the bonding layer — essential for predictable impedance and minimal insertion loss in filter, coupler, and power divider designs.

Phased Array Radar and Defense Electronics

Defense radar systems, particularly phased array antennas operating at X-band (8–12 GHz), Ku-band (12–18 GHz), and Ka-band (26.5–40 GHz), routinely use PTFE multilayer constructions with CuClad 6700 as the bondply. The material’s NASA/ESA compliance and its long established reliability record make it standard in many aerospace defense programs where both performance and supply chain traceability matter.

Satellite and Space Electronics

The explicit NASA/ESA compliance rating is significant here. Space electronics have zero tolerance for materials that outgas, since outgassing in vacuum can contaminate optical surfaces and sensors. CuClad 6700’s low outgassing behavior, combined with its proven electrical stability over wide temperature ranges, makes it a qualified bonding material for satellite RF subsystems.

Heat Sink and Metal Core PCB Bonding

CuClad 6700 is not just for layer-to-layer bonding within a PCB stack. It’s also used to attach PTFE-based circuit boards to heavy metal base plates — typically aluminum or copper-molybdenum — that serve as heat sinks in high-power RF amplifier modules. The bondply provides both the mechanical bond and a consistent dielectric layer between the PCB and the metal carrier.

Communication Infrastructure

Base station power amplifier boards, combiner networks, and feed networks for antenna arrays often use PTFE laminate constructions where CuClad 6700 serves as the inter-layer adhesive. The material’s short lamination cycle compared to thermoset prepregs is an advantage in higher-volume production of these platforms.

Arlon CuClad 6700 Multilayer Lamination Process: Step-by-Step

Getting the lamination right with CuClad 6700 requires attention to a few process steps that are non-negotiable. Skipping or shortcutting any of these is how you end up with a delaminated board or spotty bond in the center of the panel — which you won’t see until far downstream.

Table 4: CuClad 6700 Lamination Process Parameters

Step	Parameter	Value/Requirement
Surface Prep	PTFE etching	Chemical (FluoroEtch / Tetra-Etch) or gas plasma
Post-Etch Storage	Time before lamination	Within 24 hours of surface prep
Environment	Handling conditions	Clean, dust-free; use gloves
Bondply Prep	Pre-lamination prep required?	None — ready to use as received
Film Placement	Orientation	Lay between layers, ensure full coverage including trace heights
Thermocouple	Placement	Edge of bond line, inside the laminate (not the press platen)
Press Preheat	Set temperature	450°F (232°C) suggested
Minimum Bond Temp	At the bond line	400°F (204°C) minimum
Maximum Bond Temp	At the bond line	475°F (246°C) maximum
Pressure	Applied pressure	~100 psi (up to 200 psi for complex pattern fill)
Hold Time	Time at bonding temp	15 minutes minimum — do not cut short
Cool-Down Rate	Maximum rate	10°F/min (5.5°C/min) — under pressure throughout
Cool-Down Exit	Temperature for press opening	Below 200°F (93°C)
Transfer to Cooling Press	Acceptable?	Yes — transfer hot, maintain pressure

Surface preparation is the step most often shortcut, and shortcutting it is the most common root cause of bond failures. PTFE’s non-stick character means mechanical lamination alone — even at the right temperature and pressure — produces an unreliable bond to bare PTFE surfaces. Chemical etching with FluoroEtch or Tetra-Etch creates reactive sites on the PTFE surface by partially stripping fluorine atoms and exposing carbon, which then bonds chemically with the CTFE film. Gas plasma treatment achieves a similar result and is preferred in some clean-room fabrication environments.

The 15-minute hold time at temperature is equally important and equally often truncated in high-volume production. Insufficient time at temperature results in incomplete wetting of the PTFE surface — the bond will look complete visually but will fail under thermal cycling or mechanical stress. Whenever you’re qualifying a new fabricator for PTFE multilayer work, ask specifically about their hold time discipline.

