RO4835T extends the RO4835 concept into thin spread-glass constructions for multilayer RF designs. The suffix is consequential: process Dk, Design Dk, loss and thermal properties vary with the chosen thickness. Treating it as ordinary RO4835 made thinner hides data that are explicitly separated in the manufacturer table.
Material system
Ceramic-filled hydrocarbon thermoset with spread woven glass
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Dissipation factor | 0.003 | Typical for 2.5 mil and 5.0 mil constructions; 10 GHz, 23°C, Z direction, IPC-TM-650 2.5.5.5. 3.0 and 4.0 mil constructions have different values. Source |
| Thermal conductivity | 0.52 W/(m·K) | Typical for 2.5, 3.0 and 5.0 mil constructions; 50°C, Z direction, ASTM D5470; 4.0 mil construction is 0.54 W/(m·K). Source |
| Process dielectric constant | 3.33 at 2.5/3.0/5.0 mil; 3.32 at 4.0 mil | Typical; 10 GHz, 23°C, Z direction, IPC-TM-650 2.5.5.5; clamped-stripline method, construction table. Source |
| Design dielectric constant | 3.52 / 3.50 / 3.49 / 3.48 | Typical; 2.5 / 3.0 / 4.0 / 5.0 mil, respectively; 8–40 GHz, Z direction, differential phase length method. 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 it where the RF layer needs a thin dielectric and a thermoset process, while checking that the required line width remains manufacturable. Thin cores can make copper geometry and etch tolerance especially significant.
- Read across one construction column before entering values into a simulator. Mixing the Design Dk of the 5 mil column with the Df of the 3 mil column creates a material that Rogers did not characterize.
Thickness and copper options
The datasheet separates 2.5, 3.0, 4.0 and 5.0 mil cores. Use one complete column of properties for the selected thickness.
Use the foil listed for the selected construction; CU4000 references support foil-lamination discussions but do not replace the core specification.
Fabrication considerations
- Coordinate core handling, copper preparation and a qualified RO4450T or other bonding construction. Balance the layer stack and define pressed dielectric spacing, because the uncured prepreg thickness is not a substitute for the final distance between conductors.
Application fit
- Thin RF multilayers
- Backhaul radios
- Compact microwave interconnects
Limits and substitution checks
- No universal automatic preset is supplied. The table also shows a sign change in temperature dependence over different ranges; a single constant temperature coefficient would conceal that behavior. Use frequency- and temperature-appropriate data when phase stability is part of the requirement.