UGPCB Rogers RO4350B+FR4 High Frequency Hybrid PCB: The Perfect Balance of Performance and Cost

Product Overview

Modern wireless systems face a critical challenge: high-frequency signals demand premium materials, but using Rogers laminates for the entire board drives costs prohibitively high. UGPCB’s Rogers RO4350B+FR4 High Frequency Hybrid PCB solves this dilemma. It combines high-performance RF material with standard FR4 in a single, cost-effective 4-layer stackup .

This hybrid construction places Rogers RO4350B on the outer layers for critical signal routing. FR4 forms the inner layers for power distribution and mechanical support . The result? Exceptional RF performance at a fraction of the cost of full-Rogers boards .

Key Specifications:

• Model: Rogers RO4350B + FR4 High Frequency Hybrid PCB

• Dielectric Constant (Dk): 3.48 @ 10GHz

• Structure: 2 Layers Rogers RO4350B + 2 Layers FR4

• Layer Count: 4 Layers

• Finished Thickness: 1.6mm

• Base Copper Thickness: ½ (18μm) HH/HH

• Finished Copper Thickness: 1/0.5/0.5/1 (OZ)

• Surface Treatment: Immersion Gold (ENIG)

• Application: Wireless Induction Communication Systems, RF Front-End Modules

What Is a Rogers RO4350B+FR4 Hybrid PCB?

A hybrid PCB combines two or more different dielectric materials within a single multilayer board . The Rogers RO4350B+FR4 hybrid uses:

• Rogers RO4350B on signal layers: A ceramic-filled hydrocarbon laminate designed for high-frequency applications .

• FR4 on inner layers: Standard epoxy glass-reinforced laminate for power and ground planes .

This material mix allows engineers to route RF signals on low-loss Rogers material while handling DC power and control logic on cost-effective FR4 .

Advantages at a glance:

• 30-50% cost reduction compared to full-Rogers boards .

• Superior signal integrity for high-frequency circuits .

• Mechanical stability from FR4’s rigid structure .

• Seamless integration of RF and digital sections on one board .

Design Guidelines and Stackup Structure

Layer Configuration

UGPCB’s standard 4-layer hybrid stackup follows a symmetrical design :

Total thickness: 1.6mm ±10% .

Critical Design Considerations

When designing for this hybrid stackup, follow these rules:

1. Impedance Matching
Rogers RO4350B has Dk=3.48 at 10GHz, while FR4 typically ranges from 4.2-4.8 . This difference affects trace widths for controlled impedance. Always calculate 50Ω or 100Ω traces specifically for the material they reside on.

2. Layer Transition
Keep high-frequency traces entirely within Rogers layers whenever possible . Avoid routing RF signals through FR4 regions to prevent signal degradation.

3. Symmetrical Stackup
The 1.6mm finished thickness with symmetrical copper distribution (1/0.5/0.5/1 OZ) minimizes warpage during lamination .

Material Properties and Performance

Rogers RO4350B

RO4350B belongs to Rogers’ RO4000 series, designed as a direct alternative to PTFE/woven glass materials .

Electrical Properties :

• Dielectric Constant (Dk): 3.48 ±0.05 @ 10GHz

• Dissipation Factor (Df): 0.0037 @ 10GHz

• Thermal Conductivity: 0.69 W/m·K

Thermal & Mechanical :

• Glass Transition Temperature (Tg): >280°C

• CTE (Z-axis): 32 ppm/°C

• Flammability: UL 94 V-0

RO4350B’s stable Dk across frequency makes it ideal for broadband designs up to millimeter-wave frequencies .

FR4

The FR4 inner layers provide structural integrity and cost efficiency.

Typical Properties :

• Dielectric Constant (Dk): 4.3-4.8 @ 1GHz

• Dissipation Factor (Df): 0.015-0.025

• Thermal Conductivity: ~0.3 W/m·K

• Tg: 130-180°C (depending on grade)

Cost Advantage: FR4 costs approximately 1/5 to 1/3 of Rogers materials .

Hybrid Compatibility

UGPCB selects modified high-performance FR4 grades that pair well with RO4350B. Recommended matching materials include Isola 370HR, TU-872, and Megtron 6 for optimal electrical and thermal compatibility .

