RO4835 is part of Rogers Corporation’s renowned RO4000 series of laminates, specifically designed for high-frequency applications. This hydrocarbon ceramic material possesses unique properties, eliminating the need for specific via treatments typically required by other ceramic-based PCBs.
One notable advantage of RO4835 is its compatibility with FR4 processes, a widely used standard for PCB manufacturing. This characteristic makes it a cost-effective choice compared to high-end high-frequency materials composed of ceramics and/or PTFE, which are also manufactured by Rogers.
In addition to its high-frequency capabilities, RO4835 offers exceptional resistance to oxidation, ensuring prolonged performance and reliability. This feature further enhances its appeal as an effective solution for various applications.
By highlighting its FR4-process compatibility, cost-effectiveness, and oxidation-delaying properties, Rogers Corporation positions RO4835 as a versatile and efficient material within their comprehensive range of high-frequency laminates.
Specification Parameter: Rogers Ro4835 PCB Base Material
|Dielectric Constant,εProcess||3.48±0.05||Z||–||10 GHz/23℃||IPC-TM-650 184.108.40.206 Clamped Stripline|
|Dielectric Constant,εDesign||3.66||Z||–||8 to 40 GHz||Differential Phase Length Method|
|Dissipation Factortan,δ||0.0037||Z||–||10 GHz/23℃||IPC-TM-650 220.127.116.11|
|Thermal Coefficient of ε||+50||Z||ppm/℃||-100℃to 150℃||IPC-TM-650 18.104.22.168|
|Volume Resistivity||5 x 108||MΩ.cm||COND A||IPC-TM-650 22.214.171.124|
|Surface Resistivity||7 x108||MΩ||COND A||IPC-TM-650 126.96.36.199|
|Electrical Strength||30.2(755)||Z||Kv/mm(v/mil)||IPC-TM-650 188.8.131.52|
|Tensile Modulus||7780(1128)||Y||MPa(ksi)||RT||ASTM D 638|
|Tensile Strength||136(19.7)||Y||MPa(ksi)||RT||ASTM D 638|
|Flexural Strength||186 (27)||Mpa (kpsi)||IPC-TM-650 2.4.4|
|after etch+E2/150℃||IPC-TM-650 2.4.39A|
|Coefficient of Thermal Expansion|
|Td||390||℃TGA||ASTM D 3850|
|Thermal Conductivity||0.66||W/m/oK||80℃||ASTM C518|
48hrs immersion 0.060″
sample Temperature 50℃
|ASTM D 570|
|Density||1.92||gm/cm3||23℃||ASTM D 792|
|Copper Peel Stength||0.88 (5.0)||N/mm (pli)|
after solder float 1 oz.
|Lead-free Process Compatible||Yes|
Key Advantages of RO4835 Laminates
The use of RO4835, a hydrocarbon ceramic material from Rogers Corporation’s RO4000 series, offers several advantages in high-frequency printed circuit board (PCB) applications:
High-Frequency Performance: RO4835 is specifically designed for high-frequency applications, offering excellent electrical properties. It provides low insertion loss and controlled impedance, ensuring efficient signal transmission and minimal signal degradation. Its high dielectric constant (Dk) and low loss tangent (Df) contribute to superior signal integrity, making it suitable for demanding high-frequency circuits.
FR4-Compatible: One significant advantage of RO4835 is its compatibility with FR4 processes. This means it can be manufactured using standard FR4 fabrication techniques, which are widely used and familiar in the industry. This compatibility simplifies the manufacturing process and reduces costs compared to specialized fabrication methods required for some high-end high-frequency materials.
Cost-Effectiveness: By being FR4-process friendly, RO4835 offers a cost-effective solution for high-frequency applications. It provides comparable performance to high-end materials composed of ceramics or PTFE but at a more affordable price point. This cost advantage can be particularly beneficial when budget considerations are a priority without compromising on performance.
Oxidation Resistance: RO4835 exhibits excellent resistance to oxidation. This property enables the material to maintain its electrical performance over an extended period, even in challenging environmental conditions. The ability to delay oxidation ensures the longevity and reliability of circuits using RO4835, making it suitable for applications where long-term performance is crucial.
Versatility: RO4835 is available in various thicknesses, copper foil options, and surface finishes, allowing for flexibility in design and application-specific requirements. It can be used in single-sided, double-sided, and multilayer PCBs, accommodating a wide range of circuit complexities.