How CuClad 6700 Fits Into the Broader CuClad Laminate Family

Understanding the full CuClad product line helps designers make stackup decisions that keep material properties consistent throughout the build.

Table 5: CuClad Substrate and Bondply Family Overview

Product	Type	Dk	Df	Primary Use
CuClad 217	PTFE/glass laminate	2.17–2.20	0.0009	Ultra-low Dk RF/microwave substrate
CuClad 233	PTFE/glass laminate	2.33	0.0013	Balanced Dk/loss RF/microwave substrate
CuClad 250	PTFE/glass laminate	2.40–2.60	0.0022	Higher Dk, better dimensional stability
CuClad 6700	CTFE thermoplastic bondply	2.30–2.35	0.0025	Multilayer bonding film for PTFE substrates
CuClad 6250	EAA thermoplastic bondply	2.32	~0.002	Low-pressure bondply for foam/sensitive substrates

The Dk of CuClad 6700 (2.30–2.35) sits comfortably in the middle of this family, between CuClad 217 and CuClad 250. For most multilayer designs using CuClad 233 (Dk 2.33), the bondply introduces essentially no dielectric discontinuity at the layer interface. For designs using CuClad 217 (Dk 2.17), there’s a small Dk step at each bondply layer — something to account for in your electromagnetic simulations of embedded transmission lines.

Design Considerations When Using CuClad 6700 in Your Stackup

A few points that engineers often overlook until they’ve been burned by them:

Account for the bondply thickness in your stackup. CuClad 6700 comes in 0.0015″ and 0.003″ thicknesses. These are nominal values before pressing. The actual finished bond line thickness after flow and compression under pressure will be slightly less — and it varies with your copper pattern density. In regions with dense copper, the film has less space to flow into and compresses less; in open areas, it flows more. Your SI models should treat the bond line thickness as an estimate, not an absolute, and should be calibrated against your fabricator’s actual process data.

Specify “LX” grade testing if your application demands tight Dk control. The standard CuClad product ships with lot-level electrical property assurance. For critical applications — military phased arrays, space-grade filters — you can specify that each piece be individually tested with a test report issued with the order.

Plan for the remelt temperature in your assembly flow. If your board will go through any process above 350°F (177°C) post-lamination, check whether your bond lines will see that temperature and plan accordingly. Many RF module builds keep the circuit lamination separate from any solder process, precisely to avoid exposing CuClad 6700 bonds to solder temperatures.

Gas plasma surface treatment improves adhesion repeatability in production. Chemical etching works, but its efficacy varies with the etchant concentration, temperature, and exposure time. Gas plasma is more controllable and repeatable in a production environment, and some fabricators find it produces more consistent peel strength results across a panel.

Useful Resources and Datasheet Downloads

Every engineer working with CuClad 6700 should have these resources bookmarked:

Resource	Link / Contact
Rogers Corp CuClad 6700 Product Page (official)	rogerscorp.com – CuClad 6700
CuClad 6250 & 6700 Combined Datasheet (PDF)	Available at rogerscorp.com product page / Arlon distributor
CuClad Laminate Series (217, 233, 250) Datasheets	rogerscorp.com – CuClad Series
Arlon EMD Official Website	arlonemd.com
Rogers Bonding Material Selector Tool	Available at rogerscorp.com/acs
IPC-4103 High-Frequency Laminate Standard	ipc.org
IPC-TM-650 Test Methods (Dk/Df)	ipc.org/test-methods
Insulectro (North American Arlon distributor)	insulectro.com
MatWeb CuClad 6700 Material Data	matweb.com – CuClad 6700

For space-grade or defense program applications, request material certificates with each shipment and verify lot traceability through your distributor. Rogers/Arlon maintains full traceability documentation for NASA/ESA-qualified material lots.

5 Frequently Asked Questions About Arlon CuClad 6700

Q1: Can CuClad 6700 be used to bond non-CuClad PTFE substrates — like Rogers RT/duroid or Taconic TLY?

