Rogers vs Taconic: Choosing a High Frequency Laminate

Two laminates can share a dielectric constant and still behave very differently on the bench and on the production line. Rogers and Taconic both supply high frequency materials that engineers compare constantly, and the Rogers vs Taconic question has no single right answer, because the two families optimise for different things. This comparison looks at the electrical parameters, the thermal and mechanical behaviour, the processing consequences and the price level of each family.

The Material Families

The Rogers range includes ceramic filled hydrocarbon laminates such as RO4350B and RO4003C, and PTFE based materials such as RO5880. The hydrocarbon grades dominate RF and microwave work because they combine low loss with processing that resembles FR-4, while the PTFE grades serve millimeter wave and other applications where the lowest possible loss is required. Radar, 5G infrastructure and automotive radar are the largest application areas.

Taconic builds its RF laminates on a lightweight glass reinforced PTFE laminate structure, with grades such as RF-35, TLY-5 and TLX aimed at power amplifiers, phased array antennas, satellite links and RFID. The common thread is low moisture absorption and good dimensional stability, which matters on large antenna panels where a small change in dielectric constant shifts the phase across the array.

Electrical Parameters Side by Side

Take RO4350B and RF-35 as the most directly comparable pair. RO4350B has a dielectric constant of 3.48 plus or minus 0.05 and a dissipation factor of 0.0037, and it holds its dielectric constant across a band reaching 40 GHz. RF-35 has a dielectric constant of 3.50 plus or minus 0.05 and a lower dissipation factor of 0.0018, with performance characterised to about 20 GHz.

The trade is loss against bandwidth and stability. Taconic wins on raw loss, which matters for a long feed line in a phased array or a low noise receive chain. Rogers wins on consistency over a wide frequency range, which matters when the same material has to serve several bands or when the design has to be simulated reliably rather than tuned experimentally.

Thermal and Mechanical Behaviour

Thermal properties separate the two families more sharply than the electrical ones. RO4003C has a thermal conductivity of about 0.71 W/mK, a Z axis coefficient of thermal expansion near 11 ppm per degree Celsius and a glass transition temperature above 280 degrees Celsius. Taconic TLX-8 has a thermal conductivity of 0.45 W/mK, a Z axis expansion of about 16 ppm per degree Celsius and a glass transition temperature above 220 degrees Celsius.

The practical consequence is that the Rogers hydrocarbon grades tolerate more lamination cycles and more thermal cycling, which makes them the safer choice for multilayer constructions. Higher thermal conductivity also helps move heat away from a power amplifier, and lower Z axis expansion reduces stress on plated holes during assembly and in service.

Processing and Manufacturing Consequences

The Rogers hydrocarbon materials were designed to run on standard FR-4 equipment, which means familiar drilling, lamination and plating windows and a yield that a fabricator can predict. That compatibility is worth more than a small electrical advantage on a production program, because it shortens qualification and reduces the chance that a build fails for process reasons rather than design reasons.

PTFE based materials, including most of the Taconic range, need more care. Copper adhesion requires plasma or sodium activation, drilling parameters must be adjusted because the material smears and burrs easily, and lamination runs at lower pressure with a controlled ramp. These steps are well understood by an experienced shop, but they reduce the number of suppliers able to build the board and they shift the risk profile of the program.

Price Levels

For a two layer 1.6 mm board in RO4350B, prototype quantities of one to five pieces typically quote around 120 to 160 dollars per square metre, falling to 80 to 110 dollars per square metre above a hundred pieces. Taconic RF-35 sits in a similar range for comparable constructions, with the final figure driven more by panel utilisation, layer count and finish than by the laminate itself.

Where the two diverge is in processing cost rather than material cost. A PTFE laminate that needs activation and adjusted drilling will carry a higher fabrication charge even when the sheet price is comparable, and that difference grows with layer count. On a simple two layer RF board it may be a few percent; on a six layer mixed dielectric design it can be considerably more.

Choosing Between Them

Choose a Rogers hydrocarbon laminate when the design is multilayer, when several frequency bands have to be served by one stackup, when thermal cycling is a concern, or when the program needs several qualified suppliers. Choose a Taconic PTFE laminate when loss is the dominant constraint, when the frequency band is narrow and well characterised, and when the board is a large antenna or a feed network where phase consistency across the panel matters most.

Mixed designs are common, and a hybrid stackup that uses the low loss material only on the RF signal layers keeps the cost of either family under control. The rules for balancing such a stackup are described in layer stackup for one to eight layers, and they apply to both families because the mechanical challenge of laminating different dielectrics together is the same, and the shielding and partitioning principles in EMI suppression design principles apply to both. A partner such as gopcb can model both options against the loss budget before the material is committed.

Moisture, Aging and Long Term Stability

Moisture absorption is a quiet parameter that shows up later in the program. Water has a dielectric constant near 80, so any moisture taken into the laminate raises the effective dielectric constant and increases loss. Both families are far better than FR-4 in this respect, but the PTFE based grades have an advantage, absorbing on the order of hundredths of a percent, which is why they appear in marine, outdoor and aerospace hardware where humidity cycles are unavoidable.

Aging matters for the same reason. A laminate that absorbs moisture during assembly shifts its electrical behaviour after reflow, so a design characterised on dry material may not match a measurement taken from a finished board. Baking before lamination and controlling storage conditions are standard practice for both families, and the expected shift belongs in the tolerance budget rather than arriving as a surprise during qualification.

For most designs that shift is small enough to ignore. On a narrowband filter or a phase sensitive array it is not, and in those cases the material characteristic that decides the choice is often moisture behaviour rather than dissipation factor.

FAQ

Which material has lower loss? Taconic RF-35 has a dissipation factor of about 0.0018 against 0.0037 for RO4350B, so it is the lower loss option, though the difference only matters on electrically long paths.

Which is easier to manufacture? The Rogers hydrocarbon grades process much like FR-4 and need no special activation. PTFE based laminates require plasma or sodium treatment, adjusted drilling and lower pressure lamination.

Can the two be used in the same board? Yes, and mixed stackups are common. The bonding film and the lamination cycle have to be chosen so that both dielectrics consolidate correctly and the panel stays flat.