The complete specifications of this board are outlined in the table below.

 

Specification	Details
Layer Structure	3 Copper Layers
Base Materials	1.575mm RT/duroid 5880 + Prepreg + 0.5mm TG170 FR-4
Finished Board Thickness	2.3 mm
Outer Layer Copper Weight	1 oz (35 μm) Finished
Inner Layer Copper Weight	0.5 oz (17.5 μm) Finished
Solder Mask	None, Both Sides
Silkscreen	None, Both Sides
Surface Finish	ENIG (Electroless Nickel Immersion Gold)
Board Dimensions	74 mm x 101 mm per unit
Mechanical Features	Stepped Profile

2. Understanding RT/duroid 5880 High-Frequency Laminate

2.1 Introduction to RT/duroid 5880

RT/duroid 5880 is a glass microfiber reinforced PTFE composite material manufactured by Rogers Corporation, specifically designed for high-performance stripline and microstrip circuit applications. The randomly oriented microfibers distributed within the material provide maximum strength enhancement for circuit applications and production processes while ensuring exceptional dielectric constant uniformity from panel to panel.

This material features the lowest dielectric constant among its class, with electrical properties that remain constant over a wide frequency range. Its extremely low dissipation factor extends its usefulness to Ku-band and above, making it suitable for demanding high-frequency and broadband applications requiring minimum dispersion and signal loss.

The very low moisture absorption of RT/duroid 5880 makes it an ideal choice for applications in high humidity environments. The material resists corrosion from all solutions and reagents used in etching and plating through-hole processes, and it can be easily cut, sheared, and machined to desired shapes, perfectly meeting the requirements of various cavity structures and stepped profiles in high-frequency applications.

2.2 Key Features and Properties of RT/duroid 5880

The RT/duroid 5880 material offers the following performance characteristics:

Property	Value
Dielectric Constant	2.20 ± 0.02 at 10 GHz
Dissipation Factor	0.0009 at 10 GHz
Thermal Coefficient of Dielectric Constant	-125 ppm/°C
Volume Resistivity	2 x 10⁷ MΩ·cm
Surface Resistivity	3 x 10⁷ MΩ
Moisture Absorption	0.02%
Thermal Conductivity	0.20 W/m/°K
Coefficient of Thermal Expansion X Axis	31 ppm/°C
Coefficient of Thermal Expansion Y Axis	48 ppm/°C
Coefficient of Thermal Expansion Z Axis	237 ppm/°C
Density	2.2 g/cm³
Copper Peel Strength	31.2 lb/in with 1 oz foil
Flammability Rating	UL 94 V-0
Lead-Free Process Compatible	Yes

2.3 Typical Applications for RT/duroid 5880

The exceptional electrical properties of RT/duroid 5880 make it suitable for numerous high-frequency applications:

Commercial airline broadband antennas requiring consistent dielectric properties

Microstrip and stripline circuits benefiting from low signal loss

Millimeter wave applications operating at frequencies up to Ku-band and beyond

Military radar systems demanding reliable performance under demanding conditions

Missile guidance systems requiring stable electrical characteristics

Point-to-point digital radio antennas needing low dispersion for efficient signal transmission

3. Understanding Hybrid PCB Construction

3.1 What is a Hybrid PCB?

A hybrid PCB, also known as hybrid construction PCB, is a circuit board that combines different dielectric materials within a single multilayer stackup. In hybrid construction, only the layers where high-performance signals are required utilize higher cost but lower loss copper clad laminate materials such as RT/duroid 5880, while all other layers use lower cost FR-4 derivative core materials.

This design technique serves as an effective strategy to control costs in high-speed and high-frequency designs while maintaining necessary electrical performance where it matters most. By limiting expensive high-frequency materials to the critical signal layers, designers can achieve optimal performance without unnecessarily increasing overall board cost.

A common requirement for hybrid construction is maintaining homogeneous prepreg materials throughout the board to bond the core layers together. Mixing different prepreg types can result in lamination issues because different temperatures may be required for different materials to bond properly. In this design, the stackup incorporates RT/duroid 5880 with FR-4 core and appropriate prepreg bonding layers to ensure reliable lamination.

