What are the important ingredients of solder bars?

In the modern electronics industry, the application of tin bars has been extensive. So what are the important ingredients of tin bars? The following is explained by Xing Hongtai.

In addition to the main elements tin, lead, copper, and silver, the tin bar often contains a small amount of its elements, such as nickel, bismuth, antimony, In, and rare earth. These trace alloy elements in lead-free tin bars have a great influence on the physical and mechanical properties of tin bars: 铋 can reduce the melting temperature of tin bars and improve wet spreadability, but excessive addition will reduce the fatigue life of solder joints and Plasticity, the appropriate amount of bismuth is about 0.2 to 1.5%. Nickel (Ni) can improve the mechanical properties and fatigue life of solder joints by changing the alloy structure and refining the grains. Among the systematically designed chemical compositions, it is clear that the performance of all aspects of the tin bar can be optimally balanced, such as weldability, melting temperature, strength, plasticity and fatigue life.

Generally, the content of lead (Pb) in the tin bar is within 100 PPM, and it is made of raw materials. If the lead (Pb) content exceeds 100 PPM, it is mostly caused by miscellaneous tin or recycled tin.