Taconic PCB Materials: TLX, TLY and RF-35 for Microwave and RF Applications

What Is Taconic and Why RF Engineers Specify Its Laminates

Taconic has supplied PTFE-based copper-clad laminates to the RF and microwave industry since 1961, building a product catalog that became a default reference point for radar, satellite, and base-station designers long before “5G” or “mmWave” entered the PCB vocabulary. In 2019, AGC acquired Taconic’s Advanced Dielectric Division and folded it into the same AGC Multi Material group that also owns the Nelco brand, but the TLX, TLY, and RF-35 product lines kept their original names and formulations. For engineers searching a BOM or a stackup spec, “Taconic PCB material” today almost always means one of these three families — or one of their close variants such as TLC, TLE, or RF-35TC.

What unites them is the base resin: polytetrafluoroethylene, or PTFE, the same fluoropolymer used in non-stick cookware and known commercially as Teflon. PTFE has an intrinsically low and frequency-stable dielectric constant, which is precisely the property that standard FR-4 lacks. Where FR-4’s dissipation factor climbs sharply above a few hundred MHz, a Taconic PTFE laminate stays well-behaved into the tens of gigahertz, making it the material of choice whenever insertion loss, phase stability, or VSWR cannot be compromised.

1. Table of Contents

• What Is Taconic and Why RF Engineers Specify Its Laminates
• Understanding Taconic’s PTFE-Based Laminate Family
• Taconic TLX Series: Woven-Glass PTFE for Volume RF Production
• Taconic TLY Series: Ultra-Low-Loss PTFE for Antennas and Sensitive Paths
• Taconic RF-35: Ceramic-Filled PTFE for Power Amplifiers and Couplers
• Comparing TLX, TLY and RF-35: Dk, Df and Processing Difficulty
• Typical Applications Across the Taconic Product Line
• Fabrication Considerations: Drilling, Plating and Hybrid Stackups
• How to Choose Between TLX, TLY and RF-35
• Manufacturing Taconic-Based RF Boards with NextPCB

Understanding Taconic's PTFE-Based Laminate Family

PTFE’s repeating molecular unit, —(CF₂–CF₂)_n—, is chemically inert and almost perfectly non-polar, which is why the bulk resin carries a dielectric constant (Dk, also written ε_r) of roughly 2.0 and a dissipation factor (Df, or tan δ) in the ten-thousandths. Pure PTFE film, however, is mechanically too soft and too prone to creep to use as a standalone PCB core, so Taconic blends it with a reinforcement and, in some products, a ceramic filler. The reinforcement choice is what separates the three families covered in this guide:

TLX uses a woven fiberglass reinforcement, the same general concept used in FR-4, which gives the laminate good dimensional stability and panel-to-panel consistency at a moderate Dk. TLY ruses a much lighter, more sparsely woven fiberglass than TLX, rather than eliminating the weave altogether microfiber mat, removing the periodic glass-knuckle pattern that causes small Dk variations across a board and pushing the dielectric constant lower still. RF-35 keeps a woven glass reinforcement but adds a ceramic filler to the PTFE resin, raising Dk to 3.5 and, more importantly, making the laminate behave mechanically much closer to FR-4 during drilling, plating, and lamination. Each path trades off loss, Dk precision, and ease of fabrication differently, which is why all three remain in production rather than one simply replacing the others.

Taconic TLX Series: Woven-Glass PTFE for Volume RF Production

TLX is Taconic’s workhorse microwave substrate and the laminate most commonly specified when a design needs a known, repeatable Dk without the handling sensitivity of a non-woven PTFE. The product line is sold in five grades — TLX-0, TLX-9, TLX-8, TLX-7, and TLX-6 — that share the same PTFE/woven-fiberglass construction but differ in glass content, which shifts the dielectric constant in controlled half-step increments.

