ENGINEERING ANSWER
RT/duroid 5880 and RO4350B differ in dielectric system and processing requirements. A useful comparison starts with a specific circuit objective, such as loss, size, bandwidth, thermal behavior or manufacturing volume.
What to decide before release
Use current manufacturer data and supported foil constructions. A different Dk changes physical dimensions, so compare redesigned circuits rather than identical artwork on different materials. Include process capability and availability in the decision.
Checks to put in your design brief
- Define the performance constraint
- Review fabrication methods
- Model each material with its own data
Important distinction
Lower Dk does not automatically mean a better or smaller design; it changes the electrical-to-physical scaling.
Sources & basis
Material facts follow the cited source. Design checks are preliminary guidance, not supplier process instructions.