The RO4000 data sheet separates typical properties from specification limits. Use its values with their frequency, temperature, direction and test method. A headline dielectric constant without those conditions is not enough to set an RF simulation.
What to decide before release
Start a requirements table with four columns: property, design assumption, source condition and acceptance method. For example, process Dk describes a controlled material test, while design Dk is intended to help model circuit behavior. Do not transfer a tolerance from one measurement method to the other.
Checks to put in your design brief
- Record the document revision
- Read footnotes for thin cores and LoPro
- Ask Rogers or the fabricator for procurement limits
Important distinction
Typical data is not a guarantee that every finished board will meet the same number. Finished-board acceptance needs an agreed test.
| Property | Value | Measurement basis |
|---|---|---|
| Process dielectric constant | 3.48 ± 0.05 | 10 GHz, 23°C; clamped stripline |
| Design dielectric constant | 3.66 | 8–40 GHz; differential phase length |
| Dissipation factor | 0.0037 | 10 GHz, 23°C; typical |
| Dissipation factor | 0.0031 | 2.5 GHz, 23°C; typical |
| Glass transition temperature | >280°C | TMA; not a continuous-use rating |
| Decomposition temperature | 390°C | TGA; not a reflow setting |
| Thermal conductivity | 0.69 W/(m·K) | 80°C; typical |
| CTE, X / Y / Z | 10 / 12 / 32 ppm/°C | −55 to 288°C |
| Moisture absorption | 0.06% | 48 h, 50°C immersion; 0.060-inch sample |
| Density | 1.86 g/cm³ | 23°C |
| Copper peel strength | 0.88 N/mm | 1 oz ED foil; after solder float |
| Flammability | UL 94 V-0 | Standard laminate; verify exact construction |
The 4 mil core has a separate process-Dk value of 3.33 ±0.05. Typical values are not procurement limits. Read conditions and exceptions.
Sources & basis
Material facts follow the cited source. Design checks are preliminary guidance, not supplier process instructions.