RO3003 and RT/duroid 5880 are both PTFE-based RF candidates, but their filler systems and dielectric behavior lead to different circuit geometries. Decide whether your limiting constraint is area, propagation loss, phase stability or the mechanical build.
Start from a fixed electrical function
Compare the materials at the same impedance and circuit function rather than the same artwork. A different dielectric constant changes the required width and electrical length. For a resonator or patch antenna, re-optimize dimensions before comparing loss or bandwidth. Otherwise, an apparent material disadvantage may simply be detuning caused by an unchanged layout.
Include the copper and thickness choices
Open the RO3003 and RT/duroid 5880 records and identify configurations a fabricator can actually produce. A smooth copper option on one material versus a rougher option on the other is a construction comparison. That can be useful, but report it accurately and do not attribute every insertion-loss difference to Df.
Example: a compact feed board
Suppose a board has a fixed connector position and enclosure width. Calculate feasible transmission-line dimensions on each candidate at an available dielectric thickness. Check clearance around the connector launch and the required line-to-ground transitions. Then evaluate electrical length, coupling and thermal drift. The candidate that fits the physical envelope with robust tolerances may be more practical than one that looks best in a single isolated property.
Choose a verification plan before procurement
Both routes need appropriate PTFE fabrication practices, but the detailed process and dimensional response remain grade-specific. Ask for representative finished spacing, drill preparation and handling controls. Measure phase and attenuation over the real band and temperature range when those limits matter. Use the Dk and Df guide to keep the evidence comparable. Preserve a baseline sample and the as-built stackup so later production changes can be assessed against an actual circuit rather than nominal catalogue numbers.
Also review the mechanical placement of tuning features. A wider line or longer resonator may fit the board outline but leave less room near a fastening point or grounded housing wall. Those clearances belong in the electromagnetic and fabrication comparison, not only the final mechanical check.
Source-aware property comparison
RO3003
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 3.00 ± 0.04 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5 clamped stripline; thickness direction. Source |
| Design dielectric constant | 3 | Typical, 8–40 GHz; differential phase length method. Average across the common constructions in the cited datasheet. Source |
| Dissipation factor | 0.001 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; thickness direction. Source |
| Thermal conductivity | 0.5 W/(m·K) | Typical; ASTM D5470, 50°C, through-thickness direction. Source |
| Design dielectric constant | 3.16 | Typical; 77 GHz differential phase length method, selector guide footnote 29. Distinct frequency from the 8–40 GHz datasheet Design Dk observation. Source |
| CTE, X axis | 17 ppm/°C | Typical; -55°C to 288°C, IPC-TM-650 2.4.41; average expansion over the interval, not necessarily linear. Source |
| CTE, Y axis | 16 ppm/°C | Typical; -55°C to 288°C, IPC-TM-650 2.4.41; average expansion over the interval, not necessarily linear. Source |
| CTE, Z axis | 25 ppm/°C | Typical; -55°C to 288°C, IPC-TM-650 2.4.41; average expansion over the interval, not necessarily linear. Source |
| Thermal coefficient of dielectric constant | -3 ppm/°C | Typical; -50°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
| Water absorption | 0.04 % | Typical; D48/50, IPC-TM-650 2.6.2.1. Source |
| Density | 2.1 g/cm³ | Typical; 23°C, ASTM D792. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
RT/duroid 5880
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 2.20 ± 0.02 | Specification-labelled process Dk; 10 GHz, C24/23/50; IPC-TM-650 2.5.5.5, Z direction. Datasheet footnote 1 describes 1 oz ED copper acceptance testing. Source |
| Design dielectric constant | 2.2 | Typical, 8–40 GHz; differential phase length method. Average across the common constructions in the cited datasheet. Source |
| Dissipation factor | 0.0009 | Typical; 10 GHz, C24/23/50; IPC-TM-650 2.5.5.5, Z direction. Source |
| Thermal conductivity | 0.2 W/(m·K) | Typical; ASTM C518, 80°C; through-thickness thermal conduction. Source |
| CTE, X axis | 31 ppm/°C | Typical; 0°C to 100°C, IPC-TM-650 2.4.41. Source |
| CTE, Y axis | 48 ppm/°C | Typical; 0°C to 100°C, IPC-TM-650 2.4.41. Source |
| CTE, Z axis | 237 ppm/°C | Typical; 0°C to 100°C, IPC-TM-650 2.4.41. Source |
| Thermal coefficient of dielectric constant | -125 ppm/°C | Typical; -50°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
Re-optimize the circuit on each material and compare complete, manufacturable configurations.