Key Advantages of UGPCB’s Hybrid Solution

1. Cost-Performance Balance

By using Rogers only where needed, UGPCB’s hybrid boards deliver:

• Full RF performance on critical layers

• 30-50% material cost savings vs. all-Rogers designs

• No compromise on signal integrity

2. Superior Signal Integrity

RO4350B’s stable Dk (±0.05) ensures :

• Consistent phase response across temperature

• Minimal insertion loss at high frequencies

• Reduced signal dispersion in broadband applications

3. Mechanical Reliability

FR4 cores add stiffness that pure Rogers laminates lack . Benefits include:

• Reduced warpage during assembly

• Higher board rigidity for component mounting

• Better handling through manufacturing

4. Thermal Management

RO4350B’s thermal conductivity (0.69 W/m·K) exceeds FR4 by over 2x . Place high-power components on Rogers areas for:

• Efficient heat spreading

• Lower operating temperatures

• Extended product life

5. Excellent Solderability

Immersion gold (ENIG) surface finish provides :

• Flat pads for fine-pitch components

• Oxidation resistance

• Wire-bondable surfaces when required

Manufacturing Process at UGPCB

Producing hybrid PCBs requires specialized process control . UGPCB follows rigorous procedures:

Step 1: Material Preparation

RO4350B and FR4 cores are baked to remove moisture . This prevents delamination during lamination.

Step 2: Inner Layer Imaging

L2 and L3 FR4 cores undergo standard PCB processing :

• Dry film lamination

• LDI exposure

• Etching

• AOI inspection

Step 3: Layup and Lamination

Critical for hybrid success :

• Bondply selection (often RO4450B or compatible prepreg)

• Precise alignment of cores

• Optimized temperature profile to accommodate different CTEs

• Gradual cooling to minimize stress

Step 4: Drilling

Special considerations for mixed materials :

• Carbide drills with optimized speeds/feeds

• Reduced stack height

• Aggressive peck drilling cycles

Step 5: Desmear and Plating

Plasma desmear removes resin smear from drilled holes . Hybrid boards require extended plasma time compared to standard FR4.

Step 6: Outer Layer Imaging

L1 and L4 Rogers layers receive:

• LDI exposure for fine features

• Controlled etching for impedance accuracy

Step 7: Surface Finish

Immersion gold (ENIG) applied per specification :

• Nickel: 100-200 µ”

• Gold: 2-5 µ”

Step 8: Electrical Test

100% electrical testing ensures :

• Continuity

• Isolation

• Impedance verification on critical nets

Applications and Use Cases

5G Communication Systems

Base station antennas and RRUs benefit from :

• Low-loss signal paths

• Cost-effective large boards

• Stable performance at mmWave frequencies

Automotive Radar (77GHz)

Collision avoidance systems require :

• Tight Dk control

• Excellent thermal stability

• Reliable hybrid construction

Wireless Infrastructure

Point-to-point radios, Wi-Fi access points :

• RF power amplifiers on Rogers layers

• Control logic on FR4

• Single-board integration

Satellite Communications

LEO terminals and ground equipment :

• Low PIM performance

• Thermal cycling reliability

• Compact form factors

IoT and Sensors

Industrial wireless systems :

• Cost-sensitive production

• Moderate frequencies (2.4GHz, 5GHz)

• Mixed-signal requirements

Product Classification

By industry standards, UGPCB’s Rogers RO4350B+FR4 hybrid PCB falls into these categories:

Why Choose UGPCB for Your Hybrid PCBs?

UGPCB combines technical expertise with manufacturing excellence:

• 10+ years of RF PCB manufacturing experience

• Specialized hybrid process for Rogers+FR4 combinations

• Full material traceability and stock availability

• ISO9001, ISO14001, IATF16949, UL certified facilities

• Engineering support for stackup and impedance design

• Prototype to production capability

Get Your Quote Today

Designing high-frequency circuits is challenging enough. Let UGPCB handle the manufacturing complexity.

Email us your Gerber files: sales@ugpcb.com

What we need:

• Layer stackup details

• Impedance requirements

• Quantity and timeline

Our engineers will review your design and respond within 24 hours with:

• Manufacturing feasibility feedback

• Competitive pricing

• Lead time options

UGPCB – Your Trusted Partner for High-Frequency Hybrid PCBs