TP2500 high DK frequency double side PCB buile on 0.8mm laminate with Pure Gold Plating for Aerospace RF

Hi, I'm Sally. Today I'm showcasing a custom PCB built on Wangling TP2500—a fiberglass-free thermoplastic with a nickel-free pure gold finish, designed for demanding aerospace and defense applications.

This custom PCB was fabricated using Wangling TP2500, a ceramic-filled PPO thermoplastic from the TP series. A nickel-free pure gold plating was applied as the surface finish, making it suitable for wire-bonding and sensitive RF applications. With only 1 net, the design is a highly specialized single-circuit component—likely a miniaturized antenna or feed network for Beidou navigation, missile-borne equipment, or fuzes.

Key Takeaways

Material: Wangling TP2500 — ceramic-filled PPO thermoplastic

Key Benefit: Fiberglass-free construction, nickel-free pure gold finish, radiation resistance

Board Size: 78mm x 43.05mm | Finished Thickness: 0.9mm

Construction: Double-sided, no solder mask was applied on either side, no silkscreen was used

Surface Finish: Pure gold plating (nickel-free) — ideal for wire-bonding and low-loss RF

Design: 26 components, 36 vias, only 1 net — a highly specialized single-circuit design

Quality: IPC-Class-2 was met, and 100% electrical testing was performed

The Challenge: Nickel-Free Performance for Sensitive RF

An RF board was required by our customer for a mission-critical aerospace application. A nickel-free surface finish was specified—a critical requirement because nickel is slightly magnetic and can introduce losses or affect performance in sensitive RF circuits. Wire-bonding capability was also needed. Additionally, the design required radiation resistance and low outgassing for space and defense environments.

Wangling TP2500 with Pure Gold Plating

TP2500 was selected from the Wangling TP series, combined with a pure gold (nickel-free) surface finish. Here's why this combination was chosen:

Nickel-Free Pure Gold Finish
Nickel was eliminated from the surface finish, removing any potential magnetic interference or loss contribution in sensitive RF circuits. The pure gold surface also provides excellent wire-bonding capability—critical for specialized RF assemblies.

Fiberglass-Free Construction
The dielectric layer was composed solely of ceramics and PPO resin—no glass fiber cloth was used. This eliminated the "fiberglass effect" and ensured exceptional signal consistency.

Precisely Controllable Dk (3 to 25)
Dk values can be tuned in the TP series by adjusting the ceramic-to-resin ratio, providing design flexibility for specific impedance requirements.

Radiation Resistant & Low Outgassing
These properties were critical for space and aerospace applications. The material maintains performance in high-radiation environments with minimal outgassing.

Wide Operating Temperature Range
Reliable performance from -100°C to +150°C was achieved, with excellent low-temperature resistance.

Superior Machinability
Unlike ceramic substrates, TP2500 can be machined using standard PCB techniques—drilling, milling, shearing, and etching were all applied.

The Build: Details That Matter

Design Statistics

The single-net design is the most revealing statistic—a single conductive path was created, such as an antenna feed line or passive RF network. This confirms the application is a highly specialized RF component, likely a miniaturized antenna or feed network.

Design Choices: Purpose-Built for Aerospace RF

Pure Gold Plating (Nickel-Free)
Nickel was eliminated to prevent magnetic interference and loss in sensitive RF circuits. Pure gold also provides excellent wire-bonding capability.

No Solder Mask (Both Sides)
Solder mask was eliminated to prevent any potential dielectric loss or outgassing contributions—critical for space and aerospace applications.

No Silkscreen
Silkscreen was omitted to keep the board clean and optimize RF performance.

0.9mm Finished Thickness
A balance was struck between mechanical robustness and lightweight construction.

Comparison: How TP2500 Stacks Up

Why This Matters: TP2500 with pure gold plating delivers the wire-bonding capability and radiation resistance of ceramic substrates with the machinability of PTFE—and without the magnetic interference of nickel.

Ideal Applications

1. Beidou navigation systems requiring compact, reliable RF circuitry
2. Missile-borne equipment demanding shock and radiation resistance
3. Fuzes requiring extreme miniaturization and reliability
4. Miniaturized antennas for aerospace and defense applications

Q: Why was a nickel-free pure gold finish specified?
A: Nickel is slightly magnetic and can introduce losses or affect performance in sensitive RF circuits. Pure gold eliminates this concern while providing excellent wire-bonding capability.

Q: What makes TP2500 different from PTFE materials?
A: TP2500 uses no fiberglass reinforcement—the dielectric is composed entirely of ceramics and PPO resin. This eliminates Dk variations and provides superior dimensional stability and radiation resistance.

Q: Why does this design have only 1 net?
A: A single conductive path was designed, such as an antenna feed line or passive RF network. This is typical of highly specialized RF components like miniaturized antennas.

Q: What's the significance of 36 vias with a 1-net design?
A: Extensive grounding structures were likely created by the high via count, forming a well-defined ground plane or shielding for the single signal path.

Q: Is pure gold plating suitable for wire-bonding?
A: Yes. Pure gold provides an excellent surface for wire-bonding, making it ideal for specialized RF assemblies and chip-level interconnections.

Q: Is this material suitable for space applications?
A: Yes. The radiation resistance and low outgassing make TP2500 an excellent choice for space and aerospace environments.

Final Thoughts

Wangling TP2500 with pure gold plating delivers a unique combination of properties—fiberglass-free construction, nickel-free finish, radiation resistance, and excellent machinability. When your RF design demands wire-bonding capability and freedom from magnetic interference, this material delivers.

Got an aerospace or antenna project in mind? I'd love to hear about it.

— Sally :)