The main raw materials of solder paste include alloy solder powder, paste flux and some additives. Alloy solder powder accounts for a large proportion of solder paste, usually 85% to 90%, while flux accounts for 10% to 15%. Alloy solder powder is made by spraying in an inert gas. Commonly used are two major categories: lead and lead-free. Specific ingredients include tin-lead, tin-silver, tin-copper, etc.
In addition, solder paste also contains other auxiliary materials such as activators, base materials and flow agents. Activators include flux and antioxidants. Flux improves the activity of welding reaction, and antioxidants prevent oxidation; base materials are usually metal powders or alloys, which affect the shape and quality of solder joints; flow agents improve wettability and fluidity, and help form uniform solder joints. These raw materials work together to ensure the quality and effect of welding.
