An overview on the corrosion rehability of electronics

摘要

Miniaturization and high density packing combined with the wide spread use of electronic systems under varying climatic conditions causing humidity related reliability issues. Several materials associated with the printed circuit board and other components undergo degradation in the presence of moisture as well as the electrochemical corrosion of metallic parts due to a number of factors including water film formation and bias conditions on the PCBA surface. Thickness of the water film and electrical property is the key parameter determining the possible corrosion reliability issues on the PCBA surface. Parameters such as surface morphology of the board surface, solder mask chemistry, hygroscopic flux residues, temperature, and humidity level influence the water film formation and its electrochemical nature, which cause corrosion and leak current issues. This paper provides an overview of the humidity related reliability issues of electronic devices and components with a focus on the water film formation characteristics and effect of various parameters. Reliability prediction of circuits based on the knowledge of water film characteristics will also be discussed. Some aspects related to device and enclosure design will be considered.