Arlon CLTE vs CLTE-MW vs CLTE-P: Which Laminate Is Right for You?

If you’ve spent any time specifying materials for phase-sensitive RF circuits, phased array antennas, or 5G millimeter-wave modules, you’ve probably run into the Arlon CLTE comparison problem: the product family shares a common name, but CLTE, CLTE-MW, and CLTE-P are solving three distinct problems. Picking the wrong one — or worse, not understanding that CLTE-P is a bonding layer rather than a core laminate — is the kind of mistake that costs you a spin on a prototype.

This article breaks down the entire CLTE family from first principles, using actual material specs and real application scenarios. It’s written for engineers who already understand the basics of PTFE laminate selection and want clarity on where each CLTE variant belongs in a design.

What Is the Arlon CLTE Family and Why Does It Exist?

CLTE is a ceramic powder-filled and woven micro fiberglass reinforced PTFE composite engineered to produce a stable, low water absorption laminate with a nominal Dielectric Constant of 2.98. Arlon’s proprietary formulation for CLTE materials creates a reduced Z-direction thermal expansion, nearer to the expansion rate for copper metal, improving plated through hole reliability.

That last sentence is the key to understanding why the CLTE family exists at all. Pure PTFE/glass composites have excellent dielectric properties but suffer from high Z-axis CTE — the kind of thermal expansion mismatch with copper that degrades PTH barrel reliability over time. The CLTE formulation introduced ceramic loading specifically to bring Z-axis CTE under control while preserving the low-loss character of PTFE.

The formulation was chosen to minimize the change in εr caused by the 19°C second-order phase transition in the molecular structure of PTFE. This temperature-stable εr simplifies circuit design and optimizes circuit performance in applications such as phased array antennas.

That 19°C PTFE phase transition is a real design headache: pure PTFE composites exhibit a measurable Dk shift at around 19°C, which translates directly into phase shift in beam-steering arrays and impedance drift in filter networks. The ceramic loading in CLTE suppresses that transition, making it the preferred material for phase-sensitive structures where Dk stability across temperature is mandatory.

CLTE retains the low loss tangent associated with PTFE. While once required only for microwave frequencies, low loss is also of great value in reducing crosstalk in high-speed digital applications and minimizes the power consumption of a circuit design.

Understanding the Three CLTE Members: Core Roles First

Before diving into spec comparisons, it’s worth being explicit about what each member of the CLTE family actually is — because CLTE-P is categorically different from the other two.

CLTE is the original standard laminate: a copper-clad, rigid core material used as the primary substrate in single- or multi-layer RF boards. It’s the material your traces are etched into.

CLTE-MW is a newer, thinner variant of the core laminate concept, optimized specifically for millimeter-wave frequencies. Like standard CLTE, it’s a copper-clad rigid substrate — but its reinforcement and thickness options were engineered for the constraints of 5G above 24 GHz and 77 GHz automotive radar.

CLTE-P is not a laminate at all. Arlon’s CLTE-P Prepreg Bonding Layer is a ceramic-filled PTFE coated glass stock that is used as a bonding ply for CLTE, CLTE-X, or CLTE-AT laminates. CLTE-P is a pre-preg material that consists of woven fiberglass fabric coated with a proprietary resin formulation. The proprietary resin is thermoplastic, not thermoset in nature.

That thermoplastic nature matters enormously in fabrication, as we’ll cover later. For now, the important point is that CLTE-P exists to bond CLTE and CLTE-MW layers together in multilayer assemblies — it’s not competing with the laminates for your trace layer; it’s enabling them to be stacked reliably.

Full Property Comparison: Arlon CLTE vs CLTE-MW vs CLTE-P

The table below brings the three family members together on the properties that matter most at the design and fabrication stage. Note that CLTE-P values reflect its role as a bonding layer — peel strength and flow behavior are the relevant metrics, not trace-level electrical properties.

