Mixed Dielectric  (Hybrid stack-up)

Mixed high frequency construction can reduce costs when the need for RF dielectric is local and only between some layers. The rest of the dielectric can be FR4 or halogen-free FR4. It is also possible to combine PTFE (Teflon) materials with FR4.

   
Cross section of mixed Rogers 4350B, high Tg FR4 and embedded C-coin