Accelerated ageing and solderability test of tin plated components

With the introduction of lead (Pb)-free surface finishes on semiconductor components the solderability test conditions used for SnPb surface finishes need a review for their applicability. Due to the lack of data about the correlation of natural ageing and accelerated ageing on the one hand and the correlation of a solderability test like "dip & look" to real board assembly conditions on the other hand it is hardly possible to decide on a solderability test set-up reproducing the reality. In this paper we introduce a suitable mathematical model for the oxidation kinetics of tin surfaces and establish a correlation of natural ageing to accelerated ageing. In a second part results of solderability test are correlated to results from real board assembly.