Introduction to Rogers PCB Materials
Rogers Corporation began developing specialized polytetrafluoroethylene (PTFE) based circuit board materials in the 1950s for early microwave systems and radars. Over the past 60+ years, Rogers has continued pioneering innovative PCB materials technology focused on the growing needs of high frequency, high speed, and high-reliability electronic designs.
While FR-4 excels in cost and manufacturability for many general circuit boards, it lacks the optimal electrical and thermal properties required in high-performance systems. Rogers leverages advanced materials science to create circuit board laminates with precisely engineered dielectric properties and shallow loss characteristics.
Rogers’ extensive PCB material portfolio enables its use in diverse applications, including:
- 5G NR mmWave antennas
- Satellite communications
- Radar systems
- Automotive sensors
- Aerospace Avionics
- High-speed datacom
- Test instrumentation
- And many others
Let’s explore what makes Rogers PCB materials such superior solutions for these cutting-edge electronics domains.
Fundamental Properties and Benefits of Rogers Materials
Rogers’ material technology provides distinct benefits that empower PCB designers to overcome limitations and push the boundaries of electrical performance and reliability.
Excellent High-Frequency Performance
The standout feature of Rogers PCB materials is the exceptionally high-frequency performance, enabling stable, low-loss operation up to mmWave frequencies. This results from:
- Deficient dissipation factor (loss tangent)
- Tight dielectric constant consistency over frequency
- Low coefficient of thermal expansion
This permits more minor circuit features, higher component densities, faster edge rates, and precision impedance control – which is critical in high-frequency applications.
Reliability and Consistency
Consistency and stability of electrical parameters are critical for reliability over product lifecycles, varying operating temperatures, and diverse environments.
Rogers materials deliver:
- Excellent Z-axis coefficient of thermal expansion matching with copper
- High glass transition temperature
- Low moisture absorption
- Superior adhesion
- Low outgassing
This provides the long-term stability and resilience required in defense, aerospace, automotive, telecom, and other demanding applications.
Thermal Management Capability
Effective heat dissipation is imperative for reliable performance and for preventing hot spots in high-power devices.
Key thermal advantages of Rogers’ materials include:
- High thermal conductivity options
- Low thermal coefficient of dielectric constant
- Low thermal expansion
- High glass transition temperatures
This enables power handling, thermal design, and reliability even in small, dense PCBs.
Broad Design Flexibility
Rogers offers an extensive selection of dielectric constants, loss tangents, substrate thicknesses, reinforcement materials, copper types, and other parameters.
This material diversity provides design flexibility to dial in the optimal electrical, thermal, and mechanical characteristics.
Ease of Fabrication
Rogers’ materials use manufacturing processes compatible with standard PCB production methods. This includes:
- Photolithography patterning
- Plating
- Drilling
- Routing
- Solder mask
- Automated assembly
Enabling straightforward integration into existing PCB workflows.
Overview of Major Rogers PCB Materials
Rogers offers an extensive portfolio of circuit board materials engineered to meet the needs of diverse applications and operating environments. Here is an overview of some of the most popular Rogers PCB materials:
RO4000® Series High-Frequency Laminates
The RO4000 series consists of thermoset ceramic-PTFE composite materials that deliver exceptional high-frequency performance up to mmWave frequencies and low loss, moisture absorption, and low outgassing. Common variants include:
- RO4003TM – The most widely used with a dielectric constant of 3.38. Balances cost and performance.
- RO4350BTM – Features a dielectric constant of 3.48 and higher thermal conductivity, making it well-suited for high power and thermal management.
- RO4450TTM – Provides increased thermal reliability and density with a dielectric constant of 3.54.
- RO4835TM – Offers outstanding dielectric consistency for stable, low-loss applications up to 77 GHz.
RO3000® Series High-Frequency Laminates
The RO3000 series offers more affordable PTFE-ceramic-based materials than the RO4000 series, with trade-offs of slightly higher loss and reduced performance. Options include:
- RO3010TM – Low-cost microwave material with a dielectric constant of 10.2.
- RO3006TM – Higher 6.15 dielectric constant suits power amplifiers and thermal management.
- RO3003TM – Provides good insertion loss for high-frequency applications up to 10GHz.
