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

CROSS-REFERENCE(S) TO RELATED APPLICATIONS[0001]The present invention claims priority of Korean patent application number 10-2007-0050905, filed on May 25, 2007, which is incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates to a lead (Pb)-free solder composition, and more particularly, to a quaternary Pb-free solder composition incorporating tin-silver-copper-indium (Sn—Ag—Cu—In), which can reduce the amount of silver by using indium.[0003]A Sn—Ag—Cu-based composition is most popularly used as a Pb-free solder composition at present, and its representative composition may be expressed as Sn-3.0Ag-0.5Cu. To improve anti-oxidation properties of such a Pb-free solder composition, phosphor (P), germanium (Ge), gallium (Ga), aluminum (Al), silicon (Si), or the like may be added at a concentration of several tens to several thousands of ppm. Furthermore, to enhance mechanical properties and interfacial reaction properties, nickel (Ni), c...

AI Technical Summary

Benefits of technology

[0014]Embodiments of the present invention are directed to providing a quaternary lead (Pb)-free solder composition incorporating tin-silver-copper-indium (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.

[0016]In the Pb-free solder composition of the present invention, the amount of Ag is reduced to save fabrication cost. Therefore, to improve reliability on a thermal cycling and a mechanical impact and also prevent a decrease in wettability caused by the decrease in the addition amount of Ag, indium (In) is added into the Pb-free solder composition. Accordingly, it is possible to provide a high-quality Pb-free solder composition with low price.

Problems solved by technology

However, as there are ongoing demands and efforts to reduce fabrication cost in packaging electronic devices, several attempts are being made to reduce the amount of silver (Ag) because Ag is the most expensive among additive elements.

However, such a Pb-free solder composition satisfying the above conditions has not been developed yet.

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