Leadfree SnZn-base alloy solder containing rare-earth elements

Abstract

A lead-free alloy as solder contains Zn (5-10 wt.%), the rare-earth elements chosen from La, Ce, Pr and Nd (0.05-1), one or more of Bi (0.1-6), Cu (0.1-3), In (0.5-3), Al (0.1-1), Ni (0.01-1) and P (0.001-1), and Sn (rest). Its advantages are better wettability, fine structure, excellent mechanical performance, low cost and no poison and pollution.

Description

technical field [0001] The invention belongs to the field of metal materials, relates to the technical field of electronic packaging brazing materials, and in particular relates to a lead-free solder alloy suitable for brazing electronic components without causing thermal damage. technical background [0002] Since the traditional tin-lead solder contains lead element which is extremely harmful to the human body and the environment, the development of lead-free solder has become an urgent task for current materials scientists. The United States, Japan and other countries are actively enacting laws to prohibit the use of lead. According to the European Union’s directive on waste of electrical and electronic products and machinery, it will completely prohibit the use of toxic and harmful elements such as lead and cadmium in the electronics industry from January 1, 2008. use in . Therefore, in order to eliminate lead pollution, there is an urgent need for lead-free solder to r...

AI Technical Summary

Problems solved by technology

However, Zn element has flexible chemical properties and metallurgical properties, which makes the alloy have poor wettability and corrosion resistance, which greatly affects the application.

In recent years, in order to improve the performance of Sn-9Zn alloy, researchers have added In, Bi, Al and other elements as alloying elements to the alloy, but the effect is not significant enough

Moreover, the Sn-9Zn alloy structure contains coarse β-Sn grains, and the bonding strength of the brazed joint is also low due to poor wettability

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