RT Duroid 5880LZ PCB: Properties & Design

What Is an RT Duroid 5880LZ PCB?

An RT Duroid 5880LZ PCB is a printed circuit board built on Rogers Corporation’s glass-microfiber-reinforced PTFE composite with a controlled foam microstructure. This laminate delivers a dielectric constant (Dk) of 1.96 ± 0.04 at 10 GHz—the lowest Dk among production-grade microwave laminates—and a dissipation factor (Df) of 0.0019 at 10 GHz. The “LZ” designation stands for “Low Z,” referencing the very low characteristic impedance achievable with this near-air-like permittivity.

The material belongs to the broader RT/duroid family of PTFE laminates, but its foam microstructure sets it apart. By introducing microscopic voids into the PTFE matrix, Rogers reduces the effective permittivity toward that of free space (Dk = 1.0) while keeping the mechanical integrity needed for PCB fabrication. The result is a substrate that behaves electrically almost like air, yet can be drilled, plated, and assembled using modified conventional processes—making the RT Duroid 5880LZ PCB a go-to choice for phased-array antennas, radomes, and space-borne feed networks.

RT Duroid 5880LZ PCB Electrical and Mechanical Properties

The Dk of 1.96 means that electromagnetic waves travel through an RT Duroid 5880LZ PCB at roughly 71 % of the speed of light—much closer to free-space propagation than in conventional PTFE laminates (Dk ≈ 2.2) or hydrocarbon ceramic laminates (Dk ≈ 3.0–3.5). This has direct consequences for trace width, wavelength and radiation efficiency, all discussed below.

Why Choose a Dk of 1.96 for Your PCB?

Wider Traces for High-Impedance Lines

Lower Dk produces wider traces for any given impedance. A 50 Ω microstrip on 31 mil (0.787 mm) 5880LZ is roughly 2.4 mm wide, compared to about 1.9 mm on standard RT/duroid 5880 (Dk 2.20). Wider traces are easier to etch with tight tolerance and exhibit lower ohmic loss because of increased conductor cross-section.

Larger Effective Wavelength

The guided wavelength on a substrate scales as λ_g ∝ 1/√ε_eff. With 5880LZ, the effective dielectric constant of a microstrip is in the range of 1.5–1.7 depending on geometry, so the guided wavelength is 10–15 % longer than on solid PTFE. For antenna designers, this means wider bandwidth and reduced surface-wave excitation—both critical above 20 GHz.

Low Loss at Millimeter-Wave

At 77 GHz, total insertion loss on a 5880LZ microstrip can be 25–30 % lower than on a Dk 2.20 substrate of the same thickness, because dielectric loss scales with Dk × Df and the foam microstructure minimizes both. For long feed networks in phased-array antennas, this translates directly into improved G/T (gain-to-noise-temperature ratio).

Weight Reduction

At 1.4 g/cm³, 5880LZ is roughly 35 % lighter than solid PTFE composites and about 55 % lighter than ceramic-filled laminates such as RT/duroid 6006 (Dk 6.15, density ≈ 2.6 g/cm³). In airborne and space-borne antenna systems, every gram counts toward payload budgets.

RT Duroid 5880LZ PCB Stackup Design

Most RT Duroid 5880LZ PCB designs are single- or double-sided boards used as antenna substrates or as a spacer layer in multilayer hybrid stackups. A common architecture pairs a thin 5880LZ radiating layer with a denser bonding film and a feed network on a separate laminate.

Typical Two-Layer Antenna Stackup

• Layer 1 (top copper): Patch elements or slot radiators
• Dielectric: 31 mil RT/duroid 5880LZ (Dk 1.96)
• Layer 2 (bottom copper): Ground plane

Hybrid Multilayer Stackup

• Layer 1: Patch array on 5880LZ (31 mil)
• Bond film: Rogers 3001 bonding film (2 mil, Dk ≈ 2.28)
• Layer 2: Ground / slot coupling layer
• Core: RO4350B or RO3003 feed network layer
• Layer 3: Stripline feed traces
• Layer 4: Ground plane

Enter your own layer thicknesses and materials below to visualize the cross-section and verify your design intent before sending files to the fabricator.

For example, a stackup with 31 mil 5880LZ on top, 2 mil 3001 bond film, and a 20 mil RO4350B feed core gives a total dielectric height of roughly 53 mil (1.35 mm). The visualizer confirms layer ordering and helps catch errors such as misplaced ground references before they reach the fab shop.

RT Duroid 5880LZ PCB Fabrication Considerations

Drilling

The foam microstructure is softer than solid PTFE, so drill bit selection matters. Use carbide-tipped bits with a low chip load (0.025–0.05 mm per revolution) and moderate spindle speeds (40,000–55,000 RPM) to avoid smearing the PTFE into the hole barrel. Back-up and entry materials should be aluminum rather than phenolic to dissipate heat.

Plating and Hole Preparation

PTFE is inherently non-wettable. Sodium-naphthalene or plasma etch treatments are mandatory before electroless copper deposition. The foam variant can absorb treatment chemicals into its pore structure if immersion times are too long, so process windows are tighter than for solid 5880. Follow IPC-6012 Class 3 plating requirements for aerospace-grade reliability.

Lamination and Bonding

When building hybrid multilayer boards, the foam core compresses more than solid PTFE under lamination pressure. A typical bonding cycle uses 100–200 psi at 220 °C for 60–90 minutes, but the exact profile depends on the bond film. Rogers 3001 bonding film (Dk 2.28, Df 0.003) is the recommended adhesive because its flow characteristics are matched to PTFE surfaces. Excessive pressure crushes the foam cells and shifts Dk upward—sometimes by 0.05 or more—so pressure uniformity across the panel is critical.

