Solder is used to establish a permanent bond or connection between metal pieces on a PCB (Printed Circuit Board.) It is made of metal alloys, with tin-lead being the most common composition (i.e. Sn63Pb37 or Sn60Pb40). However, due to health and safety issues, an on-going shift to lead-free solder bars continues to be implemented following RoHS (Restriction of Hazardous Substances Directive) and WEEE (European Union Waste Electrical and Electronic Equipment Directive). Manufacturers of electronic and electrical equipment in the US may qualify for tax benefits by going lead-free or by minimizing the use of conventional lead-based solder.
Although a lead-free solder bar may help increase the safety of workers and the environment, it may not be the best solution for certain applications where medical projects and aerospace equipment are being manufactured. Providers of SMT (Surface Mount Technology) assembly solutions continue to come up with ways to create lead-free solders that can apply to those industries. A lead-free solder bar for commercial use may contain bismuth, silver, copper, tin, antimony, zinc, indium, and bits of other metals with melting point typically ranging from 5°C to 20°C, which is higher than lead-based solder bars. However, there are manufacturers that have formulated lead-free solder that can melt at much lower temperatures.
Lead-free solder bar is commonly used in the wave soldering process. Sn96Ag4 and Sn97Ag3 alloys are preferred when there is the need to reduce or stabilize the copper content in a wave solder bath, especially when process conditions require the removal of oxides and other impurities that can increase dross generation and defects, like solder bridging. Reputable manufacturers of lead-free solder bars carefully formulate the composition of their Sn-Ag variants to ensure best-in-class yield, fast wetting speed, excellent solderability, excellent performance across various flux technologies, and reliable drainage. They use a process that controls the amount of impurities, while making sure that it meets or exceeds acceptable standards like IPC J-STD-006C.
Although a lead-free solder bar may help increase the safety of workers and the environment, it may not be the best solution for certain applications where medical projects and aerospace equipment are being manufactured. Providers of SMT (Surface Mount Technology) assembly solutions continue to come up with ways to create lead-free solders that can apply to those industries. A lead-free solder bar for commercial use may contain bismuth, silver, copper, tin, antimony, zinc, indium, and bits of other metals with melting point typically ranging from 5°C to 20°C, which is higher than lead-based solder bars. However, there are manufacturers that have formulated lead-free solder that can melt at much lower temperatures.
Lead-free solder bar is commonly used in the wave soldering process. Sn96Ag4 and Sn97Ag3 alloys are preferred when there is the need to reduce or stabilize the copper content in a wave solder bath, especially when process conditions require the removal of oxides and other impurities that can increase dross generation and defects, like solder bridging. Reputable manufacturers of lead-free solder bars carefully formulate the composition of their Sn-Ag variants to ensure best-in-class yield, fast wetting speed, excellent solderability, excellent performance across various flux technologies, and reliable drainage. They use a process that controls the amount of impurities, while making sure that it meets or exceeds acceptable standards like IPC J-STD-006C.
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