It is thought that the irons cannot be used indiscriminately for all work; the voltage across and current through the tip can damage electronic circuits being soldered. When not in contact with a joint, the split tip has 6 or more volts across it, enough to destroy semiconductor p-n junctions on contact if the iron accidentally touches multiple closely spaced pads. This is not static-electricity damage; any voltage over about 0.7V capable of delivering high current can destroy a semiconductor junction.
