Wetting Balance Testing
The wetting balance test is used to measure the wetting forces between molten solder and the test surfaces as a function of time. Solderable surface differ in speed and strength of adhesion. The wetting balance measures the time for the solder to wet the component termination or pad. Solderability is determined by thermal demand and wettability of the surface. The wettability is influenced by type of metal or contaminants on the surface. It is often used in testing for counterfeit parts, as resurfaced leads will react differently than new parts.
The wetting balance test can be performed on leaded or leadless components. Leaded components use a molten solder bath and for leadless parts, a globual of solder is used instead of the solder bath. Many specification require some kind of preconditioning, such as steam age, prior to testing. The pre-condition would simulate shelf life to show solderability and wettability after long periods of storage.
Some of the specifications and methods for Wetting Balance Testing are: ANSI J-STD-002, ANSI J-STD-003, MIL-STD 883, ISO 9455-16, ISO 12224-3, and JIS Z 3198.