Why Do An Analysis?
A solder bath or pot can become contaminated in various ways. The solder can already include impurities when received, especially if the supplier uses re-cycled materials, or it may become contaminated over a period of time by leaching copper and other contaminants from the work being soldered.
Many contaminants such as silver and bismuth are not specifically detrimental in small quantities, therefore are only an indication of the purity of the solder. Contaminants such as aluminium, cadmium and zinc however are very detrimental to the performance of the alloy. Non metallic impurities such as sulphur and phosphorous are dangerous to the solder in as much as they can cause de-wetting conditions.
Some inclusions can be considered as either alloying additions or contaminants depending on particular applications. Other inclusions must be avoided at all costs. A description of the effect of impurities in a solder bath, some common contaminants and how they can have an effect on solderability, dross creation, joint formation and wetting ability are shown in the table below.