Guideline

A Guide to Rogers PCB Material: Commonly Used Types, Features, and Applications

PCBs are widely used in all electronic devices. Different PCBs are produced by different materials. According to the flexibility, PCB material can be classified as Rigid  PCB, Flexible PCB and Rigid-flex PCB. But there is another kind of PCB material which is specially used in high-frequency PCBs. For high frequency with good electrical properties need a reliable material which can maintain their data frequency.  Also,  it should work on increasing temperatures environment and may need thermally conductive materials there would be heat dissipation.  All characteristics are required as per their application. The most widely accepted high-frequency materials are Rogers PCB materials. In this article, we will talk about them.

The Elements in PCB Material

Most PCB materials are built with copper and dielectric, copper is used to etch out conductors or traces, the types of copper foil like rolled annealed, reverse treated, and electro-deposited. Dielectric is an insulation material with different kinds of properties.  Example: Df, Tg, Dk, the important thing is that it must be compatible with copper. There are different requirements for different kinds of materials according to IPC standards:

PCB Material TypesIPC Standards
Rigid PCB and Multilayer PCBsIPC-4101
Flexible PCB boardIPC-4202
High Speed & High-frequency ApplicationsIPC-4103
Flexible PCB Material &  Bonding FilmsIPC-4203

 

Important Terms in PCB Material

Tg-Glass Transition Temperature: This value indicates after that point material converts to deformable from rigid.  The general PCB materials Tg comparison is below.

MaterialDkTg (°C )Applications
FR44.2-4.8135-140Standard
FR44.2-4.8150-170Standard & High Tg
FR43.2-3.8180-220High-Speed & High Tg
PTFE2.0-2.8160RF-Radio Frequency
Polyimide3.5-4.2≥250Flex PCBs
  • Td-Decomposition Temperature: Decomposition Temperature:  This is the temperature when the material gets decompose.
  • CTE-Coefficient of Thermal Expansion: At this rate when temp increases material expansion increases.
  • Dk- Relative Dielectric Constant: This represents the electromagnetic waves produced in the propagation path.
  • Df- Loss Tangent: Df is the property which shows the amount of energy transfer by the material.

One of the best materials, here is Rogers RO4000 which has hydrocarbon ceramic laminates and the best prepregs. For microwave frequency it uses, It is low loss material and easier to fabricate than PTFE materials.

  • Use it like the FR4 fabrication process
  • It has low CTE when temp increases
  • It has the best controlled dielectric constant
  • Dielectric constant available in between 2.55 to 6.15
  • It has more conductivity then average materials.

Applications Made By Rogers PCB Material

Applications of Rogers PCB materials

We use FR4 material most widely, but high-speed signal, sensitive signal and antenna board preferable material is rogers PCB. So due to its high-frequency performance, reliability, consistency (glass transition is high, moisture absorption is low, superior adhesion) and, Rogers material has the good thermal capability. The following are the main applications for Rogers PCB materials.

  • Test instrumentation
  • Aerospace Avionics
  • Radar systems
  • Mm Wave antennas
  • Automotive sensors
  • Satellite
  • High-speed datacom

 

The Widely Used Roger Materials  In Market

Rogers Corporation is the most famous producer of RF and microwave PCB materials. The main features of Rogers material are excellent performance in microwave and radio frequency applications. Their products are widely used in a lot of areas, including automotive, telecommunications, medical, wireless, aerospace, and portable devices., etc.  Here we talk about some most widely used types.

RO4000 Series

  • RO4350B – Dielectric constant is 3.48, Thermal conductivity is higher, Good thermal & power management.
  • RO4003 –  It has a low dielectric constant value of 3.38. It is used more widely.  It is best for performance and cost.
  • RO4450 –  This material has good thermal reliability. The dielectric constant is 3.54.
  • RO4835 –  Uses for low loss, maintained 77GHz frequency, Dielectric constant is reliable.