RT/duroid® PTFE Composite Materials
The RT/droid series utilizes PTFE composites reinforced with microfiber for lightweight, low-loss performance up to mmWave bands. Key variants are:
- RT/duroid® 5880 – Ultra-low density PTFE composite with a dielectric constant of 2.2 for mmWave antennas and modules.
- RT/duroid® 6002 – Cost-optimized PTFE material with low loss and improved thermal conductivity over FR-4.
- RT/duroid® 6202 – Features a stable dielectric constant of 2.94 from MHz to GHz frequencies.
TC350TM Thermoset Material System
The TC350 series offers high-performance thermoset materials engineered as replacements for the RO4000 series in cost-driven applications like automotive radar:
- TC350TM – Dielectric constant of 3.5 with low loss comparable to RO4350B.
- TC350 Plus – Enhanced Z-axis CTE and insertion loss over standard TC350.
DiClad® and LoPro® Copper Claddings
Advanced copper foil treatments applied to Rogers laminates improve signal integrity.
- DiClad® Series – Doubled-treated rolled copper foils that reduce surface roughness for better high-frequency loss characteristics.
- LoPro® Series – Electrodeposited copper foils with lower profile surface roughness to enable finer line widths and spacing.
Flexible LCP Films
Rogers offers thin, lightweight, flexible films, including:
- ULTRALAM® 3850 – Liquid crystal polymer (LCP) flexible films combine high-frequency properties and outstanding dimensional stability with flexibility.
- RT/duroid® 6006/6010 – Flexible PTFE composites for ultra-thin constructions.
Rogers PCB Material Selection Guidelines
Selecting the optimal Rogers material for a specific application requires carefully weighing many interdependent electrical, mechanical, thermal, and economic considerations. Here is a more extensive look at critical factors to consider when choosing a Rogers PCB material:
Operating Frequency
The intended operating frequency spectrum of the application is one of the foremost considerations. Rogers offers an extensive range of materials engineered for optimal performance across MHz, GHz, mmWave, and THz frequencies.
For instance, the RO3003 laminate is rated for up to 10 GHz, making it a fit for lower GHz applications. Meanwhile, the RT/droid 6002 material excels for mmWave antennas up to 90 GHz. Matching the material’s frequency response to the application’s bands ensures stable, low-loss operation.
Dielectric Constant
The dielectric constant (Dk) profoundly impacts frequency performance, miniaturization capability, and achievable impedance values. Materials with a lower Dk permit higher operating frequencies, greater impedance control, and more minor features. But this comes at the expense of requiring larger trace widths.
Conversely, higher Dk materials allow increased circuit density and smaller components but with limitations in frequency range and impedance control. Select a Dk that balances size and impedance needs.
Loss Tangent
The loss tangent indicates the material’s inherent signal loss. Lower loss tangents minimize signal attenuation, dissipation, and attenuation for best signal integrity. But higher-loss materials can offer cost savings.
Evaluate whether the budget can accommodate lower loss laminates like RO4350B (loss tangent of 0.0037) or if a higher loss alternative such as RO4003C (0.0027 loss tangent) is acceptable.
Board Thickness
Thinner materials inherently improve high-frequency performance by reducing dielectric effects. However, thinner laminates are more challenging to handle and fabricate. Thicker boards (>0.031″) facilitate fabrication, provide better power distribution, and reduce wrinkling.
Determine the minimum thickness to realize electrical performance goals and meet manufacturing and assembly requirements.
Layer Count
Higher layer counts, with thinner dielectrics between layers, demand materials with lower Dk and loss tangents to prevent interlayer signal degradation. Conversely, single or dual-layer boards can utilize higher-loss materials.
Carefully model signal integrity as layer count increases to identify materials less prone to interlayer skew, loss, and reflection.
Thermal Design
Effective thermal design to avoid hot spots and overheating requires materials capable of conducting and spreading heat. Materials with higher thermal conductivity, like RO4450F (0.71 W/m/K), enhance heat dissipation compared to traditional FR-4 (0.25 W/m/K).
Additionally, a lower coefficient of thermal expansion better maintains mechanical stability and registration at higher temperatures. Use thermally superior materials when the thermal design is critical.
