RO4450T is a spread-glass, ceramic-filled thermoset bonding material offered in several thin constructions. The current datasheet separates dielectric constant, loss, expansion and thermal behavior by thickness and glass style. A single generic RO4450T number would conceal differences explicitly supplied by the manufacturer.
Material system
Ceramic-filled thermoset prepreg with spread-glass constructions
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 3.26, 3.23, 3.19, 3.35, 3.29, 3.28, 3.24; each ±0.05 | Typical; respective nominal constructions 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0 mil. 10 GHz, 23°C/50% RH, Z direction; IPC-TM-650 2.5.5.5. Issued 091026, pages 2–3. Source |
| Dissipation factor | 0.0037 / 0.0039 / 0.0033 / 0.0042 / 0.0044 / 0.0038 / 0.0044 | Typical for 2.5 / 3.0 / 3.5 / 4.0 / 4.5 / 5.0 / 6.0 mil respectively; 10 GHz, 23°C/50% RH, Z direction, IPC-TM-650 2.5.5.5. 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
- Choose the construction that provides adequate copper fill and the required pressed dielectric spacing. Compare a full column of properties rather than combining the lowest loss with the dielectric constant of another thickness.
- In a thin RF multilayer, the bonding layer can dominate a substantial fraction of the field region. Confirm glass style and resin content along with nominal thickness before final impedance or phase optimization.
Thickness and copper options
The current table covers 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 and 6.0 mil constructions; identify the exact glass/resin combination.
Unclad prepreg; choose compatible foil explicitly. CU4000 LoPro is not a universal default for every RO4450T stack.
Fabrication considerations
- Review the latest product table and RO4000 bonding guidance with the fabricator, especially for sequential lamination. The copper pattern and flow window determine final spacing, so a catalogue film dimension is not a substitute for pressed-stack validation.
Application fit
- Thin RF multilayers
- Sequential lamination
- RO4835T bonding
Limits and substitution checks
- Automatic numeric presets are disabled for this multi-construction record. The September 2026 table extends and updates the selector's 3 mil example, including moisture values and construction-dependent Df. The nonmonotonic Dk values across thickness are retained as data, not smoothed into a fabricated trend.