| 摘要 |
PURPOSE: A Sn-Cu-Bi-In-P based lead-free solder is provided which actively inhibits the generation of dross in the process of soldering compared to a conventional Sn-Ag based or Sn-Cu-Ag based lead-free solder so as to reduce the thermal damage of electronic components and smoothly carrying out soldering work. CONSTITUTION: The low melting point lead-free solder comprises 0.1 to 2.0 wt.% of Cu, 0.01 to 2.0 wt.% of In, 0.01 to 1.5 wt.% of P, 0.1 to 6.5 wt.% of Bi and a balance of Sn, wherein the copper(Cu) contained in the lead-free solder lowers a melting point of the solder and improves thermal fatigue characteristics, more preferably about 0.1 to 0.75 wt.% of the copper is contained in the lead-free solder, the indium(In) contained in the lead-free solder lowers a melting point of the solder and balances elongation and strength of the solder containing bismuth(Bi), preferably about 0.01 to 2.0 wt.% of In is contained in the lead-free solder considering raw material cost and elongation and strength of the solder, the phosphorus(P) contained in the lead-free solder inhibits formation of dross which is solder oxides known as remnants of molten solder during soldering, preferably 0.01 to 1.5 wt.% of phosphorus is contained in the lead-free solder so as to prevent soldered part from being hardened and obtains effects of wettability, spreadability and bridge performance, an appropriate amount of bismuth(Bi) also lowers a melting point and improves wettability of solder, and preferably 0.1 to 6.5 wt.% of Bi is contained in the lead-free solder since addition of Bi lowers elongation and aging resistance.
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