Rogers RO4350B + High Tg FR-4 4-Layer Hybrid PCB with ENIG Finish for RF and Mixed-Signal Applications

1. RO4350B Material Introduction

RO4350B is a proprietary woven glass reinforced hydrocarbon/ceramic laminate developed by Rogers Corporation, specifically designed to bridge the gap between high-performance PTFE-based materials and standard epoxy/glass laminates. It offers electrical performance close to PTFE/woven glass while maintaining the manufacturability of epoxy/glass materials.

RO4350B laminates provide tight control on dielectric constant (Dk) and maintain low loss while utilizing the same processing methods as standard epoxy/glass. Available at a fraction of the cost of conventional microwave laminates, RO4350B does not require special through-hole treatments or handling procedures required for PTFE-based materials. The material is UL 94 V-0 rated, making it suitable for active devices and high-power RF designs.

The thermal coefficient of expansion (CTE) of RO4350B is similar to that of copper, providing excellent dimensional stability essential for mixed dielectric multilayer board constructions. The low Z-axis CTE ensures reliable plated through-hole quality even in severe thermal shock applications. With a Tg exceeding 280°C, its expansion characteristics remain stable over the entire range of circuit processing temperatures.

2.RO4350B Key Features and Benefits

Dk 3.48 ± 0.05 at 10 GHz ensures tight impedance control for consistent RF performance
Df 0.0037 at 10 GHz minimizes signal loss in high-frequency circuits
Thermal conductivity 0.69 W/m/°K enables effective heat dissipation
CTE X:10 ppm/°C, Y:12 ppm/°C matched to copper for excellent dimensional stability
Z-axis CTE 32 ppm/°C ensures reliable plated through-hole quality under thermal stress
Tg >280°C maintains stability throughout circuit processing temperatures
Low water absorption 0.06% preserves electrical properties in humid environments
UL 94 V-0 rated for safety compliance in active devices and high-power designs
Standard epoxy/glass processing eliminates need for special through-hole treatments
Cost-effective alternative to PTFE-based microwave laminates

3. PCB Construction Details

4. PCB Stackup (4-Layer Rigid Structure)

L1 (Top): 1oz Copper, 35μm
Core 1: RO4350B, 0.254mm (10mil)
L2: 1oz Copper, 35μm
Prepreg: 1080 (RC63%) + 7628 (RC43%), 0.254mm (10mil)
Core 2: High Tg FR-4, 0.4mm
Prepreg: 1080 (RC63%) + 7628 (RC43%), 0.254mm (10mil)
L3: 1oz Copper, 35μm
Core 3: RO4350B, 0.254mm (10mil)
L4 (Bottom): 1oz Copper, 35μm

5. PCB Statistics:

Components: 17
Total Pads: 45
Thru Hole Pads: 21
Top SMT Pads: 16
Bottom SMT Pads: 8
Vias: 9
Nets: 10

6. Primary Application Areas

Commercial Airline Broadband Antennas
Microstrip and Stripline Circuits
Millimeter Wave Applications
Radar Systems
Guidance Systems
Point to Point Digital Radio Antennas
Wireless Infrastructure
Automotive Radar Sensors
Test and Measurement Equipment
Aerospace and Defense Communications

7. Quality Assurance

Artwork supplied: Gerber RS-274-X
Accepted standard: IPC-Class-2
Availability: Worldwide