Overall, the advantages of using RO4835 include its high-frequency performance, compatibility with FR4 processes, cost-effectiveness, oxidation resistance, and versatility. These characteristics make RO4835 a favorable choice for high-frequency PCB designs, offering a balance of performance, reliability, and affordability.
Disadvantages of the Rogers RO4835 PCB Base Materials
Here are some potential disadvantages of using Rogers RO4835 laminates for PCB fabrication:
Cost – RO4835 is significantly more expensive than conventional FR-4 laminates. The fabricated PCB cost will be higher.
Availability – As a specialty material from Rogers Corporation, lead times and availability of RO4835 can be a concern compared to widely available FR-4.
Fabrication difficulty – RO4835 requires specialized processing like plasma etchback and careful drilling/routing. Not all PCB shops may have expertise.
Thermal conductivity – While better than FR-4, the thermal conductivity of RO4835 (0.69 W/mK) is lower than other exotic materials like polyimide or thermally conductive dielectrics. This may limit heat dissipation capability in some high power designs.
Moisture absorption – RO4835 absorbs more moisture (0.03%) than PTFE-based laminates. Careful handling and baking is needed to prevent issues during soldering.
Lead-free soldering – The relatively lower glass transition temperature of RO4835 (280°C) may limit lead-free soldering processes to lower peak temperatures.
Panel sizes – Standard panel sizes of RO4835 may be smaller than FR-4, impacting panel utilization and cost.
Via and hole wall quality – RO4835 is more prone to fracture during mechanical drilling and routing, requiring specific drill bits and careful drilling parameters.
Signal loss – While superior to FR-4, dielectric loss is higher compared to PTFE or ceramic filled materials, limiting high frequency performance.
So for many applications, the electrical and thermal benefits of RO4835 outweigh the disadvantages, but they should be carefully considered.
Key Considerations when Choosing Rogers RO4385 Laminates
Here are some key considerations when choosing Rogers RO4385 laminates for PCB fabrication:
Frequency of operation – RO4385 is designed for high frequency applications up to mmWave bands like 5G, automotive radar, etc. It may be overkill for lower frequency applications where FR-4 would suffice.
Dielectric constant requirements – RO4385 has a dielectric constant of 3.55. This may be required for impedance control in high-speed designs. Lower Dk materials like RO4350 (Dk 3.48) may provide better performance.
Loss tangent specifications – RO4385 has a low loss tangent of 0.0037. This is important for high frequency boards but may not be critical for some applications.
Thermal management – RO4385 has a thermal conductivity of 0.71 W/mK in the z-direction. This helps dissipate heat from high power components. If not a factor, cheaper materials can be used.
Layer count – RO4385 is available for up to 20+ layers. For simpler boards, FR-4 or cheaper materials may suffice.
Fabrication capability – RO4385 requires special processing like plasma etchback. Confirm the PCB supplier has the capability to properly fabricate RO4385 multilayers.
Lead-free soldering – RO4385 has high Tg and can withstand lead-free reflow up to 280°C. Other materials like polyimides may be needed if higher temp soldering is required.
Budget – RO4385 is significantly more expensive than FR-4. Weigh costs against the electrical and thermal benefits it provides.
Availability – Order early as Rogers materials may have long lead times. Check regional availability.
So in summary, analyze design requirements and fabrication complexities to determine if RO4385 is an appropriate choice or if a lower cost material can meet the needs.
Rogers Ro4385 PCB Fabrication Guide
Here is a brief guide to some important considerations when fabricating PCBs with Rogers RO4385 laminates:
Storage and Handling:
● Store RO4385 cores in vacuum sealed bags at <= 23°C and 50% relative humidity. Limit exposure to UV light.
● Allow cores to reach room temperature before unsealing to prevent moisture condensation.
● Use sharp, carbide-tipped drill bits and tools to avoid fraying or tearing.
Inner Layer Processing:
● Use chemical/plasma etching for fine line etching. Mechanical processes can fracture glass fibers.
● Control etchant temperature and circulation to avoid undercutting.
● Watch for pink ring effect – rinse well after etching.
● Use low flow prepregs to avoid resin starvation around small features.
● Apply even pressure of 14-28psi during lamination. Use sacrificial layers on outer surfaces.
● Cure per recommended profile – 30 min above Tg of 280°C.
Drilling and Routing:
● Use rigid entry/exit materials to prevent burring.
