OPTIMUM PALLADIUM CONTENT IN ENEPIG SURFACE TREATMENT FOR ENHANCING MECHANICAL PROPERTIES

摘要

PURPOSE: An optimum palladium content in ENEPIG(electroless nickel / electroless palladium / immersion gold) surface treatment for enhancing mechanical properties is provided to obtain the maximum reliability of the surface treatment by maintaining palladium content to be 0.04 wt% or less. CONSTITUTION: An ENEPIG surface treatment comprises a step of plating electroless nickel on a printed circuit board; a step of plating palladium on the electroless nickel plating; and a step of plating gold on the palladium plating. The content of palladium is 0.04 wt% or less. An ENEPIG surface treatment comprises a step of plating electroless nickel on a printed circuit board; a step of plating electroless palladium on the electroless nickel plating; and a step of plating gold on the electroless palladium plating. Solder ball may be welded on the gold plating. After welding the solder ball put on component side through reflow, the substrate put on the substrate of the board side is weld again through reflow. [Reference numerals] (AA,DD,II) Solder ball; (BB) Plating process layer; (CC) Printed circuit board(PCB); (EE) Gold planting; (FF) Pd planting(0.02,0.04,0.06 wt%); (GG) Nickel planting; (HH) Copper circuit surface(PCB); (JJ) Cross-sectional diagram of binding the solder ball after planting nickel, palladium and gold on the PCB copper circuit surface