MATERIALS

RO4350B laminate thicknesses and tolerances

Standard thicknesses in the cited sheet include 4, 6.6, 10, 20, 30 and 60 mil. Core thickness means dielectric thickness before adding the complete finished-board construction. Copper, bonding layers and solder mask change the final thickness.

ENGINEERING ANSWER

Standard thicknesses in the cited sheet include 4, 6.6, 10, 20, 30 and 60 mil. Core thickness means dielectric thickness before adding the complete finished-board construction. Copper, bonding layers and solder mask change the final thickness.

What to decide before release

Choose thickness from impedance geometry, component launch dimensions, mechanical constraints and radiation behavior. For the same target impedance, a thicker substrate generally needs a wider trace. Very thin constructions may instead challenge minimum feature size or handling.

Checks to put in your design brief

  • Request the available nominal core and tolerance
  • Distinguish core from finished thickness
  • Check connector pin-to-ground geometry

Important distinction

Do not assume a distributor stocks every listed thickness or copper combination. Confirm availability before releasing artwork.

Turn this into a design decision

Record your selected construction, the assumptions that affect this topic, and the evidence needed before release. Use the engineering workbench to prepare a preliminary calculation, then discuss the exact stackup and acceptance requirements with the fabricator.

Prepare a fabrication RFQ →

Sources & basis

Material facts follow the cited source. Design checks are preliminary guidance, not supplier process instructions.

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