A Rogers printed circuit board (PCB) is a type of PCB made using high frequency, high performance dielectric material supplied by Rogers Corporation. Rogers is a leading manufacturer of advanced materials used in electronics, transportation, aerospace and defense applications.
Some key things to know about Rogers PCBs:
- They are designed for high frequency, high speed signals and applications where performance is critical. This includes things like radar systems, satellite communications, 5G infrastructure, automotive radars, etc.
- They use specialized dielectric materials patented by Rogers that have very low loss, tight dielectric constants, and low moisture absorption. This results in boards that have excellent signal integrity and allow signals and systems to perform at very high frequencies with minimal loss and distortion.
- Common Rogers materials used include: Rogers RO4000 series, Rogers RO3000 series, RT/duroid 6000, RT/duroid 5880/5870. Each material has specific dielectric properties important for different applications.
- Rogers PCBs cost more than standard FR-4 PCBs but enable much higher performance. For leading edge electronic systems, the benefits usually outweigh the additional costs.
In the sections below we'll explore more details around Rogers PCB technology, materials, properties, design considerations and applications.
Why Use Rogers PCB Technology?
There are several key advantages gained by using a Rogers high frequency PCB material rather than standard glass reinforced FR-4 PCB material:
Ultra Low Loss
Loss refers to how much of the signal is absorbed by the dielectric material as it propagates along a trace. Rogers materials have extremely low loss, especially at higher frequencies. This enables much longer trace lengths and allows high speed signals to propagate with minimal attenuation.
Tight Dielectric Constant Tolerances
The dielectric constant defines the velocity of the signal as it travels through the material. Tight control of Dk translates into tightly controlled propagation delays and impedances. This helps maintain signal integrity and ensure proper functioning of high speed digital circuits and synchronous systems.
Low Moisture Absorption
Moisture absorption decreases PCB performance and alters dielectric properties. Rogers materials use high glass transition temperature resins that resist moisture absorption, even under high humidity or aqueous conditions.
Thermal Management
Certain Rogers materials have high thermal conductivity, which allows circuits to dissipate heat efficiently. This helps stabilize temperatures during operation.
Lead-Free Compatibility
Many Rogers materials are compatible with lead-free assembly processes like immersion tin, immersion silver and OSP surface finishes. This makes them suitable for modern RoHS compliant electronics manufacturing.
Consistent Quality
Rogers maintains tight controls in its manufacturing processes to ensure consistency in properties like dielectric constant, loss tangent, thermal coefficient of expansion, and more. This gives engineers confidence during the design process.
Common Rogers High Frequency Materials
Rogers offers many different circuit board materials engineered for specialized applications. Some of the most common and popular Rogers materials used are:
Rogers RO4000 Series
The RO4000 series combines excellent electrical performance with outstanding processing characteristics. These versatile circuit materials have low loss, high frequencies, tightly controlled electrical properties, and good thermal conductivity while still being cost effective. They are halogen-free for safety and meet UL flammability standards. The RO4000 series includes:
- RO4003C/TM - Most popular, general purpose high frequency material
- RO4350B - Loaded variant for even better performance
- RO4835 - High reliability, high thermal conductivity
- RO4830 - Bondply version for multilayer boards
Rogers RO3000 Series
The RO3000 series offer outstanding performance at higher frequencies with low loss, tight dielectric constant tolerances and thin constructions. Materials include:
- RO3010/#TM - 10 mil dielectric good for mmWave frequencies
- RO3003/#TM - 3 mil dielectric for compact designs
- RO3006/#TM - 6 mil dielectric balancing thickness and performance
RT/duroid 6000 Series
The RT/duroid 6000 series contain ceramic-filled, PTFE composite materials capable of performance exceeding 10 GHz. This family features low loss, tight dielectric constant tolerance, and low moisture absorption. Variants include:
- RT/duroid 6002 - Thin, 2 mil dielectric for high layer count Multilayer PCBs
- RT/duroid 6006/#LM - 6 mil, low loss dielectric good for antenna boards
- RT/duroid 6010 - Most popular, general high frequency 10 mil dielectric
RT/duroid 5870 / 5880
The RT/duroid 5870 (2.33 Dk) and 5880 (2.20 Dk) materials offer advanced electrical performance combined with high thermal conductivity for excellent dissipation of heat. These materials perform well at frequencies above 10 GHz.
