A drilled hole can be either plated or unplated. The walls of a plated hole are called the via barrel. This creates a connection between the top of the board, the inner layers (if present) and the bottom of the board.
A drilled hole can be either plated or unplated. The walls of a plated hole are called the via barrel. This creates a connection between the top of the board, the inner layers (if present) and the bottom of the board.