According to IPC, the association Connecting Electronics industry all over the world, Printed Circuit Board Immersion Tin is a metallic finish deposited by a chemical displacement reaction that is applied directly over the basis metal of the bare copper of Printed Circuit Board. The technology of PCB Immersion Tin protects the underlying copper from oxidation, extend the shelf life Printed Circuit Board.
Copper and tin, however, has a strong affinity for each other, which will inevitably spread a metal to another metal inside. This will directly affect the shelf life of deposit and the performance of finish.
Advantages of PCB Immersion Tin surface treatment:
Smooth surface
Not containing lead(Pb)
Can be re-workable
Disadvantages of PCB Immersion Tin surface treatment:
Handling damage easily
Process use a kind of carcinogenic substance (thiourea, dangers chemical)
Tin exposed outside may be corroded in final PCB assembly
Tin whiskers
Unsuitable for multiple reflow soldering and assembly
Thickness of tin is difficult to be measured
