RO4350B PCB material is one of the most widely used laminates for high-frequency circuit design, especially in RF, microwave, and high-speed digital applications. As signal frequencies continue to increase in modern electronics—such as 5G communication, automotive radar, and satellite systems—the limitations of standard FR4 materials become more evident. Engineers increasingly require materials that can maintain low signal loss, stable dielectric performance, and reliable thermal behavior.

What Is RO4350B PCB Material?

RO4350B PCB material is a hydrocarbon ceramic-filled laminate developed by Rogers Corporation, specifically engineered for high-frequency and RF circuit applications.

Unlike standard FR4 materials, RO4350B is designed to deliver:

• Low dielectric loss for minimal signal attenuation
• Stable dielectric constant (Dk) across wide frequency ranges
• High thermal reliability under lead-free assembly
• FR4-compatible processing, reducing manufacturing complexity

This combination allows engineers to design RF, microwave, and high-speed PCBs with predictable electrical performance while maintaining scalable production.

RO4350B Datasheet Overview

Category	Property	RO4350B Typical Value	Engineering Meaning
Thermal	Tg (DSC/TMA)	>280 °C	Excellent thermal stability, lead‑free safe
	Td (5% weight loss)	≥390 °C	High thermal decomposition resistance
	T260	>30 min	Strong resistance to delamination
	T288	>15 min	Withstands high‑temp reflow
	CTE (X/Y)	10–12 ppm/°C	Matches copper, minimal warpage
	CTE (Z‑axis, <Tg)	32 ppm/°C	Improves PTH reliability
	Thermal Conductivity	0.69 W/m·K	Better heat dissipation than standard FR‑4
Electrical	Dielectric Constant (10 GHz)	3.48 ±0.05	Design Dk = 3.66 for impedance
	Dissipation Factor (10 GHz)	0.0037	Ultra‑low signal loss
	Volume Resistivity	1.2×10¹⁰ MΩ·cm	High insulation stability
	Surface Resistivity	4.2×10⁹ MΩ	Low leakage risk
	Dielectric Strength	≥30 kV/mm	Good insulation performance
Mechanical	Flexural Strength	≥250 MPa	Good rigidity
	Peel Strength	≥1.0 N/mm	Reliable copper adhesion
	Young’s Modulus	~18 GPa	Structural stability
Moisture & Reliability	Water Absorption	≤0.06%	Stable in humid environments
	CAF Resistance	Very Good	Safe for dense multilayer RF boards
	Flammability	UL 94 V‑0	High safety standard
Process	Lead‑Free Compatible	Yes	Standard SMT assembly
	Max Layer Count	Up to 20–30 layers	Works for multilayer RF/HDI
	Compatible Prepreg	RO4450B	Optimized multilayer bonding

Key Features of RO4350B PCB Material

1. Excellent High‑Frequency Electrical Performance

Stable Dk 3.48 ±0.05 and ultra‑low Df minimize insertion loss and phase shift, supporting precise impedance control for antennas, filters, and high‑speed lines up to 77 GHz and beyond.

2. Outstanding Thermal Reliability

Tg >280 °C and high Td ensure stability during multiple lead‑free reflows. Low CTE in X/Y/Z axes reduces thermal stress, greatly improving via and board reliability under thermal cycling.

3. Easy Processing Like FR‑4

Unlike PTFE materials, RO4350B uses standard drilling, plating, and lamination. It supports mixed stackups with FR‑4, cutting cost while keeping RF performance.

4. Low Moisture & High Environmental Stability

Water absorption ≤0.06% maintains consistent electrical properties in high humidity. V‑0 rating and robust mechanical strength suit automotive, industrial, and aerospace environments.

5. Versatile Multilayer Compatibility

Paired with RO4450B prepreg for multilayer RF boards. Supports hybrid designs: RO4350B for RF layers, FR‑4 for digital/power layers to balance performance and BOM cost.

What Is the Dielectric Constant of RO4350B?

The RO4350B dielectric constant is:

• 3.48 ± 0.05 at 10 GHz
• ~3.66 for design calculations

This value remains stable from MHz to tens of GHz, which is critical for impedance-controlled RF designs.

Why This Matters

A stable Dk enables:

• Accurate 50Ω transmission line design
• Reliable RF matching networks
• Consistent signal timing and phase control

In contrast, FR4 materials show significant variation with frequency, which leads to impedance drift.

