Plating finishes, thicknesses and quality are critical in surface mount applications. Since surface mount components are exposed to higher soldering temperatures for longer times, improperly plated leads could become susceptible to excessive intermetallic formation, which could cause solder joint brittleness and solder dewetting. Solder dewetting can be caused when the solder remains liquid for too long a time and reacts with organics to form gases. These gases can passivate the surface that was initially wetted by the solder. Organics can become trapped in porous plating if the process is not properly controlled.

A dense 50µ" (1,27µm) minimum nickel underplating is desirable to protect the copper-based lead from oxidation and leaching of the copper during the soldering process. The nickel underplating is then overplated with 150µ" to 200µ" (8,81 µm to 5,08 µm) of tin to protect the nickel and improve solderability.