RO4835IND LoPro is a specific thin thermoset construction for short-range industrial radar in the 60–81 GHz region. The product combines spread reinforcement and reverse-treated LoPro copper. Its datasheet supplies separate 60 and 77 GHz Design Dk observations, making it more specific than a generic RO4835 dielectric preset.
Material system
Ceramic-filled thermoset with expanded-weave glass and LoPro copper
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 3.48 ± 0.05 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5 clamped stripline; thickness direction. Source |
| Design dielectric constant | 3.49 | Typical; 77 GHz, microstrip differential phase length method. Do not relabel this observation as a 10 GHz measurement. Source |
| Dissipation factor | 0.0037 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; thickness direction. Source |
| Design dielectric constant | 3.48 | Typical; 60 GHz, microstrip differential phase length method; 4 mil LoPro construction. 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 an industrial radar RF layer where a 4 mil construction and thermoset fabrication fit the product. Check line dimensions, coupling and the antenna enclosure at the operating band rather than using a low-frequency Dk by convenience.
- Use the published transmission-line examples only as construction references. Their dB-per-inch values are not universal substrate constants and do not predict an arbitrary launch or finished sensor range.
Thickness and copper options
The standard dielectric is 4.0 mil (0.102 mm), ±0.7 mil. Verify the final conductor-to-plane spacing after fabrication.
The standard offering uses 18 µm LoPro reverse-treated ED foil; identify it explicitly in the stackup.
Fabrication considerations
- The datasheet names several compatible bonding families, including SpeedWave 300P, 2929 and RO4450 grades. Select one with the fabricator and review the actual cap-layer or inner-layer process, copper distribution and subsequent assembly temperatures.
Application fit
- Industrial radar
- Occupancy and motion sensing
- Short-range radar RF layers
Limits and substitution checks
- The ordinary RO4835 Design Dk is not the documented millimeter-wave input for this grade. The sheet's moisture and peel tests have specimen conditions that differ from the thin standard offering, so those values should not be presented as direct tests of every 4 mil board.