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.

At our PCB manufacturing facility in Dallas, Texas, we have a significant amount of stock in all of the high-frequency laminates as we have been producing PCBs with these materials for many years. Some of the applications of these PCBs are RF antenna, wi-fi (Carrier-Grade and Licensed Access), IP infrastructure, power amplifiers, diplexers/multiplexers, test and measurement, and many more.

With PCBs made from these products, it is important to have significant experience in producing PCBs with these materials, but also you must have invested in the equipment to properly process these RF PCBs. Experience in engineering and CAM is critical to being able to ensure that your PCBs are built to last as these materials all have very different scaling factors along with the fact that they all behave differently; you are removing the copper during the etching process. Without a proper process for managing registration, lamination layer shirt, and other factors using the proper equipment like X-ray, fabricators will have a difficult time producing the yield that gives the customer confidence.

Here at Epec, we work with our customers during the design stage as well as investing in the leading-edge equipment every year to ensure that we stay ahead of the needs for RF PCBs.

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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 (W/m/K)
			X	Y	Z
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

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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. Rogers Corporation's motto is "Helping power, protect, connect our world." Using the Rogers' advanced materials with Epec's application knowledge, global resources, engineering, and design resources, our team provides the most comprehensive suite of solutions of any PCB fabricator.

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 (W/m/K)
			X	Y	Z
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

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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 (W/m/K)
			X	Y	Z
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

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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 (W/m/K)
			X	Y	Z
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

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Panasonic MEGTRON 6

MEGTRON 6 from Panasonic is an advanced circuit board laminate material designed for high-speed applications such as network equipment, mainframes, IC testers, and high frequency measuring instruments. MEGTRON 6 material is best known for low dielectric constant and dielectric dissipation factors, as well as low transmission loss and high heat resistance.

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  Panasonic MEGTRON6 - Laminate R-5775 - Prepreg R-5670

  
  

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  Panasonic MEGTRON6 - Laminate R-5775N - Prepreg R-5670N

  
  

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  Panasonic MEGTRON6 - Laminate R-5775 - Prepreg R-5670 - 50GHz

  
  

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  Process Guidelines

  
  

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  IPC-4101E - Slash Sheet Matrix

  
  

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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. Optimize your microwave frequency PCB design with our expertise and leading-edge laminate materials.

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