SMT assembly quality is the abbreviation of SMT product assembly quality. It is a description of the degree to which the inherent characteristics involved in the SMT product assembly process and results meet the requirements. It generally refers to the assembly design quality, assembly raw materials (components, PCB, solder paste and other assembly materials) quality, assembly process quality (process quality), assembly solder joint quality (result quality) during the assembly process of electronic circuit products using SMT , Assembly equipment quality (conditional quality), assembly inspection and assembly management quality (control quality) and other quality design, inspection, control and management behaviors and results. It takes as the measurement standard whether the assembled SMT products meet its specific design requirements, and its content involves SMT and its assembly design, assembly materials, assembly process, assembly equipment, assembly system, assembly environment, and technical personnel.
Poor assembly quality of SMT products can be reflected in the three main types of failures: device failures, operating failures, and assembly failures. Among them, the device fault (Device Fault) mainly refers to the fault caused by the quality of the component, such as the component performance index exceeds the error range, necrosis or failure, misplaced placement caused by the wrong label model, pin missing, etc. Operation fault (Operation Fault) means that the product cannot work normally, but it is not caused by component failure or assembly failure. It is generally caused by design problems, such as timing faults (timing faults), error accumulation faults, and PCB circuit errors. Assembly Fault (Assembly Fault) refers to faults caused by problems in the assembly process, such as solder bridging short circuit, virtual solder open circuit, wrong or missing components, and so on.
In production practice, the failure rate of the above three types of failures is roughly that device failures and operating failures are both less than 8%, and assembly failures are more than 85%. Among these three types of failures, component failures can be minimized by enhancing the quality of incoming materials. Operation failures have become secondary in today’s continuous improvement of circuit CAD technology and component manufacturing technology. As the main source of failure of SMT products, assembly failure is the core problem to be solved by SMT assembly quality control. Therefore, although in the assembly and production process of SMT products, all aspects of quality factors have an impact on the final result of the product, but the quality factors in assembly design and assembly raw material quality, assembly equipment and testing equipment performance, etc. have a basic guarantee of the premise Next, the main link that affects the final result of assembly quality is the assembly process quality link, and the main manifestation of poor assembly quality is assembly failure.