Applications of RO4350B PCB Material

• 5G base stations, antennas, microwave filters
• Automotive radar (24 GHz / 77 GHz ADAS)
• RF power amplifiers, couplers, dividers
• Satellite communications, aerospace radar
• High‑speed backplanes and interconnects
• WLAN, RFID, point‑to‑point radio
• Test & measurement instrumentation

RO4350B vs RO4003C vs FR‑4

Property	RO4350B	RO4003C	Standard FR‑4
Dk @10 GHz	3.48	3.38	~4.4
Df @10 GHz	0.0037	0.0027	0.020–0.030
Tg	>280 °C	>280 °C	130–150 °C
Thermal Conductivity	0.69	0.64	~0.25
FR‑4 Process Compatibility	Yes	Yes	N/A
Flame Retardant	V‑0	Non‑V‑0	V‑0
Max Frequency	Up to 77 GHz+	Up to 40 GHz	~3 GHz
Cost	Medium	Medium‑High	Low
Best For	General RF, 5G, automotive radar	Ultra‑low‑loss RF	Low‑speed digital

How to Choose RO4350B for Your PCB Design?

Choose RO4350B if:

• Your design involves RF, microwave, or high‑speed signals >3 GHz
• You need stable impedance and low insertion loss
• You want FR‑4‑like processing but better performance
• Applications: automotive radar, 5G, aerospace, test instruments
• You need V‑0 flame retardant for commercial/industrial use

Consider alternatives if:

• Extreme low loss → RO4003C
• Pure cost priority → FR‑4 / S1000H
• Non‑RF low‑speed digital → standard high‑Tg FR‑4

Frequently Asked Questions

1. What is the difference between RO4350B and FR-4?

While both can be processed using standard fabrication methods, they differ significantly in electrical performance. RO4350B is a hydrocarbon/ceramic laminate designed for high-frequency applications (up to 77 GHz), offering a stable dielectric constant (Dk) and much lower signal loss (Loss Tangent of 0.0037) compared to FR-4 (Loss Tangent of ~0.015–0.025). FR-4 typically struggles with signal integrity above 2–3 GHz, whereas RO4350B maintains its properties into the millimeter-wave range.

2. Is RO4350B compatible with standard lead-free soldering?

Yes. RO4350B has a high glass transition temperature (Tg > 280°C) and a decomposition temperature (Td) of 390°C. This makes it fully compatible with automated assembly and lead-free reflow soldering processes, which typically peak around 260°C. Its low Z-axis coefficient of thermal expansion (32 ppm/°C) also ensures that plated through-holes (PTH) remain reliable during thermal cycling.

3. What is the Dielectric Constant (Dk) of Rogers 4350B?

The standard design Dielectric Constant for RO4350B is 3.48 ± 0.05 at 10 GHz. This value is exceptionally stable across a wide frequency range, which is critical for designing controlled impedance transmission lines and wideband matching networks.

Note: For very thin materials (e.g., 0.004″), the Dk specification may shift slightly to 3.36.

4. How does RO4350B compare to RO4003C?

Both belong to the Rogers 4000 series, but the primary difference is the flame retardancy rating. RO4350B is UL 94 V-0 rated, making it the industry standard for commercial and active devices where fire safety certification is required. RO4003C is not UL 94 V-0 rated, though it offers a slightly lower loss tangent (0.0027) and a slightly lower Dk (3.38), making it preferable for specific passive applications where every fraction of a decibel counts.

5. Does RO4350B require special plasma etching for through-hole plating?

No. Unlike PTFE-based materials (like the Rogers 5000 or 6000 series), RO4350B is a thermoset hydrocarbon laminate. This means it can be processed using standard epoxy/glass (FR-4) techniques. It does not require specialized via preparation, such as sodium naphthenate or plasma etching, which significantly reduces manufacturing costs and lead times.

Get RO4350B PCB Support

If your project involves RF or high-speed PCB design, selecting the right material is critical.

We’re happy to support you with:

• Stack-up design
• RF PCB optimization
• Fast PCB & PCBA production

📧 sales@bestpcbs.com

Feel free to reach out — your project will be supported by engineers who understand real RF challenges.

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