Development of 0.5 and 0.65 mm pitch QFP technology in surface mounting

Results from a series of experimental studies on the effect of assembly process conditions and design rules on solder joint quality for 0,5 and 0,65 mm pitch surface mounted devices are summarized. A four-layer 200 × 300 mm² test board is used for experimental purposes. The main objective of the work is to optimize design and manufacturing conditions for 0.5 mm pitch quad flatpack (QFP) components. A large number of design and process parameters are studied using factorial analysis. The parameters studied are pad width, lead inplanarity and lead sweep of component, placement position, squeegee speed and squeegee angle, number of strokes and surrounding temperature. It is found that at optimum design and process conditions, zero defect failure rate can be obtained for the 0.65 mm pitch components, while for the 0.5 mm pitch component, 400 ppm in solder joint failure rate can be obtained