The high oxidation sensitivity of the utilized substrate causes an extremely fast and resistant oxidation.
Diffusion Processes
A further important aging mechanism are the so-called diffusion processes. These are, during long-term storage, responsible for an insufficient subsequent processing as well as for a reduction in terms of reliability and functionality of electronic components.
Functionally, in connection with it, tin atoms of a surface coating for instance move continuously to the substrate located thereunder (copper, copper-iron, aluminium,...). In case the coating material is totally disintegrated, the substrate moves forward to the surface. The high oxidation sensitivity of the utilized substrate causes an extremely fast and resistant oxidation. In consequence, that implies a non-processibility of the parts.
However, comparable processes occur inside the parts as well. Considering their structure, the production processes and the functionality of electronic components, it is clearly documented that their reliability is also reduced within the scope of long-term storage. Oxidation processes motivated by moisture and hazardous substances provoke for example a disintegration of conductors and isolation coatings during long-term storage. On the other hand, internal diffusion processes can create minimal leakage currents subsequent to operations fail, reducing reliability and life cycle of electronic components sustainably. But these are only simple examples for complex and critical long-term processes.
Basically a concentration balance between different substances, via stochastic atomic change of functional location, is causative for such diffusion processes. Precondition is to overcome the so-called activation energies. By means of such complex interdependence it is obvious that procedures for durable conservation of electronic components and consequently a high reduction of the so-called growth of intermetallic phases can be achieved only in connection with the increase of activation energies.