Study On The Design Of PCB Alignment System Based On Video And Confocal

With the fact that PCB is developing to large area, high density direction, those tradition exposure ways such as contact and approximation imaging technology,step-and-repeat imaging technology,laser direct imaging technology exist in some problems: the mask easy to contaminate and easy to distort when it be heated; The resolution is lower; Output is lower, and so on, therefore it has some limitations in making large area, high density PCB. This article studies the design of Alignment system based on video and confocal, Mask-Panel Alignment is one of the threes key technologies (projectionlens, aligner, wafer stage)in lithography.For the requirement of laser projection lithography system, we designed laser projection lithography system based on video image alignment system. This paper introduces the optical path of laser confocal microscopy, analyzes its imaging principles and key point of technology. Analysis to precision of the alignment system shows that the precision is dependent greatly on that of CCD image sensor output signal. The factors that have effect on CCD precision are studied, we analyze correlated couple sampling to make the quality of CCD image and the output S/N of the CCD improve. Using the digital image processing soft , the quality of image is improved, thus the precision of alignment system is improved, which meet the need of overall alignment tolerance of 2.5um.