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|AUTHOR WITHDREW 9-13-11 VISA NOT APPROVED: A Study of Screen Printer Parameters and Reflow Profiles for Pin-in-Paste Soldering Process|
|Keywords: Pin in paste, THC, Solder Reflow|
|AUTHOR WITHDREW 9-13-11 VISA NOT APPROVED: It was studied two relevant processes involved in the PiP (Pin-in-Paste) electronics soldering process using SAC lead-free soldering: screen printer parameters and reflow profiles. The main objective of PiP is to allow soldering in the same step THCs (Through Hole Components) and SMDs (Surface Mount Devices) in order to eliminate the step of soldering THCs by wave or manual soldering, generating benefits like reduction in cost and production time and also environmental aspects. It was analyzed in the screen printer process the influence of squeegee angle, speed and pressure on solder paste quality deposition. Also, to increase the amount of solder paste printed over the PTH (Plated Through Hole) a double printing method was proposed. In order to evaluate the volume of solder paste printed over the PCB and also to compare the volume deposited over the SMD pads and the THC holes a tree-dimensional solder paste measurement system were used. The reflow oven soldering profile was optimized using a commercial temperature profiling systems aiming at enhances the solder paste reflow, the complete filling of the PTH and lower the defects rate. The obtained sample was analyzed by optical microscopy to evaluate the whole quality of the PCB. The samples were analyzed also by x-ray in order to evaluate the presence of voids and poor filled holes after reflow process. To confirm these results the metallographic preparation was used too. The results obtained from the x-ray and optical microscopy were quite satisfactory and were in agreement with the international standards. However it was observed the formation of solder biding, which can be reduced by changing the process parameters and stencil design.|
|Ricardo Barbosa de Lima,
University of Sao Paulo, Laboratory of Integrated System, LSI - Polytechnic School
Sao Paulo 05508-090,