Sulphur Damages in Electronic Assemblies


Electronic assemblies are often requested to function in critical service environments.
They are submitted to extreme moisture and temperature conditions and sometimes they are also prone to chemical exposure of corrosive agents which could be responsible of severe failures.
These conditions are due to atmosphere, to fluxes residues employed during assembly processes, to packaging materials, vulcanized rubbers, vapor or gases emissions containing Sulphur such as petrol.

In this paper a failure related to a motorcycle headlights will be reported.

Preventlab Failure Analyses

Motorcycle headlight failure

LED device inside the motorcycle headlight

Defect reproduction in laboratory: TEST @ 60°C for 144 hrs of new LEDs near a sealing sponge

Crystal growth analysis in laboratory: optical and scanning electron microscopy
LED leads with growths
Silver Sulphides SEM images

EDX spectrum (chemical micro-analysis): Sulphur peak is relevant
Sulphur coming from sealing sponge, under service environment conditions, volatilizes and reacts with Silver LED surfaces causing the motorcycle headlight failure.