PURPOSE: To provide an improved method for efficiently refining a high purity copper of ≥4N and also to provide an apparatus suitable for this method.
CONSTITUTION: A base material of copper is temporarily melted and successively held at a prescribed temp. for a prescribed time to undergo annealing refining, by which the impurities remaining in the base material are changed from solid- solution state to precipitated state to improve residual resistance ratio. It is preferable to regulate the temp. for the annealing refining to 550-650°C and also the time to at least ≥1min. Further, it is preferable to previously apply zone melting refining to the base material of copper to be refined, in order to increase the effects of the annealing refining. Moreover, annealing refining can be done simultanelusly with zone melting refining.
AOYAMA MASAYOSHI
TAMURA KOICHI
