دانلود رایگان مقاله طراحی پارامتر قوی برای فرایند چاپ استنسیل میکرو BGA

Abstract

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.

. Results and concluding remarks

Stencil printing is the most important process in SMA but exhibits complex behaviors which can increase soldering defects which can lead to significant loss of quality and production time. In particular, soldering defects have become more prevalent and are difficult to detect for BGA packages in the process of leadfree assembly and can require costly quality recovery efforts. One approach to increasing first pass yield and reducing manufacturing costs is to optimize the process of solder paste printing and its multiple quality characteristics before the failures are detected in the downstream manufacturing steps. To solve the parameter optimization problem for the fine-pitch micro-BGA stencil printing with multiple quality characteristics, a fuzzy logic-based Taguchi method is proposed. The method is used to derive robust parameter settings which are then compared