Re:Dielectric Constant of Prepreg layer

[Sal Hernandez]

The dielectric Constant of the FR4 material we use for our online services is 4.5 +/- 0.10. You can review the pcb stackups along with tolerances and Dk on our construction detail page. The dielectric constant is the same for the prepreg and core.

http://www.sunstone.com/products-servic ... etail.aspx

We also offer Rogers 4350 through our PCBexpress (Rogers 4350 material, .020 inch thickness, 2 layer prototype board, no silkscreen, no solder mask, 25 qty max with dimensions no more than 8 X 8 inches.)service. The dielectric constant for this material is 3.66.