Aerospace-Grade CuClad 250: Cross-Plied PTFE Laminate with NASA Outgassing and 0.0017 Df for Phased-Array Radars

Description de produit

What is CuClad 250?
CuClad 250 is a woven fiberglass/PTFE composite laminate manufactured by Rogers Corporation. It features a dielectric constant range of 2.40 to 2.55 at 10GHz, a dissipation factor of 0.0017 at 10GHz, and a unique cross-plied construction where alternating fiberglass layers are oriented 90° to each other. This provides true electrical and mechanical isotropy in the XY plane—a feature unmatched by other woven or non-woven PTFE laminates. With its higher fiberglass/PTFE ratio, CuClad 250 delivers mechanical properties approaching those of conventional substrates, making it ideal for filters, couplers, low-noise amplifiers, and phased-array antennas.

 

 

Key Takeaways (At a Glance)

 

Dk (10GHz): 2.40 to 2.55

 

Dissipation Factor: 0.0017 @ 10GHz

 

CTE (X/Y/Z): 18 / 19 / 177 ppm/°C (0°C to 100°C)

 

Thermal Conductivity: 0.25 W/(m·K)

 

Moisture Absorption: 0.03%

 

Peel Strength: 14 lbs/in (after thermal stress)

 

Flammability: UL 94 V-0 compliant

 

NASA Outgassing: TML 0.01%, CVCM 0.00%, WVR 0.00%

 

Key Differentiator: Cross-plied woven fiberglass construction provides true XY isotropy—critical for phased-array antenna applications

 

 

1. Why Choose CuClad 250? – Material Selection Rationale

For engineers designing high-frequency circuits, material selection impacts not only electrical performance but also mechanical stability and manufacturability. CuClad 250 addresses these demands through four key advantages:

 

True XY Isotropy – The Cross-Plied Advantage: CuClad laminates are cross-plied, meaning alternating layers of coated fiberglass plies are oriented 90° to each other. This provides true electrical and mechanical isotropy in the XY plane—a feature unique to CuClad laminates. No other woven or non-woven fiberglass reinforced PTFE laminate can make this claim. Designers have found this degree of isotropy critical in some phased-array antenna applications.

 

Superior Dimensional Stability: With a higher fiberglass/PTFE ratio, CuClad 250 provides mechanical properties approaching those of conventional substrates. Better dimensional stability and lower thermal expansion in all directions are significant benefits, especially for designs requiring tight registration and fine-feature processing.

 

Consistent Dielectric Constant: The precision control of the PTFE-to-fiberglass ratio allows Rogers to offer a greater variety of dielectric constants and produces a laminate with better dielectric constant uniformity than comparable non-woven fiberglass reinforced laminates.

 

Aerospace-Grade Reliability: With NASA outgassing values (TML 0.01%, CVCM 0.00%, WVR 0.00%) and UL 94 V-0 compliance, CuClad 250 meets the stringent requirements for spaceborne and avionics applications. For critical performance applications, CuClad products may be specified with an "LX" testing grade, where each sheet is individually tested and a test report is issued with the order.

 

 

2. Properties of CuClad 250 Laminate

The table below consolidates all electrical, mechanical, thermal, and physical specifications for CuClad 250 as provided in the official datasheet. All values represent typical measured data and are intended to aid in material selection.

