Through hole generally divided into three categories: blind via, buried via and via hole.
Blind via: located at the top and bottom surface of the printed circuit board, with a certain depth, for the inner surface of the line and below the line connection, the depth of the hole diameter is usually not more than a certain percentage.
Buried via: located at the inner connection hole printed circuit board, it does not extend to the circuit board surface.
Blind vias and buried vias both are located in the inner layer circuit board, the use of through-holes prior to lamination molding process completed during the formation of the through via may also do some inner overlap.
Via hole:This hole through the entire circuit board which can be used to achieve internal interconnect or as component installation positioning holes. Since the via holes in the process easier to implement, the cost is low.
Now let us find a very popular PCB manufacturers compare K2 - PCB Manufacturers, PCB Prototype & PCB Assembly - ALLPCB.com
Hope the belowing listed can be a little helpful to you!