Rogers RO4350B Material Guide

Material selection connects electrical performance, mechanical constraints and a repeatable manufacturing process. Start with the current laminate data sheet, then translate its values into the actual PCB cross-section.

Separate material data from finished-board requirements

A dielectric constant measured using one test method does not automatically reproduce the effective behavior of every transmission line. Record the test method, frequency and material construction alongside the value. Use a design value appropriate to your model and correlate it with a representative test structure.

Specify a complete material construction

• Laminate grade and approved alternatives, if any.
• Core thickness and its tolerance.
• Copper foil type and starting copper weight.
• Bonding material for multilayer constructions.
• Finished copper, surface finish and solder mask coverage.
• Required lot traceability and change notification.

Understand the tradeoffs

Thinner dielectric can reduce trace width and the size of some transitions, but it changes conductor loss and manufacturing sensitivity. Thicker dielectric can permit wider traces while increasing coupling and radiation concerns in some layouts. Neither choice is universally better. Compare the complete geometry against the circuit requirements.

Proceed to the microstrip design tool and manufacturing review.