Research On Error Of Solder Paste Printer And Inspection Technology Of Solder Paste Printing

Along with the global electronic products market demand is upgrading and expanding rapidly, the miniaturization and complicated trend of electronics and is pushing for printed circuit board technology into a rapid development period.Meanwhile, SMT-related equipment is faced with higher precision, higher speed,better production quality to adapt to low cost, large quantities, much more specifications of the production requirements.As the first step of SMT production, solder paste printing quality is Is particularly critical to follow-up process and product quality. High precision, fast automatic solder paste printer becomes the key equipment to ensure the quality of solder paste printing.After PCB is transported into the printer, the location offsets between PCB and stencil are obtained by industrial camera,and input into rectifying calculation model to obtain adjustment quantity of rectifying platform, so as to reach alignment accuracy. That is to say, the high precision of solder paste printer mainly refers to the alignment accuracy between PCB with stencil.In this paper, based on error and sensitivity analysis of automatic vision solder paste printer researched and developed with a company, error sources are summarized and the main error source is confirmed. Optical calibration system of printer based on machine vision is usedforimage distortion correction, local coordinate system calibration and assembling error measurement and compensation, so that the printer achieves higher correction accuracy.Dedicated AOI equipment own high price and cost, and high printing precision and quality of automatic solder paste printer makes 2D solder paste inspection system integrated in the solder paste printer become focus of the market.However, 2D solder paste inspection system still existsshortcomings, such as high misjudgment rate, low accuracy, thus it cannot be applied to engineering use though its cost is low.As solder paste detection algorithm based on machine vision and pattern recognition classifier is put forward, 2D solder paste inspection system is improved, so as to increase its accuracy and reduce misjudgment rate.It also enhance the integrated level of solder paste printer, simplifythe SMT production process, and improve the quality of SMT printing.