Property	CLTE (Standard)	CLTE-MW	CLTE-P (Bonding Layer)
Material role	Core laminate	Core laminate (mmWave)	Bonding prepreg for CLTE builds
Dielectric Constant (Dk)	2.98 nominal	~2.98 (matched to CLTE)	~2.98 (Dk-matched to CLTE/CLTE-XT)
Dissipation Factor (Df @ 10 GHz)	~0.0025	~0.0015	N/A (bonding layer)
Z-axis CTE	Low (ceramic-controlled)	30 ppm/°C	N/A
Moisture absorption	Very low	0.03%	Very low
Glass reinforcement type	Woven micro-fiberglass	Spread glass	Woven fiberglass
Available thickness range	Standard (0.005″–0.125″+)	Thin (3–10 mil)	~0.0032″ as-received / ~0.0024″ post-lamination
Copper foil options	½, 1, 2 oz ED; rolled available	ED, reverse-treat ED, rolled	½ oz max (not recommended above)
Lamination temperature	Standard PTFE cycle	Standard PTFE cycle	288–300°C (thermoplastic reflow)
Lamination pressure	200–400 PSI	200–400 PSI	Full pressure throughout heat+cool
Target frequency range	Microwave, sub-40 GHz	5G mmWave, 28–77+ GHz	N/A
Primary applications	Phased arrays, radar, satellite	5G base station, automotive radar	Multilayer CLTE/CLTE-MW bonding
IPC spec reference	IPC-4103 (PTFE-based)	IPC-4103	IPC-4203 (adhesive/bonding ply)

CLTE: The Standard-Bearer for Phase-Stable Microwave Design

H3: What Standard CLTE Does Best

Standard CLTE has been the material of choice for phase-sensitive microwave circuits for decades. Its combination of Dk 2.98, low Df, suppressed PTFE 19°C phase transition, and controlled Z-axis CTE makes it a strong default specification for:

• Phased array antenna feed networks where element-to-element phase consistency is the primary specification
• Radar manifolds and power dividers operating in the 2–40 GHz range
• PA and LNA boards where thermal management and insertion loss both matter
• Satellite and space electronics requiring stability across wide temperature swings

CLTE’s tight Dk and thickness tolerance, thermally stable Dk and Df, and dimensional stability make it ideal for radar manifolds, phased array antennas, microwave feed networks, phase-sensitive electric structures, PAs, LNAs, LNBs, and satellite and space electronics.

H3: CLTE’s Processing Characteristics

The Arlon CLTE family of laminate and bonding products is designed to be physically and electrically stable for use in high frequency applications where low loss, dimensional stability, thermal stability of dielectric constant, and low water absorption are required. CLTE materials used in stripline or microstrip applications can be processed using conventional PTFE board fabrication processes and techniques. CLTE can be processed using typical FR-4 process parameters with few in-line adjustments.

That last point deserves emphasis: CLTE sits in a useful middle ground compared to other PTFE systems. It can be run through more conventional equipment than some high-performance PTFE grades, without the radical process departures that pure PTFE composites sometimes demand. Drill with highly polished carbide tools, stack panels conservatively, and follow Arlon’s guidelines on sodium or plasma etch for PTH wall activation — the process is established and well-documented.

Dielectric constant of CLTE does vary with thickness up to about 0.015 inches. This is a practical note for designers: when working at thin substrates in the 5–15 mil range, confirm Dk from the datasheet’s thickness-dependent table rather than assuming the nominal value.

CLTE-MW: Why a Separate Grade for Millimeter-Wave?

H3: The Glass Weave Problem at High Frequency

Standard CLTE uses woven micro-fiberglass reinforcement — a good choice for dimensional stability and Dk uniformity in the 1–40 GHz range. But at millimeter-wave frequencies (28 GHz, 39 GHz for 5G; 77 GHz for automotive radar), the periodic structure of a woven glass weave becomes a non-trivial issue. The alternating resin-rich and glass-rich zones in a woven fabric create a spatially varying effective Dk. For a microstrip transmission line at 77 GHz, the electrical wavelength is short enough that this variation causes measurable phase and loss inconsistency depending on trace orientation relative to the weave direction.

Rogers CLTE-MW laminates are reinforced with spread glass, which along with a high filler loading helps minimize the high frequency glass weave effects on electromagnetic wave propagation. Their woven glass reinforcement also provides excellent dimensional stability.

