With the development of economy and scientific technology, people begin to hold increasingly higher requirement to electronic products that have to meet the requirements of multiple functions, miniature, high density and high performance and feature high quality. Therefore, for SMT industry, high soldering quality is the life insurance of electronic products.
However, in the practical manufacturing, soldering defects usually take place, especially in the stage of reflow. As a matter of fact, the soldering issues seen in this stage aren't completely caused by reflow technology because SMT soldering quality is closely correlated with manufacturability of PCB pad, stencil design, components and PCB pad solderability, manufacturing equipment state, quality of solder paste and technical parameters of each link and operation skills of each worker. Manufacturing procedure of SMT is displayed in Figure 1 below.