Taconic PCB Manufacturing: Materials and Process Guide

When FR-4 Stops Being Enough

Below a few gigahertz, FR-4 is a reasonable substrate and the cost advantage is enormous. Above roughly 6 GHz the picture changes: dissipation factor starts to dominate insertion loss, dielectric constant drifts with frequency and temperature, and copper foil roughness begins to matter as much as the trace geometry. At 77 GHz, which automotive radar now uses routinely, the substrate is a design element rather than a commodity.

Taconic laminates are one of the two families that engineers reach for in that region, the other being Rogers. Both are built around PTFE and ceramic filled composites, and both demand a fabrication process that is closer to RF instrument work than to ordinary digital boards.

What the Materials Offer

• Dielectric constant: typically 2.17 to 3.5 for the standard microwave grades, with high dielectric ceramic filled versions reaching 10 for miniaturised circuits.
• Dissipation factor: as low as roughly 0.0009 in the lowest loss grades, which is more than an order of magnitude better than FR-4.
• Frequency stability: consistent behaviour above 10 GHz, which is where ordinary laminates begin to drift.
• Thermal expansion: controlled to match copper over the temperature range a radar or a base station module sees.

Three grades come up most often. TLY is the ultra low loss PTFE used for antenna feeds and low insertion loss paths. RF-35 is a ceramic filled hydrocarbon intended for power amplifier circuits, where a small amount of loss is acceptable in exchange for better thermal behaviour and easier processing. CER-10 is a high dielectric constant ceramic filled PTFE for compact RF modules, where the wavelength has to shrink to fit a small package.

Taconic Compared With FR-4

• Insertion loss: high on FR-4 above 5 GHz, low on the PTFE grades.
• Dielectric stability: acceptable on FR-4, excellent on the microwave laminates.
• Frequency capability: below about 5 GHz for FR-4, up to 40 GHz and beyond for the PTFE grades.
• Impedance tolerance: plus or minus 10 percent for typical FR-4 controlled impedance work, plus or minus 5 percent achievable on these materials with the right process.

The decision rule that follows is simple. Above 6 GHz, or whenever the impedance requirement is tighter than plus or minus 5 percent, the material upgrade pays for itself. Below that, FR-4 with a hybrid stack usually delivers the same performance for less money.

Design Points That Matter More Than Usual

Changing the laminate does not by itself produce a working RF board. Six items deserve attention during layout.

• Stackup design. The dielectric thickness controls the trace width for a given impedance, and the fabricator should be involved before the geometry is fixed.
• Microstrip or stripline. The choice sets the loss and the isolation, and it depends on how much room the mechanical design allows.
• Copper roughness. At microwave frequencies the surface profile of the foil adds to loss. Low profile foil is a specification, not a detail.
• Drilling parameters. PTFE is soft and behaves differently under a drill than FR-4, so feeds and speeds have to be tuned to avoid smearing and burrs.
• Plasma treatment. This is the critical step. PTFE has very low surface energy, and without plasma activation the plated copper will not adhere reliably. A shop that does not run plasma on a dedicated line should not be given PTFE work.
• Expansion matching. The dielectric and the copper expand at different rates, and the via and pad geometry has to accommodate that over the operating temperature range.

The Fabrication Sequence

A proper RF build follows a specific order, and each step exists because of a property of the material.

• Material cutting and preparation. PTFE panels are dimensionally sensitive, so they are conditioned before lamination rather than cut and pressed immediately.
• Low pressure lamination. These laminates need a gentler press cycle than FR-4 to avoid resin starvation and thickness variation.
• Drilling with tuned parameters. Slower feeds and dedicated tooling reduce smearing on the hole wall.
• Plasma activation. The surface is prepared so the electroless copper will bond. This is the step that separates a shop with RF experience from one without.
• Electroless and electrolytic copper. The barrel is plated to the same 20 to 25 micron range used on ordinary boards, but on a surface that is harder to wet.
• Imaging and etching. Fine line capability matters here, because the impedance tolerance depends on the finished width.
• Surface finish. ENIG or immersion silver, both flat and both stable at high frequency. A thick solder coating is not appropriate on a microwave trace, and the reasoning behind the alternatives is set out under immersion silver PCB finishing.
• Inspection and impedance test. Optical inspection, X-ray for layer registration, and TDR measurement of the coupon.

