MANUAL VISION SYSTEM
Vision Alignment & Inspection system for Semi-Automatic Screen Printers
The VA100 is a manually adjusted alignment and inspection system designed for use with MPS's semi-automatic screen printer models TF-100, and SP-1500. The closed-circuit monochrome system includes two video cameras mounted on self locking, adjustable arms, 17" flat screen monitor, image splitter, and 2 LED ring lights mounted to the zoom lens with an adjustable intensity dimmer.
After the normal setup routine for the screen printer has completed, the operator establishes the alignment targets for the production run using the VA100. First, the operator selects two pad patterns from opposite corners of the PC board as targets and then rough aligns the camera positions until the selected targets appear on the video monitor. The light source is easily adjusted until the sharpest image of the selected pattern is obtained.
The operator now prints the first board and verifies the print alignment through the cameras magnified image. Once proper registration is achieved, the successive boards are loaded and aligned to the set cross hair patterns using the screen printer's X, Y, and Theta table micrometers. Once they have been set up, neither the camera positions nor cross hair controls are moved again. Only the position of the board is moved, if needed, before successive prints to assure proper registration of each deposition.
The use of the VA100 assures precise alignment of each and every PC board printed for fewer defects and higher yields.
The operator places MPS's reusable Mylar Alignment Fixture over the PC board and produces a test print. Then the operator uses the table micrometers to make the adjustments along the X, Y, and Theta axes moving the circuit board under the mylar print until the ink or paste deposition is properly registered directly over the center of the targeted pads. Necessary fine adjustments to the board position can now be made while viewing a close-up of the pattern through the camera at 20X magnification. The table is finally locked into position and the mylar fixture removed.
One of the video cameras is rotated until the image is parallel to the cross hairs displayed on the monitor. The cross hair controls are then used to "box" the board targets, both vertically and horizontally. This prodcedure creates a cross hair pattern which encompasses one corner of the targeted pad pattern. The entire process is then repeated for the second camera.