Bi base high-temperature leadless soft solder

Abstract

The invention relates to a Bi-based high-temperature lead-free soft solder and a preparation method, which belong to the soldering technology for encapsulation. The material components of the Bi-based high-temperature lead-free soft solder include: 80 to 90wt percent of Bi, 2 to 8wt percent of Sb as well as 2 to 12wt percent of Sn; the prescription components also comprise at least one from mixedrare earth lanthanum and neodymium with the content of 0.05 to 1.5wt percent. The melting point of the Bi-based high-temperature lead-free soft solder is between 250 and 450 DEG C; besides, the Bi-based high temperature lead-free soft solder has the advantage of good spreading and wetting performance, high intensity and good corrosion resistance; the Bi-based high-temperature lead-free soft solder can adapt the demands of various technologies, environments and artificial factors in the electron industry which is continuously developed.

Description

technical field [0001] The invention relates to a brazing solder technology such as electronic packaging and assembly, in particular to a Bi-based high-temperature lead-free solder and a preparation method thereof. Background technique [0002] With the enhancement of people's awareness of environmental protection and the negative impact of SnPb alloy materials, after the European Union (EU) has passed the ROSH directive and the Waste Electrical and Electronic Equipment (WEEE), countries have successively legislated to limit the use of lead in electronic products. use. China has also formulated the "Administrative Measures for the Prevention and Control of Pollution in the Production of Electronic Information Products", which stipulates that manufacturers of electronic information products should ensure that they implement measures to reduce the production of toxic and harmful substances from July 1, 2003; from July 1, 2006 The electronic information products in the nationa...

AI Technical Summary

Problems solved by technology

[0007] Chinese patent CN101048521A proposes a high-temperature solder made of Ag2~12wt.%, Au40~55wt.%, and the rest is Sn. This alloy has a suitable melting point and high strength, but its cost is high, which is not conducive to popularization and use.

[0008] European patent EP1705258A2 proposes to contain 2% to 18wt.% of Ag, 98 to 82wt.% of Bi, and 0.1 to 5.0wt.% of trace elements Au, Cu, Pt, Sb, Zn, In, Sn, Ni and Ge The Bi-Ag-X alloy is used to replace the high Pb solder. The alloy has a suitable melting point and a solidus temperature greater than 262.5°C, but the alloy has high brittleness, poor processability, weak bonding strength with the matrix, wide solid-liquid phase interval and wide A series of problems such as poor wettability on Cu and Ni substrates

[0009] Chinese patent CN155896A proposes to replace the high Pb solder with a Bi-Ag alloy containing Ag of 2% to 18wt.%. A series of problems such as weak bonding strength, wide solid-liquid phase interval, and poor wettability on Cu and Ni substrates

However, when the Sb content is low (<10%), the melting point of the Sn-Sb binary alloy is relatively low, which is unfavorable for the reliability of the solder joints that need to withstand high temperature packaging processes, and the alloy has a fast corrosion of Cu or Ni substrate pads The problem

[0011] U.S. Patent 20040241039 (at least 5% Sn, 0.5-7% Cu, 0.05-18% Sb) and Chinese Patent CN1954958A (8-20% Sb, 3-7% Cu, and the rest are 5% Sn) respectively propose to use SnSbCu ternary Alloys are used as high-temperature lead-free solders, but this series of alloys has poor oxidation resistance, and a large amount of tin slag will be generated during high-temperature soldering, and this alloy still has the problem of rapid corrosion of Cu or Ni substrate pads