CuClad 250 covers a selectable dielectric range in a cross-plied woven-glass PTFE family. It is not one fixed Dk material that can be identified completely by the product name. Its usefulness lies in matching a particular antenna or microwave design to an ordered dielectric construction and a controlled fabrication route.
Material system
Cross-plied woven-glass-reinforced PTFE
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Dissipation factor | 0.0017 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Process dielectric constant | 2.40–2.60 | Typical; 1 MHz, C23/50, IPC-TM-650 2.5.5.3, current product datasheet electrical table. Frequency differs from the selector heading. 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 when a design needs a specific permittivity within the available range rather than the lower fixed nominal points of CuClad 217 or 233. State the selected Dk grade in the bill of materials and model.
- For a production antenna platform, preserve the relationship between the approved construction and the tuned artwork. Substituting another point in the range can change dimensions electrically even if the mechanical board drawing remains unchanged.
Thickness and copper options
Thickness and ordered Dk must be specified together; the family designation alone is insufficient for purchasing.
ED foil options are configuration dependent. Preserve copper treatment when qualifying an alternate construction.
Fabrication considerations
- Coordinate core tolerance, orientation and foil with a PTFE-capable fabricator. Use representative coupons to confirm impedance and phase when the selected material is incorporated into a different stackup or copper process.
Application fit
- Specified-Dk antennas
- Cross-plied microwave boards
- Tuned RF feed platforms
Limits and substitution checks
- The current datasheet reports a 1 MHz dielectric range, while the selector uses its own microwave summary. These are not one interchangeable observation. A range midpoint is intentionally not supplied as an automatic model; supplier confirmation and frequency-appropriate data are needed for a selected construction.