Abstract
In electroless copper plating using hypophosphite as a reducing agent, nickel ions are generally added to the electroless copper plating bath to initiate the auto catalytic reaction, because catalytic activity for anodic oxidation of hypophosphite on copper is low. If nickel ions are excluded from the plating bath, the plating reaction is be initiated only at palladium-catalyzed sites on resin and reaction finally terminates on deposited copper.
Adhesion strength between roughened epoxy resin and deposited copper by electroless copper plating using hypophosphite was studied. The plating reaction on palladium-catalyzed epoxy resin initiated and terminated when copper is deposited about 0.3μm. Accordingly, the amount and activity of adsorbed Pd on resin are influenced by the following plating reaction. Adsorbed Pd was increased by immersion in 0.3g/dm3-PdCl2 solution followed by immersion in 0.25mol/dm3-NaH2PO2 solution after conventional mixed catalyst processing. Adhesion strength between epoxy resin and deposited copper is about 1.53kgf/cm. Adhesion strength is higher than that in the plating using formaldehyde since deposited copper reaches small complicated etched pits.
