EFFECT OF LOW-TEMPERATURE (100-200-DEGREES-C) ANNEALING ON THE DUCTILITY OF ELECTROLESS COPPER

The ductility of electroless copper generally increases upon low-temperature (100-200-degrees) annealing. It is shown in this paper that this phenomenon can be due to either or both of two different physical changes that occur in the deposit during annealing: (i) the decrease in pressure of the hydrogen gas trapped in voids, which results from the outdiffusion of the hydrogen, and (ii) the microstructural change resulting from recrystallization and grain growth. It is also shown that the extent of the grain growth is influenced by the volume occupied by voids and nonvolatile impurities contained within the deposits. In particular, voids and impurities trapped at the grain boundaries can effectively prevent the boundaries from migrating and thus retard recrystallization and grain growth.