On a PC board is the first dielectric layer looking into the board from the top or the bottom layer of copper always prepreg or can it be a core? Here "can" would mean conventional. If not then why?
I asked this leaving work for the weekend. This week I asked the board house this question and they said generally prepreg is always used under the outer layers. I didnt ask why though. If no one will do it then the why doesnt really matter.