Immersion Tin is a RoHS compliant (lead-free) surface finish that is an ideal choice for flat surface requirements and fine pitch components. The tin layer’s appearance is usually mostly white, so the finish is sometimes referred to as White Tin. Immersion Tin is a deposit of a thin layer of Tin on Copper layer of a PCBs, that can protect the copper beneath from oxidation throughout the PCB’s intended shelf life. It is not used as often as other surface finishes because not all PCB manufacturers offer it. The flatness of this particular coating makes this an ideal surface finish choice for small geometries and components.
suitable for horizontal production. Suitable for fine line processing, suitable for lead-free soldering, especially suitable for crimping technology. Very good flatness, suitable for SMT.
Good storage conditions are required, preferably not more than 6 months to control the growth of tin whiskers. Not suitable for contact switch design. The production process has relatively high requirements for the solder mask process, otherwise it will cause the solder mask to fall off. N2 gas protection is best when welding multiple times. Electrical testing is also a problem.
|Surface Finish||Content||Technological Capability|
(According to IPC-4554)
|Max panel size||406*533mm|
|Board thickness||0.20 – 3.2mm|
|Immersion Tin thickness||0.75-1.2um|
Immersion tin is applied using an electroless chemical bath that will apply approximately 0.7 to 1.0 microns (or about 44 micro inches) of tin to the copper. You should also adhere to the correct requirements of temperature, time, and bath composition to make the process successful.