Sharp AR-5316 Service Manual page 55

LEAD-FREE SOLDER
The PWB's of this model employs lead-free solder. The "LF" marks indicated on the PWB's and the Service Manual mean "Lead-Free" solder.
The alphabet following the LF mark shows the kind of lead-free solder.
Example:
(1) NOTE FOR THE USE OF LEAD-FREE SOLDER THREAD
When repairing a lead-free solder PWB, use lead-free solder thread.
Never use conventional lead solder thread, which may cause a breakdown or an accident.
Since the melting point of lead-free solder thread is about 40°C higher than that of conventional lead solder thread, the use of the exclusive-use
soldering iron is recommendable.
(2) NOTE FOR SOLDERING WORK
Since the melting point of lead-free solder is about 220°C, which is about 40°C higher than that of conventional lead solder, and its soldering capacity is
inferior to conventional one, it is apt to keep the soldering iron in contact with the PWB for longer time. This may cause land separation or may exceed
the heat-resistive temperature of components. Use enough care to separate the soldering iron from the PWB when completion of soldering is
confirmed.
Since lead-free solder includes a greater quantity of tin, the iron tip may corrode easily. Turn ON/OFF the soldering iron power frequently.
If different-kind solder remains on the soldering iron tip, it is melted together with lead-free solder. To avoid this, clean the soldering iron tip after
completion of soldering work.
If the soldering iron tip is discolored black during soldering work, clean and file the tip with steel wool or a fine filer.
Solder composition
code (Refer to the
table at the right.)
Lead-Free
a
5mm
<Solder composition code of lead-free solder>
Solder composition Solder composition code
Sn-Ag-Cu
Sn-Ag-Bi
Sn-Ag-Bi-Cu
Sn-Zn-Bi
Sn-In-Ag-Bi
Sn-Cu-Ni
Sn-Ag-Sb
Bi-Sn-Ag-P
Bi-Sn-Ag
a
b
z
i
n
s
p