Taconic PCB Laminate Guide: TLY, RF-35 and CER Grades

A Laminate Family Built for RF

Taconic laminates are engineered composite materials used where the dielectric properties of standard FR-4 are not good enough: RF and microwave circuits, 5G antennas, aerospace systems and automotive radar modules. The family spans PTFE based composites, glass reinforced materials and ceramic filled laminates, which together cover dielectric constants from roughly 2.2 up to 10.

The value of the range is that it lets a design match material to requirement rather than paying for the lowest loss material everywhere. This guide covers the properties, the grades, the fabrication implications and the cost.

The Properties That Matter

Five characteristics decide whether a material is suitable for a given RF design.

• Low loss tangent (Df). This is the attenuation per unit length. It is the single most important figure at high frequency, because loss cannot be recovered downstream.
• Stable dielectric constant (Dk). The Dk should change as little as possible with frequency and temperature, since any drift shifts impedance away from the target.
• Thermal stability. The laminate must hold its dimensions through lamination, assembly and operation, which is what makes aerospace and automotive applications viable.
• Dimensional precision. Tight thickness control across the panel reduces warping in multilayer stackups and keeps impedance uniform.
• Compliance. RoHS compliance is expected as standard in most markets.

Where these properties are traded, the trade is normally against cost and, in some cases, against mechanical robustness. That is the reason a ceramic filled grade exists alongside a pure PTFE one.

The Grades

• TLY series. PTFE based material with a very low dielectric constant, around 2.17 for TLY-5A, and a loss tangent near 0.0009. Suited to flexible RF circuits, antennas and any application where loss has to be minimised. Its low Dk means wider traces for a given impedance, which some designs find convenient.
• RF-35. Glass reinforced PTFE with a dielectric constant around 3.5 and a loss tangent near 0.0018. The middle ground of the range, used for high frequency radar and 5G base station work.
• RF-60 and similar glass reinforced grades. Higher dielectric constants in the region of 6, which allow narrower traces for the same impedance. Useful where board area is the binding constraint.
• CER series. Ceramic filled laminates, with CER-10 reaching a dielectric constant near 10 and a loss tangent around 0.0035. Higher loss than PTFE, but far better mechanical strength and thermal stability, which suit power amplifiers and aerospace systems.

The selection decision follows three inputs: the frequency range the design must cover, the board thickness and layer count available, and the thermal environment. Higher Dk allows more compact circuits; lower Df allows longer paths. Where a design needs both, the answer is usually a hybrid stackup rather than a compromise material.

Applications

RF and microwave circuits including amplifiers, filters and antennas. 5G base station radios and antenna arrays, where loss directly affects coverage. Aerospace and satellite communication, where temperature extremes and dimensional stability rule out general purpose material. Automotive radar and driver assistance modules, which combine high frequency with a harsh environment. And high speed digital routing in routers and backplanes, where loss at the laminate level is part of the link budget. The common thread is that the laminate is part of the electrical design rather than a mechanical carrier, a point explored further under telecommunications PCB design.

Fabrication

PTFE and ceramic filled laminates behave differently from FR-4 on the shop floor, and the process changes accordingly.

• Laminate preparation and stackup design. Thickness and copper type selected, and the stackup defined so that impedance targets are achievable before any tooling is made.
• Drilling and plating. Parameters optimised for PTFE or ceramic filled material to avoid burring, smear and hole wall damage.
• Etching and imaging. Line width control tight enough that impedance stays within tolerance across the panel.
• Lamination. Controlled temperature and pressure under vacuum to prevent voiding and warping.
• Surface finishing. ENIG, immersion silver or OSP, whichever suits the assembly and the loss requirement.

Material pre-baking before lamination is worth noting because it removes absorbed moisture, which otherwise produces voids and delamination. Done properly, this class of laminate holds its performance at frequencies well into the tens of gigahertz.

Taconic Against Rogers

The two families overlap heavily in capability, and the differences are largely commercial.

• Cost. Taconic laminates typically run 80 to 250 US dollars per square metre depending on type and layer count, while comparable Rogers materials cost fifteen to twenty five percent more.
• Dielectric stability. Both are excellent, and the practical difference for most designs is small.
• Thermal conductivity. Rogers materials hold an advantage, which matters in high power applications.
• Best fit. Taconic suits cost effective RF and microwave boards; Rogers is often specified for the most demanding aerospace and millimetre wave work.

The honest guidance is that the difference between them is smaller than the difference between a good process and a poorly controlled one. A well fabricated board on a mid-range laminate will outperform a badly fabricated board on the best material available.

Cost

Pricing depends on layer count, material type and quantity.

• Two layer RF-35: 80 to 120 US dollars per square metre.
• Four layer TLY material: 120 to 180 per square metre.
• Six layer CER material: 180 to 250 per square metre.

Four factors move the figure within those ranges: the material grade and its dielectric properties, board thickness and layer count, surface finish and tolerance requirements, and whether the order is a prototype or volume production run. As with any high frequency board, the useful cost lever is to restrict the expensive laminate to the layers and areas that carry the RF path, and to use standard material elsewhere. The general pricing structure is explained in our notes on custom PCB pricing.

Design Guidance

Five practices improve results on these materials.

• Control impedance explicitly, defining trace width and spacing from the dielectric constant at the operating frequency rather than from a generic table. The principles are shared with any controlled impedance design, described under PCB design and layout.
• Use a continuous ground plane beneath RF traces, because the return path is part of the transmission line.
• Avoid sharp bends, which create reflections and local impedance change.
• Pre-bake the laminate before lamination to remove moisture.
• Optimise the stackup for thermal balance, so that the board does not bow during assembly.

Where a design mixes RF and digital circuitry, a hybrid stackup that bonds the high frequency laminate to FR-4 is the standard answer. It controls cost, and it works reliably provided the transition between the two materials is designed deliberately rather than left to the fabricator. Verifying the result calls for impedance measurement, described in our notes on TDR impedance testing.

FAQ

What dielectric constants are available? From around 2.17 in the TLY series to 10 in the CER series, with glass reinforced grades in between.

Is Taconic suitable for flexible circuits? Yes. The TLY series is specifically used for flexible RF circuits and antennas.

Can Taconic be combined with FR-4 in one board? Yes. Hybrid stackups are common and are usually the most cost effective arrangement for designs that only need high frequency material in part of the circuit.

What lead times apply? Roughly five to seven working days for prototypes and ten to fifteen days for volume production.

How does it compare with Rogers? Similar dielectric performance, lower cost by roughly fifteen to twenty five percent, with Rogers holding an advantage in thermal conductivity.

Summary

Taconic laminates cover the frequency range where FR-4 stops being adequate, from PTFE based TLY material with a dielectric constant near 2.2 through glass reinforced RF grades around 3.5 to ceramic filled material at 10. Selection follows frequency, available thickness and thermal environment, and a hybrid stackup with FR-4 is often the most economical answer. Fabrication requires PTFE specific drilling, moisture removal before lamination and tight line width control, because those three steps decide whether the impedance target is met. Cost runs from roughly 80 to 250 US dollars per square metre, which is fifteen to twenty five percent below comparable alternatives in the same performance class.