Grade	Dk @ 10 GHz	Df @ 10 GHz (typical)
TLX-0	2.45	≈0.0012–0.0019
TLX-9	2.50	≈0.0015–0.0019
TLX-8	2.55	≈0.0017–0.0019
TLX-7	2.60	≈0.0020
TLX-6	2.65	≈0.0022

Beyond the electrical numbers, TLX is notable for moisture absorption under 0.02%, dielectric breakdown above 60 kV, and a long flight heritage — its low outgassing (TML around 0.02%, CVCM under 0.01%) is why it shows up repeatedly in satellite antenna feeds and space-qualified phased arrays. On the production floor, the woven glass gives TLX enough rigidity to be sheared, drilled, milled, and plated using methods that are recognizably similar to other PTFE/glass systems, which keeps fabrication risk lower than with the non-woven TLY series described next.

Taconic TLY Series: Ultra-Low-Loss PTFE for Antennas and Sensitive Paths

When a design has already squeezed out every other source of loss and the dielectric itself becomes the bottleneck, engineers turn to TLY. Removing the woven glass pattern in favor of a randomly oriented microfiber mat lowers the achievable Dk range to roughly 2.17–2.40 across grades such as TLY-5A (2.17), TLY-5 (2.20), and TLY-3 (2.33), with a dissipation factor around 0.0009 at 10 GHz — roughly half the loss of TLX at a comparable frequency.

That loss advantage comes with a fabrication trade-off. Because TLY relies on a fiber mat rather than a tight weave, the laminate is softer and more pliable, and panel-to-panel registration during multilayer lamination needs tighter process control than a woven-glass product requires. Thinner TLY cores in particular call for careful handling during drilling and routing to avoid distortion. For applications where the lowest possible insertion loss outweighs that extra process discipline — broadband antenna elements, LNA/LNB front ends, GPS and satellite-communication antennas, and high-Q filter sections — TLY remains difficult to beat on electrical performance.

Taconic RF-35: Ceramic-Filled PTFE for Power Amplifiers and Couplers

RF-35 takes a different design philosophy: instead of chasing the lowest possible Dk, it targets a moderate Dk of 3.5 by loading the PTFE resin with ceramic filler on top of a woven-glass reinforcement. The result is a dissipation factor in the 0.0018–0.0025 range depending on test frequency, a glass transition temperature above 315 °C that comfortably survives lead-free reflow, and CTE values closer to copper than pure PTFE laminates achieve — all of which combine to make RF-35 the most “FR-4-like” laminate in the Taconic catalog from a processing standpoint.

That processability is the real selling point. RF-35 can typically run through standard permanganate or plasma desmear rather than the sodium-etch step pure PTFE laminates often require, and its rigidity gives better inner-layer registration during lamination. Combined with respectable thermal conductivity, this makes RF-35 (and the higher-conductivity RF-35TC variant) a frequent choice for power amplifier pallets, narrow- and broadband couplers, and filters where every tenth of a dB and every degree of junction temperature matters, but where a full pure-PTFE process flow would add unnecessary cost.

Comparing TLX, TLY and RF-35: Dk, Df and Processing Difficulty

Property	TLX	TLY	RF-35
Reinforcement	Woven fiberglass	Lightweight woven fiberglass	Woven fiberglass + ceramic filler
Dk @ 10 GHz	2.45–2.65	2.17–2.40	3.50
Df @ 10 GHz	≈0.0019	≈0.0009	≈0.0018–0.0025
Moisture absorption	<0.02%	<0.02%	<0.02%
Relative ease of fabrication	Moderate	Most demanding (softer, less dimensionally stable)	Closest to standard FR-4 processing
Typical role	General-purpose microwave, radar, couplers	Ultra-low-loss antenna and front-end paths	Power amplifiers, thermally sensitive RF modules

The reason Df matters more than the table alone suggests comes down to how dielectric loss scales in a transmission line. A commonly used approximation for the dielectric component of microstrip attenuation is:

α_d ≈ 27.3 × D_f × √D_k ⁄ λ₀  (dB per unit length)

Because Df enters this relationship linearly while Dk only enters under a square root, halving the dissipation factor (as TLY does relative to TLX) cuts dielectric loss roughly in half, whereas a similar percentage change in Dk barely moves the needle. That is the electrical logic behind specifying TLY for loss-critical paths even when it costs more to fabricate. For engineers translating Dk and target impedance into actual trace geometry, NextPCB’s PCB impedance calculator can shortcut the hand math during early stackup planning.

