Sometimes you need to have a special dielectric constant of PCB material, but it should be not expensive. In this case for multilayer PCBs we can offer you the following solution (see stack-up on the picture):

The outer layers of PCB are made of PTFE material which provides the stable Dk and low loss for high speed (or RF) traces. And the inner layers are made using FR-4 cores and prepregs which reduces the overall costs of large volume orders, as well as improves the rigidity of PCB, to allow good SMT assembly, handling and long term reliability. Please contact our engineers to choose the proper combination of PTFE cores and FR-4 prepregs.

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• See additional information on hybrid PCB in this article.
• See information on Taconic HF materials and prepregs in this article.