Property	Test Method	Condition	CuClad 250
Dielectric Constant @ 10 GHz	IPC TM-650 2.5.5.5	C23/50	2.40 to 2.55
Dielectric Constant @ 1MHz	IPC TM-650 2.5.5.3	C23/50	2.40 to 2.60
Dissipation Factor @ 10 GHz	IPC TM-650 2.5.5.5	C23/50	0.0017
Thermal Coefficient of Er (ppm/°C)	IPC TM-650 2.5.5.5 Adapted	-10°C to +140°C	-153
Peel Strength (lbs per inch)	IPC TM-650 2.4.8	After Thermal Stress	14
Volume Resistivity (MΩ-cm)	IPC TM-650 2.5.17.1	C96/35/90	8.0 × 10⁹
Surface Resistivity (MΩ)	IPC TM-650 2.5.17.1	C96/35/90	1.5 × 10⁸
Arc Resistance (seconds)	ASTM D-495	D48/50	>180
Tensile Modulus (kpsi)	ASTM D-638	A, 23°C	725, 572
Tensile Strength (kpsi)	ASTM D-882	A, 23°C	26.0, 20.5
Compressive Modulus (kpsi)	ASTM D-695	A, 23°C	342
Flexural Modulus (kpsi)	ASTM D-790	A, 23°C	456
Dielectric Breakdown (kV)	ASTM D-149	D48/50	>45
Specific Gravity (g/cm³)	ASTM D-792 Method A	A, 23°C	2.31
Water Absorption (%)	MIL-S-13949H 3.7.7 / IPC TM-650 2.6.2.2	E1/105 + D24/23	0.03
Coefficient of Thermal Expansion – X Axis (ppm/°C)	IPC TM-650 2.4.24 / Mettler 3000 TMA	0°C to 100°C	18
Coefficient of Thermal Expansion – Y Axis (ppm/°C)	IPC TM-650 2.4.24 / Mettler 3000 TMA	0°C to 100°C	19
Coefficient of Thermal Expansion – Z Axis (ppm/°C)	IPC TM-650 2.4.24 / Mettler 3000 TMA	0°C to 100°C	177
Thermal Conductivity	ASTM E-1225	100°C	0.25
Outgassing – Total Mass Loss (TML) (%)	NASA SP-R-0022A	125°C, ≤10⁻⁶ torr	0.01
Outgassing – CVCM (%)	NASA SP-R-0022A	125°C, ≤10⁻⁶ torr	0
Outgassing – Water Vapor Regain (WVR) (%)	NASA SP-R-0022A	125°C, ≤10⁻⁶ torr	0
Outgassing – Visible Condensate (±)	NASA SP-R-0022A	125°C, ≤10⁻⁶ torr	NO
Flammability	UL 94 Vertical Burn / IPC TM-650 2.3.10	C48/23/50, E24/125	Meets requirements of UL94-V0

 

 

 

3. Frequency Stability of CuClad 250

CuClad 250 demonstrates excellent stability of dielectric constant across frequency, as confirmed by free space and circular resonator cavity measurements. This characteristic demonstrates the inherent robustness of Rogers laminates across the EM spectrum, simplifying the final design process when working across different frequencies. The stability of the dielectric constant ensures easy design transition and scalability of design—a significant advantage for engineers developing multi-band or wideband systems.

 

 

Dissipation Factor vs. Frequency for CuClad 250:

Note: The dissipation factor remains exceptionally low across the frequency range, with only a slight increase at higher frequencies—confirming CuClad 250's suitability for broadband and millimeter-wave applications.

 

 

4. Material Availability 

 

Copper Cladding:

Standard: 1/2 oz, 1 oz, or 2 oz electrodeposited copper on both sides

 

Optional: Other copper weights and rolled copper foil available

 

Metal-backed options: Bonded to heavy metal ground planes (aluminum, brass, or copper plates) for integral heat sinking and mechanical support

 

 

Standard Panel Sizes:

Master sheet size: 36" × 36" in cross-plied configuration

 

Other sizes available upon request

 

 

Ordering Information:
When ordering CuClad 250, please specify:

Dielectric constant

Thickness

Cladding (copper weight and type)

Panel size

Any special considerations (e.g., "LX" testing grade)

 

 

 

5. PCB Design Case Study – From Specification to Reality

To illustrate how CuClad 250 performs in a real-world design, here is a 2-layer board example featuring a 0.4mm finished thickness.