Spread glass — a mechanically opened version of standard woven fabric — distributes glass strands more uniformly and reduces the peak spatial variation in Dk. Combined with high ceramic filler loading, CLTE-MW essentially presents a more homogeneous dielectric to the electromagnetic wave at millimeter-wave frequencies, reducing the orientation sensitivity that would otherwise require designers to carefully align trace routing to the weave direction.

H3: Thickness Strategy for mmWave Design

The seven available thickness options from 3 mils to 10 mils ensure that ideal signal to ground spacing exists for today’s 5G and other mmWave designs.

This is a practical constraint that standard CLTE doesn’t address. At 28 GHz in a 50-ohm microstrip on a material with Dk ~3, the substrate thickness that gives you a manufacturable trace width (say, 10–15 mils) is in the 5–8 mil range. Standard CLTE builds — typically starting at 10 mils or more — produce traces that are either very narrow (increasing conductor loss) or require moving to coplanar waveguide topologies. CLTE-MW’s thin substrate options let designers hit 50-ohm impedance with reasonable trace widths at these frequencies.

Other key features of CLTE-MW include low Z-axis CTE of 30 ppm/°C for excellent plated through hole reliability, a low loss tangent of 0.0015 at 10 GHz to enable low loss designs, and low moisture absorption of 0.03 percent to ensure stable performance in a range of operating environments.

The Df of 0.0015 at 10 GHz represents a meaningful improvement over standard CLTE’s ~0.0025. At 28 GHz and above, where dielectric loss scales with frequency, that lower baseline Df contributes directly to lower insertion loss in filters, feed networks, and antenna transitions.

H3: CLTE-MW Copper Foil Options

A variety of copper foil options are available including rolled, reverse treated ED, and standard ED. Resistive foil and metal plate options are also available upon request.

For millimeter-wave work, reverse-treated ED and rolled copper are preferred choices. Standard ED copper has surface roughness that becomes a significant conductor loss contributor at these frequencies — the skin depth at 77 GHz is roughly 0.24 µm, meaning that even moderate copper surface roughness adds measurable resistance. Specifying reverse-treat or rolled copper when ordering CLTE-MW is not optional for serious mmWave designs.

CLTE-P: The Bonding Layer That Makes Multilayer CLTE Possible

H3: Why CLTE-P Exists and What Makes It Unusual

Building multilayer boards from PTFE-based cores is fundamentally different from standard FR-4 multilayer fabrication. Standard epoxy prepregs cure at 170–185°C through a thermoset crosslinking reaction — they flow, fill, and then permanently set. You cannot re-flow them after cure. Standard PTFE cores require bonding approaches that accommodate PTFE’s non-adhesive surface chemistry and high melting point.

CLTE-P addresses this as a Dk-matched, ceramic-filled, woven fiberglass prepreg with a thermoplastic resin system. Unlike thermoset prepregs, CLTE-P flows at its lamination temperature, wets out the laminate surfaces, and solidifies on cooling — but remains capable of reflowing if re-exposed to sufficient temperature. This thermoplastic character sets the process requirements that dominate the CLTE-P fabrication discussion.

The prepreg material consists of woven fiberglass fabric coated with a proprietary resin formulation that is matched in Dk to the CLTE-XT and CLTE laminates. As received, the thickness of prepreg is approximately 0.0032 inches. After lamination, the thickness is compressed to approximately 0.0024 inches.

That dimensional change — from 3.2 mils to 2.4 mils after lamination — must be accounted for in stackup design. A four-layer CLTE board with two CLTE-P bonding plies has 0.8 mil less total dielectric height than you’d calculate from as-received materials. For tight impedance tolerances at microwave frequencies, that matters.

H3: CLTE-P Lamination Process Requirements

CLTE-P requires a lamination temperature of 550°F–572°F (288–300°C) to allow sufficient flow of the resin. The lamination temperature should be measured at the bond line using a thermocouple located in the edge of the product panel.

The 288–300°C bond-line temperature requirement is the headline constraint for shops new to CLTE-P processing. Standard epoxy lamination presses typically run to 200°C; running CLTE-P requires a press with both heat and cool cycles in the same opening, capable of reaching and accurately controlling temperatures at the 288–300°C level.

