Upgraded F4BTMS450 DK4.5 PCB: The Next-Generation PTFE Ceramic Laminate for Phase-Sensitive Microwave and Aerospace Applications

Product Description

What is F4BTMS450?
F4BTMS450 is an upgraded PTFE-based composite laminate developed by Taizhou Wangling Insulating Material Factory. It represents a technological breakthrough over the F4BTM series, incorporating a significant amount of ceramic filler with ultra-thin and ultra-fine woven fiberglass reinforcement. With a dielectric constant of 4.50 ± 0.09 at 10GHz, a dissipation factor of 0.0015 at 10GHz, and a CTE matched to copper (12 ppm/°C in X/Y), it is an aerospace-grade, high-reliability material that can replace similar imported products. The ultra-thin fiberglass minimizes the glass weave effect while enhancing dimensional stability, making it ideal for phase-sensitive applications including radar, feed networks, phased-array antennas, and satellite communications.

 

 

Key Takeaways (At a Glance)

 

Dk (10GHz): 4.50 ± 0.09

 

Dissipation Factor: 0.0015 @ 10GHz; 0.0019 @ 20GHz

 

TCDK (-55°C to 150°C): -58 ppm/°C

 

CTE (X/Y/Z): 12 / 12 / 45 ppm/°C (-55°C to 288°C)

 

Thermal Conductivity: 0.64 W/(m·K) – improved for higher power applications

 

Moisture Absorption: 0.08%

 

Flammability: UL 94 V-0

 

Electrical Strength (Z-direction): >45 kV/mm

 

Key Differentiator: Ultra-thin/ultra-fine fiberglass reinforcement minimizes glass weave effect while providing excellent dimensional stability

 

 

1. Why Choose F4BTMS450? – Material Selection Rationale

F4BTMS450 is the upgraded successor to the F4BTM series, featuring significant technological breakthroughs in both formulation and manufacturing processes. For engineers designing high-frequency circuits that demand both electrical performance and mechanical reliability, F4BTMS450 addresses these requirements through five key advantages:

 

Minimized Glass Weave Effect: Unlike traditional woven-glass PTFE laminates, F4BTMS450 uses ultra-thin and ultra-fine fiberglass cloth reinforcement. This minimizes the glass weave effect on electromagnetic wave propagation, reducing dielectric loss and decreasing X/Y/Z anisotropy. The result is more consistent impedance and phase response—critical for phase-sensitive applications like phased-array antennas.

 

Enhanced Dimensional Stability: The combination of ultra-thin fiberglass reinforcement with high ceramic loading provides excellent dimensional stability, ensuring tight registration during PCB fabrication and reliable performance across temperature extremes.

 

Superior Electrical Performance: With a Dk of 4.50 ± 0.09 and low dissipation factor (0.0015 @ 10GHz), F4BTMS450 delivers consistent electrical properties across frequency. The material maintains stable dielectric constant and low loss up to 40GHz, making it suitable for phase-sensitive applications.

 

Excellent Thermal Properties: The thermal conductivity of 0.64 W/(m·K) is improved over standard PTFE laminates, enabling better heat dissipation in higher-power applications. The low CTE in X/Y (12 ppm/°C) matches copper closely, ensuring reliable plated through-hole integrity.

 

Aerospace-Grade Reliability: With low outgassing properties meeting space application requirements, excellent radiation resistance, and stable performance from -55°C to +260°C, F4BTMS450 is qualified for demanding aerospace and defense environments.

 

 

2. Properties of F4BTMS450 Laminate

The table below consolidates all electrical, mechanical, thermal, and physical specifications for F4BTMS450 as provided in the official datasheet. All values represent typical measured data and are intended to aid in material selection.

