Flux is an essential chemical in soldering, aiding in the flow and improving the quality of solder. The melting point of lead-free eutectic solder (SAC387) is notably higher by 34°C compared to traditional lead eutectic solder (Sn37Pb). Lead-free solder wire may comprise various materials such as copper, zinc, tin, silver, bismuth, antimony, and traces of other elements, tailored for specific uses. In contrast, Plumbright Leaded Solder Wire, suitable for non-potable water supplies, has a different composition.
Choosing the right solder wire depends on the metals being joined. Tin-Lead Solder, melting between 180°C to 190°C, is preferred for its lower temperature requirement. The ALPHA OM-5100 activation system is designed to enhance joint solderability while minimizing post-reflow defects. In electronics soldering, lead-free rosin core solder is commonly used. The harmonized classification for lead, established in 2016 [Regulation (EU) 2016/1179], became effective on March 1, 2018. However, lead poisoning remains a serious risk, as evidenced by two known cases of fatal lead poisoning from solder.
During the transition from traditional SnPb to Pb-free board soldering, not all components will have the required solder finish. This transition can present challenges such as stress issues and mismatched temperature profiles. Lead-free solder has a higher melting point than leaded solder, which can be advantageous in reducing thermal effects on PCBs and components. Proper extraction methods can significantly reduce exposure to harmful components.
The composition of leaded solder wire typically ranges from 60/40 to 63/37, with a percentage of tin and lead. Soldering in a commercial-grade ventilated building without the ability to open windows poses its own challenges. Despite the benefits of lead-containing solder, such as low melting point and cost, environmental and health regulations increasingly restrict its use.
When soldering, it’s essential to set the soldering iron temperature above the solder’s melting point. For those complying with regulations, Number 23 Tin/Copper Alloy Soft Solder, meeting BS EN ISO 9453 standards with a melting point of 230°C to 240°C, is a viable option.
