TMM 13i extends the TMM thermoset family to still higher permittivity for compact microwave structures. Its process dielectric test uses a different IPC method from the other listed TMM grades, and its Design Dk is numerically lower than its process Dk. These are reasons to retain method labels, not to average the two values.
Material system
Ceramic-filled thermoset polymer
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 12.85 ± 0.35 | Typical; 10 GHz, Z direction; IPC-TM-650 2.5.5.6, datasheet footnote 3. Test temperature is not stated in this datasheet row. Source |
| Design dielectric constant | 12.2 | Typical, 8–40 GHz; differential phase length method. Average across the common constructions in the cited datasheet. Source |
| Dissipation factor | 0.0019 | Typical; 10 GHz, Z direction; IPC-TM-650 2.5.5.5. Test temperature is not stated in this datasheet row. Source |
| CTE, X axis | 19 ppm/°C | Typical; 0°C to 140°C; ASTM E831 and IPC-TM-650 2.4.41, product datasheet. Source |
| CTE, Y axis | 19 ppm/°C | Typical; 0°C to 140°C; ASTM E831 and IPC-TM-650 2.4.41, product datasheet. Source |
| CTE, Z axis | 20 ppm/°C | Typical; 0°C to 140°C; ASTM E831 and IPC-TM-650 2.4.41, product datasheet. Source |
| Thermal coefficient of dielectric constant | -70 ppm/°C | Typical; -55°C to 125°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); frequency not separately stated in this datasheet row. Source |
| Water absorption | 0.16 % | Typical; D24/23, 0.050 inch (1.27 mm) specimen, ASTM D570; product datasheet, not the selector's different moisture conditions. 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 only when the additional size reduction provides a clear circuit benefit. Compare manufacturable gaps, bandwidth and tolerance margin with a lower-Dk design before accepting the smallest possible resonator.
- A geometry that concentrates fields differently may respond differently to the material's dielectric behavior. Use a compatible electromagnetic model and a measured component to confirm the chosen design value.
Thickness and copper options
Confirm the offered TMM 13i thickness and tolerance; family-wide tables do not prove every grade is stocked in every size.
Specify foil construction and minimum copper features before optimizing a highly miniaturized layout.
Fabrication considerations
- Review mechanical support and machining with a fabricator familiar with high-filled thermosets. Very compact copper features and substrate edges should be evaluated together so that handling and routing do not undermine electrical repeatability.
Application fit
- Very compact resonators
- High-permittivity RF components
- Miniaturized filters
Limits and substitution checks
- The selector marks the thermal-conductivity number as estimated, so it is intentionally omitted from automatic thermal data here. Its high Dk and temperature dependence also make an unverified scalar model a poor basis for claiming final filter performance or a drop-in substitute for ceramic components.