RO3000 Series

  • RO3003 – Insertion loss is very low for high-frequency applications up to 10GHz.
  • RO3006 – The dielectric constant is 6.15. It is best for amplifier applications.
  • RO3010 – Dielectric constant is 10.2. The cost is low.

RT/duroid PTFE

Rogers RT/duroid is a material especially for high-frequency circuits which is filled by PTFE laminates. Best for durability and reliability, Uses: Aerospace and defense. They capture a wide market for their reliability property.

  • RT/duroid 5880 –  Density – Very low.  Dielectric constant- 2.2.  Applications- mmWave Antennas.
  • RT/duroid 6002 – Cost-effective PTFE.  It has better thermal conductivity than FR4.
  • RT/duroid  6202 – Dielectric constant is 2.94, which is stable. It Works up to GHz.  Low electrical loss. Moisture absorption is low.

TC350 Material

It is a replacement of RO4000, with a dielectric constant is 3.5, It has less loss compared to RO4350B

DiClad and LoPro Copper

Better signal integrity improvement performance.

  • DiClad Series – It is double rolled foils, with less roughness. Good for high-frequency applications.
  • LoPro Series –  Specially, for fine pitch components and less width trace and surface roughness is less.

Flexible LCP Films

  • It has thin and lightweight film, which is very flexible.
  • ULTRALAM  3850 – Better flexibility, reliable, stable in dimension, works in high frequency .
  • RT/duroid  6006/6010 – PTFE flexible composites has very thin property.

PCBs with Rogers 4350 PCB Material

How to select Rogers PCB Material?

Before we selecting of Rogers PCB material, we need to know the functions and requirements of our devices first. And then we compare the main parameters as below.

  • Frequency: For high frequency application, this material is the best consideration. Like take example RO3003 material works up to 10GHz, Same time, RT/DROID 6002 use up to 90GHz.
  • Dielectric Constant: As we know for high frequency application less dielectric constant required. So, Roger material has best choice in that case. Less dielectric means high capacitance and lower impedance. Due to this we get best impedance matching.
  • Loss tangent: The loss tangent, presents the signal loss because of material. If material has low tangent loss it will low dissipation, attenuation and signal integrity problem. So rogers RO4350B and RO4003C is the best choice.
  • Coefficient of thermal expansion: When the temp goes up to beyond level then material gets expand for this case Rogers is far better than other materials.
  • Glass transition temperature: It has good glass transition temperature value to survive in high temperature.
  • Peel strength:  It has good peel strength.
  • Flammability Rate: It stands as per UL 94 and  IPC standards.

The Differences between FR4 and Rogers PCB Material

Both FR4 and Rogers PCB materials are rigid PCB materials. But they have a lot of differences. Generally speaking FR4 materials are used for standard circuit boards, but Rogers PCB material are used for high frequency, radio frequency or microwave applaications. Here are the main different parameters.

Frequency  capability

FR4 works superb up some frequency range. As frequency ranges increase more than 500Mhz FR4 not work properly then prefer material is rogers. Due to this rogers always use for high speed. But it is costly.

Thermal Management

The thermal conductivity of FR4 PCB materials is about 0.3 W/mK, by comparison, Rogers PCB materials have a range of thermal conductivity from 0.5 to 0.95 W/mK. As such, the Rogers material can transport heat at a faster rate than the FR4 material hence making it easier to manage thermals during PCB manufacturing and assembly.

Absorbing Moisture

PCB board materials absorb about 0.1-0.2% moisture from the surrounding environment. This moisture absorption directly affects the electrical, as well as, thermal properties of such materials; for instance, its efficiency and performance will degrade with greater moisture content.

Contrarily, Rogers PCB material has low moisture absorption rates from 0.02 to 0.08%, so it would be fit for use in areas experiencing extreme conditions such as aerospace defense applications.

Impedance Stability

The dielectric constant of FR4 is approximately four point five while that of Rogers falls within two point five 2.5 to eleven 11, therefore giving rise to a higher impedance stability for Roger’s PCB materials.

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