Introduction to printed circuit board failures

Printed circuit boards form the mechanical and electrical connections between electrical components in the complex circuits of modern electronic designs. Printed circuits not only interconnect components through conductors routed through the board with traces and vias, but also must provide effective electrical insulation between conductors of different potentials and in different circuit nodes. Printed circuits need to be mechanically robust to withstand the field conditions imposed while maintaining their electrically conductive and insulating properties. Electrical considerations or potential printed circuit board failure modes can be overlooked in physical circuit design. The large volume of typical consumer electronics products makes it important to consider low rate failure modes in physical circuit board design, particularly the modes of high severity. This paper will discuss lower rate failure modes that can produce outcomes ranging from simple circuit failure to burning propagating faults which may not be fail safe. Failure mechanisms of various root causes that manifest into more severe failures will be discussed; topics include interconnect overheating, contamination, electrochemical migration such as dendrite formation and conductive anodic filaments, tin whiskers, and component overheating and failures. Preventive measures in printed circuit board design will also be discussed.