High-Frequency Hybrid PCB – What Is the Most Suitable Material for Manufacturing?
With increasing demands on high-speed and high-frequency electronics, printed circuit board design is becoming an increasingly complex discipline. Traditional materials such as FR-4 are no longer sufficient, particularly in microwave and RF applications. The solution lies in the use of advanced dielectric materials such as Rogers RO4350B, often combined with conventional substrates.
Basic Characteristics of Rogers RO4350B Material
Rogers RO4350B material is a high-frequency laminate developed for applications in the approximate range of 8–40 GHz, where low loss and stable dielectric properties are critical.
Its main parameters include:
- Dielectric constant (Dk): approx. 3.48
- Dissipation factor (Df): approx. 0.0031–0.0037
- High thermal stability (Tg > 280 °C)
- Low moisture absorption (~0.0006)
- Good dimensional stability and mechanical strength
These properties enable precise impedance control, minimal signal loss, and stable performance even at high frequencies, usable for example, for space and satellite projects.
RO4350B is designed to be compatible with standard PCB manufacturing processes:
- does not require special PTFE processing
- can be processed similarly to FR-4
- allows easy lamination in hybrid structures
This simplifies manufacturing and improves production yield.
Hybrid PCB Construction (Rogers + FR-4 Combination)
Modern designs often use a hybrid structure that combines Rogers RO4350B material with standard FR-4 material. This approach provides an optimal balance between performance and cost.
Hybrid PCBs typically include:
- RF layers made of Rogers material for high-frequency signals
- support and logic layers made of FR-4 for mechanical stability and cost reduction.
This combination ensures:
- high signal integrity
- mechanical strength
- cost-effective manufacturing
Comparison and Alternatives Rogers RO4350B material belongs to the so-called “mid-range” class of high-frequency laminates (low-loss hydrocarbon/ceramic). There is no single fully equivalent material. However, several alternatives offer comparable or even superior performance in certain parameters—depending on project requirements such as cost, loss, frequency, and manufacturing compatibility.
Material Comparison Table (Including Suitability for Hybrid PCB)
| Material | Dk (≈) | Df (≈) | RF Performance vs. RO4350B | Cost vs. RO4350B | Manufacturing Complexity | Suitable for RF PCB | Suitable for Hybrid (FR-4) | Notes |
| RO4350B (Rogers) | 3.48 | 0.0035 | Reference | Reference | Low | Yes | Yes | Industry standard for RF + hybrid PCB |
| RO4003C (Rogers) | 3.38 | 0.0027 | Better loss | Lower | Low | Yes | Yes | Most common alternative to Rogers RO4350B material |
| RO4835 (Rogers) | 3.48 | 0.0030–0.0037 | Better stability | ≈ Similar | Low | Yes | Yes | Automotive-grade RF, improved reliability |
| RO4360G2 (Rogers) | ~3.5 | ~0.0038 | ≈ Similar | Lower | Very low | Yes | Yes | Optimized for FR-4 hybrid constructions |
| TC350 | ~3.5 | ~0.002–0.003 | Similar / better | Lower | Low | Yes | Yes | Cost-effective RF alternative |
| RO3003 (Rogers) | 3.0 | 0.0010 | Significantly better | Higher | Medium | Yes | Limited | mmWave applications, CTE mismatch risk |
| RO3035 (Rogers) | 3.5 | 0.0015 | Better | Higher | Medium | Yes | Limited | Higher-frequency designs, more complex processing |
| RT/duroid 5880 (PTFE) | 2.2 | 0.0009 | Best | Very high | High | Yes | No | Ultra-low loss, not compatible with hybrid PCB |
| Isola I-Tera / Astra MT | ~3.3–3.7 | ~0.002–0.004 | ≈ Rogers-level | Lower–Medium | Low | Yes | Yes | Strong competitor in EU/US high-speed market |
| Panasonic Megtron 6/7 | ~3.2–3.7 | ~0.002–0.003 | Comparable / better | High | Medium | Yes | Limited | High-speed + RF hybrid for datacenter applications |
| Taconic RF laminates | ~2.17–3.5 | ~0.0015–0.003 | ≈ Rogers | Medium | Medium | Yes | Limited | Widely used in US RF antenna applications |
| FR-4 (HF variants) | ~4.2 | 0.010–0.020 | Worse | Lowest | Very low | Limited | Yes (base only) | Not suitable for RF layers |
High-frequency hybrid PCBs based on Rogers RO4350B material represent a key technology for modern electronics, particularly in RF and microwave applications. The combination of advanced materials, precise manufacturing processes, and optimized design enables high signal quality, reliability, and efficiency.
With the rapid development of 5G networks, autonomous systems, and high-speed communication, the importance of these technologies will continue to grow, becoming a standard for advanced electronic designs.