Rogers Material Guide for High Frequency Boards

Rogers is a brand name that has become a shorthand for the family of laminates used in high frequency and microwave work. The family covers several chemistries, from a soft polytetrafluoroethylene to a ceramic filled composite and a thermoset material, and they are not interchangeable. Choosing a grade means comparing the dielectric constant, the loss, the mechanical behaviour and the process that each one needs.

The Families in the Range

The first family is based on polytetrafluoroethylene with a glass or a ceramic reinforcement. These materials have the lowest loss and a dielectric constant close to two or three, and they are the traditional choice for a microwave circuit.

The second family is a ceramic filled composite with a higher dielectric constant, up to about ten, which allows a much smaller circuit for the same frequency. The loss is higher than the PTFE group and the temperature stability is generally better.

The third family is a thermoset material, which behaves more like an epoxy in the fabrication process while offering a lower loss than a standard FR4. It is used where a moderate improvement in loss is enough and where a PTFE process is not available, and it is the grade most often chosen for a first high speed design.

Dielectric Constant and Design

The dielectric constant sets the geometry. A higher constant gives a shorter wavelength on the board, which reduces the size of a distributed element, and it also narrows the trace for a given impedance.

The tolerance on the dielectric constant is as important as its value. A material specified at a nominal figure with a wide tolerance produces a filter whose centre frequency varies between boards, and a material with a tight tolerance costs more and is worth it for a narrow band design.

The constancy with frequency matters for a broadband circuit. A material whose constant falls with frequency will shift the response of a wideband element, and the datasheet should give the value over the band of interest rather than at a single frequency.

<img src="https://www.gopcba.com/wp-content/uploads/2026/09/24-2.jpg" alt="High frequency laminate samples beside a circuit board” />

Loss and Where It Shows

The loss tangent describes how much energy the dielectric absorbs. In a short trace the effect is small, while in a long feed line, a resonator or an antenna array the loss is repeated and becomes the dominant term.

The loss also rises with frequency, so a material that is adequate at one gigahertz may be unsuitable at ten. The comparison should be made at the operating frequency rather than from a single figure on a summary sheet, and the measurement should be made by a method suited to that frequency.

The conductor loss is a separate term and it depends on the copper finish and on the surface roughness. A smooth foil on a low loss laminate gives the lowest total loss, and a rough foil on a high quality dielectric can undo part of the benefit.

Mechanical and Thermal Behaviour

The PTFE based materials are soft and they creep. They expand more with temperature than a thermoset and they need care in the drilling, the plating and the assembly, as well as a design that avoids a sustained compression.

The ceramic filled materials are stiffer and their expansion is lower, which makes them easier to handle and more suitable for a multilayer board where the layers have to stay in registration.

The thermal conductivity of the range is generally low, so a design with a significant power dissipation needs a thermal path that does not rely on the laminate. That is often the point at which a metal backed construction is considered instead.

Fabrication Differences

A PTFE material needs a surface treatment before plating and a bonding layer between the cores in a multilayer stack. The drilling parameters are gentler and the tool wear is higher because the filler is abrasive.

A ceramic filled material behaves more like a conventional laminate in the process, and a thermoset material is close enough that an existing line can be used with the profile adjusted.

The choice of grade is therefore a decision about the fabrication route as much as about the electrical performance. A design that needs the lowest loss may have to accept a process that only one fabricator can run.

Selecting a Grade

The selection starts with the loss budget. A circuit that can tolerate a certain loss at the operating frequency does not need the lowest loss material, and choosing a lower loss grade than necessary pays a premium for nothing.

The second input is the size. A compact design with a high dielectric constant can be smaller, at the cost of a tighter tolerance on the constant and a higher loss.

The third is the manufacturing route and the volume. A material that is only available in a limited range of thicknesses or that requires a specialist process may not be the right choice for a product that will be built for years.

Validation and Measurement

The dielectric properties should be verified on the finished board rather than accepted from the datasheet. A resonator or a transmission line on the panel gives a measurement of the effective dielectric constant, which is what the design actually uses.

The measurement should be made with a method that suits the frequency and the sample. A method that works at low frequency will not describe the behaviour of a thin laminate at ten gigahertz.

The batch to batch variation should be tracked. A supplier change, a resin content change or a change of the glass style will move the properties, and the measurement on the finished board is what detects it.

Cost and Availability

The high frequency materials cost a multiple of a standard laminate, and the price depends on the thickness and the panel size. The cost of the panel should be compared with the value of the performance rather than with the price of an FR4 board.

The availability is narrower. Some grades are stocked in a limited range of thicknesses and some are made to order, and the lead time should be part of the project plan rather than a surprise at the first build.

The overall cost should include the yield. A material that is difficult to process will produce more scrap, and the scrap of a high frequency material is expensive.

Practical Rules

Start from the loss budget and the size, then compare the dielectric constant, its tolerance and the loss at the operating frequency. Confirm the fabrication route before the stack is fixed.

Record the material data with the build records and the high frequency laminate guide, and review the PTFE properties and the laminate data when a grade is selected.

FAQ

Is Rogers one material? No. The range covers PTFE based, ceramic filled and thermoset laminates with dielectric constants from about two to ten and very different process requirements.

Why does the tolerance on the dielectric constant matter? It sets the geometry. A wide tolerance produces a filter or a matching network whose centre frequency varies from board to board.

When is a low loss material not worth the cost? When the loss budget is comfortable at the operating frequency. Paying for the lowest loss grade adds cost without changing the result.