Taconic TLY-5 PCB

Taconic TLY-5 occupies a specific niche in the RF laminate landscape: PTFE-level electrical performance with glass-reinforced mechanical stability. When your design operates above 10GHz and your loss budget demands better than Rogers 4003C or 4350B can deliver, TLY-5 is one of the materials on the short list.

This guide covers what you need to know to specify and manufacture with TLY-5 — properties, processing requirements, stackup considerations, and practical trade-offs against alternative materials.

Material Overview

Taconic TLY-5 is a woven E-glass reinforced PTFE (polytetrafluoroethylene) composite laminate. The “TLY” family from Taconic uses different filler loadings to achieve different Dk values; TLY-5 targets Dk 2.20, making it a direct alternative to Rogers RT/duroid 5880.

Electrical Properties

Mechanical Properties

Available Configurations

Why TLY-5: The Low-Loss Advantage

Insertion Loss Comparison

The primary reason to specify TLY-5 is insertion loss. At millimeter-wave frequencies, the difference between Df 0.0009 (TLY-5) and Df 0.0027 (Rogers 4003C) is not academic — it is the difference between a working radar module and a failed link budget.

For a 50Ω microstrip, 50mm long:

At 77GHz over 50mm, TLY-5 saves 1.85 dB compared to 4003C. In a radar receiver with an 8-element patch array and corporate feed network, that difference can mean 3-5 dB of total system improvement.

Dimensional Stability: TLY-5 vs Unreinforced PTFE

The woven glass in TLY-5 provides mechanical stability that unreinforced PTFE laminates lack:

For multilayer PTFE designs with tight layer-to-layer registration (phased array antenna boards, for example), TLY-5’s glass reinforcement provides a meaningful manufacturing advantage.

Processing TLY-5: What Your Manufacturer Needs to Know

PTFE materials require specialized processing. If your manufacturer routinely builds on RT/duroid 5880, they can handle TLY-5. If they have only FR4 experience, TLY-5 will require process development.

Surface Preparation for Copper Adhesion

PTFE surfaces are chemically inert — standard electroless copper chemistry will not adhere. Two preparation methods are used:

Sodium etch (chemical):

• Immerse exposed PTFE surfaces in sodium/naphthalene solution
• Creates a chemically modified surface layer that accepts electroless copper
• Proven process, widely used
• Environmental concerns with sodium/naphthalene waste

Plasma treatment (dry process):

• Expose PTFE surfaces to CF₄/O₂ or Ar/O₂ plasma
• Roughens and chemically activates the surface
• Cleaner process, no wet chemistry waste
• Requires plasma chamber equipment

Both methods achieve adequate peel strength (>4 lb/in) for reliable plated through-holes.

Drilling

Key difference: Lower feed rate and surface speed prevent PTFE smearing, which creates resin deposits on hole walls that block copper plating.

Lamination (Multilayer)

For multilayer TLY-5 constructions, Taconic provides TacBond bondply (Dk 2.35) for inter-layer bonding:

Engineer’s Note: PTFE multilayer lamination requires careful thermal profiling. Unlike FR4 where the resin flows and self-levels, PTFE bondply has a narrower processing window. Request lamination qualification data from your manufacturer before committing to production.

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Stackup Design with TLY-5

All-PTFE Stackup (2-6 Layers)

For pure RF boards where all signal layers require ultra-low loss:

Layer 1: RF signal — TLY-5, 10mil
         TacBond HT bondply
Layer 2: Ground plane — 1oz copper
         TLY-5 core, 20mil
Layer 3: RF signal / DC routing
         TacBond HT bondply
Layer 4: Ground plane — 1oz copper
         TLY-5, 10mil
Layer 5: RF signal — microstrip

Hybrid PTFE/FR4 Stackup

For mixed RF + digital designs, keep PTFE for RF layers and use FR4 for digital/power:

Layer 1: RF signal — TLY-5, 10mil (microstrip)
         TacBond HT bondply
Layer 2: Ground plane — 1oz copper
         FR4 prepreg (standard)
Layer 3: Digital signal — FR4
         FR4 prepreg
Layer 4: Power plane — 1oz copper
         FR4 prepreg
Layer 5: Ground plane — 1oz copper
         TacBond HT bondply
Layer 6: RF signal — TLY-5, 10mil (microstrip)

Caution: The PTFE/FR4 interface requires careful CTE management. TLY-5’s z-axis CTE (150 ppm/°C) is significantly higher than FR4 (50-70 ppm/°C), creating stress at the interface during thermal cycling. Minimize via count through the PTFE/FR4 boundary and use thermal relief on ground vias.

