Screenprinters

Screenprinters Description:

Accurate repeatable printing and simple-safe operation have all been achieved with the screen printers from Mechatronic systems GmbH in Regensburg. The units are designed for fast workflow and job change over including both the pcb and frame. The equipment, a semi-automatic precision screen printer, is designed for the application of solder paste and/or glue in small to medium size production runs. The printers are loaded and unloaded by hand, otherwise operation is rapid and virtually automatic. This entirely new unit utilities a tee slot work table for simple-accurate positioning of the board to be screened. The PCB holder itself can be configured to suit the users needs. This might be simple shoulder rails, centering parallel pins, mechanical hold-down clamps or vacuum chucks. Additionally, careful initial positioning of the board with reference to its fiducial points can simplify adjustments. At the beginning of a production run the position of the board is adjusted in four axis (including rotation) using micrometer screws with an accuracy of 0.01 mm. At this time the squeegee pressure and setting angle can also be adjusted if required. Subsequently after each pcb is positioned the powered work table automatically carries the board to the underside of the screen. The stiff double squeegee, which is then driven forward by an automatic adjustable speed mechanism, ensures a constant paste thickness. At the completion of the forward stroke the squeegee is lifted automatically. Following this the quick action handling mechanism lowers the complete work table with the pcb. The movement commences slowly, to prevent the solder paste pattern from being damaged and then accelerates in order to facilitate rapid work flow. Finally the work table, with the pcb, are driven out of the machine, without alteration of the initial settings, in order for the pcb to be replaced. In this way paste application to each pcb takes only a few seconds to complete. A very useful addition for fine pitch boards is the optical system. This uses a camera and PC. The operator simply adjusts the board position, where necessary, to change a red screen to a green one prior to commencing the printing cycle.