CLTE-XT is a low-loss reinforced PTFE material in the CLTE family. The current product sheet explicitly varies process Dk with core thickness, while giving a separate transmission-line Design Dk. This distinction is especially relevant when comparing thin cores used in multilayers with thicker reference samples.
Material system
Ceramic-filled, woven-glass-reinforced PTFE
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Design dielectric constant | 2.93 | Typical; 10 GHz, microstrip differential phase length method, C-24/23/50 conditioning. Source |
| Dissipation factor | 0.001 | Typical; 10 GHz, 23°C/50% RH; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Thermal conductivity | 0.56 W/(m·K) | Typical, through thickness; ASTM D5470. The product table does not state test temperature. Source |
| Process dielectric constant | 2.79 at 5.1 mil; 2.89 at 9.4 mil; 2.92 at 20 mil; 2.94 at 30 mil; each ±0.03 | Typical; 10 GHz, 23°C/50% RH, IPC-TM-650 2.5.5.5. Datasheet construction table, page 4. Inch labels retained because paired metric labels are inconsistent. Source |
| Thermal coefficient of dielectric constant | -8 ppm/°C | Typical; -50°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
| Water absorption | 0.02 % | Typical; E1/105 + D24/23, IPC-TM-650 2.6.2.1. Source |
| Density | 2.17 g/cm³ | Typical; C-24/23/50, ASTM D792. 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 a long microwave path or multilayer network where reduced dielectric loss is valuable alongside dimensional control. Compare complete line structures, including copper, because lower Df does not establish the same proportional reduction in total attenuation.
- Select the actual thickness before choosing a material model. The table ranges from a lower process Dk on the thinnest core to 2.94 on the 30 mil entry; one headline number would conceal that construction dependence.
Thickness and copper options
Construction table: 5.1, 9.4, 20 and 30 mil. The current PDF has inconsistent paired metric labels; confirm the order dimensions.
ED and reverse-treated foil offerings require an explicit copper selection and appropriate loss characterization.
Fabrication considerations
- Use a fabricator familiar with the CLTE PTFE process and qualify the intended thin-core bonding stack. Include registration and phase-sensitive coupons if a design relies on repeatable line lengths across a large or multilayer structure.
Application fit
- Low-loss multilayers
- Long microwave feeds
- Precision antenna distribution
Limits and substitution checks
- The current sheet's Df, density and dielectric-temperature observations differ from the selector. Some paired inch and metric thickness labels are also inconsistent; this record retains the inch construction labels and requires order confirmation rather than converting the ambiguous text into a fabricated configuration.