CHAPTER 3 ■ SAFETYLead
Lead is being banned from an increasing number of products including electronic components and assembly.
Airborne exposure to lead is the worst, followed by ingestion, with the least absorption through touch.
High levels of lead can cause death in adults, but even moderate blood levels cause permanent loss of
IQ in children. To give you a sense for the danger, the current “safe” level of lead in blood for children is only
one-tenth the level acceptable for non-pregnant adults.
Avoid purchasing products containing lead, even at surplus sales. Don’t throw away items containing
lead, but instead take them to a local hazardous waste collection site for proper disposal or recycling.
Lead-acid and lead-gel batteries are okay to buy, because they are easily recycled.
Like most technicians, I learned to solder using standard 60/40 (60% tin and 40% lead) solder. It flows
well. However, I made the switch to a tin-silver lead-free alternative (see Figure 3-4).
When lead-free solder is purchased in the small 16-ounce rolls, the cost is insignificantly higher than
leaded solder. Initially, if lead-free solder seems more difficult to apply cleanly, it may be because you aren’t
accustomed to it. With the correct temperature and practiced technique, lead-free solder works as well and
even forms a stronger bond.
Flux, the cleaning material within solder, is irritating and a potential carcinogen. So, being lead free
doesn’t completely eliminate all dangers. Adequate ventilation and clean-up helps here.
Mercury
Old-fashioned mercury tilt switches are sure cool to look at (see Figure 3-5). However, mercury is a
particularly toxic element. Small amounts can poison you, as well as make their way into rivers and streams.
Figure 3-4. Use lead-free solder