F4BM275 RF substrate Double-sided copper clad laminate ED copper in weights of 0.5oz 18µm, 1oz 35µm 1.5oz 50µm, 2 oz 70µm

F4BM275: A High-Performance RF Laminate for Balanced Design

Engineered as a pivotal member of the versatile F4BM/F4BME product family, the F4BM275 PTFE/glass fiber laminate provides an outstanding balance of electrical, thermal, and mechanical properties, tailored for advanced RF and microwave applications. With a carefully tuned dielectric constant (Dk) of 2.75, it occupies the higher tier of the series' Dk spectrum, offering designers a unique combination of enhanced structural stability and preserved signal integrity. This material is a robust, high-value alternative to imported laminates, designed to meet the stringent demands of modern high-frequency circuits.

Core Material Advantages

The F4BM275's composition leverages an increased proportion of woven glass fabric relative to PTFE resin to achieve its target dielectric constant. This higher glass content directly translates to superior dimensional stability, lower in-plane coefficient of thermal expansion (CTE), and improved thermal performance. Consequently, it is exceptionally well-suited for multilayer board constructions and applications where physical robustness under thermal cycling is critical.

Clad with standard Electrodeposited (ED) copper foil, this variant is optimized for cost-effective performance in applications where ultra-low Passive Intermodulation (PIM) is not a primary constraint. It delivers reliable, low-loss performance essential for power dividers, couplers, filters, and antenna feed networks. Its excellent thermal and environmental resilience also makes it a strong candidate for aerospace, satellite, and radar systems.

Data Sheet

Electrical Performance (@ 10 GHz):

• Dielectric Constant (Dk): 2.75 ±0.05
• Dissipation Factor (Df): 0.0015 (increases to 0.0021 @ 20 GHz)
• Thermal Coefficient of Dk (TCDk): -92 ppm/°C (-55°C to 150°C)
• Insulation: Volume Resistivity ≥ 6×10⁶ MΩ·cm; Surface Resistivity ≥ 1×10⁶ MΩ

Thermal & Structural Properties:

• Coefficient of Thermal Expansion: XY-Axis: 14-16 ppm/°C (-55°C to 288°C), Z-Axis: 112 ppm/°C (-55°C to 288°C)
• Thermal Conductivity (Z-axis): 0.38 W/(m·K)
• Operational Range: -55°C to +260°C
• Moisture Absorption: ≤ 0.08%
• Flammability: UL 94 V-0 Certified

Mechanical Reliability:

• Copper Peel Strength (1 oz. ED): > 1.8 N/mm
• Thermal Stress: No delamination after 3 cycles of 10 seconds at 260°C

Configurations & Availability

The F4BM275 is offered with remarkable flexibility to suit diverse manufacturing needs:

Copper Cladding: Available with standard ED copper in weights of 0.5 oz (18µm), 1 oz (35µm), 1.5 oz (50µm), and 2 oz (70µm).

Panel Sizes: Standard sizes include 460x610mm, 500x600mm, 850x1200mm, 914x1220mm, and 1000x1200mm, with custom sizes available upon request.

Core Thickness: A broad range is offered, from 0.2mm (minimum for Dk 2.75) up to 12.0mm, with specified manufacturing tolerances.

Enhanced Solutions: Available as metal-clad laminates (F4BM275-CU or F4BM275-AL) for applications requiring superior heat dissipation (copper base) or effective shielding (aluminum base).

Conclusion

The F4BM275 stands out as a strategically engineered substrate that masterfully balances a higher, stable dielectric constant with the inherent low-loss benefits of PTFE chemistry. Its enhanced glass fabric content ensures the dimensional and thermal stability required for reliable, high-density assemblies. Offering extensive configuration options and backed by high-volume commercial production, the F4BM275 presents a compelling, high-performance, and cost-effective solution for the next generation of RF and microwave designs.