PURPOSE: To stabilize reduced state of a copper oxide layer by making adherence of zinc powder to a surface of copper uniform.
CONSTITUTION: The method for surface treating copper of a circuit board comprises the steps of oxidizing copper for forming a circuit provided on a surface of a circuit board to form a copper oxide layer on a surface of the copper, coating the surface of the board with zinc powder to adhere the powder to the surface of the copper, then treating it with acid to dissolve the powder in the acid, and simultaneously reducing the layer with hydrogen generated in this case. In this case, as the powder, powder containing 95wt.% or more of powder of pure zinc having a mean particle size of 4μm or less and less than 5wt.% of powder of zinc oxide having a mean particle size of 5μm or less is used. When the sizes of the pure zinc powder and the zinc oxide powder are set as above, an adhering amount of the zinc powder to the surface of the copper can be stabilized. Further, the zinc oxide powder is mixed to stabilize dissolving velocity of the pure zinc powder in the acid can be stabilized.
URAKUCHI YOSHINORI
KITAGAWA YOSHIFUMI
Next Patent: SURFACE TREATING METHOD FOR CIRCUIT BOARD