ENGINEERING ANSWER
RO4350B and RO3003 belong to different laminate families. The choice should consider frequency-relevant loss, dielectric model, fabrication process and the supplier’s experience with the exact material.
What to decide before release
Ask for current official data for both candidates and a quotation on the same drawing requirements. Compare the modeled and measured circuit response after adjusting geometry. Processing differences can affect cost and schedule as well as performance.
Checks to put in your design brief
- Obtain current material data
- Confirm qualified fabrication capability
- Recalculate the transmission-line geometry
Important distinction
Do not substitute a material solely because one published Df number is lower under a different test condition.
Sources & basis
Material facts follow the cited source. Design checks are preliminary guidance, not supplier process instructions.