TMM 10i is the isotropic high-permittivity variant in this part of the TMM family. Its process and Design Dk differ from TMM 10, and the i suffix should remain in both the electrical model and purchase specification. It is a candidate for compact microwave components where field orientation deserves explicit attention.
Material system
Ceramic-filled thermoset polymer
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 9.80 ± 0.245 | Typical; 10 GHz, Z direction; IPC-TM-650 2.5.5.5. Test temperature is not stated in this datasheet row. Source |
| Design dielectric constant | 9.9 | Typical, 8–40 GHz; differential phase length method. Average across the common constructions in the cited datasheet. Source |
| Dissipation factor | 0.002 | Typical; 10 GHz, Z direction; IPC-TM-650 2.5.5.5. Test temperature is not stated in this datasheet row. Source |
| Thermal conductivity | 0.76 W/(m·K) | Typical; 80°C, Z direction, ASTM C518; product datasheet thermal table. 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 (estimated) | -43 ppm/°C | Estimated, explicitly marked with an asterisk in the datasheet; -55°C to 125°C, IPC-TM-650 2.5.5.5. Frequency is not separately stated in this 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
- Investigate it when a geometry involves fields in more than one material direction or when the TMM 10i data fit an existing component architecture. Compare field-dependent behavior using the appropriate model rather than reducing isotropy to a single marketing claim.
- For a small filter, use a full geometry tolerance study. The Design Dk being numerically close to the process Dk does not imply that every construction or discontinuity is represented without calibration.
Thickness and copper options
Use a confirmed TMM 10i thickness and tolerance. Its material name is not a thickness or mechanical specification.
Require the actual foil weight and surface treatment when comparing Q or insertion loss.
Fabrication considerations
- Agree the substrate machining and copper patterning process with a TMM-capable fabricator. Keep dimensional controls on slots, holes and plated features aligned with the resonant structures they influence, and include a representative test coupon where practical.
Application fit
- Compact microwave filters
- High-Dk resonators
- Multidirectional RF structures
Limits and substitution checks
- TMM 10i and TMM 10 are not interchangeable variants. The published negative temperature coefficient and non-flame-retardant selector classification remain relevant. Do not treat the relatively low Df as a prediction of finished filter insertion loss, which includes conductors, launches and radiation.
- The cited TCDk of -43 ppm/°C is marked estimated in the manufacturer table; confirm measured behavior for a temperature-critical design.