Immersion Tin finishing introduction Immersion Tin, as defined by IPC, is a metallic finish applied directly over the bare copper of a PCB through a chemical displacement reaction. This technology protects the copper from oxidation and extends the PCB's shelf life. However, the strong affinity between copper and tin can affect the deposit's shelf life and finish performance. While Immersion Tin offers advantages such as a smooth surface, being lead-free, and reworkable, it also has several disadvantages. These include susceptibility to handling damage, the use of a carcinogenic substance (thiourea) in the process, potential corrosion during final assembly, the formation of tin whiskers, unsuitability for multiple reflow soldering, and difficulty in measuring tin thickness.
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