2. Core Product Specifications

Specification Item	Technical Details
Layer Count	4-Layer Hybrid High Frequency Rigid PCB
Overall Pressed Thickness	1.47mm
Stackup Configuration	Top: 0.305mm WL-CT338Middle: 3 × 0.185mm FR4 PPBottom: 0.5mm TG170°C FR4
Finished Copper Weight	Inner layers: 0.5oz; Outer layers: 1oz
Board Dimension & Quantity	175mm × 121mm, 10 PCS
Surface Finish	ENIG
Solder Mask	Top & Bottom: Green Solder Mask
Silkscreen	Top & Bottom: White Legend

 

3. PCB Stackup Structure

The 4-layer structure adopts a scientific hybrid collocation of WL-CT338 high-frequency material and standard FR4 materials, which balances high-frequency electrical performance, mechanical strength and production cost. It supports multi-lamination processing and fits the manufacturing requirements of complex multilayer circuits.

• Outer Copper Layer 1 (1oz)
• Dielectric: 0.305mm WL-CT338
• Inner Copper Layer 1 (0.5oz)
• Dielectric: 3 × 0.185mm FR4 Prepreg
• Inner Copper Layer 2 (0.5oz)
• Dielectric: 0.5mm TG170°C FR4
• Outer Copper Layer 2 (1oz)
•  Total Thickness: 1.47mm

 

 

4. Production & Process Advantages

• Dual Material Hybrid Design: Integrates WL-CT338 high-frequency substrate and TG170°C FR4, realizing perfect combination of low-loss RF performance and FR4 mature processing technology.
• Differentiated Copper Foil Design: Matches 0.5oz inner copper and 1oz outer copper to adapt to different current-carrying and signal transmission demands of inner and outer circuits.
• Uniform Surface Treatment: Dual-side green solder mask with white legend provides clear marking and full protection against oxidation and short circuit.
• Universal Process Compatibility: Processed following standard FR4 production workflows, easy for dense holes and fine trace fabrication, suitable for mass production.
• High Thermal Reliability: The bottom FR4 substrate with TG 170°C cooperates with high-TG WL-CT338, maintaining stable structure during multiple lamination and thermal cycling.

5. Introduction of WL-CT Series & WL-CT338 Copper Clad Laminate

WL-CT series are thermoset high-frequency copper clad laminates composed of organic polymer, ceramic fillers and fiberglass cloth. Formulated with hydrocarbon resin, composite ceramics and reinforced fiberglass, WL-CT material family delivers excellent low-loss characteristics to meet stringent high-frequency design demands.

Different from traditional PTFE substrates, WL-CT series laminate features FR4-equivalent processability, bringing more stable and consistent circuit performance while simplifying manufacturing procedures. It acts as a cost-effective alternative to imported high-frequency laminates.

Benefiting from the inherent properties of hydrocarbon resin and composite ceramics, the material boasts stable dielectric parameters against temperature change and low coefficient of thermal expansion. Its glass transition temperature exceeds 280°C, delivering prominent high-temperature resistance.

The WL-CT series offers diversified dielectric constant options: 3.00, 3.30, 3.38, 3.48, 4.10 and 6.15, supporting customized selection for various high-frequency scenarios. It can be paired with standard ED copper foil or reversed RTF copper foil. The RTF copper foil version features superior PIM performance, lower conductor loss and insertion loss. With adhesive backing, RTF copper foil increases material thickness by 0.018mm (0.7mil) and achieves strong bonding force.

In addition, WL-CT series can be combined with aluminum base to develop aluminum-based high-frequency substrates. Owning excellent mechanical and physical properties, the material supports repeated lamination, ideal for multilayer boards, high-layer-count PCBs and backplanes. It also presents remarkable machinability for dense vias and ultra-fine circuit traces.

