The brazing industry pollutes the environment to some extent. With environmental issues becoming a hot spot in the world, the industry is changing the traditional model and implementing green brazing materials. The main types are:
1, cadmium-free solder
Solder users often prefer to use silver-based cadmium-containing solder because cadmium can significantly reduce the liquidus of the solder, reduce the melting temperature range, and improve solder flow performance under the same silver content conditions. However, the harmful heavy metal cadmium in the solder is a carcinogenic element that directly causes serious harm to the human body.
In view of the hazards of cadmium, various countries have conducted extensive research to develop green cadmium-free silver solders. The 4900 component developed in Germany is Ag49Cu16Zn23Ni4.5Mn7.5, the composition of Safety-silv60T developed in the United States is Ag60Cu29Ni3Mn6, and the component of the United States AWS standard solder BAg24 is Ag50Cu20Zn28Ni2. The common non-cadmium solder in our country is BAg30CuZnSn. The newly developed cadmium-free solder is Ag30CuZnSnInP, which has good fluidity and high brazing efficiency and is suitable for home current waterline operation. In addition, there is also a high-strength and tough cadmium-free solder Ag50CuZnNiCoB.
2, lead-free solder
Tin-lead solder provides excellent mechanical, thermal, and electrical conductivity at a relatively low price, and has been widely used in the electronics industry. Lead is also a very hazardous heavy metal. For the harm of lead, after more than 20 years of extensive research, the world has developed more than 600 kinds of lead-free solder.
Among them, the most likely substitute for the conventional Sn-Pb alloy solder is Sn, and a small amount of alloy capable of producing a low-temperature eutectic metal element such as Ag, Cu, Zn, Bi, and In is added. The composition of lead-free solder is mainly concentrated on Sn-Ag, Sn-Ag-Cu, Sn-Cu, Sn-Zn and Sn-Sb alloys.
3, composite solder
At present, for most of the brazing processes, brazing material and flux are used separately. A large amount of flux volatilizes before it functions, pollutes the environment, endangers the health of operators, causes waste of flux, and the residual flux is easy. It has become one of the root causes of chemical corrosion damage in solder joints.
In order to increase the utilization rate of brazing flux, the composite welding material becomes one of the development directions of the brazing material. The brazing filler metal and the brazing filler metal are compounded together, and at the same time, they appear at the position to be welded. At present, there are a series of composite solder products on the market, such as self brazing filler metal, flux core brazing welding wire, brazing filler metal welding rod, and sandwich brazing ribbon.
Green efficient brazing materials have begun to be widely used in China, but domestic high-end green brazing materials have a low market share. The brazing materials that should be developed in the future are low-cadmium non-cadmium brazing fillers, new lead-free solder pastes, and solder balls. High-efficiency composite solder.