Routing and Scoring

Diamond-coated router bits at 24,000–30,000 RPM produce clean edges. Scoring (V-groove) is not recommended because the foam core tends to delaminate along the score line under flexure.

Selecting the Right Low-Dk Material for Your RT Duroid 5880LZ PCB Alternative

RT/duroid 5880LZ is not the only low-Dk option. Use the comparison below alongside the material selection wizard to confirm whether an RT Duroid 5880LZ PCB fits your frequency, loss, and mechanical requirements—or whether a different laminate serves better.

If the wizard recommends 5880LZ, you are likely designing an antenna or radome where the lowest possible Dk directly improves bandwidth or scan performance. If dimensional stability under thermal cycling matters more than absolute Dk, IsoClad 917 (woven reinforcement, CTE x/y ≈ 10 ppm/°C) may be the safer choice despite its slightly higher permittivity.

Application Domains for RT Duroid 5880LZ PCBs

Phased-Array Antenna Substrates

The RT Duroid 5880LZ PCB is widely used in military and commercial phased-array panels from Ku-band (12–18 GHz) through Ka-band (26.5–40 GHz). Its near-air Dk minimizes scan blindness and surface waves, while the low weight keeps array assemblies within airframe mass budgets.

Radome-Integrated Layers

Because its Dk approaches that of air, a 5880LZ layer can serve as an impedance-matching section inside a multilayer radome. A quarter-wave section at 35 GHz is only about 1.53 mm thick in 5880LZ, providing a broadband impedance transition between free space and a higher-Dk structural skin.

Space-Borne Feed Networks

Outgassing is a concern for space applications. RT/duroid 5880LZ has been qualified to NASA outgassing requirements (ASTM E595: TML < 1.0 %, CVCM < 0.10 %), making it acceptable for LEO and GEO satellite antenna assemblies.

Millimeter-Wave Sensors

At 60 GHz and 77 GHz, dielectric loss dominates total loss. The combination of Dk 1.96 and Df 0.0019 gives 5880LZ one of the lowest loss-tangent products (Dk × Df ≈ 0.0037) of any commercial laminate, directly reducing noise figure in receiver front-ends.

Design Tips and Common Pitfalls

• Dk shift under compression: If your lamination process applies more than 200 psi, measure Dk on a coupon after bonding. A 3–5 % rise is possible.
• Moisture sensitivity: Although moisture absorption is low (0.02 %), the open-cell foam structure can trap moisture during wet processing. Bake panels at 120 °C for 2 hours before final assembly to stabilize Dk.
• Solder reflow: PTFE substrates do not degrade at standard Pb-free reflow temperatures (peak 260 °C), but the foam is mechanically weaker at elevated temperature. Support the board on a flat carrier during reflow to prevent warping.
• Copper type: Rolled-annealed (RA) copper is preferred for lowest conductor loss above 30 GHz due to its smoother surface profile (Rz ≈ 0.5 µm vs. 2–3 µm for standard ED copper). Specify RA copper when ordering RT Duroid 5880LZ PCB panels for mmWave designs.
• Tolerance stack: The ±0.04 Dk tolerance is tight by PTFE standards but still represents a ±2 % swing. At 77 GHz, this shifts a quarter-wave patch resonance by roughly 1.5 GHz—enough to move it outside a narrow allocated band. Simulate worst-case corners.

Relevant Standards and Specifications

• IPC-4103: Specification for base materials for high-frequency applications; 5880LZ falls under slash sheet /10 family (PTFE/microfiber).
• IPC-6012 Class 3/A: Qualification and performance for rigid printed boards in high-reliability and space applications.
• MIL-PRF-55110: Military specification for printed wiring boards, often invoked for defense antenna programs.
• ASTM E595: Outgassing test for spacecraft materials.

For the full RT/duroid 5880LZ datasheet, consult the Rogers Corporation product page, which includes detailed Dk-vs-frequency curves and recommended processing guidelines.

Frequently Asked Questions

Is RT/duroid 5880LZ the same as RT/duroid 5880?

No. Both are PTFE/microfiber composites, but 5880LZ has a foam microstructure that lowers Dk from 2.20 to 1.96 and reduces density by about 35 %. The solid 5880 has slightly lower Df (0.0009 vs. 0.0019) and better dimensional stability, so the two serve different design priorities.

Can I use standard FR-4 prepreg to bond 5880LZ in a multilayer?

It is technically possible but not recommended. FR-4 prepreg (Dk ≈ 4.2) creates a large Dk discontinuity at the bond interface, degrading impedance control. Rogers 3001 bonding film or CuClad 6700 bond plies (Dk ≈ 2.35) maintain a more uniform dielectric environment.

What is the maximum operating frequency for an RT Duroid 5880LZ PCB?

Rogers characterizes 5880LZ up to 40 GHz in published data, but it has been successfully used at 77 GHz and above in research and production radars. At frequencies beyond 60 GHz, conductor loss typically dominates, so the substrate’s dielectric advantage remains relevant.

How does 5880LZ compare to air-cavity designs?

An air cavity (Dk = 1.0) offers even lower loss, but requires machined housings and suspended-substrate mounting—adding cost, weight, and assembly complexity. 5880LZ closes much of the electrical gap while remaining a standard PCB laminate that can be etched, drilled, and plated on conventional PTFE processing lines.

Is 5880LZ suitable for flex or rigid-flex constructions?

No. The foam core is brittle under repeated flexure. For flexible low-loss RF interconnects, consider liquid-crystal polymer (LCP) films or thin polyimide-based constructions instead.