CuClad 6250 is a thermoplastic bonding film used to join PTFE microwave laminates. Its relatively low bonding temperature can be useful for a suitable assembly, but it also makes downstream temperature exposure an important design constraint. It should be assessed as part of a bonded structure, not as a core laminate.
Material system
Thermoplastic bonding film
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 2.32 | Typical; 10 GHz; datasheet lists IPC-TM-650 without a submethod or conditioning details. Not a separate Design Dk observation. Source |
| Dissipation factor | 0.0013 | Typical; 10 GHz; datasheet lists IPC-TM-650 without a submethod or conditioning details. 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 the assembly and service temperatures fit the film's limits and the low-temperature bonding route offers a concrete manufacturing advantage. Review subsequent soldering, rework and storage before selecting the material.
- For stripline construction, include the bondline dielectric and finished thickness in the RF model. A good Dk match alone does not establish adequate flow around the inner-layer copper.
Thickness and copper options
Use the exact supplied film gauge and qualified pressed thickness. Sheet or roll handling and fill requirements affect the final spacing.
This is an unclad bonding film. The surface treatment of the adjoining copper and PTFE must be part of the process specification.
Fabrication considerations
- Follow the film datasheet's thermocouple, pressure, dwell and controlled-cooling guidance with the fabricator. Temperature at the bond interface is the relevant process variable; a press setpoint does not prove the interface reached a uniform bonding condition.
Application fit
- Low-temperature PTFE bonding
- Microwave stripline assembly
- Temperature-limited RF bondlines
Limits and substitution checks
- The selector does not mark 6250 as lead-free-process compatible. Do not assume a low-temperature adhesive can survive a standard lead-free PCB assembly sequence merely because the PTFE cores can. Published conductivity is omitted here because the retrieved film table does not supply its measurement conditions.