Discussion of failure cases for contamination in electronics assembly process

Nowadays, with more and more functions of electronic products, an electronic product usually consists of thousands of electronic components, and the reliability of an electronic product is not only determined by the inherent reliability of each component, but is also closely related to the assembly technologies of these components. Soldering is an important process in electronics assembly technologies, and soldering flux is an essential part of it. To enhance the adaptability of products in various environments and protect the components on the printed circuit board (PCB), conformal coating is widely used in electronics assembly technologies. However, incorrect selection or use of these electronic auxiliary materials, it will usually cause a fatal failure in products instead of higher reliability, especially for the components with contact units. This paper will discuss several failure cases on relays, switches and potentiometers, which caused by contamination resulted from incorrect selection or use on electronic auxiliary materials. General ideas and basic methods for failure analysis will also be introduced while the discussion on failure cases. In the end, some helpful advices which would improve the reliability of electronics assembly processes are suggested.