Electronic technicians use soldering irons and solder for things like computers, medical equipment and precision measurement systems. There are 2 main types of solder: lead based and lead free. Because of concerns around disposal of electronic items, lead free solder is often used however they do melt at higher temperatures and require a higher dwell time. Leaded solder is an obvious health hazard because the lead can rub off onto your fingers and be ingested through the skin. Before you start soldering, make sure you have flux on hand to clean the solder joints.