Sharp LC-37SH20U Service Manual page 5

Precautions for using lead-free solder
1 Employing lead-free solder
"All PWBs" of this model employs lead-free solder. The LF symbol indicates lead-free solder, and is attached on
the PWBs and service manuals. The alphabetical character following LF shows the type of lead-free solder.
Example:
L F a
2 Using lead-free wire solder
When fixing the PWB soldered with the lead-free solder, apply lead-free wire solder. Repairing with conventional
lead wire solder may cause damage or accident due to cracks.
As the melting point of lead-free solder (Sn-Ag-Cu) is higher than the lead wire solder by 40°C, we recommend
you to use a dedicated soldering bit, if you are not familiar with how to obtain lead-free wire solder or soldering bit,
contact our service station or service branch in your area.
3 Soldering
As the melting point of lead-free solder (Sn-Ag-Cu) is about 220°C which is higher than the conventional lead
solder by 40°C, and as it has poor solder wettability, you may be apt to keep the soldering bit in contact with the
PWB for extended period of time. However, Since the land may be peeled off or the maximum heat-resistance
temperature of parts may be exceeded, remove the bit from the PWB as soon as you confirm the steady soldering
condition.
Lead-free solder contains more tin, and the end of the soldering bit may be easily corroded. Make sure to turn on
and off the power of the bit as required.
If a different type of solder stays on the tip of the soldering bit, it is alloyed with lead-free solder. Clean the bit after
every use of it.
When the tip of the soldering bit is blackened during use, file it with steel wool or fine sandpaper.
Be careful when replacing parts with polarity indication on the PWB silk.
Lead-free wire solder for servicing
Part No.
ZHNDAi123250E
ZHNDAi126500E
ZHNDAi12801KE
Indicates lead-free solder of tin, silver and copper.
#
Description
φ0.3mm
J 250g(1roll)
φ0.6mm
J 500g(1roll)
φ1.0mm
J 1kg(1roll)
5
Code
BL
BK
BM
LC-37SH20U