The last item is not optional. A board intended for plus or minus 5 percent impedance has to be measured on the finished panel, and the data should ship with the boards. The measurement method and what it does and does not prove are covered under TDR impedance testing.

Where the Difficulty Lives

Four items cause most of the trouble on PTFE work. Dimensional stability under heat is poorer than FR-4, so panel shrinkage has to be predicted rather than observed. Drilling produces burrs and smear unless the parameters are right. Copper adhesion fails without plasma treatment, and the failure appears later as a lifted pad or a delaminated trace. And multilayer builds tend to warp, because the material behaves differently from the prepregs it is bonded with. Every one of those is a process control issue, which is why the supplier choice matters more here than on any other board type.

Prices in 2026

• Two layer Taconic prototype: roughly 180 to 350 US dollars per square metre.
• Four layer RF board: roughly 320 to 650 per square metre.
• Six layer controlled impedance board: roughly 580 to 980 per square metre.
• Small batch, 100 by 100 mm: about 8 to 25 dollars per piece.

Material grade is the largest single factor, followed by layer count, board thickness, copper weight, impedance tolerance and quantity. Against Western manufacturing, Chinese production of the same specification typically runs 25 to 45 percent lower, which is the main reason the RF supply chain has concentrated there.

Lead Times

• Prototype: 5 to 7 working days.
• Small batch: 10 to 14 days.
• Volume: 3 to 4 weeks.

Two factors can extend those figures. The laminate is often imported and stocked in limited thicknesses, so an unusual substrate may need to be ordered in. And each additional lamination cycle for a buried via construction adds a pass through the press. Planning the stackup around stocked material is the cheapest way to protect the schedule.

Typical Applications

5G base station RF modules, 77 GHz automotive radar, satellite communication terminals, aerospace microwave assemblies and medical RF imaging equipment all rely on this class of laminate. They share a common requirement: the signal path has to survive a long run through connectors, filters and amplifiers without losing more energy than the link budget allows. Where the board is also populated with fine pitch RF devices, the assembly side matters as much as the bare board, and the same considerations described under PCB assembly apply with tighter process windows. For equipment that has to pass a network operator’s acceptance test, the wider context is set out under telecommunications PCB design.

FAQ

How high in frequency can these laminates go? Above 40 GHz with the right grade and structure, though the design and the finish become increasingly critical.

Is Taconic cheaper than Rogers? For many commercial RF applications it offers a better balance of performance and cost. The two are close enough that the decision should follow the datasheet rather than the price list.

Can high layer count RF boards be built? Yes, above ten layers, but the lamination and drilling requirements rise sharply and the yield risk with them.

Is assembly available with the boards? Yes, and it should be quoted together. RF assembly needs a controlled reflow profile and an RF test after soldering, and splitting the two suppliers makes it hard to assign responsibility when a measurement is off.

What should a buyer check before ordering? Plasma treatment capability, impedance test equipment, experience with the specific grade, and a documented PCB manufacturing process for PTFE materials.

Summary

Taconic laminates exist to solve a specific problem: keeping insertion loss and impedance variation low when the signal moves above a few gigahertz. TLY, RF-35 and CER-10 cover low loss feeds, power amplifiers and miniaturised modules respectively, with dielectric constants from 2.17 to 10 and dissipation factors down to 0.0009. Turning those materials into a working board depends on plasma treatment, tuned drilling, low pressure lamination and measured impedance within plus or minus 5 percent. Budget roughly 8 to 25 dollars per piece for small batch work, allow 5 to 7 days for a prototype, and choose the supplier on process capability rather than on the price of the laminate.