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

a technology of sn-ag-cu-in and pb-free solder, which is applied in the direction of welding/cutting media/materials, manufacturing tools, and soldering apparatus, etc., can solve the problems that the pb-free solder composition does not meet the above conditions, and achieves the effects of reducing the amount of ag, improving reliability, and saving fabrication costs

Inactive Publication Date: 2008-11-27
KOREA INST OF IND TECH
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  • Abstract
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  • Application Information

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Benefits of technology

[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 decrea

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 si

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[0032]Hereinafter, a quaternary lead (Pb)-free composition incorporating tin-silver-copper-indium (Sn—Ag—Cu—In) in accordance with the present invention will be described in detail with reference to the accompanying drawings. Herebelow, specific descriptions for a related well-known function or construction will be omitted when it is deemed that they make the gist of the present invention vague unnecessarily.

[0033]In a Pb-free solder composition of the present invention, the weight percent of Ag is less than about 2.5 wt. % but not less than about 0.3 wt. %. If the weight percent of Ag is less than 0.3 wt. %, a liquidus temperature hardly drops, leading to an increase in a melting point of a solder and a packaging process temperature. On the contrary, if the weight percent of Ag is 2.5 wt. % or more, the fabrication cost increases unfavorably. Consequently, the weight percent of Ag should be less than about 2.5 wt. % but not less than about 0.3 wt. %, preferably about 1.2 wt. %.

[003...

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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...

Claims

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Application Information

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IPC IPC(8): C22C13/02C22C13/00
CPCB23K35/262C22C13/00C22C13/02B23K35/0222B23K35/3006B23K35/302B23K35/3033B23K35/3046
Inventor LEE, JONG-HYUNLEE, CHANG-WOOKIM, JEONG-HAN
Owner KOREA INST OF IND TECH
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