Typical Applications Across the Taconic Product Line

TLX’s combination of moderate cost and proven flight heritage puts it in radar systems, phased-array antennas, mobile communication infrastructure, and microwave test equipment. TLY’s loss advantage concentrates it in front-end-sensitive hardware: low-noise amplifier and LNB stages, broadband and multi-band antenna elements, and satellite ground-terminal RF paths where every fraction of a dB of noise figure is budgeted. RF-35’s thermal and mechanical profile suits power amplifier output stages, base-station combiners and couplers, and filter banks — the kind of hardware found throughout 4G/5G RF infrastructure and increasingly referenced in the communication industry PCB segment.

Automotive is a growing application area for all three families, particularly in RF front-end and antenna sections that sit alongside the 76–81 GHz radar transceivers covered in our ADAS PCB design guide; while the radar MMIC layout itself usually lands on a ceramic-loaded laminate similar in spirit to RF-35, nearby antenna and coupler sections often reuse the same low-Dk PTFE logic discussed here.

Fabrication Considerations: Drilling, Plating and Hybrid Stackups

PTFE’s chemical inertness, the same property that gives it such low loss, also makes copper adhesion to via walls genuinely difficult. Pure-PTFE laminates like TLX and TLY typically require a sodium-etch or plasma surface treatment before electroless copper deposition, sharp PTFE-rated drill bits run at controlled-depth parameters to avoid smearing, and a lamination press cycle tuned to PTFE’s relatively high coefficient of thermal expansion. RF-35’s ceramic-filled, woven-glass construction tolerates standard permanganate or plasma desmear without the sodium-etch step, and its closer match to FR-4 mechanical behavior generally yields better drill registration on multilayer panels.

Many designs don’t use a Taconic laminate in isolation — they bond an RF-35 or TLX core to FR-4 structural layers in a hybrid stackup, keeping the expensive, loss-critical material only where the signal actually needs it. Hybrid bonding requires a blended lamination profile that accommodates both resin systems' cure characteristics simultaneously. Before committing a stackup to fabrication, running the design through NextPCB’s HQDFM software helps flag via, drill, and copper-balance issues specific to mixed-material panels early, when changes are still inexpensive.

How to Choose Between TLX, TLY and RF-35

A practical way to narrow the decision:

• If the design is loss-critical — an antenna element, LNA path, or any stage where noise figure or insertion loss dominates the budget — TLY is usually worth its extra process care.
• If the design needs a well-characterized, moderate-Dk substrate for general microwave work, couplers, or anything with space/flight heritage requirements, TLX offers the best balance of performance and manufacturing familiarity.
• If the design dissipates real power — a PA stage, a high-power coupler, or anything where junction temperature and processability matter as much as Df — RF-35 is the more practical choice.

It’s also worth situating these PTFE options against the broader laminate landscape. For high-speed digital interconnect rather than RF/microwave signal paths, a low-loss FR-4-class system such as the materials covered in our Isola PCB material guide is the more appropriate comparison point, since those laminates target SerDes channel loss rather than microwave Dk precision. Within the RF/microwave space itself, NextPCB’s Rogers PCB capability is the most common point of comparison to Taconic’s catalog, and the choice between the two brands often comes down to specific Dk targets, lead time, and panel cost rather than a fundamental performance gap.

Manufacturing Taconic-Based RF Boards with NextPCB

NextPCB fabricates TLX, TLY, and RF-35 boards as part of its broader high-frequency PCB capability, covering single laminate builds as well as hybrid PTFE/FR-4 stackups that combine RF performance with cost-effective structural layers. If you have a Gerber set ready, our advanced PCB quote tool can price non-standard laminate builds directly; for stackups still in development, our engineering team is available through contact us to help confirm material selection, copper weight, and panel size before the design is locked.