Contaminated Solder
Any material which, when found in sufficiently high concentration, negatively affects the properties of solder is considered to be a contaminant. They can, amongst numerous others, have a negative effect on the wetting ability of the solder, or they can affect the flow- or oxidization behavior. Especially solders in wave and selective solder bath are affected, since any contaminant released from the assembly ends up in the solder and accumulates. To know the composition of the solder, it is highly recommended to have the solder analyzed on a regular basis.