 

 

PCB Design Specifications

Parameter	Specification
Base Material	Rogers CuClad 250
Layer Count	2
Board Dimensions	48.6mm × 76.9mm (±0.15mm)
Finished Board Thickness	0.4mm
PCB Stackup	Cu (35μm) / CuClad 250 Core (0.254mm / 10mil) / Cu (35μm)
Minimum Trace / Space	4 / 6 mils
Minimum Hole Size	0.3mm
Blind Vias	None
Finished Copper Weight (Outer Layers)	1oz (35μm / 1.4 mils)
Via Plating Thickness	20 μm
Surface Finish	Immersion Gold (ENIG)
Top Silkscreen	White
Bottom Silkscreen	None
Top Solder Mask	Blue
Bottom Solder Mask	None
Quality Standard	IPC Class-2
Testing	100% Electrical Test
Artwork Format	Gerber RS-274-X
Availability	Worldwide

 

 

Engineering Rationale for Key Specifications:

Parameter	Rationale
CuClad 250 Selection	Chosen for its unique cross-plied construction providing true XY isotropy, consistent Dk (2.40–2.55), and low Df (0.0017)—critical for phase-sensitive circuits like filters and couplers.
0.4mm Finished Thickness	Achieved using 10mil (0.254mm) CuClad 250 core; supports compact designs while maintaining mechanical rigidity.
4/6 mils Trace/Space	Fine-feature capability enabled by CuClad 250's dimensional stability; supports dense RF and DC routing.
0.3mm Minimum Hole Size	Mechanical drilling capability; no laser or blind vias required, simplifying fabrication.
1oz Copper Weight	Balances current-carrying capacity with fine-feature etching capability.
20 μm Via Plating	Exceeds IPC Class-2 minimum; ensures robust PTH reliability.
Immersion Gold (ENIG)	Provides a flat, oxidation-resistant surface for soldering and wire bonding.
Top Silkscreen (White)	Provides component reference designators for assembly; white offers good contrast on blue solder mask.
Top Solder Mask (Blue)	Protects top-side circuits; blue color option per customer preference.
No Bottom Solder Mask	Left bare for potential grounding or heat sinking applications.
IPC Class-2	Balances cost and reliability for commercial aerospace and telecom applications.
100% Electrical Test	Ensures impedance, continuity, and isolation before shipment.

 

 

Key Fabrication Notes for CuClad 250:

 

Drilling: CuClad 250's woven fiberglass construction requires sharp carbide drills with optimized speeds and retract rates. The cross-plied construction provides balanced mechanical properties, contributing to clean hole walls and reduced burr formation.

 

Surface Preparation: For ENIG or other finishes, standard PTFE surface preparation techniques apply. Plasma treatment (e.g., CF₄/O₂) is recommended to activate the PTFE surface and ensure strong plating adhesion.

 

Dimensional Stability: The higher fiberglass/PTFE ratio and cross-plied construction provide superior dimensional stability compared to non-woven alternatives, resulting in tighter registration and higher yields—particularly valuable for designs with fine-pitch components (16 SMT pads) and dense via fields.

 

 

6. Comparative Positioning – How CuClad 250 Stands Out

Aspect	CuClad 250 (Cross-Plied Woven Glass)	Non-Woven PTFE Laminates	Standard Woven PTFE
XY Isotropy	True isotropy – cross-plied construction	Limited	Limited
Dimensional Stability	Superior – higher glass ratio	Lower	Good
Dk Uniformity	Excellent – precision PTFE/glass control	Less consistent	Good
Dielectric Constant	2.40–2.55	Variable	Variable
Dissipation Factor	0.0017 @ 10GHz	Typically higher	Comparable
CTE Match	Lower thermal expansion in all directions	Higher Z-axis expansion	Moderate
Unique Feature	Cross-plied construction (90° orientation)	None	None

 

Note: The cross-plied construction of CuClad 250 provides true electrical and mechanical isotropy in the XY plane—a feature unique to CuClad laminates. No other woven or non-woven fiberglass reinforced PTFE-based laminate makes this claim.

