Lead-free nanometer solder containing Yb, A1 and B

Abstract

The invention discloses a lead-free nanometer solder containing Yb, A1 and B, and belongs to the field of lead-free solders for microelectronic assembly. The lead-free solder comprises 0.5-4.5% of Ag, 0.2-1.5% of Cu, 0.01-0.5% of Yb, 0.01-0.5% of A1, 0.01-0.5% of B, and the balance being Sn. The preparation method for the lead-free nanometer solder includes the steps of preparing Sn ingot, intermediate alloy of Sn-Cu, intermediate alloy of Sn-Ag, intermediate alloy of Sn-Yb, intermediate alloy of Sn-A1, and intermediate alloy of Sn-B which are commercially available, smelting the lead-free solder by means of the manufacturing process of high-energy and ultrasonic stirring based on ratio requirements, smelting and casting the lead-free solder into a bar under the protection atmosphere of an inert gas so as to prevent burning loss of the elements, make the bar into an electrode, and finally prepare the lead-free nanometer solder particles by a DC (direct current) electric arc method of consumable electrodes. The lead-free nanometer solder containing Yb, A1 and B has the advantages of good wettability and mechanical properties, and capability of meeting the needs of the electronics industry.

Description

technical field [0001] The invention discloses a nano-lead-free solder containing Yb, Al and B, which belongs to the field of high-density electronic device solder, and is a novel lead-free solder with wettability and excellent mechanical properties. Background technique [0002] With the rapid development of the electronics industry, people's requirements for environmental protection are getting higher and higher. The traditional SnPb solder has been unable to meet the development needs of the electronics industry due to the toxicity of Pb. Therefore, the industry seeks lead-free solder to replace the traditional SnPb. Among many lead-free solders, SnAgCu has better wettability and mechanical properties. Higher merits are recommended as the best choice to replace SnPb. Compared with SnPb, SnAgCu still has its own disadvantages, for example, the melting temperature is significantly higher than that of SnPb solder, and its wettability is also significantly lower than that of...

AI Technical Summary

Problems solved by technology

However, in many research results, the alloying elements that reduce the melting point of the solder are more significant than the Bi element, and other elements and particles are more prominent in improving the mechanical properties, and have little contribution to the melting temperature of the solder.

Representative patents include Sn-(0.05~3%)Ag-(0.5~6)Cu-(0.1~3)Bi (US Patent: US4879096), Sn-(2.0~4.0%)Ag-(0.5~1.5% )Cu-(1.0~10%)Bi-(0.05~1.5%)Cr[Chinese patent: CN2009910199580.0], but when the Bi element is added too much, it is easy to cause the solder joints to peel off during the service period, resulting in the failure of the device

At present, there are no reports that the melting temperature of solder can be significantly reduced and the mechanical properties can be improved by adding alloying elements.

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