A Fuzzy Method for Global Quality Index Evaluation of Solder Joints in Surface Mount Technology

In recent years, the requirement of compact devices caused an increasing use of Surface Mount Technology. This technology guarantees the reduction of the size of electronic packages by exploiting solder joint interconnection technology. Nevertheless, parameter variations can occur during the deposition and printing of the soldering paste on a board, compromising its correct working. In this paper, it is proposed a fuzzy architecture for computing an index which provides a quantitative refined assessment about the quality of the soldered interconnections. This task is performed by reproducing the modus operandi of the human experts during their assessments. The proposed architecture consists of three modules connected in series: a feature extraction block and two fuzzy ones. The presented solution keeps the benefits of a neurofuzzy system previously proposed in literature, like the reduction of equipment and computational costs. Moreover, it implies two further advantages: the influence of the human experts in its design is reduced and its implementation is reasonable. Experimental results confirm such advantages, in fact, the architecture approximates the human assessments reliably.