DIRECT EXPOSURE SYSTEM BASED ON A LIQUID CRYSTAL DISPLAY

The paper investigates the possibility of using liquid crystal displays (LCDs) as photomasks for transferring a conductive pattern to a photosensitive material using ultraviolet light in the workflow of printed circuit boards (PCBs). In the course of the study, an analysis of the exposure technologies used in the PCB workflow was carried out. A block diagram of the direct exposure system with the use of LCD has been developed, and the main elements of its design have been determined. Based on the monochrome LCD PengJi PJ3D623V1, a prototype of the exposure device was created, on which a number of experiments were carried out. During the experiments, the following design parameters of the device were clarified: the type of lens (with frosted glass), the distance between the lens and the LCD (37 mm), the wavelength of the ultraviolet light source (365 nm). The experiments also allowed us to determine the manufacturing parameters of the exposure operation: the required exposure time for sources with various wavelengths, the minimum reproducible dimensions of the conductive pattern (conductor width and spacing). The possibility of using the developed system has been confirmed: a PCB corresponding to the fourth accuracy class according to GOST R 53429-2009 with a minimum width of 0.2 mm conductors and spaces has been successfully manufactured (thickness of the copper foil is 35 μm). The advantages and disadvantages of the system are analyzed, on the basis of which the scope of possible applications of the technology under study is determined, as well as the prospects for its development.