Is dielectric constant of prepreg same to that of core in PCB?

Discussion in 'General Electronics Chat' started by Dong-gyu Jang, Jan 13, 2016.

  1. Dong-gyu Jang

    Thread Starter Member

    Jun 26, 2015

    My PCB is stacked layer - core (doubled-side PCB) - stacked layer so 4 layers. There is prepreg between 1st layer and 2nd layer (also between 3rd and 4th layer).

    I know dielectric constant of core which is normally 4.6 If it is FR-4. However, what is dielectric constant of prepreg?

    My ground plane is 2nd layer so knowledge of this is important to make impedance-matched microstrip.

    Some article said it is same to the core but is it normally true?
  2. kubeek


    Sep 20, 2005
    Prepreg should be the same material as core, but if you still have doubt ask your manufacturer of the PCB.
    Dong-gyu Jang likes this.