RF/Microwave PCB Laminate Material

When designing PCB circuits at microwave frequencies, the key characteristics that define circuit laminate performance for microwave/RF printed-circuit boards (PCBs) include dielectric constant(Dk), dissipation factor (Df), coefficient of thermal expansion (CTE), thermal coefficient of dielectric constant (TCDk), and thermal conductivity.

The high-frequency material perhaps most familiar to users of PCB laminates is polytetrafluoroethylene (PTFE) which is a synthetic thermoplastic fluoropolymer that has excellent dielectric properties at microwave frequencies. Below is a brief outline of the major material suppliers that we have experience with as every material is processed a bit differently and it is critical to know exactly how the materials will respond to every process.

Isola High Performance PCB Laminates

Since their founding in 1912, Isola has been the industry leader in developing and manufacturing copper-clad laminate products used to fabricate advanced multilayer printed circuit boards (PCBs). They have an optimal balance between cost and performance when selecting base materials. Key factors microwave and millimeter wave designers must consider when choosing a high speed RF or microwave laminate include dielectric thickness, dielectric constant and dissipation factor, and maintaining tight tolerance within a batch as well as batch-to-batch.

RF high-frequency designs require extremely precise controls on dielectric constant, line widths, and dielectric thickness. The chart below lists some of the most common Isola laminates.

Material Name Dk @ 10GHz Df @ 10GHz CTE * ppm/°C Thermal Conductivity
ASTRA MT77 3 0.0017 12 12 70 0.45
I-TERA MT40 3.38 0.0028 12 12 55 0.61
IS680 AG-348 3.48 0.0029 12 12 45 0.38
I-SPEED 3.63 0.0071 16 18 60 0.4

Rogers Advanced Materials for RF/Microwave Designs

As one of the oldest public companies in America, Rogers has a rich legacy of innovative and collaborative problem-solving techniques with our customers. In 1949, Rogers introduced the first RT/duroid® material for electronic applications and today the RT/duroid® family of high frequency PTFE laminates is the leader in the industry for high speed RF/microwave PCB designs.

Most PTFE PCB laminates require special equipment and processes to manufacture the highest reliability PCBs along with significant expertise in the material properties as many of the materials behave differently during PCB processing. The best known brand name of PTFE-based formulas is Teflon, which is used in non-stick cooking pans which means that this material can be difficult to work with if you don’t have the proper experience.

A partial list of the most common Rogers PCB laminates for RF/microwave boards is below:

Material Name Dk @ 10GHz Df @ 10GHz CTE * ppm/°C Thermal Conductivity
RO3203 3.02 0.0016 13 13 58 0.48
RO3206 6.15 0.0027 13 13 34 0.67
RO3210 10.2 0.0027 13 13 34 0.81
RO4003C 3.38 0.0027 11 14 46 0.71
RO4350B 3.48 0.0037 10 12 32 0.69
RO4450B 3.3 0.004 19 17 50 0.6
RO4450F 3.52 0.004 19 17 50 0.65

Arlon Electronic PCB Materials

While Arlon was recently purchased by Rogers Corporation, Arlon Electronic Materials specializes in thermoset resin technology including polyimide, high Tg epoxy, and low loss thermoset laminate systems. These resin systems are available on a variety of substrates including woven glass and non-woven aramid that are used in high reliability high speed and RF/microwave PCB circuits. Applications that encounter significant exposure to high temperatures such as aircraft instrumentation, down-hole drilling and RF antenna applications are typically good candidates for Arlon materials.

See below for a partial list of their laminates used in RF/microwave applications:

Material Name Dk @ 10GHz Df @ 10GHz CTE * ppm/°C Thermal Conductivity
AD250C 2.5 0.0014 16 16 50 0.3
AD255C 2.55 0.0014 16 16 50 0.3
AD260C 2.6 0.0017 16 16 80 0.32
AD300C 2.97 0.002 9 15 54 0.5
AD320A 3.2 0.0032 14 14 128 0.45
AD350A 3.5 0.003 5 9 35 0.45

Taconic Advanced Dielectric Materials

Taconic has been a world leader in the PTFE products since 1961. Today they provide PTFE and silicone coated fabrics, tapes, and laminates for a range of high performance applications. Thermally stable, low Dk, low Z axis CTE PTFE laminates are the focus for the Taconic materials used in the manufacturing of RF/microwave PCBs. Many of the Taconic products are designed with ultra-low fiberglass content to achieve world class insertion loss properties and a homogeneous dielectric constant throughout the laminate.

The uniform dispersion of ceramic throughout the laminate yields extremely low X and Y coefficients of thermal expansion. Taconic has materials for every application and a partial list of their offering.

Material Name Dk @ 10GHz Df @ 10GHz CTE * ppm/°C Thermal Conductivity
TLY-5 2.17 0.0009 20 20 280 0.22
TLC-30 3 0.0028 9 12 70 0.24
TLC-32 3.2 0.003 9 12 70 0.24
TLF-34 3.4 0.002 21 23 85 0.24
RF-35 3.5 0.0018 19 24 64 0.32
TLF-35 3.5 0.002 21 23 85 0.24
RF-60A 6.15 0.0038 9 8 69 0.4
TLE-95 2.95 0.0026 9 12 70 0.28

Not Sure What Material Is Best For Your Application?

Contact us for more information and we will work with you to understand your application and goals for the PCB design so that we can give you the best options available.


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