—	Test Condition	Units	Typical Value
Dielectric Constant (Typical)	10 GHz, Stripline (Z-direction)	—	4.50
Dielectric Constant (Design Value)	10 GHz, 50Ω Microstrip (Z-direction)	—	4.5
Dielectric Constant Tolerance	—	—	±0.09
Dissipation Factor (Typical)	2 GHz	—	0.0015
Dissipation Factor (Typical)	10 GHz	—	0.0019
Dissipation Factor (Typical)	20 GHz	—	0.0024
Dielectric Constant Temp. Coefficient (TCDK)	-55°C to 150°C	ppm/°C	-58
Peel Strength (1oz RTF copper)	—	N/mm	>1.2
Volume Resistivity	Normal condition	MΩ·cm	≥1 × 10⁸
Surface Resistance	Normal condition	MΩ	≥1 × 10⁸
Dielectric Strength (Z-direction)	5kV, 500V/s	kV/mm	>45
Breakdown Voltage (X/Y-direction)	5kV, 500V/s	kV	>54
CTE – X-axis	-55°C to 288°C	ppm/°C	12
CTE – Y-axis	-55°C to 288°C	ppm/°C	12
CTE – Z-axis	-55°C to 288°C	ppm/°C	45
Thermal Stress	260°C, 10s, 3 cycles	—	No delamination
Thermal Conductivity (Z-direction)	—	W/(m·K)	0.64
Long-term Operating Temperature	—	°C	-55 to +260
Density	Room temperature	g/cm³	2.53
Moisture Absorption	20±2°C, 24 hours	%	0.08
Flammability Rating	UL-94	—	V-0
Material Composition	—	—	PTFE + Ultra-thin/ultra-fine fiberglass + Ceramic

Test Methods Reference:

 

Dielectric constant (typical) is measured per GB/T 12636-1990 or IPC-TM-650 2.5.5.5 (stripline method) in the Z-direction.

 

Design Dk values are measured using the 50Ω microstrip method.

 

Other properties follow IPC-TM-650 or GBT4722-2017 standards.

 

All test data are typical measurement values intended to aid in material selection and do not constitute express or implied warranties.

 

 

3. Frequency & Temperature Stability

F4BTMS450 demonstrates excellent stability across both frequency and temperature:

 

Frequency Stability: The material maintains stable dielectric constant and low loss values from 0.5GHz to 20GHz and beyond (usable up to 40GHz), meeting design requirements across a wide frequency range.

 

Temperature Stability: With a TCDK of -58 ppm/°C from -55°C to 150°C, F4BTMS450 provides excellent phase stability across temperature extremes. The actual usable temperature range significantly exceeds this tested range.

 

 

4. PCB Design Case Study – From Specification to Reality

To illustrate how F4BTMS450 performs in a real-world design, here is a 2-layer board example featuring a 0.6mm finished thickness.

 

 

PCB Design Specifications

Parameter	Specification
Base Material	F4BTMS450
Layer Count	2
Board Dimensions	38.4mm × 56.35mm (±0.15mm)
Finished Board Thickness	0.6mm
PCB Stackup	Cu (35μm) / F4BTMS450 Core (0.508mm / 20mil) / 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	HASL LF (Lead-Free Hot Air Solder Leveling)
Top Silkscreen	White
Bottom Silkscreen	None
Top Solder Mask	Black
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
F4BTMS450 Selection	Chosen for its high Dk (4.50), low loss, excellent dimensional stability, and minimized glass weave effect—critical for phase-sensitive RF and radar applications.
0.6mm Finished Thickness	Achieved using 20mil (0.508mm) F4BTMS450 core; provides mechanical rigidity while maintaining a compact form factor.
4/6 mils Trace/Space	Fine-feature capability enabled by F4BTMS450'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.
HASL LF Surface Finish	Lead-free HASL provides a solderable, cost-effective finish suitable for through-hole and SMT assembly.
Top Silkscreen (White)	Provides component reference designators for assembly; white offers excellent contrast on black solder mask.
Top Solder Mask (Black)	Protects top-side circuits; black color option per customer preference for aesthetic or optical requirements.
No Bottom Solder Mask	Left bare for potential grounding or heat sinking applications.
IPC Class-2	Balances cost and reliability for commercial aerospace and defense applications.
100% Electrical Test	Ensures impedance, continuity, and isolation before shipment.

 

 

Key Fabrication Notes for F4BTMS450:

 

Drilling: F4BTMS450's ultra-thin/ultra-fine fiberglass construction requires sharp carbide drills with optimized speeds and retract rates. The fine glass reinforcement reduces tool wear compared to standard woven-glass PTFE while providing excellent hole quality.

 

Surface Preparation: Standard PTFE processing techniques apply. Plasma treatment (e.g., CF₄/O₂) is recommended before plating to activate the PTFE surface and ensure strong adhesion.

 

Dimensional Stability: The combination of ultra-thin fiberglass and ceramic filler provides excellent dimensional stability, resulting in tight registration and high fabrication yields—particularly valuable for fine-pitch designs (4/6 mils trace/space).

 

Solder Mask Application: Black solder mask requires careful process control for consistent color and coverage; standard PTFE-compatible solder mask formulations are recommended.