Full lamination pressure must be maintained throughout the cycle. Full pressure may range from 400 PSI for a hydraulic press to 200 PSI for a vacuum-assist press, depending on the specific application.

It is not recommended for bonding layers involving more than ½ ounce copper. This is a practical limitation: thick copper foil on inner layers resists the uniform resin flow that CLTE-P requires for void-free bonding. In designs requiring heavier inner-layer copper for power handling, consider building the copper up through plating after via formation rather than using heavy-clad inner layers at the lamination stage.

H3: CLTE-P Surface Preparation

Improved adhesion to the laminate surface can be obtained by using a sodium or plasma etch prior to bonding. Improved adhesion to the copper surface can be obtained by using a micro-etch prior to bonding. Black or Brown Oxide processes are not recommended due to the high temperatures reached during the bonding process.

The oxide process prohibition is a common trap for shops migrating from polyimide multilayer experience. Brown oxide is standard inner-layer preparation for most thermoset multilayer systems. With CLTE-P, the high bonding temperatures degrade the oxide layer and produce weak bonding. The ammonium persulfate micro-etch for copper surfaces and sodium/plasma etch for PTFE laminate surfaces are the correct approach.

Side-by-Side Application Decision Guide

The table below maps common RF and microwave design scenarios to the appropriate CLTE family member, with specific reasoning for each choice.

Design Scenario	Right Choice	Reason
6–18 GHz phased array feed network, 4-layer	CLTE (core) + CLTE-P (bonding)	Standard CLTE Dk stability, CLTE-P for multilayer bonding
Single-layer 10 GHz radar manifold	CLTE standard	No multilayer; standard CLTE is sufficient
28 GHz 5G base station antenna module	CLTE-MW	Spread glass eliminates weave effect; thin options enable 50-ohm geometry
77 GHz automotive radar front-end	CLTE-MW	Thin substrates, lower Df, spread glass critical at this frequency
High-power PA board (2–6 GHz) with thermal constraints	CLTE standard	High thermal conductivity in standard CLTE; proven at these frequencies
6-layer CLTE multilayer for satellite payload	CLTE (cores) + CLTE-P (5 bond plies)	CLTE-P is the only Dk-matched bonding option for CLTE multilayer builds
Multilayer mmWave module with CLTE-MW cores	CLTE-MW + CLTE-P	CLTE-P bonds CLTE-MW cores; Dk match preserved through stackup
LNA board with tight noise figure budget at 12 GHz	CLTE or CLTE-MW	Both low-loss; CLTE-MW preferred if conductor loss also in spec
Hybrid stackup mixing CLTE and polyimide	CLTE + polyimide-compatible bondply	CLTE-P is not appropriate for polyimide/PTFE hybrid bonds

Processing Comparison Summary

The following table gives fabrication engineers the at-a-glance process comparison they need when qualifying a new CLTE build.

Process Step	CLTE	CLTE-MW	CLTE-P
Inner-layer oxide treatment	Sodium/plasma etch (not oxide)	Sodium/plasma etch	Micro-etch on copper; sodium/plasma on laminate
Pre-lamination bake	1 hr at 110–120°C (moisture removal)	1 hr at 110–120°C	Vacuum desiccation recommended
Lamination temperature	Standard PTFE cycle	Standard PTFE cycle	288–300°C at bond line
Lamination pressure	200–400 PSI	200–400 PSI	200–400 PSI (constant through heat+cool)
Press requirement	Heat-only press acceptable	Heat-only press acceptable	Heat-and-cool cycle in same opening required
Copper foil limit	½, 1, 2 oz	½, 1 oz (thin builds)	½ oz maximum on bonded surfaces
Drilling	Polished carbide; no repointed tools	Polished carbide	N/A (bonding layer)
PTH wall activation	Sodium etch or plasma	Sodium etch or plasma	N/A
Solder mask timing	Apply promptly after etch; bake before HAL	Same	N/A

Where the Rest of the CLTE Family Fits In

The Arlon CLTE comparison doesn’t end at the three members in the article title. The full CLTE product family also includes:

CLTE-XT: The premium performance grade with a loss tangent of 0.0012 — the lowest in the CLTE class. It uses a micro-dispersed ceramic PTFE composite with the tightest available Dk and thickness tolerances and the highest thermal conductivity in the CLTE family. CLTE-XT is specified when insertion loss budget, Dk uniformity, or thermal management requirements are tighter than standard CLTE can satisfy. It uses CLTE-P as its bonding prepreg.

