2026-05-30
In modern RF antenna, 5G communications, and high-power RF designs, achieving the perfect balance between high performance and cost efficiency is a top priority. To achieve this, utilizing a hybrid laminate stackup—combining Rogers RO4350B with standard FR-4—has become the industry-standard solution.
Rogers RO4350B hydrocarbon ceramic laminates deliver PTFE-grade electrical performance while maintaining the processing ease of conventional epoxy/glass (FR-4) materials. However, in a successful hybrid PCB design, selecting the compatible FR-4 core or prepreg (PP) is critical to ensuring the long-term reliability of the finished board.
In a multilayer PCB design, placing high-frequency RF signals on the Rogers RO4350B layer while utilizing FR-4 for lower-frequency signal, ground, and power layers drastically optimizes overall material costs. RO4350B offers distinct electrical and physical advantages in hybrid processing:
Strict Dielectric Constant (Dk) Control: A stable Dk of 3.48 allows for precise impedance control, which is essential for high-frequency signal integrity.
Ultra-Low Dissipation Factor (Df): With a Df of 0.0037 at 10 GHz, it minimizes signal attenuation, making it ideal for low-loss applications.
Excellent Z-Axis CTE Control: A Z-axis Coefficient of Thermal Expansion (CTE) of 32 ppm/°C closely matches that of copper, ensuring superior reliability for Plated Through-Holes (PTH) under thermal shock.
Standard Manufacturing Compatibility: RO4350B can be processed using standard FR-4 manufacturing flows. It does not require specialized plasma desmear or complex pre-plating treatments and easily tolerates mechanical scrubbing before solder mask application.
To prevent customer data leakage while demonstrating real manufacturing capabilities, below is a standard, fully optimized 14-layer hybrid PCB stackup template engineered by Beton Tech. It perfectly illustrates the combination of high-frequency Rogers materials and reliable High-Tg FR-4 (ShengYi) layers with standard via structures:
Figure 1: Example of a balanced 14-layer hybrid stackup showcasing Rogers RO4350B top/bottom RF layers integrated with ShengYi High-Tg FR-4 cores.
When designing a Rogers RO4350B + FR-4 hybrid stackup, choosing a low-grade, generic FR-4 is highly discouraged. The physical property mismatches between different laminates can lead to warpage, delamination, or register errors during lamination.
Hardware engineers and manufacturers must evaluate the following parameters carefully:
This is the most critical factor for hybrid PCB reliability. Since Rogers RO4350B features a high Tg (over 280°C), the chosen FR-4 must withstand lead-free reflow temperatures (up to 260°C) without causing excessive stress at the material interfaces.
Industry Recommendation: We highly recommend choosing High-Tg FR-4 (Tg 170°C) materials, such as ShengYi S1000-2M. These resins provide excellent thermal stability, high peeling strength, and seamless compatibility when laminated with RO4350B.
FR-4 provides the rigid structural integrity of the PCB. In a hybrid multi-layer layout, engineers should adopt a symmetrical stackup design to balance the differential X/Y-axis dimensional expansion (shrinkage and stretch) between the RO4350B and FR-4 layers. This effectively prevents board warpage during assembly.
Standard FR-4: Dk $\approx$ 4.2–4.7, Df 0.015–0.020 (not suitable for high-frequency RF transmission).
Rogers RO4350B: Dk 3.48, Df 0.0037.
To optimize signal quality, all microstrip lines, coplanar waveguides, and critical RF traces must be tightly routed on the RO4350B dielectric layer. Standard control lines, digital signals, and power planes should be allocated to the FR-4 layers to bypass its higher dielectric losses.
The selected FR-4 material must comply with the UL 94V-0 flame retardant standard and meet modern global supply chain mandates, including RoHS and Halogen-Free requirements, ensuring high chemical and environmental resistance.
A hybrid stackup combining Rogers RO4350B and High-Tg FR-4 (such as S1000-2M) delivers the ultimate combination: the premium, low-loss capabilities of Rogers for RF paths, and the robust mechanical strength and cost benefits of FR-4 for the rest of the board.
As a leading high-end PCB & PCBA manufacturer, Beton Tech brings years of advanced manufacturing expertise to high-frequency hybrid multilayer PCBs. From rigorous DFM stackup evaluations and dimensional stability controls to high-precision impedance testing, we provide turn-key solutions tailored to your design requirements.
Have questions about RO4350B hybrid stackups, DFM Engineering Questions (EQs), or looking for a quick quotation? Contact the Beton Tech engineering team today!