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).

Description

[0001] Cross References to Related Applications [0002] This application claims priority from Korean Patent Application No. 10-2007-0050905 filed May 25, 2007, the entire contents of which are hereby incorporated by reference. technical field [0003] The present invention relates to a kind of lead (Pb) solder composition, more specifically, the present invention relates to a kind of tin-silver-copper-indium (Sn-Ag-Cu-In) quaternary lead-free solder composition, the solder Compositions can reduce the amount of silver by using indium. Background technique [0004] Currently, the Sn-Ag-Cu based composition is most commonly used as a lead-free solder composition, and its representative composition can be expressed as Sn-3.0Ag-0.5Cu. In order to improve the oxidation resistance of this lead-free solder composition, phosphorus (P), germanium (Ge), gallium (Ga), aluminum (Al), or silicon (Si) etc. In addition, in order to improve mechanical properties and interfacial reaction ...

AI Technical Summary

Problems solved by technology

[0007] 1) As the addition of Ag decreases, the difference between the liquidus temperature and the solidus temperature increases, resulting in an increase in the slurry range or mushy region

[0008] 2) As the addition of Ag decreases, the wettability decreases due to the increase of slurry range or mushy area

[0009] 3) As the addition of Ag decreases, the strength and creep resistance of the alloy decrease

[0010] 4) As the amount of Ag decreases, the fracture speed of the solder joint in the thermal cycle test is accelerated due to the decrease in the strength and creep resistance of the alloy

[0011] 5) As the amount of Ag decreases, the elongation of the alloy increases, and the fracture speed of the solder joint in the mechanical impact test becomes slower

[0014] However, no lead-free solder composition satisfying the above conditions has been developed so far.

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