 

7. Typical Applications – Where CuClad 250 Shines

Based on its property set and the design case above, CuClad 250 is well-suited for:

 

Radars: Phased-array antennas, ground-based radar, and airborne radar systems

 

Electronic Countermeasures (ECM) : EW (electronic warfare) and electronic support measures (ESM) systems

 

Microwave Components: Low-noise amplifiers (LNAs), filters, couplers, and power dividers

 

Satellite Communications: Spaceborne and ground-based communication systems

 

Aerospace & Avionics: Navigation systems, altimeters, and communication equipment

 

Phased-Array Antennas: Where true XY isotropy is critical for consistent phase and amplitude response across array elements

 

 

Q1: What is unique about CuClad 250's construction?
CuClad 250 features a cross-plied construction where alternating layers of coated fiberglass plies are oriented 90° to each other. This provides true electrical and mechanical isotropy in the XY plane—a feature unique to CuClad laminates and critical for phased-array antenna applications.

 

 

Q2: What is the dielectric constant range for CuClad 250?
At 10GHz, the Dk ranges from 2.40 to 2.55. At 1MHz, the range is 2.40 to 2.60. The precision control of the PTFE-to-fiberglass ratio ensures excellent Dk uniformity.

 

 

Q3: Is CuClad 250 suitable for aerospace/space applications?
Yes. With NASA outgassing values (TML 0.01%, CVCM 0.00%, WVR 0.00%) and UL 94 V-0 compliance, CuClad 250 meets aerospace-grade requirements. For critical applications, "LX" testing grade is available, where each sheet is individually tested and a test report is issued with the order.

 

 

Q4: How does CuClad 250 perform across frequency?
CuClad 250 demonstrates excellent stability of dielectric constant across frequency. The dissipation factor remains exceptionally low, increasing only slightly from ~0.0017 at 10GHz to ~0.0023 at 30GHz, confirming its suitability for broadband and millimeter-wave applications.

 

 

Q5: What copper and panel options are available?
CuClad 250 is supplied with 1/2 oz, 1 oz, or 2 oz electrodeposited copper on both sides. Other copper weights and rolled copper foil are available. Metal-backed options (aluminum, brass, or copper) are also available for heat sinking. Master sheet size is 36" × 36" in cross-plied configuration.

 

 

Q6: What surface finishes are compatible with CuClad 250?
Immersion gold (ENIG) is commonly used, as in the design case above. Other finishes such as immersion silver, ENEPIG, or OSP are also compatible with proper surface preparation (plasma treatment) prior to finishing.

 

 

Q7: Are all values in the property table guaranteed?
The data provided are typical measured values intended to aid in material selection. They do not constitute specification limits or warranties. The properties of Rogers laminates may vary depending on the design and application.

 

 

Q8: What is the "LX" testing grade?
"LX" is a testing grade designation for critical performance applications. When specified, each sheet is individually tested and a test report is issued with the order. "LX" designated products are higher priced, as a portion of each sheet is utilized in destructive testing.

 

 

Conclusion

CuClad 250 from Rogers Corporation represents a unique and compelling solution for engineers designing high-frequency circuits that demand true XY isotropy, consistent dielectric properties, and excellent dimensional stability. As demonstrated by the 2-layer PCB design case—featuring a 0.4mm thickness, 4/6 mils trace/space, and immersion gold finish—CuClad 250 integrates smoothly into standard fabrication workflows while delivering the electrical performance required for radars, microwave components, and phased-array antennas. With its cross-plied construction, CuClad 250 offers a feature unmatched by any other woven or non-woven PTFE laminate: true electrical and mechanical isotropy in the XY plane. For engineers seeking a reliable, high-performance material for phase-sensitive circuits and aerospace applications, CuClad 250 is a field-proven, trusted choice.