The invention discloses a chemical
nickel,
palladium and
gold plating technique for a
printed circuit board. The chemical
nickel,
palladium and
gold plating technique for the
printed circuit board comprises the steps of deoiling, hot
water washing, dual
water washing, micro-
etching, dual
water washing, presoaking, treatment through a
palladium activating agent, dual water washing, deposition of chemical
nickel, dual water washing, deposition of chemical palladium, dual water washing, deposition of chemical gold and the like. According to the chemical nickel, palladium and
gold plating technique for the
printed circuit board, chemical palladium plating is introduced,
diffusion and migration of nickel are prevented by means of a palladium layer, contact between the nickel and a
gold leaching solution is also prevented, and thus the common problem of black discs of existing chemical nickel and
gold surface treatment techniques is effectively solved; a chemical plated palladium layer is completely dissolved in
welding flux, no hyperphosphate layer appears at an
alloy connector, a new chemical plated palladium layer can be exposed to be used for generating good nickel-
tin alloy when the original chemical plated palladium is dissolved, and thus the reliability of
welding spots is improved; a plated palladium layer with larger
hardness is introduced, a thin clad layer can has good abrasion resistance and gold line printing performance, can serve as a key touch surface and is suitable for being applied to products with high connection reliability, and meanwhile surface treatment cost is reduced.