Impedance Calculations

For TLY-5 with Dk 2.20, a 50Ω microstrip requires a wider trace than on FR4 or Rogers 4003C:

The wider trace on TLY-5 reduces conductor loss (lower resistance per unit length), partially offsetting the wider board area required. This is actually a performance benefit at high frequencies where conductor loss dominates.

Application Guide

Primary Applications

When TLY-5 Is Not Needed

• Below 5GHz: Rogers 4003C or 4350B provides adequate loss at significantly lower cost and easier processing
• Consumer products: Cost-sensitive designs should evaluate low-loss FR4 (Megtron 6, Dk 3.71, Df 0.004) before committing to PTFE
• Flex circuits: TLY-5 is rigid; consider liquid crystal polymer (LCP) for flexible RF
• High layer count (>8): PTFE multilayer registration challenges increase with layer count; consider hybrid approaches

TLY-5 vs Alternative PTFE Materials

Decision framework:

• Best availability + spec compliance: RT/duroid 5880
• Best dimensional stability at low cost: TLY-5
• Lowest z-axis CTE: RT/duroid 6002
• Best overall mechanical properties: Isola IT-958

Design Checklist for TLY-5

• Confirm application frequency justifies PTFE cost (>5GHz typically)
• Verify manufacturer has PTFE processing capability (sodium etch or plasma)
• Specify Dk 2.20 ±0.02 in stackup notes
• Use TacBond HT bondply for multilayer construction
• Account for wider trace widths in routing (Dk 2.20 = wider 50Ω trace)
• Minimize via count through PTFE/FR4 interfaces in hybrid stackups
• Specify modified drill parameters in fab notes
• Request lamination qualification coupon for multilayer builds
• Add TDR coupon to panel for impedance verification
• Verify z-axis CTE compatibility in thermal cycling profile

How Atlas PCB Handles TLY-5

Atlas PCB’s partner factories maintain full PTFE processing capabilities including sodium etch surface preparation, modified drilling protocols, and TacBond lamination qualification. We process TLY-5 alongside other PTFE materials (RT/duroid 5880, 6002, 6035HTC) on dedicated PTFE production lines.

Atlas PCB fabricates Taconic TLY-5 boards in 2-8 layer configurations with ±5% impedance control, hybrid PTFE/FR4 stackups, and full PTFE processing capability including plasma desmear and modified drilling. Every TLY-5 order includes our 12-hour human engineering review, where we verify stackup feasibility, material interface compatibility, and drilling parameters before production starts.

Summary

• Taconic TLY-5 delivers Dk 2.20 / Df 0.0009 — ultra-low loss with woven glass stability
• Better dimensional stability than RT/duroid 5880 thanks to woven glass reinforcement
• PTFE processing required — not FR4-compatible; manufacturer must have PTFE capability
• Ideal for 10GHz+ applications where every 0.1 dB of insertion loss matters
• Hybrid stackups with FR4 reduce cost while maintaining RF performance on critical layers

Building a millimeter-wave or radar PCB? Upload your Gerbers for a free engineering review — we will verify your PTFE stackup and drilling specifications before production.

Related guides: [Rogers 4350B vs FR4]/blog/rogers-4350b-vs-fr4/) | [RF PCB Design Guidelines]/blog/rf-pcb-design-guidelines/) | [RF PCB Materials Comparison]/blog/rf-pcb-materials-comparison/) | [HDI PCB Design Guide]/blog/hdi-pcb-design-guide/)

Further Reading

• [Rogers 4003C Material Properties: Dk, Df, and Design Considerations]/blog/rogers-4003c-properties/)

• [Multilayer PCB Stackup Design Guide: 8 to 30+ Layers Step by Step]/blog/multilayer-pcb-stackup-design-guide/)

• [PCB Manufacturer with Engineering Review: Why Human DFM Audit Matters]/blog/pcb-manufacturer-engineering-review/)

• [PCB Grounding Techniques: Star, Split, and Solid Ground Plane Strategies]/blog/pcb-grounding-techniques/)

• [PCB DFM Checklist: 50 Points to Review Before Sending Gerbers]/blog/pcb-dfm-checklist/)