Table summarizing key properties of common Rogers materials
| Material | Dielectric Constant | Loss Tangent | Thermal Conductivity |
|---|---|---|---|
| RO4003C | 3.38 | 0.0027 | 0.35 W/m/K |
| RO4350B | 3.48 | 0.0037 | 1.1 W/m/K |
| RO4835 | 3.54 | 0.0031 | 0.84 W/m/K |
| RT/duroid 6002 | 2.94 | 0.0012 | 0.51 W/m/K |
| RT/duroid 6006 | 6.15 | 0.0025 | 1.1 W/m/K |
| RT/duroid 5880 | 2.20 | 0.0009 | 1.5 W/m/K |
Rogers PCB Material Selection Process
Choosing the right Rogers material depends on electrical, thermal, mechanical, and cost requirements. Here is a general process for selecting a Rogers PCB material:
1. Determine Electrical Needs
- Frequency range (max frequencies needed)
- Loss requirements (how much loss can be tolerated)
- Impedance control needs
- Signal speed and propagation delay requirements
2. Define Thermal Requirements
- Power dissipation needs
- Maximum operating temperatures
- Whether thermal vias or ground planes are required
3. Evaluate Mechanical Needs
- Number of conductive layers
- Board thickness
- Aspect ratio of traces
- Flexibility/rigidity needs
- Environmental operating conditions
4. Consider Manufacturing Process Requirements
- Compatibility with lead-free assembly & soldering
- Compatibility with lamination cycles
- Suitable for standard PCB processes or more advanced ones needed?
5. Determine Project Budget & Cost Limitations
- Rogers materials have higher cost than FR-4
- Can choose lower cost material if performance allows
By methodically stepping through these areas, engineers can zero in on one or two candidate Rogers materials suited for their particular PCB application and requirements. Pre-release material samples are often ordered to aid final decision making and confirmation testing during prototyping stages.
Designing Rogers High Frequency PCBs
Designing PCBs using Rogers materials requires attention to special considerations for high frequency signals in order to maximize performance.
Signal Routing
For best performance, signals should be routed over uninterrupted dielectric with minimal discontinuities. Changes in trace width or dielectric thickness introduce impedance discontinuities that should be minimized. Avoid acute angle turns or abrupt stubs.
Stackup Configuration
The layered PCB stackup must be engineered to provide tightly coupled reference planes that form transmission lines. This guides EM fields inside the dielectric and prevents crosstalk or external radiation/coupling.
Layer Transitions
Minimize the number of times critical traces change reference plane layers. Vias act as impedance discontinuities, especially at higher frequencies. Use backdrilling or other techniques to remove unused via portions.
Thermal Management
Incorporate thermal vias, internal power planes, or metallic substrates to conduct heat away from hot components. This maintains temperature stability for reliable electrical performance.
Material Property Tolerances
Account for typical tolerances in dielectric constant, loss tangent, and other properties per the material data sheet during engineering design stages. This ensures adequate margin and wiggle room.
Modeling & Simulation
Model routed PCBs with full-wave 3D EM simulation software and use signal integrity tools when approaching 10 Gb/s speeds or maximum material frequency limits. Verify acceptable loss, efficiency, eye diagrams, and response over expected manufacturing variations.
Paying attention to guidelines like these helps produced robust Rogers PCB designs that deliver the expected level of electrical functionality.
Typical Applications of Rogers PCBs
Some examples of where Rogers PCB technology is commonly used include:
High Frequency Communication Systems
- Satellite communication ground stations
- 5G NR base stations and massive MIMO antennas
- Microwave point-to-point radios
- Military tactical radios
- Automotive radar and autonomous driving sensors
Aerospace & Aviation Electronics
- Phased array radars
- Inflight entertainment systems
- Aircraft instrumentation & engine controllers
High Speed Digital Systems
- High performance computing clusters
- Data center
