The Study Of Solder Paste Printing Parameter Optimizing Control Based On Lead-free Sourface Mount Technology

On the purpose of environment protection, two legislations-WEEE(Waste of Electrical and Elecrtonic Equipment) and RoHS (Restriction of The Use of Certain Hazardous Substances in Electrical and Electronic Equipment) in Euro has been set up recently, which will be effective on July .1^St, 2006. In coordinate with the requirement, there are worldwide activities that all electronic factories are busily engage in turning their products lead - freely.The production system of SMT mainly includes six steps which are stencil printing, component placement , reflow soldering , adhesive dispense , wave soldering and inspection. Stencil printing acts as the first important step in the production line. If solder paste is insufficient, the missing solder will occur. If solder paste is excessive, the phenomenon of bridge joint will lead to short circuit. Generally speaking, the factors which affects in the proeess of stencil printing includes the size and shape of stencil, the pressure and angle of shaving knife, printing speed, snap-off, wipe frequency, the type of solder paste, temperature, humidity and so on.This research combines the JMP statistics software to optimize parameters in the process of stencil printing. The achievements as below:ComPared lead/lead-free solder Paste about their ingredient and characteristics, and analyzed the relative influence to the Products and Production.Compared the influence of printing parameter to solder paste printing, and identify the design window of printing parameter.Designed solder printing comparison experiment,printing parameter influence comparison experiment and printing observation numeric experiment to identify the process-optimized parameters of screen print.