Silver solderis a widely used technology, primarily utilizing systems based on tin-lead alloys.Silver solderDue to its good diffusivity with copper alloys and steel, low melting point, good corrosion resistance, certain strength, good electrical conductivity, and excellent mechanical processing performance, silver solder is widely used in the electronics industry, as well as in the manufacturing of instruments, electrical appliances, automotive industry, food industry, and other mechanical manufacturing sectors. One of the issues with lead-tin alloy solder is surface oxidation at high temperatures, which directly affects the reliability of the manufactured devices, especially in wave soldering where the surface of the liquid alloy is rapidly oxidized by air at high temperatures, forming tin dross on the oxidized surface, which can easily lead to poor soldering and waste. However, due to the irreversible environmental pollution caused by lead to human beings, soil, water sources, and the biological chain of animals and plants, the use of lead has gradually decreased, leading to the emergence of lead-free solders. Among many lead-free solders, zinc is easily oxidized, and the solder alloy has good wettability with its dross, producing a large amount of floating dross. During dross removal, a significant loss of liquid solder occurs, making it unsuitable for wave soldering. Indium-containing solders have better performance but cannot meet global indium reserves' demand and are relatively expensive. Therefore, considering adding silverSilver solderis undoubtedly a better choice.

To address the shortcomings of existing technologies, technicians have provided a lead-free tinSilver solder, which has excellent process performance, low melting point, good wettability and filling performance. To achieve the above objectives, it adopts the following technical scheme: it is a lead-free tin-silver solder with a chemical composition by weight percentage including: high-purity tin, 3% to 5% silver and a small amount of copper, where silver can form a tin-silver eutectic with the tin matrix to lower the melting point of the solder and improve its mechanical properties. After adding more than 5% silver, the liquidus temperature of the solder alloy will rise sharply, leading to an increase in solder temperature and causing thermal damage to electronic components. Among them, the silver content is 3.5-3.8%. Adding copper can allow tin, silver, and copper to form a ternary eutectic that further lowers the melting point of the solder while improving the wettability and strength of tin-silver solders. Various physical forms of silver solder can be obtained through known common manufacturing methods in existing technologies such as paste-like, powdery, blocky, rod-like, spherical and wire-like forms; then various welding processes such as reflow soldering, wave soldering and manual soldering can be performed to meet various needs.

This lead-free tinSilver solderhas beneficial effects such as: low melting point, good wettability and filling performance; excellent strength, plasticity, conductivity and corrosion resistance; can be used for brazing almost all black metals and non-ferrous metals except for low melting point metals like aluminum and magnesium; it has broad market development potential and promotion capability.