3）Please use exclusive soldering iron with lead-free solder: The iron used for lead solder is
not for lead-free soldering. Please use soldering iron which is specially designed for
lead-free soldering.
4）The temperature at the tip of soldering iron is required to be the same as ordinary solder.
Although the lead-free melting point is higher than that of ordinary solder, it doesn’t need to
rise to the temperature at the soldering iron tip. The temperature of iron tip must be
controlled in the tolerant range of the components/parts.
Note: The tolerant temperature of lead-free is raised while the tolerant temperature of
parts or components to be welded is not raised.
5）Use soldering iron correctly
Although the melting point of lead-free solder is higher, the welding must be operated in the
range of designated temperature at the soldering iron tip. The heat accumulated by the part
via the soldering iron tip must be applied effectively especially for low-cast metal. For more
effective heat application, the shape of soldering iron tip and the operation of soldering iron
(the relative position and angle of low-cast metal) needs to be controlled more strictly.
6）When applying soldering iron, it must be maintained longer at the welding joint than
ordinary solder. This is because the amount of heat must be accumulated and provide a
higher temperature in low-cast metal due to the high melting point of lead-free solder.
Additionally it takes a longer period for the melted solder to cool down and solidify, and it
must be maintained longer in the welding area after removing the soldering iron.
7）The welding operation needs local ventilation system and special gloves
Lead-free solder doesn’t contain lead (Pb) but breathing the smoke may be hazardous. The
silver contained in lead-free solder is also a hazardous substance, although its toxicity is
lower than Pb. Therefore the requirement for lead-free solder operation is the same as using
ordinary solder, which requires a local ventilation system and special gloves.
5. Soldering iron
When manual welding with lead-free solder, it needs a higher temperature soldering iron.
It is indicated that the soldering iron tip temperature is relatively higher, but if the soldering
iron is applied to low-cast metal or solders, it will recover to the designed temperature quickly.
Then the required temperature of soldering iron tip is the same as the ordinary solder,
however the efficiency would be decreased when using the lead-free solder, the melting point
of which is higher than ordinary solder. Some tool manufacturers sell soldering irons that are
specially designed for lead-free solder to maintain the efficiency of welding operation. The
price of those with a temperature controller inside for lead-free soldering is 3 or 4 times
higher than ordinary irons.
6. Make sure not to mix different types of solders
When repairing a PCB marked with “LF”, you must use lead-free solder containing the metal
corresponding to that in the figures on the back of the “LF” mark. Lead solder or lead-free
solders containing metals different than listed on the LF label are forbidden on a PCB with the
“LF” mark.
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