Environmental Factors
The operating environment exposes boards to humidity, temperature extremes, shock, vibration, UV radiation, and more. Select materials like RO4350B that offer low moisture absorption, high glass transition temperatures, improved adhesion, and reduced outgassing when environmental resilience is vital.
Budgetary Constraints
In cost-driven applications, balanced trade-offs may require sacrificing some electrical performance for savings. Lower-priced materials like the RO3003 or TC350 series may suffice when top-tier performance is optional.
Certification Requirements
Stringent applications require materials qualified for certifications like IPC 4104, UL 94V-0 flammability rating, IPC 6012 automotive specs, or military specifications. Ensure the chosen laminate meets all mandatory compliance standards.
Conductor and Dielectric Losses
Consider materials with lower conductor loss from thicker copper and lower dielectric loss tangents at higher frequencies. This combination minimizes total loss.
Lead Times and Availability
Check material inventory and lead times when selecting to avoid excessive delays. Consider mildly lower-performing materials that are readily available versus long lead premium materials.
Future Design Evolution
Evaluate whether requirements may evolve in future design iterations to demand higher-performance materials. Building in that capability upfront simplifies future upgrades.
By thoroughly evaluating these multiple considerations, PCB designers can confidently select an optimal Rogers material variant to achieve electrical, mechanical, thermal, cost, and reliability goals.
Rogers vs. FR-4 Material Comparison
While FR-4 offers a cost-effective solution for many PCBs, Rogers materials provide superior high-frequency signal integrity. Let’s compare some of the critical differences between Rogers and FR-4 laminates.
High-Frequency Performance
The most significant limitation of FR-4 is the poor high-frequency response as signals approach and exceed ~1 GHz. This results from higher signal losses, more significant material variations over frequency and temperature, and larger tolerances.
Rogers maintains excellent stability and low loss (-20% lower) even above 10 GHz, enabling high-frequency applications.
Thermal Management
The low thermal conductivity (~0.25 W/m/K) and high expansion coefficient of FR-4 compromise thermal design and reliability.
Rogers offers materials with thermal conductivity from 0.5 to 4+ W/m/K and low expansion coefficients, minimizing these issues.
Consistency and Reliability
FR-4 suffers from substantial parameter variations versus temperature and moisture ingress, leading to performance fluctuations.
Rogers provides precise consistency of dielectric properties over operating conditions and product lifetime for mission-critical electronics.
Design Flexibility
FR-4 has fixed properties constrained in what it can support.
The wide range of Roger’s material formulations provides extensive design flexibility.
Fabrication and Assembly
The well-known fabrication processes for FR-4 make it easy to manufacture.
While more complex than FR-4, Rogers materials utilize similar manufacturing techniques.
For advanced high-frequency designs, Rogers PCB materials enable performance and reliability beyond FR-4 capabilities.
Rogers PCB Material Callouts and IPC Standards
Rogers subjects all its materials to rigorous qualification testing to validate they meet the required electrical, mechanical, thermal, and performance characteristics. Rogers materials comply with applicable IPC standards and other specifications that industries like aerospace and defense require.
Some key parameters and tests include:
- Dielectric constant
- Loss tangent
- Coefficient of thermal expansion
- Glass transition temperature
- Peel strength
- Flammability per UL 94 or IPC standards
- Outgassing per ASTM E595
- IPC 4103 slash sheet testing
- IPC 4104 qualification
- RoHS compliance
Rogers provides detailed material data sheets specifying the properties, performance data, certification status, processing guidelines, and handling procedures for each of its circuit board materials.
It is critical that PCB designers carefully specify the correct Rogers laminate used based on the material datasheet when calling out board materials.
For example, a proper Rogers material callout will be specified as:
Base Laminate: RO4350B, IPC 4104, UL 94V-0
Prepreg: RO4450F, IPC 4104, UL 94V-0
Providing the specific material grade and applicable qualifications.
Rogers PCB Material Cost Considerations
A frequent concern around Rogers materials is their higher cost than standard FR-4 circuit boards. However, there are techniques to optimize and reduce costs when using Rogers laminates:
- Mix Rogers cores (for signal layers) with FR-4 prepregs (for outer layers).
- Use lower-cost Roger’s materials like RO3003 or TC350 where appropriate.