 

6. Key Features of WL-CT338 Material

• Narrow dielectric constant tolerance and ultra-low dissipation factor for pure high-frequency signal transmission
• Thermoset hydrocarbon-ceramic resin system, superior PCB processability and heat resistance
• Excellent temperature stability of dielectric constant, with minor parameter drift under varying temperatures
• X/Y-axis CTE well matched with copper foil, plus low Z-axis CTE, ensuring dimensional stability and reliable plated holes
• Ultra-high Tg over 280°C, retaining stable dimension and hole quality under long-term high temperature
• Higher thermal conductivity than conventional thermoplastic high-frequency materials, well suited for high-power applications
• Mature commercial production, available for large-batch manufacturing with high cost performance
• Outstanding radiation resistance; dielectric and physical properties remain stable after high-dose radiation exposure
• Low outgassing performance, fully compliant with vacuum outgassing standards for aerospace applications

7. WL-CT338 Datasheet

Item	Test Condition	Unit	WL-CT338
Typical Dielectric Constant	10GHz	/	3.38
Design Dielectric Constant	10GHz	/	3.55
Dielectric Constant Tolerance	/	/	±0.05
Typical Dissipation Factor	2GHz	/	0.0023
Typical Dissipation Factor	10GHz	/	0.0029
Typical Dissipation Factor	20GHz	/	0.0038
Temperature Coefficient of Dielectric Constant	-55℃ ~ 150℃	PPM/℃	45
Peel Strength (1 OZ ED Copper Foil)	1 OZ ED Copper Foil	N/mm	1.0
Peel Strength (1 OZ RTF Copper Foil)	1 OZ RTF Copper Foil	N/mm	0.72
Volume Resistivity	Normal Temperature	MΩ·cm	6×10⁹
Surface Resistivity	Normal Temperature	MΩ	7×10⁸
Dielectric Strength (Z-axis)	5KW, 500V/s	KV/mm	31
Breakdown Voltage (XY-axis)	5KW, 500V/s	KV	30
Coefficient of Thermal Expansion (X, Y-axis)	-55℃ ~ 288℃	ppm/℃	14~16
Coefficient of Thermal Expansion (Z-axis)	-55℃ ~ 288℃	ppm/℃	50
Thermal Stress	288℃, 10s, 3 cycles	/	No Delamination
Water Absorption	23.5±2℃, 24h	%	0.04
Density	Normal Temperature	g/cm³	1.78
Continuous Operating Temperature	Temperature Chamber	℃	-55 ~ +260
Thermal Conductivity (Z-axis)	/	W/(M·K)	0.70
PIM Value (Matched with RTF Copper Foil)	Matched with RTF Copper Foil	dBc	≤-158
Flame Retardancy	UL-94	Class	Non-flame retardant
Glass Transition Temperature (TG)	Standard Condition	℃	＞280
Thermal Decomposition Temperature (TD)	Initial Value	℃	421
Halogen Content	/	/	Halogen-free
Material Composition	/	/	Hydrocarbon, Ceramic and Fiberglass Cloth

 8. Typical Application Fields

• Aerospace equipment, spaceborne & cabin devices, airborne aircraft electronics
• Microwave circuits, common antennas and phase-sensitive antennas
• Early warning radar, airborne radar and other radar systems
• Phased array antennas and beam forming networks
• Satellite communication and navigation systems
• RF power amplifiers and high-power microwave modules

9. Product Overall Summary

WL-CT338 4-layer 1.47mm ENIG PCB is a hybrid high-frequency rigid board combining WL-CT338 ceramic-filled high-frequency CCL and TG170°C FR4 materials. With customized inner/outer copper weight, standard FR4 processing compatibility and dual-side green solder mask & white legend design, this product integrates low-loss high-frequency performance, superior heat resistance and high structural reliability.

Supported by WL-CT series’ advantages including high Tg, matched CTE, radiation resistance and low outgassing, the PCB is an ideal solution for aerospace, various radar systems, phased array antennas, satellite communication and high-power amplifiers. It realizes high performance and cost efficiency, and can fully replace equivalent imported high-frequency circuit boards.

 

Tags：WL-CT338 Multilayer PCB, WL-CT338 High Frequency PCB, Hybrid FR4 PCB, High Power Amplifier PCB, Thermoset Hydrocarbon Ceramic Laminate, Low Loss RF PCB, High Tg 280°C PCB, Aerospace Radar PCB, Phase Sensitive Antenna PCB, Satellite Navigation PCB, Airborne Radar PCB,  Low Outgassing Aerospace PCB, Radiation Resistant PCB