What Is Taconic TLY PCB Material? Properties, Applications and Design Guidelines

What Is Taconic TLY PCB Material?

TLY is Taconic’s lowest-dielectric-constant PTFE laminate family, and within the broader Taconic catalog covered in our Taconic PCB materials guide, it’s the line designers reach for when insertion loss — not Dk precision, not cost, not ease of fabrication — is the binding constraint on the design. With a dissipation factor around 0.0009 at 10 GHz, it remains one of the lowest-loss commercially available PCB laminates on the market, which is why it shows up disproportionately often in antenna elements, LNA front ends, and any RF path where every fraction of a dB matters.

1. Table of Contents

• What Is Taconic TLY PCB Material?
• Why TLY Achieves a Lower Dk Than TLX: Lightweight Woven Construction
• TLY Grades Compared: TLY-5, TLY-5A and TLY-3
• Electrical, Mechanical and Thermal Properties
• Typical Applications for TLY
• Copper Foil, Cladding and Sheet Size Options
• Design Guidelines: Drilling, Laser Vias and Flexible Variants
• TLY vs the Rest of the Taconic Family: When to Choose It
• Sourcing TLY Boards with NextPCB

Why TLY Achieves a Lower Dk Than TLX: Lightweight Woven Construction

It’s worth being precise about what actually makes TLY different from TLX, because the answer is often described imprecisely. TLY is not a non-woven or chopped-fiber laminate — it’s still built on a genuine woven fiberglass scrim, just a far lighter and more sparsely woven style than TLX uses. Since the glass fiber itself carries a dielectric constant well above pure PTFE resin’s roughly 2.1, reducing glass content pulls the composite’s bulk Dk down toward that resin baseline, landing TLY in the 2.17–2.40 range against TLX’s 2.45–2.65.

Taconic’s own published material analysis draws a direct comparison here: TLY’s woven construction is positioned as more dimensionally stable in production than the chopped-fiber-reinforced 2.2 Dk PTFE composites some competing suppliers use. That said, the same analysis is candid that it remains an open question whether woven or chopped-fiber reinforcement ultimately produces the more dielectrically homogeneous laminate at a microscopic level — both show comparable-scale variation in local glass-rich versus resin-rich domains. For the overwhelming majority of antenna and filter designs working from a few GHz up into low Ka-band, that domain-level variation sits well below anything that affects measurable performance; it only becomes a real design consideration at the tightest tolerances and highest frequencies.

TLY Grades Compared: TLY-5, TLY-5A and TLY-3

TLY-5A is worth calling out specifically: comparative OEM testing at 77 GHz against its closest chopped-fiber-reinforced competitor showed equivalent, “drop-in” insertion loss and dielectric performance, while delivering meaningfully higher manufacturing yields — a practical reason it has become a common substitute where TLY-5 was originally specified.

Electrical, Mechanical and Thermal Properties

Across the TLY family, Dk can typically be specified anywhere within the 2.17–2.40 range to a tolerance of ±0.02, which is tight enough to matter for resonant-frequency repeatability in antenna designs (more on that below). Dissipation factor in the low-Dk range runs approximately 0.0009 at 10 GHz, moisture absorption stays consistent with the broader PTFE family at well under 0.02%, and the material carries a UL-94 V-0 flammability rating. Peel strength is tested separately by copper type — ED copper and rolled copper claddings are both characterized — and dielectric breakdown is verified per ASTM D149.

That Dk tolerance has a direct, calculable effect on antenna performance. A microstrip patch antenna’s resonant frequency scales approximately as:

f_r ∝ 1 ⁄ √D_k

At Dk = 2.20 ± 0.02, that’s roughly a ±0.9% Dk tolerance, which — because resonant frequency scales with the inverse square root of Dk — translates to roughly ±0.45% frequency tolerance. For a 28 GHz element, that’s on the order of ±125 MHz of expected resonant-frequency shift across the material’s specified Dk window — a manageable margin for most phased-array designs, but worth budgeting explicitly rather than assuming away.

Typical Applications for TLY

TLY’s loss performance concentrates its use in satellite communications hardware, automotive radar designed around the 77 GHz band (the same application space covered in our ADAS PCB design guide), filters and couplers, avionics, phased array antennas, and LNB/LNA/LNC front-end stages where noise figure is as critical as insertion loss. Higher-frequency variants extend its use into Ka-, E-, and W-band millimeter-wave applications, where dielectric loss becomes an even larger share of total path loss.

Copper Foil, Cladding and Sheet Size Options

TLY ships in a standard sheet size of 36×48 inches (914×1220 mm), with electrodeposited (ED) copper as the most common cladding and rolled copper available on thinner constructions — generally under 15 mils — on a case-by-case basis, which matters for flexible or curved antenna builds. Heavier metal claddings, including aluminum, brass, and copper, are available on request for designs needing extra thermal mass or grounding, and resistive foil films can be specified where the design calls for integrated thin-film resistors directly on the laminate.

Design Guidelines: Drilling, Laser Vias and Flexible Variants

TLY follows the same general PTFE handling rules as the rest of the Taconic catalog — via walls typically need a sodium-etch or plasma surface treatment before plating, since copper doesn’t bond readily to untreated PTFE. Laser drilling is where TLY’s lightweight weave specifically pays off: heavier woven-glass laminates generally don’t laser-ablate as cleanly as chopped-fiber composites, but TLY’s sparse weave style ablates on par with chopped-fiber equivalents, and a dedicated laser-via-optimized construction exists specifically to push hole quality further for HDI-style microvia builds on RF boards.

Two purpose-built variants are worth knowing before you finalize a part number rather than after: a lightweight-fiberglass construction tuned specifically for laser-via hole quality, and an enhanced-flexibility version designed for antennas that need to conform to some curvature — relevant any time the mechanical form factor isn’t flat. NextPCB’s flexible PCB capability can support these conformal builds where the application calls for it. Even with TLY’s comparatively good dimensional stability for a low-Dk laminate, its lighter glass content still makes it less stiff than TLX, so multilayer registration benefits from the same controlled lamination pressure and temperature profiles used across the broader Taconic family.

TLY vs the Rest of the Taconic Family: When to Choose It

If your design needs Dk in the high-2s to mid-3s range, or needs to process more like standard FR-4, TLX or RF-35 — both covered in our Taconic PCB materials guide — are usually the better starting point. TLY earns its place specifically when insertion loss is the dominant constraint and a Dk in the 2.17–2.40 window fits your impedance and geometry targets; outside that combination, the extra process care it demands generally isn’t worth paying for.

Sourcing TLY Boards with NextPCB

NextPCB fabricates TLY-based RF and antenna boards as part of our broader high-frequency PCB capability, including the laser-via and flexible-variant builds described above. Before finalizing a stackup, our HQDFM software can help verify via and copper-foil specifications against your chosen TLY grade. Ready to quote? Start with our advanced PCB quote tool, or reach our engineering team through contact us for help selecting the right grade for your application.

About the Author

Arya Li, Project Manager at NextPCB.com

With extensive experience in manufacturing and international client management, Arya has guided factory visits for over 200 overseas clients, providing bilingual (English & Chinese) presentations on production processes, quality control systems, and advanced manufacturing capabilities. Her deep understanding of both the factory side and client requirements allows her to deliver professional, reliable PCB solutions efficiently. Detail-oriented and service-driven, Arya is committed to being a trusted partner for clients and showcasing the strength and expertise of the factory in the global PCB and PCBA market.

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