- Minimize layer count by careful layout and stacking.
- Design with panel utilization optimization.
- Work with experienced Rogers PCB manufacturer to advise cost-reduction.
- Qualify alternative supply sources.
- Review pricing regularly as volumes increase.
While Rogers materials carry a premium, the unparalleled performance they enable often justifies the additional cost in the applications that require it.
Rogers PCB Manufacturing and Fabrication
Realizing the benefits of Rogers materials requires working with a PCB manufacturer highly experienced in processing these specialized laminates. Here are some of the keys to reliable Rogers PCB fabrication:
- Stringent process controls to handle tight Rogers tolerances.
- Rogers qualified lamination cycles and parameters.
- Precision drilling and via formation.
- Use of DiClad/LoPro copper foil options.
- Advanced impedance tuning.
- Conformal coating for environment protection.
- Rigorous QA testing.
- Handling and storage procedures to avoid contamination.
- Certified for aerospace and defense work.
Strategizing early with your PCB fabrication partner when planning to use Rogers materials to ensure successful manufacturing is highly advisable.
Applications of Rogers PCB Materials
The exceptional high-frequency properties and reliable performance of Rogers laminates make them critical solutions across a diverse range of leading-edge applications:
5G mmWave Antennas and Modules
The higher bands used in 5G NR rely extensively on Rogers materials for the antenna and phased arrays crucial to mmWave performance.
Automotive Radar Sensors
Roger’s materials meet the radars’ tight tolerance and reliability requirements, enabling collision avoidance and ADAS functionality.
Aerospace and Avionics
Rogers materials are certified for and widely used in commercial and military aircraft systems and components needing high frequency and reliable operation.
Satellites and Space Systems
The extreme conditions of space require materials like Rogers that provide stable, resilient performance despite outgassing, thermal shifts, and radiation.
Defense Electronics
Rigorous defense applications leverage Rogers to ensure electronics meet stringent high-frequency, thermal, and reliable performance requirements.
Test and Measurement
Roger’s low loss, thermal stability, and precision electrical properties empower test instrumentation needing unambiguous high-frequency measurements.
High-Speed Data Communications
The fast edge rates, high frequencies, and signal integrity vital in 100+ Gbps networks are enabled by Rogers microwave materials.
Conclusion
As next-generation electronics push further into the GHz and mmWave frequency spectrums to achieve faster speeds, higher densities, and new capabilities, Rogers Corporation remains at the forefront of developing the PCB materials technology needed to make these breakthroughs possible.
Rogers’ materials science and engineering expertise produces a diverse portfolio of circuit board laminates with the essential electrical, thermal, and mechanical properties to overcome the limitations of standard FR-4-based boards.
While requiring specialized design and manufacturing techniques, the unparalleled signal integrity, reliability, consistency, and performance Rogers materials provide are enabling key innovations across communications, radar, aerospace, defense, automotive, instrumentation, and other cutting-edge electronic sectors.
Frequently Asked Questions (FAQs)
What is the key benefit of using Rogers PCB materials?
The main benefit of Rogers materials is their exceptional high-frequency performance with low loss, stability, and precision electrical properties for optimal functionality in RF, microwave, and millimeter-wave applications.
What are some examples of Rogers PCB materials?
Some common Rogers materials are RO4003C, RO4350B, RO4450F, RO4835, RT/duroid 5880, and RT/duroid 6002. There are many material variants engineered for different requirements.
How do Rogers PCB materials differ from FR-4?
Compared to FR-4, Rogers offers lower loss, tighter electrical consistency, better thermal conductivity, lower expansion, higher frequencies, and superior signal integrity. But Rogers comes at a higher cost.
What industries typically use Rogers PCB materials?
Key industries using Rogers materials include telecom, aerospace, defense, test equipment, automotive, and satellite communications companies building high-frequency and high-reliability electronics.
Are Rogers PCB materials expensive?
Yes, Rogers materials are more expensive than FR-4 boards but provide much higher performance. There are cost optimization techniques to reduce Rogers’s expenses where possible.
Can Rogers PCBs be manufactured just like FR-4 PCBs?
Essentially, Rogers boards utilize similar fabrication processes as FR-4 but require specialized techniques tailored to Roger’s properties and tolerances.
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