Changes

A tin coating by ion exchange is usually not possible since copper is the more precious metal. By adding thio-urea the electro-chemical potential of copper is reduced to a level (approx. 450 mV, significantly lower than tin) that allows the exchange reaction. Using a suitable electrolyte composition and enhancer solutions like with the DODUSTAN process ''<xr id="fig:Process flow for electroless tin deposition using the DODUSTAN process"/> (Fig. 7.4)'' tin coatings can be produced that, even under usually unfavorable conditions of copper concentrations of 7 g/l in the electrolyte, are well solderable.

Fig<figure id="fig:Process flow for electroless tin deposition using the DODUSTAN process">[[File:Process flow for electroless tin deposition using the DODUSTAN process. 7.4: jpg|right|thumb|Process flow for electroless tin deposition using the DODUSTAN process]]</figure>