Water-soluble scaling powder for lead-free solder of tin silver zinc series

Abstract

The invention relates to a water-soluble soldering flux which is suitable for tin, silver and zinc series lead-free solder. The weight percentage of all the components is as follows: 0.1-22 % of activating agent, 0.1-25 % of wetting agent, 0.1-5% of thixotropic agent, 0.1-2 % of corrosion inhibitor, 0.1-5 % of oxidation inhibitor and solvent for the rest. The invention aims at the problem that the existing soldering flux of leaded solder is not suitable for lead-free solder and provides the water-soluble soldering flux which can be effectively matched with lead-free solder, especially applicable to tin, silver and zinc series lead-free solder; the water-soluble soldering flux can improve wettability, antioxidant ability and solderability of lead-free solder, can meet the requirements of welding temperature of lead-free solder, and causes little corrosion to lead-free solder alloy; postwelding residue is little and can be washed away by water; welding spots have good quality, smooth surfaces and strong stability; a dried circuit board has high insulation resistance value.

Description

technical field [0001] The invention relates to a flux, especially a water-soluble flux suitable for tin-silver-zinc lead-free solder. Background technique [0002] Various electronic products that are closely related to human life and work benefit human beings, but also increasingly endanger human health and the ecological environment due to the use of lead-containing solder in electronic products. Waste of Electrical and Electronic Equipment (WEEE), led by the European Union, called for an end to the use of lead-containing materials in the electronics assembly industry in 2006. The National Electronics Manufacturing Institute (NEMI) of the United States has implemented a special project called "NEMI's Soldering Lead-Free Program" to systematically study the use of lead-free assembly in the electronics industry; Japan's major consumer electronics manufacturers have also promised to fully implement it as soon as possible. To realize lead-free electronic assembly, all this m...

AI Technical Summary

Problems solved by technology

However, in the process of research and use, it is found that compared with traditional Sn-Pb solder, lead-free solder has poor wettability, is easy to oxidize, and has a high melting point

Therefore, the flux suitable for lead-containing solder is not suitable for lead-free solder. First, the ability of this type of flux to help lead-free solder to wet is not enough; second, it is not suitable for the high soldering temperature of lead-free solder, and the increase in melting point means The soldering temperature must be increased. On the one hand, the higher the temperature, the easier it is to oxidize the solder joints. On the other hand, it will inevitably increase the volatilization of the active agent in the flux, which will not have a good activation and protection effect, so that the solder joints will be more likely to oxidize.

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