Abstract:

Conformal coatings have been used to protect the electronic assemblies from corrosive gases, dust, and moisture. In recent years, conformal coatings have been relied on to mitigate the electrical shorting risk presented by tin mitigation, a hair like conductive filament that grows from tin rich alloys. However, there has been limited reporting on the effects of conformal coating on the thermomechanical reliability of solder joints. This paper presents details of an experimental investigation into the effect conformal coatings on the reliability of solder joints under temperature cycling, harmonic vibration, and drop tests. Acrylic and thin parylene like coatings were used. The results show that both conformal coatings can improve the reliability of solder joints under temperature cycling, the coatings have very little impact on the solder joint reliability under mechanical loadings.

Keywords: Conformal coating, Temperature cycling, vibration, drop test, Solder joint, Weibull, ALT, Testing