Wetting Balance Testing
Some metallic surfaces are more easily soldered than others. They differ in both the speed of wetting and the strength of adhesion of the solder to their surface. The speed of wetting is controlled by the combined effects of the thermal demand and the wettability of the metal surface. These combined properties are known as the solderability of the material.
The wettability of the same material may vary considerably, as it is strongly influenced by the surface condition of the metal. Thin films of oxide, grease or organic contaminants can severely affect the wettability of a metal.
With the introduction of lead-free processing, many new surface finishes are now more common and each has different wettability characteristics as well as susceptibility to degradation under various environmental conditions.
For modern production soldering it is vital that boards and components have known good solderability, before they are allowed onto the production line. The large number of solder connections that are made simultaneously by modern soldering processes mean it is vital that all the solder corrections are made correctly at the first attempt.
