Immersion Tin finishing introduction

According to IPC, the association Connecting Electronics industry all over the world, 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 PCB. The technology of Immersion Tin protects the underlying copper from oxidation, extend the shelf life PCB.

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 Immersion tin surface treatment:

Smooth surface

Not containing lead(Pb)

Can be re-workable

Disadvantages of 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