CLTE-AT: An improved-peel-strength variant that achieves CLTE-level electrical performance with better copper adhesion, using smoother reverse-treat copper foil rather than the rougher foils that competitive products sometimes require for adhesion. CLTE-AT also provides higher thermal conductivity than standard CLTE, making it the better choice for boards where heat dissipation from power amplifiers or high-current traces is a design constraint.

CLTE-LC: A lower-cost formulation for applications where the full performance specification of standard CLTE is not required. Useful when the primary constraint is dimensional stability and low moisture absorption rather than the tightest loss or Dk stability.

For the full Arlon CLTE comparison including CLTE-XT and CLTE-AT, the Arlon PCB material guide at PCBSync covers the complete CLTE family alongside Arlon’s polyimide and epoxy product lines.

Useful Resources for CLTE Design and Fabrication

Resource	What It Contains	Access
CLTE Datasheet (arlonemd.com)	Dk/Df vs. frequency and temperature curves, mechanical properties, ordering info	arlonemd.com → Products → CLTE
CLTE-MW Datasheet (rogerscorp.com)	Dk/Df specs, thickness options, copper foil options, quick reference process guide	rogerscorp.com → CLTE-MW
CLTE Fabrication Guidelines PDF	Detailed process steps for CLTE, CLTE-LC, and CLTE-P multilayer builds	Available via arlonemd.com Technical Library or cirexx.com/wp-content/uploads/CLTE-Fab.pdf
CLTE-AT Datasheet (PDF)	Peel strength data, thermal conductivity specs, CLTE-P bonding procedures	pwcircuits.co.uk/wp-content/uploads/2024/08/CLTE-AT1.pdf
Arlon Microwave & RF Materials Guide	Full portfolio reference including CLTE, AD Series, DiClad, CuClad	integratedtest.com — ArlonMaterials.pdf
Arlon Laminate FAQ Guide (“Everything You Wanted to Know”)	Deep-dive on PTFE processing, CTE, Tg, Dk measurement, and laminator guidance	arlonemd.com/wp-content/uploads/2020/05/Laminate-Guide.pdf
IPC-4103	Specification for high-frequency PTFE-based laminates	ipc.org
IPC-TM-650	Standard test methods for Dk, Df, peel strength, CTE	ipc.org
Rogers Laminate Properties Tool	Interactive Dk/Df/thickness comparison across all CLTE variants	rogerscorp.com → Laminate Properties Tool
PCBSync Arlon PCB Overview	Application guide and grade selector for Arlon materials	pcbsync.com/arlon-pcb/

5 FAQs: Arlon CLTE Comparison

FAQ 1: Can I use standard CLTE for 5G millimeter-wave above 28 GHz?

Standard CLTE will work electrically — the loss and Dk are adequate — but you’ll run into two practical problems. First, standard CLTE’s minimum thickness options are too thick for practical 50-ohm microstrip geometries at 28 GHz and above. The trace widths required for controlled impedance become so narrow that conductor losses dominate and manufacturing tolerance becomes a yield issue. Second, standard woven micro-fiberglass reinforcement introduces a spatial Dk variation that is negligible at sub-20 GHz but measurable at 28 GHz and above. CLTE-MW’s spread glass reinforcement and thin substrate options specifically address both problems. For prototype work at 28 GHz on standard CLTE, you can use coplanar waveguide topologies to tolerate substrate thickness, but for production mmWave designs, CLTE-MW is the right tool.

FAQ 2: Is CLTE-P interchangeable with standard PTFE bondply products?

No, and this is a critical point. CLTE-P uses a thermoplastic proprietary resin system — not a standard thermoset PTFE bondply or a film adhesive system. Its 288–300°C lamination temperature, full-cycle pressure requirement (heat and cool in the same press opening), and ½ oz copper limit are all specific to its thermoplastic character. Using a different bondply with CLTE cores — for example, a lower-temperature thermoset bondply — will not produce the Dk match that CLTE-P provides, and may produce void-fill, adhesion, or dielectric uniformity problems. Always specify CLTE-P as the bonding layer for CLTE, CLTE-XT, and CLTE-AT multilayer assemblies.

