Component layout has to meet both the requirement of the whole machine electric properties and mechanical structure and the requirement of SMT production
craft. Since it's difficult to overcome product quality problem caused by design, PCB design engineers have to understand the basic SMT craft attributes and implement component layout design according to different craft requirements. Excellent design is capable of reducing the soldering defects to the minimum.
In order to correct the errors generated in the process of PCB fabrication, Mark refers to a set of patterns used for optical localization. Mark can be classified into PCB Mark and local Mark.