Compositions and Preparation Methods of Solder Alloys for Surface Mount Technology Applications

摘要

PURPOSE: A complex solder for an SMT(Surface Mounting Technology) and a manufacturing method thereof are provided to improve the reliability of the solder interconnection by restricting the reliability decrease of the interconnection due to the rapid growth of an intermetallic compound layer at the interconnection interface. CONSTITUTION: The complex solder(3) using to a metal pad(1) coated with an Au anti-oxidation film coating layer(2) is made by heating the Sn alloy solder above the temperature for completing a solid solution at a vacuum or inert atmosphere and adding Cu and/or Ni to the solder. The complex solder finely and uniformly includes a precipitation phase(7) of Cu6Sn5 or Ni3Sn4 composition. Cu and/or Ni respectively added to the Sn composition alloy with 1-5 weight percent. The solder including Cu6Sn5 or Ni3Sn4 extremely restricts the growth rate of the interface intermetallic compound layer at a state reflowing on the metal pad and an annealing state after the reflowing.