A very useful guide to making a 4 layer PCB.

[Mattylad]

I found this today and thought some on here might want to watch it.

https://www.youtube.com/watch?feature=player_embedded&v=sIV0icM_Ujo

It's a very good explanation of how a 4 layer PCB is made, well worth the time to watch and for us old hands a refresher on how the processes have improved.

 

[yura717]

yes , it was very interesting.
https://www.ladyada.net/library/pcb/manufacturers.html