Robust parameter design for the micro BGA stencil printing process using a fuzzy logic based Taguchi method
Display Omitted The stencil printing parameters for a micro BGA package were robustly optimized.Three optimization methods were compared to find the best stencil printing parameter set.The three methods provide satisfactory performance compared to the mass production.The proposed fuzzy based Taguchi method outperforms the other two methodologies.Taguchi fuzzy method improves the outputs of paste volume and centroid by 23.27% and 27.47% Solder paste is the main soldering material used to form strong solder joints between printed circuit boards (PCB) and surface mount devices in the surface mount assembly (SMA) On average 60% of end of line soldering defects can be attributed to inadequate performance of solder paste stencil printing. Recently, lead free solder paste has been adopted by electronics manufacturers in compliance with the RoHS directive. However, soldering defects in the ball grid array (BGA) packages used in lead free SMA have become more prevalent and are difficult to detect. In this study, a fuzzy logic based Taguchi method is proposed to optimize the fine pitch stencil printing process with multiple quality characteristics for the micro ball grid array (micro BGA) packages using a lead free solder paste. A structured data set is first collected from an L18 (21?37) fractional factorial design experiment, followed by multi response optimizations and analysis of variance (ANOVA) for identifying significant factors. The optimization performance gained by the proposed fuzzy logic based Taguchi method is compared with the results of other two hybrid methods including a combination of neural networks and genetic algorithms, and the integration of the response surface methodology with a desirability function. The confirmation experiments show that the proposed fuzzy logic based Taguchi method outperforms the other two methods in terms of the signal to noise ratios and process capability index.
Appl. Soft Comput.