Research On Key Technology Of Graphic Transfer In PCB Laser Plating System

With the upgrading of high-end electronic products faster and faster the traditional PCB plate making technology has been unable to meet the needs of large area and high-precision PCB plate making.DMD can replace the mask of traditional PCB plate making realize mask-less lithography and provide the possibility to solve large area and high precision PCB plate making.In recent years mask-less laser projection lithography based on DMD has been gradually applied to the PCB plate making field but there is still a problem that the PCB exposure area is small and the L/S accuracy outside the exposure pixel size is low.Based on the DMD the paper studies the key technologies of PCB laser plate-making system and graphics transfer and achieves the following results:Firstly,based on DMD the architecture of PCB laser platemaking system was designed including optical system,DMD drive and precision displacement platform.The uniformity of the light path is more than 90%;the control law of the DMD is mastered;a precision displacement platform with ±5 ?m displacement accuracy and 500 mm stroke(X-axis and Y-axis)is built which satisfies the basic conditions for large-area and high-precision PCB exposure.Secondly,scan-based large-area PCB exposure improvement model was proposed.The preprocessing of the PCB circuit pattern results in binary bitmaps and buffers;feedback is provided between the DMD drive and the precision displacement platform through the external synchronization mode and the PID algorithm is used to synchronize and calibrate the two axes of the gantry structure.Simulations were performed on the improved model with minimal distortion when the DMD frame rate was fixed and the precision displacement platform was moving at a speed of 24.62 mm/s.Thirdly,high-precision PCB exposure improvement model based on grayscale modulation was proposed.The use of 1/2 sub-pixel subdivision to improve the bit-plane decomposition of the grayscale image of the traditional gray-scale modulation that is a single image generates two images with a phase difference of 1/2 pixel and then a 1/2-pixel distance displacement compensation by precise displacement.The improved model is simulated the improved exposure resolution is higher than the original model and the smaller the pixel subdivision the higher the exposure resolution.Finally,The PCB laser plate making system was set up in-kind and the PCB exposure experiment was carried out.The line width reached 20 ?m or less and the PCB size can be processed to 300 mm×400 mm which satisfies the requirement of large-area and high-precision requirements for the project index.