6-Layer PCB with RO4350B and High Tg FR-4 (S1000-2M)
This 6-layer PCB is a robust and versatile solution designed for
high-performance RF and microwave applications. Built with a hybrid
construction of RO4350B and High Tg FR-4 (S1000-2M) materials, this
PCB combines the electrical and thermal advantages of Rogers
laminates with the mechanical reliability of FR-4. Below, we
analyze the board’s features, advantages, and disadvantages to help
you understand its capabilities.
Key Construction Details
| Parameter | Specification |
| Base Material | RO4350B + High Tg FR-4 (S1000-2M) |
| Layer Count | 6 layers |
| Dimensions | 30.55mm x 37.7mm (±0.15mm) |
| Finished Thickness | 1.3mm |
| Copper Weight | 1oz (35μm) for all layers |
| Minimum Trace/Space | 4/4 mils |
| Minimum Hole Size | 0.25mm |
| Blind Vias | L1-L2 |
| Surface Finish | ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) |
| Solder Masks | Top: None; Bottom: Green |
| Silkscreen | Top and Bottom: White |
| Electrical Testing | 100% tested before shipment |
PCB Stackup
| Layer | Material | Thickness |
| Copper Layer 1 | Copper (1oz) | 35μm |
| Dielectric Layer 1 | RO4350B Core | 0.102mm (4mil) |
| Copper Layer 2 | Copper (1oz) | 35μm |
| Dielectric Layer 2 | Prepreg FR-4 | 0.254mm (10mil) |
| Copper Layer 3 | Copper (1oz) | 35μm |
| Dielectric Layer 3 | FR-4 (S1000-2M) | 0.254mm (10mil) |
| Copper Layer 4 | Copper (1oz) | 35μm |
| Dielectric Layer 4 | Prepreg FR-4 | 0.254mm (10mil) |
| Copper Layer 5 | Copper (1oz) | 35μm |
| Dielectric Layer 5 | FR-4 (S1000-2M) | 0.254mm (10mil) |
| Copper Layer 6 | Copper (1oz) | 35μm |
Advantages
RO4350B Material Properties:
- Provides a low dielectric constant (Dk) of 3.48 ±0.05 and a low
dissipation factor (Df) of 0.0037 at 10GHz, ensuring minimal signal
loss and excellent RF performance.
- Its high Tg (>280°C) and low Z-axis CTE (32 ppm/°C) improve
thermal stability and plated through-hole (PTH) reliability, even
under thermal shock conditions.
FR-4 (S1000-2M) Properties:
- Offers excellent mechanical strength, high heat resistance, and
anti-CAF performance, which enhances long-term reliability.
- Compatible with lead-free soldering processes and resistant to
delamination at high temperatures.
High-Performance ENEPIG Surface Finish:
ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) is
an advanced surface finish that provides:
- Excellent corrosion resistance and long shelf life.
- High solderability for fine-pitch components, making it ideal for
RF circuits.
Compact Yet Capable Design:
- With a size of 30.55mm x 37.7mm, the PCB is compact enough for
space-constrained applications while supporting complex designs,
thanks to its 6-layer construction.
- Blind vias (L1-L2) enable dense circuit integration, reducing board
size without sacrificing functionality.
Disadvantages
High Manufacturing Costs:
The hybrid construction with RO4350B and High Tg FR-4, along with
the ENEPIG finish, increases production costs compared to standard
FR-4 PCBs. This makes it less suitable for cost-sensitive or
high-volume applications.
No Top Solder Mask:
The absence of a top solder mask may expose components to
environmental factors, requiring extra care during assembly and
operation.
Limited Scalability:
With only 8 components, 39 pads, and 23 vias, the design is
optimized for specific applications but may lack scalability for
more complex circuit designs.
Applications
Commercial Airline Broadband Antennas
Radar and Guidance Systems
Satellite Communications
Phased Array Antennas
Conclusion
This 6-layer PCB is a high-performance, RF-focused solution that
combines the benefits of RO4350B’s low-loss dielectric properties
with S1000-2M’s mechanical robustness. Its ENEPIG surface finish,
compact design, and mixed dielectric stackup make it ideal for
aerospace, radar, and satellite communication systems. However, its
higher production costs and lack of a top solder mask may restrict
its use in more general-purpose or cost-sensitive applications.
