Sn-Ag-Cu lead-free solder containing Pr, Zr and Co

Abstract

The invention relates to a Sn-Ag-Cu lead-free solder containing Pr, Zr and Co, and belongs to soldering materials of metal materials. The solder comprises the following compositions by mass percentage: 0.5 to 4.5 percent of Ag, 0.2 to 1.5 percent of Cu, 0.001 to 0.5 percent of Pr, 0.001 to 0.1 percent of Zr, 0.001 to 0.1 percent of Co, 0.001 to 0.1 percent of Pb, and the balance of Sn. The solderhas excellent soldering performance (such as the wettability), and excellent spot weld mechanical property, creep resistant capability and thermal fatigue performance.

Description

1. Technical Field [0001] Sn-Ag-Cu lead-free solder containing Pr, Zr, and Co is mainly used in surface assembly and packaging. It has good soldering properties (such as wettability), mechanical properties of solder joints, especially creep resistance. Excellent new lead-free solder, which belongs to the brazing material in the field of metal materials and metallurgy. 2. Background technology [0002] Due to the harmful effects of Pb in the traditional Sn-Pb solder on the human body and the environment, relevant laws and regulations have been promulgated to prohibit the application of Sn-Pb solder in related industries, and lead-free solders have emerged. At present, the lead-free solders that have been studied mainly include binary Sn-Bi, Sn-Zn, Sn-Cu, Sn-Ag and other systems, and ternary Sn-Ag-Cu, Sn-Ag-Bi, Sn-Zn- Bi, Sn-Zn-Ag, Sn-Cu-Ni and other systems. The miniaturization trend of electronic devices and the increasingly demanding working environment require the existing le...

AI Technical Summary

Problems solved by technology

[0003] Existing studies have found that although the addition of trace non-rare earth elements can affect the melting characteristics, brazing performance and mechanical properties of solder joints of Sn, Ag, and Cu solders to a certain extent, it has little effect on the comprehensive performance of solders. Although the addition of Ti, Co, Mn, Ni and other elements can significantly reduce the degree of supercooling required for brazing solidification of Sn-Ag-Cu solder, it is expected to reduce solidification cracks and voids caused by excessive solidification supercooling. , can improve the performance of the solder alloy to a certain extent, but has little effect on the mechanical properties of the solder joints during service, and has little effect on the improvement of the microstructure and overall performance of the solder joints; although the addition of a single Bi can improve The thermal stability of solder joints during service, but it is easy to form low-melting eutectics at grain boundaries during solidification, which weakens the performance of joints; the addition of non-rare earth elements such as Al, In, Ge, and P has an impact on the comprehensive performance of solder alloys. The improvement is also very limited; the addition of a small amount of single rare earth Ce can improve the wetting properties of the solder, optimize the microstructure and properties of the solder, and can also improve the creep resistance and mechanical properties of the solder alloy, which can significantly improve the Sn-Ag-Cu The overall performance of the brazing filler metal alloy, the single rare earth La, Er, Y has a similar effect, but the Sn-Ag-Cu brazing filler metal obtained by adding a single rare earth element still has certain deficiencies, and needs to be researched and developed by adding a variety of The "synergistic" effect of elements to obtain Sn-Ag-Cu lead-free solder alloy with excellent wetting properties, mechanical properties, creep properties and thermal fatigue properties

[0004] In the early stage, we studied the effect of simultaneous addition of Pr, Ni, and Ga on the properties of Sn-Ag-Cu lead-free solder, and found that the "synergy" of Pr, Ni, and Ga can significantly improve the wettability of Sn-Ag-Cu lead-free solder. Wet performance, enhanced mechanical properties of solder joints and creep resistance, but there are still some deficiencies

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