Quaternary Pb-free solder composition incorporating Sn-Ag-Cu-In

Abstract

Provided is a quaternary Pb-free solder composition incorporating Sn—Ag—Cu—In, which can prevent a cost increase and sufficiently ensure proccessability and mechanical property as a solder material. To this end, indium (In) with appropriate amount is added into the Pb-free solder composition, and the addition amount of Ag is optimized, thus preventing a decrease in wettability caused by a decrease in the amount of Ag and improving resistance to a thermal cycling and a mechanical impact. The quaternary Pb-free solder composition includes silver (Ag) of about 0.3 wt. % or more, and less than about 2.5 wt. %, copper (Cu) of about 0.2 wt. % or more, and less than about 2.0 wt. %, indium (In) of about 0.2 wt. % or more, and less than about 1.0 wt. % or less, and a balance of tin (Sn).

1 . A quaternary lead (Pb)-free solder composition incorporating tin-silver-copper-indium, comprising:
 silver (Ag) of about 0.3 wt. % or more, and less than about 2.5 wt. %;   copper (Cu) of about 0.2 wt. % or more, and less than about 2.0 wt. %;   indium (In) of about 0.2 wt. % or more, and less than about 1.0 wt. %; and   a balance of tin (Sn).   
   
   
       2 . The composition as recited in  claim 1 , wherein one or more elements selected from phosphor (P), germanium (Ge), gallium (Ga), aluminum (Al) and silicon (Si) are added into the quaternary Pb-free solder composition in a weight percent range of about 0.001 wt. % to about 1 wt. % to improve anti-oxidation properties of the Pb-free solder composition. 
   
   
       3 . The composition as recited in  claim 1 , wherein one or more elements selected from zinc (Zn) and bismuth (Bi) are added into the quaternary Pb-free solder composition in a weight percent range of about 0.001 wt. % to about 2 wt. % to improve interfacial reaction properties and drop a melting point of the Pb-free solder composition. 
   
   
       4 . The composition as recited in  claim 1 , wherein one or more elements, which are selected from nickel (Ni), cobalt (Co), gold (Au), platinum (Pt), lead (Pb), manganese (Mn), vanadium (V), titanium (Ti), chromium (Cr), niobium (Nb), palladium (Pd), antimony (Sb), magnesium (Mg), tantalum (Ta), cadmium (Cd) and rare earth metals, are added into the quaternary Pb-free solder composition in a weight percent range of about 0.001 wt. % to about 1 wt. %.