Chemical nickel, palladium and gold plating technique for printed circuit board

Abstract

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.

Description

technical field [0001] The invention relates to an electroless nickel-palladium-gold plating process for printed circuit boards. Background technique [0002] The surface of the printed circuit board pad is the terminal point of the connection between the line and the external components. The surface of the pad is a copper conductor. Surface coating treatment is required to protect the copper surface of the connection pad from contamination and oxidation and ensure the reliability of component welding. Currently The surface treatment of printed circuit board pads includes OSP, hot air leveling, chemical tin, chemical silver and chemical nickel immersion gold, etc., while chemical nickel immersion gold has high coating flatness, good coating wear resistance and low contact resistance, etc. Superior performance, is widely used in the surface treatment of printed circuit boards of precision electronic products and the packaging technology of microelectronic chips and circuit bo...

AI Technical Summary

Problems solved by technology

[0002] The surface of the printed circuit board pad is the terminal point of the connection between the line and the external components. The surface of the pad is a copper conductor. Surface coating treatment is required to protect the copper surface of the connection pad from contamination and oxidation and ensure the reliability of component welding. Currently The surface treatment of printed circuit board pads includes OSP, hot air leveling, chemical tin, chemical silver and chemical nickel immersion gold, etc., while chemical nickel immersion gold has high coating flatness, good coating wear resistance and low contact resistance, etc. Superior performance, is widely used in the surface treatment of printed circuit boards of precision electronic products and the packaging technology of microelectronic chips and circuit boards. However, the electroless nickel immersion gold coating will have black disk defects during the welding process, and connection reliability problems will occur. ;In addition, if the chemical nickel gold surface treatment is used for gold wire products, a thicker gold plating layer is required to meet the requirements, which will inevitably increase the cost of surface treatment