|In Cu-Au or Cu-Au-Sn systems, pores in the older joint, or at copper interfaces occur through solid-state diffusion. Copper which has a relatively high solubility and solid-state mobility in gold diffuses into the gold.Transported by grain boundry diffusion at temperatures below 150°C, and by bulk diffusion above that temperature. Au-Sn regions result along with atomic vacancies. Then lattice vacancies are in profusion . vpods can be observed and this material depletion weakens the solder joint.
||См. Эффект Киркендалла (диффузия в твердых телах и сплавах)