3.2 Advantages of Hybrid Construction

Hybrid construction offers several key benefits:

Cost optimization by using high-performance materials only where electrically necessary

Design flexibility combining best properties of multiple material systems

Thermal management through balanced material selection

Weight reduction compared to all-high-frequency material constructions

Compatibility with standard PCB manufacturing processes

4. PCB Construction Details

4.1 Layer Stackup Configuration

This 3-copper layer hybrid board employs a specialized stackup designed for optimal high-frequency performance and mechanical stability. The construction begins with the top copper layer at 35 μm, directly bonded to the primary RF dielectric material of 1.575mm RT/duroid 5880 laminate. This thick RT/duroid layer provides the low-loss, controlled impedance environment essential for microwave signal transmission.

A prepreg bonding layer joins the RT/duroid section to the 0.5mm TG170 FR-4 core material. The inner copper layer at 17.5 μm is situated between these materials. The bottom copper layer completes the construction at 35 μm.

The 2.3mm total finished thickness provides substantial mechanical rigidity while accommodating the thick RT/duroid dielectric required for specific impedance targets. The use of high Tg 170°C FR-4 ensures thermal stability during assembly and operation, with the glass transition temperature well above standard reflow profiles.

4.2 Copper Weight Distribution

The copper configuration features outer layers at 1 oz finished weight suitable for power handling and signal transmission, while the inner layer at 0.5 oz finished weight provides interconnection capability with reduced thickness for improved layer-to-layer registration and dielectric filling. This graduated copper distribution optimizes the stackup for both electrical performance and manufacturability.

4.3 Surface Finish: ENIG

Electroless Nickel Immersion Gold provides a flat, oxidation-resistant surface suitable for fine-pitch component assembly. The nickel layer offers a robust barrier against copper migration, while the thin gold coating ensures excellent solderability and long shelf life. ENIG is particularly well-suited for high-frequency applications where surface planarity impacts signal integrity.

4.4 Stepped Profile Feature

The board incorporates a stepped profile feature, creating a non-rectangular outline or internal cavities to accommodate specific enclosure requirements or component placement. This mechanical feature enables precise integration into system housings, optimizing space utilization and potentially improving thermal management through direct contact with chassis elements.

5. Quality Assurance and Industry Compliance

5.1 Artwork Format

The board design utilizes Gerber RS-274-X format, the industry standard for PCB fabrication data. This format ensures accurate translation of design intent to manufacturing, supporting fine feature resolution and complex profile requirements including the stepped outline.

5.2 Manufacturing Standard

All fabrication conforms to IPC-Class-2 requirements, the industry benchmark for dedicated service electronic products. This classification ensures extended life and reliable performance while maintaining cost-effectiveness for production volumes. Class 2 compliance guarantees consistent quality suitable for a wide range of commercial, industrial, and military applications.

5.3 Global Availability

These boards are available for worldwide shipment, supported by standard data formats and material sourcing that ensures consistent quality regardless of manufacturing location.

6. Conclusion

This 3-copper layer hybrid PCB combining 1.575mm RT/duroid 5880 with 0.5mm TG170 FR-4 delivers exceptional value for high-frequency and microwave applications through its ultra-low dielectric constant of 2.20 ± 0.02 and dissipation factor of 0.0009 at 10 GHz, ensuring minimal signal loss and dispersion at frequencies up to Ku-band and beyond. The 2.3mm finished thickness with 1 oz outer copper and 0.5 oz inner copper provides mechanical robustness, while the ENIG surface finish ensures excellent solderability and long-term reliability. The stepped profile feature enables precise mechanical integration, and the hybrid construction optimizes cost without compromising electrical performance where it matters most. With IPC-Class-2 compliance and global availability, Rogers RT/duroid 5880 PCB board meets the rigorous demands of radar systems, broadband antennas, missile guidance systems, and millimeter wave applications worldwide.

 

Founded in 2003, Shenzhen Bicheng Electronics Technology Co., Ltd is an established high frequency PCB supplier and exporter in Shenzhen, China, serving customers worldwide.

 

We are devoted to delivering high-frequency PCB products and solutions of the highest quality, along with customized service. Get in touch with us to start your project !

Visit https://www.bicheng-enterprise.com to learn more.