 

 

5. Comparative Positioning – How F4BTMS450 Stands Out

Aspect	F4BTMS450	Standard Woven-Glass PTFE	Non-Woven PTFE Laminates
Fiberglass Type	Ultra-thin / ultra-fine	Standard woven glass	Non-woven / chopped fiber
Glass Weave Effect	Minimized	Present (phase ripple)	Minimal
Dimensional Stability	Excellent	Good	Moderate
Dk @ 10GHz	4.50 ± 0.09	Variable	Variable
Dissipation Factor @ 10GHz	0.0019	Typically higher	Comparable
CTE X/Y (ppm/°C)	12 (closely matched to Cu)	~17–26	Variable
Thermal Conductivity	0.64 W/(m·K)	~0.22–0.50	~0.20–0.50
Dielectric Strength	>45 kV/mm	Lower	Comparable
Unique Feature	Breakthrough formulation with ultra-thin fiberglass	Standard construction	Non-woven reinforcement

Note: F4BTMS450's ultra-thin/ultra-fine fiberglass construction minimizes the glass weave effect while providing superior dimensional stability—a combination not typically available in standard woven or non-woven PTFE laminates.

 

 

6. Typical Applications – Where F4BTMS450 Shines

Aerospace Equipment: Spaceborne systems, cabin equipment, and in-flight electronics

Microwave & RF Systems: High-frequency circuits requiring stable dielectric properties

Radar & Military Radar: Phased-array radars, early warning systems, and airborne radar

Feed Networks: Distribution networks for antenna systems

Phase-Sensitive Antennas: Phased-array antennas and beamforming networks

Satellite Communications: Ground stations, payloads, and communication terminals

High-Power Applications: Where improved thermal conductivity (0.64 W/(m·K)) is beneficial

 

 

Q1: What is the difference between F4BTMS450 and the F4BTM series?

F4BTMS450 is an upgraded version of the F4BTM series, featuring technological breakthroughs in material formulation and manufacturing processes. It incorporates more ceramic filler with ultra-thin and ultra-fine fiberglass reinforcement, resulting in broader Dk range, lower loss, better dimensional stability, reduced anisotropy, higher electrical strength, and improved thermal conductivity.

 

 

Q2: How does F4BTMS450 minimize the glass weave effect?
By using ultra-thin and ultra-fine fiberglass cloth combined with high ceramic loading, the glass weave effect on electromagnetic wave propagation is minimized. This reduces dielectric loss and decreases X/Y/Z anisotropy, resulting in more consistent impedance and phase response.

 

 

Q3: What is the maximum operating frequency of F4BTMS450?
The material maintains stable dielectric constant and low loss up to 40GHz, making it suitable for phase-sensitive applications across a wide frequency range.

 

 

Q4: Is F4BTMS450 suitable for space applications?
Yes. It features excellent radiation resistance, low outgassing properties meeting space requirements, and stable performance from -55°C to +260°C, making it qualified for aerospace and spaceborne applications.

 

 

Q5: What dielectric thicknesses are available for F4BTMS450?
The minimum thickness is 0.254mm (10mil), with availability in 0.127mm increments up to 6.35mm (250mil). Custom thicknesses are available upon request.

 

 

Q6: Can F4BTMS450 replace imported materials?
Yes. F4BTMS450 is specifically engineered as a high-reliability alternative to similar imported products, offering comparable or superior electrical, thermal, and mechanical properties.

 

 

Q7: What surface finishes are compatible with F4BTMS450?
HASL LF (as in the design case), immersion gold, immersion silver, ENEPIG, and OSP are all compatible with proper surface preparation (plasma treatment) prior to finishing.

 

 

Q8: 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 express or implied warranties. End-users should verify suitability for their specific application through their own testing.

 

 

Conclusion

F4BTMS450 from Taizhou Wangling Insulating Material Factory represents a significant advancement in PTFE-based high-frequency laminates. Its innovative combination of ultra-thin/ultra-fine fiberglass reinforcement with high ceramic loading delivers minimized glass weave effect, excellent dimensional stability, and superior electrical performance—all critical attributes for phase-sensitive radar, feed networks, phased-array antennas, and satellite communications. As demonstrated by the 2-layer PCB design case—featuring a 0.6mm thickness, 4/6 mils trace/space, and HASL LF finish—F4BTMS450 integrates smoothly into standard fabrication workflows while meeting the demanding requirements of aerospace and defense applications. For engineers seeking a reliable, high-performance alternative to imported materials, F4BTMS450 offers a compelling, field-proven solution.