● Drills holes >= 6 mils larger than finished hole size for routing allowance.
● Avoid using hollow or fluted drills which can cause more material tear-out.
Plating and Coating:
● Follow prescribed surface preparations like microetch, oxide treatment, etc.
● Monitor plating thickness frequently – target 1 mil copper on external layers.
● Watch for pink ring effect after plating or coating – rinse well.
Solder Mask and Legend:
● Use LPI solder masks designed for higher Tg materials. Apply per manufacturer instructions.
● Bake boards prior to legend printing to avoid bubbling or delamination issues.
Difference Between RO4350B PCB and RO4835 PCB
RO4350B and RO4835 are both popular high-frequency materials manufactured by Rogers Corporation for printed circuit board (PCB) applications. While they share similarities, there are some notable differences between RO4350B PCB and RO4835 PCB:
Composition: RO4350B and RO4835 are both thermoset laminates, but they have different compositions. RO4350B is a hydrocarbon/ceramic-based laminate, while RO4835 is a thermoset resin system with a ceramic filler. The specific composition affects their electrical and mechanical properties.
Dielectric Constant (Dk): Dk is an essential parameter for high-frequency applications. RO4350B typically has a lower Dk of around 3.66, enabling efficient signal propagation and reduced signal loss. RO4835, on the other hand, has a higher Dk ranging from 3.48 to 3.51. The choice between the two materials depends on the desired electrical performance and application requirements.
Loss Tangent (Df): The loss tangent, or dissipation factor (Df), indicates the energy loss in the material. RO4350B generally has a lower Df, contributing to lower signal loss and improved performance in high-frequency circuits. RO4835, while still offering good performance, may have a slightly higher Df compared to RO4350B.
Thermal Properties: Both materials exhibit good thermal stability, but there are differences in their glass transition temperature (Tg) and coefficient of thermal expansion (CTE). RO4350B has a higher Tg of around 280°C, providing better dimensional stability at elevated temperatures. RO4835 has a lower Tg of approximately 200°C but offers a lower CTE, which can be advantageous in applications where thermal expansion needs to be minimized.
Manufacturing Considerations: RO4350B and RO4835 are both considered to be relatively easy to handle during PCB fabrication and assembly processes. They do not require special through-hole treatments and are generally user-friendly. However, it’s worth noting that RO4835 may have a slightly higher resin content, which could result in potential resin smear during processing.
When selecting between RO4350B PCB and RO4835 PCB, it is essential to consider the specific requirements of your application, including frequency range, signal integrity, thermal management, cost, and manufacturing considerations. Consulting with PCB manufacturers and considering their recommendations based on your specific needs will help you make an informed decision.
Where to Buy RO4835 PCB Products?
At JarnisTech, we specialize in manufacturing printed circuit boards utilizing Rogers materials for advanced applications. As a leading PCB manufacturer in China, we pride ourselves on providing high-quality, reliable products with quick turnaround times at competitive prices. Our expertise with Rogers boards ensures we can meet the needs of customers requiring these high-performance materials. We have a dedicated team available 24/7 to assist with any questions about our PCB fabrication services and to ensure your project’s success.
JarnisTech Rogers RO4835 PCB Capability
|PCB Capability (RO4835)|
|PCB Material:||Hydrocarbon Ceramic Laminates|
|Dielectric constant:||3.48 (10 GHz)|
|Dissipation Factor||0.0037 (10 GHz)|
|Layer count:||Double Sided PCB, Multilayer PCB, Hybrid PCB|
|Copper weight:||0.5oz (17 µm), 1oz (35µm), 2oz (70µm)|
|Dielectric thickness (ED copper)||6.6mil (0.168mm), 10mil (0.254mm), 20mil (0.508mm), 30mil (0.762mm), 60mil (1.524mm)|
|Dielectric thickness (LoPro copper)||4mil (0.102mm), 7.3mil (0.186mm), 10.7mil (0.272mm), 20.7mil (0.526mm), 30.7mil (0.780mm), 60.7mil (1.542mm)|
|PCB size:||≤400mm X 500mm|
|Solder mask:||Green, Black, Blue, Yellow, Red etc.|
|Surface finish:||Bare copper, HASL, ENIG, Immersion silver, Immersion tin, OSP, Pure gold plated etc..|
Please consider JarnisTech for your next Rogers-based PCB order. We are confident we can deliver solutions that exceed expectations while remaining cost-effective. We look forward to the opportunity to work with you.