RT/duroid 5880LZ is a filled PTFE composite with low dielectric constant and reduced density. Its low Z-axis expansion distinguishes it from ordinary RT/duroid 5880, while its dielectric loss and moisture observations also differ. The LZ suffix represents a material change that needs a fresh electrical and fabrication review.
Material system
Low-density filled PTFE composite
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 2.00 ± 0.04 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5 clamped stripline; direction is not separately recorded here. Source |
| Design dielectric constant | 2 | Typical, 8–40 GHz; differential phase length method. Average across the common constructions in the cited datasheet. Source |
| Dissipation factor | 0.0021 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Thermal conductivity | 0.33 W/(m·K) | Typical; ASTM C518, 80°C; through-thickness thermal conduction. Source |
| CTE, X axis | 54 ppm/°C | Typical; 0°C to 150°C, IPC-TM-650 2.4.41. Source |
| CTE, Y axis | 47 ppm/°C | Typical; 0°C to 150°C, IPC-TM-650 2.4.41. Source |
| CTE, Z axis | 40 ppm/°C | Typical; 0°C to 150°C, IPC-TM-650 2.4.41. Source |
| Thermal coefficient of dielectric constant | 20 ppm/°C | Typical; -50°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
| Water absorption | 0.31 % | Typical; 24 h at 23°C, IPC-TM-650 2.6.2.1. 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 low mass, low Dk and through-thickness expansion are important together. Compare it against 5880 using the complete structural and environmental requirements rather than selecting by dielectric constant alone.
- For an airborne antenna substrate, calculate mass from the actual dielectric volume and copper stack, then separately verify mechanical stiffness and environmental response; laminate density is only one contributor.
Thickness and copper options
Standard sheet offerings include 10, 20, 50 and 100 mil; additional configurations require confirmation.
ED cladding is listed. The copper contributes disproportionately to mass and loss on very thin low-density cores.
Fabrication considerations
- Ask the fabricator to review filled-PTFE machining, drilling and bond preparation. Include handling requirements for the selected thickness and confirm any assembly or adhesive process that applies pressure or sustained heat to the dielectric.
Application fit
- Lightweight antennas
- Low-Dk RF structures
- Mass-sensitive microwave assemblies
Limits and substitution checks
- Its published Df is higher than 5880's, and the moisture test is not interchangeable with every selector entry. A low-density construction does not guarantee a low-loss or moisture-insensitive finished antenna. Do not reuse a 5880 coupon acceptance model without validating this different composite.