Yes, with surface preparation. CuClad 6700 is a CTFE thermoplastic film that bonds to PTFE-based substrates generically, not exclusively to CuClad-brand materials. The key is proper PTFE surface etching (chemical or gas plasma) before lamination. Many fabricators use CuClad 6700 successfully with RT/duroid 5880 and similar PTFE/glass substrates. Verify compatibility and peel strength for your specific substrate combination before committing to production.

Q2: What happens if I exceed the 475°F maximum press temperature during lamination?

Exceeding 475°F at the bond line can cause the CTFE film to degrade — you may see discoloration, excessive flow (potentially shorting fine traces), or reduced bond integrity. The temperature window of 400–475°F at the bond line (not the press platen) is the working range. Always use a thermocouple at the bond line edge, not just on the press controller, since the lag between platen temperature and actual bond line temperature can be significant, especially in thick boards.

Q3: My PCB needs to be wave-soldered after multilayer lamination. Can I use CuClad 6700?

This is risky. The remelt temperature of CuClad 6700 is approximately 350°F (177°C), while wave solder baths run at 250–260°C (482–500°F) — well above the remelt point. Delamination is a real risk during wave soldering if the bond lines see those temperatures. For assemblies that must be wave-soldered post-lamination, use Rogers 2929 (a thermoset that doesn’t remelt) or DuPont Teflon FEP (remelt at ~520°F). If you must use CuClad 6700, keep the board thermally isolated from solder bath contact and verify your thermal profile at the bond line location.

Q4: Does CuClad 6700 require any special pre-baking or conditioning before use?

No special pre-baking is required. CuClad 6700 comes ready to use from the package. However, storage conditions matter: keep it in the original sealed packaging at or below 25°C (77°F) and at 70% relative humidity or lower, away from direct sunlight. Store rolls on edge or suspended from the roll core — laying rolls flat causes creasing and flat spots from the roll weight, which leads to uneven bonding. There is no defined shelf life when stored correctly.

Q5: My fabricator says they can achieve better results with Rogers 2929 bondply on a CuClad 250 multilayer. Is CuClad 6700 still worth specifying?

It depends on your electrical requirements. Rogers 2929 has a Dk of 2.9 — significantly higher than CuClad 6700’s 2.30–2.35 and significantly higher than CuClad 250’s Dk of 2.40–2.60. In a multilayer stripline design, the 2929 bond lines are electrically dissimilar from the substrate layers, which introduces a periodic dielectric perturbation in your buried transmission lines. For low-frequency microwave designs (below ~6 GHz), this difference may be insignificant. For precision filter and coupler designs at X-band and above, that Dk mismatch will affect your characteristic impedance calculations and should be modeled explicitly. If your fabricator is more comfortable with 2929, get them to run electromagnetic simulations comparing the two bondply choices in your actual stackup before making a final decision.

Conclusion: Choosing CuClad 6700 for Your Next PTFE Multilayer

If you’re designing a microwave multilayer PCB using PTFE-based substrates — stripline bandpass filters, combiner networks, phased array modules, or any other application where the bondply Dk is inside your signal path — Arlon CuClad 6700 remains the most electrically matched and field-proven option for production PTFE multilayer construction. Its Dk of 2.30–2.35 sits squarely in the middle of the CuClad laminate family range, its Df of 0.0025 is among the lowest available in any bonding film, and its NASA/ESA compliance opens the door to the most demanding aerospace and defense programs.

The processing requirements are more demanding than standard epoxy prepregs — proper PTFE surface etching, controlled press temperature with thermocouple verification, strict cool-down rate discipline — but those requirements are well-documented and well-understood by any fabricator with microwave PTFE experience. The material works. It’s been qualified on radar programs, satellite platforms, and infrastructure equipment around the world.

Before finalizing your stackup, download the current Rogers/Arlon datasheet, discuss your lamination process with your fabricator, and make sure their experience with PTFE multilayer construction is genuine. The material is only as good as the process behind it.