FAQ 3: How does Arlon CLTE compare to Rogers RO3003 for phased array work?

These are direct competitors for the same applications. Rogers RO3003 has Dk 3.00 — essentially identical to CLTE’s 2.98 — with Df of approximately 0.0013 at 10 GHz, which is lower than standard CLTE’s ~0.0025. CLTE-XT, with its 0.0012 Df, is the appropriate Arlon CLTE comparison point against RO3003 on loss performance. Where CLTE has historically competed on processability and cost-effectiveness, especially for builds where the full panel-level thermal conductivity of CLTE benefits power amplifier thermal management. Both materials require PTFE-specific fabrication. For phased arrays where Dk stability across temperature is the primary specification, both materials perform well due to ceramic loading suppressing the PTFE phase transition. The final choice often comes down to fabricator qualification and volume pricing.

FAQ 4: Does CLTE-MW use CLTE-P as its bonding layer in multilayer designs?

Yes. Despite the different laminate formulations, CLTE-MW uses CLTE-P as its bonding prepreg for multilayer construction — the same material used to bond standard CLTE. CLTE-P’s Dk is matched to CLTE-XT and CLTE laminates, and its Dk at approximately 2.98 is compatible with CLTE-MW’s similarly matched Dk. The same 288–300°C lamination temperature, pressure requirements, and surface preparation guidelines apply when bonding CLTE-MW with CLTE-P. One practical note: since CLTE-MW builds are typically working at very thin core dielectrics (3–10 mil), the 2.4 mil compressed thickness of CLTE-P after lamination represents a larger fraction of the total stackup and must be explicitly accounted for in your impedance calculations.

FAQ 5: What is the right CLTE variant for a military radar that cycles from -55°C to +125°C continuously?

This is a classic CLTE application, and it’s exactly the environment the material family was engineered for. Standard CLTE or CLTE-XT are both appropriate, with the choice between them driven by how tight your insertion loss specification is. The more critical specification is likely Dk stability across the full -55°C to +125°C range — and here CLTE’s ceramic-loaded formulation, which suppresses the 19°C PTFE phase transition, makes it far more suitable than non-ceramic PTFE/glass composites like DiClad. If the radar design requires significant power handling (meaning thermal conductivity matters), CLTE-AT or CLTE-XT offer improved thermal conductivity over standard CLTE. For the multilayer bonding plies in this environment, CLTE-P’s thermoplastic character means it can survive repeated excursions through the full temperature range without delamination, since it has no glass-transition event in the normal operating range. The fabrication specification should call out CLTE-P specifically rather than a generic “PTFE bondply” to ensure a qualified supplier uses the correct material.

Making the Right CLTE Choice

The Arlon CLTE comparison comes down to three questions that align directly to the three family members.

What is your operating frequency? If you’re working above 24 GHz — 5G sub-mm wave bands, Ka-band, automotive radar at 77 GHz — CLTE-MW’s spread glass, thin substrate options, and lower Df are specifically built for you. Below that, standard CLTE or CLTE-XT covers the frequency range with a deeper fabricator pool and a longer production history.

Do you need multilayer construction? If yes, CLTE-P enters the design as the Dk-matched bonding layer — not as an alternative to the core laminate, but as the material that makes the multilayer build possible while preserving the dielectric properties your electrical design depends on.

What is your performance tier? Standard CLTE is the workhorse — suitable for the majority of phased array, radar, and satellite applications. CLTE-XT is the premium choice when insertion loss, Dk uniformity, or thermal management push beyond what standard CLTE can deliver. CLTE-AT is the right call when peel strength and thermal conductivity improvements justify the step up from standard CLTE without going to full CLTE-XT pricing.

For a complete picture of how CLTE fits within Arlon’s broader material portfolio — including the AD Series PTFE composites, polyimide grades, and epoxy systems — the Arlon PCB resource at PCBSync is a solid reference before you finalize your material specification.