TC350 is a woven-glass-reinforced, ceramic-filled PTFE laminate aimed at RF circuits where dielectric performance and heat transfer both matter. Its thermal-conductivity literature contains observations from different test methods. Those values must be kept separate when it is compared with TC350 Plus or another thermally enhanced laminate.
Material system
Ceramic-filled PTFE reinforced with woven glass
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 3.5 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5 clamped stripline; direction is not separately recorded here. Source |
| Dissipation factor | 0.002 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Thermal conductivity | 0.72 W/(m·K) | Typical, through thickness; ASTM D5470. The product table does not state test temperature. Source |
| Thermal coefficient of dielectric constant | -9 ppm/°C | Typical; -40°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
Selection and design notes
- Consider it for RF power networks where reducing the substrate contribution to thermal resistance is useful. First identify whether heat actually flows through the dielectric or mainly through copper, vias and a carrier.
- For a comparison with TC350 Plus, use the same thickness, footprint and boundary conditions. A conductivity ratio does not directly translate into the same percentage improvement in device temperature.
Thickness and copper options
Choose a documented core thickness and consider its effect on RF width and dielectric thermal resistance together.
Reverse-treated ED constructions and special backing options require exact order details; do not assume all TC350 boards use the same foil.
Fabrication considerations
- Review the filled PTFE drill process, copper adhesion and any metal-backed construction with the fabricator. Include the carrier interface and bondline thickness in the thermal drawing rather than leaving them as unspecified assembly details.
Application fit
- RF power amplifiers
- Power dividers
- Thermally demanding filters
Limits and substitution checks
- The current TC350 sheet gives 0.72 W/(m·K) by ASTM D5470; the selector also mentions a 1.0 value by ASTM E1461. Neither number should be silently substituted for the other. Thermal improvement does not establish a permissible RF power or a safe component temperature.