Abstract: An improved vacuum box assembly for use in printed circuit board manufacturing where the printed circuit board is supported during manufacturing operations on the second side of the board. The vacuum box uses a unique and improved side plate that securely retains commercially available substrate support devices within the vacuum box. The side plate has a retention cavity configured to receive one or more substrate support devices therein. The side plate retains the substrate support device in a desired position. Open or unoccupied regions of the retention cavity may be sealed by use of specifically configured vacuum blocking plates.