Flux used for lead-free solder paste

Abstract

The invention discloses flux used for lead-free solder paste. The flux comprises the following components including, by mass percent, 25%-30% of dimerization rosin, 5%-8% of octadecanoic acid, 3%-5% of polyethylene glycol, 9%-12% of an active agent, 2%-5% of a surface active agent, 4%-5.5% of a thixotropic agent, 3%-5% of a catalyst, 1%-1.5% of corrosion inhibitor and the balance solvent. The active agent is formed by compounding adipic acid and sebacic acid. The surface active agent is formed by compounding cetyl trimethyl ammonium bromide and an OP-10 non-ionic surface active agent. The solvent is tetrahydrofurfuryl alcohol. The thixotropic agent is polyamide modified hydrogenated castor oil. The corrosion inhibitor is benzotriazole. According to the flux used for the lead-free solder paste, on the condition that the use amount of the rosin is reduced, the performance of the lead-free solder paste is greatly improved, weld spot forming quality and strength after welding are obviously improved, durability is improved, and defects of existing flux are effectively overcome.

Description

technical field [0001] The invention relates to the field of soldering materials for electronic circuits, in particular to a flux used for lead-free solder paste. Background technique [0002] Solder paste is a fine chemical product with high added value. With the continuous improvement of modern technology, the production and research and development of many electronic raw materials have been stimulated, and the enthusiasm for research and development of lead-free solder materials has been greatly increased. However, in general , the development of domestic solder paste is still in a serious lagging state, and there is still a huge gap with strong countries in the industry such as Japan and the United States, especially in terms of lead-free solder paste, the country is in a very backward state. Therefore, research and development Lead-free solder paste has huge implications. [0003] Generally, solder paste is composed of solder alloy powder and flux. There are many varie...

AI Technical Summary

Problems solved by technology

However, in the prior art, the flux is generally a rosin-type flux. Since the active temperature of rosin is generally 300°C, it will lose its activity when the temperature exceeds 315°C, resulting in insufficient flux activity. At the same time, rosin-based fluxes are all Contains a certain amount of halogen. Halogen ions are easy to corrode circuit boards, solder joints and components in a high-humidity and high-heat environment, resulting in poor insulation and poor circuit contact, and may also pollute the environment

Therefore, those skilled in the art all try every means to reduce the consumption of rosin, to reduce the negative effect of rosin, but the result is unsatisfactory

At the same time, due to the complex metallurgical reaction during the welding process, the components in the flux cannot fully play their roles, which makes the welding process difficult to control, and the solder joints obtained after welding are easily corroded and discolored, and the quality of the solder joints cannot be fully guaranteed. Problems such as low flux activity need to be solved urgently. Therefore, how to develop a lead-free solder paste flux with less rosin content, high active reaction temperature, and high corrosion resistance of solder joints obtained after soldering is a direction for technicians to study.