RO4450F and RO4450T are bonding materials whose selection influences the final multilayer structure. Compare their supported constructions and cured-layer behavior alongside the cores they will join, rather than treating bondply as a passive purchasing detail.
Begin with the finished dielectric spacing
The number required by the RF model is the spacing after lamination. Resin flow, copper coverage and the chosen layup influence that result. An unpressed sheet designation alone does not establish the finished geometry. Identify which layer carries the signal and whether its fields occupy a core, the bonding layer, or both.
Check the intended material pairing
Review RO4450F and RO4450T with their source documents and the exact core material. Rogers includes these within its RO4400/RO4400T bonding range, but that does not make every core, copper pattern and press sequence automatically interchangeable. Ask the fabricator for a supported construction and the thickness tolerance it can control.
Example: a thin inner RF layer
Imagine an inner transmission line whose reference-plane separation is being reduced to fit a compact module. The new bonding construction changes the field distribution, etching sensitivity and resin-fill requirement around copper features. Recalculate impedance using the actual layered dielectric model; the site’s symmetric homogeneous stripline estimate cannot resolve a stack of unlike dielectrics. Include a cross-section and appropriate coupon in the prototype plan.
Approve process and electrical outcomes together
Discuss storage, handling, layup, curing and any sequential lamination exposure using the relevant official processing guidance. Do not invent a press temperature, pressure or dwell time from a generic prepreg recipe. Confirm that subsequent assembly temperatures fit the selected construction. Inspect for the agreed structural acceptance criteria and measure the RF response. When changing from an established bondply, document the new finished spacing, model and process approval even if the core material remains unchanged.
If copper density varies sharply across the panel, identify both dense and open regions in the inspection plan. A single thickness reading at the edge may not represent the dielectric spacing beneath a critical inner-layer line. Agree where the finished spacing will be checked.
Source-aware property comparison
RO4450F
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 3.52 ± 0.05 | Typical; 10 GHz, 23°C/50% RH; IPC-TM-650 2.5.5.5 clamped stripline; direction is not separately recorded here. Source |
| Dissipation factor | 0.004 | Typical; 10 GHz, 23°C/50% RH; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Thermal conductivity | 0.65 W/(m·K) | Typical; ASTM D5470, 80°C, through-thickness direction. Source |
| Water absorption | 0.04 % | Typical; D24/23, IPC-TM-650 2.6.2.1; current product sheet. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
RO4450T
| 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.
Select F or T with the required cured spacing, supported core pairing and verified lamination outcome.