When your design does not allow you to put enough PTH vias due to surface constrains, blind and buried vias might offer you a solution.
A. is a blind via drilled and plated through before pressing the multi layer. To produce this you will need to select the appropriate build up (reverse) and select an extra PTH run in the order details.
C. is also a blind via but laser drilled and plated after the multi layers has been pressed. That technology is not used by Eurocircuits.
B. is a buried via as he cannot be seen from outside. The via hole is drilled and plated before the pressing takes place. These holes will also represent an extra PTH run.
Blind and/or buried vias present in your data also need to be specified in your order details. This is done by selecting the appropriate build up in the Buildup Editor and the correct number of extra PTH runs and extra press cycles that are applicable.
For the above drawing we need to imagine that hole C is not there and subsequently select the buildup and order details this way: