Method for adding trace elements during preparation of composite lead-free solder

Abstract

The invention relates to a method for adding trace elements during the preparation of composite lead-free solder. According to the method, the trace elements can be added to the composite lead-free solder through carrying out high-temperature smelting in an air atmosphere by using an auxiliary adding tool, wherein the auxiliary adding tool is a composite sleeve, the lower part of the composite sleeve is provided with a ceramic tube, the upper part of the composite sleeve is provided with a soft plastic tube with a sealable top cover, and a member with high airtight performance is connected between the plastic tube and the ceramic tube and can guarantee air tightness at the air pressure of 1,500 pa. The method has the advantages that the used equipment is conventional and general equipment and is low in cost and strong in transportability, and the difficult problem that the performance of solder can not be improved caused by the fact that the trace elements with high activity can not be added to the composite lead-free solder during industrial production is solved.

Description

technical field [0001] The invention belongs to the technical field of materials and relates to a method for adding trace elements in the preparation process of composite lead-free solder. Background technique [0002] At present, with the gradual enhancement of people's awareness of environmental protection, the traditional tin-lead solder SnPb has been widely valued by countries all over the world because of its toxic effects on nature and human body. According to the WEEE and RoHS directives promulgated by the European Union, it is clearly proposed to restrict or prohibit the use of lead-containing toxic and harmful substances in household appliances from July 1, 2006. subject. [0003] After a lot of research, it was found that the ternary alloy SnAgCu series, the binary alloy SnCu series, the SnAg series, the SnZn series and other composite lead-free solders are used because of their relatively low melting point, high reliability of solder joints, and thermal fatigue r...

AI Technical Summary

Problems solved by technology

However, the above-mentioned composite lead-free solder itself also has certain shortcomings, such as poor wettability, high brittleness, etc., which have seriously affected its industrial production and promotion.

[0004] Experimental research has found that changing the composition of the above-mentioned composite lead-free solder and adding trace metal elements or rare earth elements to the composite lead-free solder overcomes the above-mentioned defects, but the addition method is demanding, and the most important method is the method of vacuum furnace smelting. Such as patent application CN00129872.0 and other prior art disclosed technical solutions, generally smelted in a vacuum furnace protected by a nitrogen atmosphere, although this method can be added with trace metal elements or rare earth elements to obtain composite lead-free solder that meets the requirements, but for The requirements for equipment and operators are high and the cost is high, so it is not suitable for popularization and application in industrial production

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