Sharp 902SH, Service Manual

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902SH
ii
CONFIDENTIAL
Employing lead-free solder
This model employs lead-free solder.
This is indicated by the “LF” symbol printed on the PWB and in the service manual.
The suffix letter indicates the alloy type of the solder.
Example:
Indicates lead-free solder of tin, silver and copper.
Using lead-free solder
When repairing a PWB with the “LF” symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder may
result in cold soldered joints and damage to printed patterns.)
As the melting point of lead-free solder is approximately 40ºC higher than tin/lead alloy solder, it is recommended that a
dedicated bit is used, and that the iron temperature is adjusted accordingly.
Soldering
As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wettability (flow), to prevent damage to the land
of the PWB, extreme care should be taken not to leave the bit in contact with the PWB for an extended period of time.
Remove the bit as soon as a good flow is achieved.
The high content of tin in lead free solder will cause premature corrosion of the bit.
To reduce wear on the bit, reduce the temperature or turn off the iron when it is not required.
Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their
characteristics, making good soldering more difficult.
It will be necessary to clean and replace bits more often when using lead-free solder. To reduce bit wear, care should be
taken to clean the bit thoroughly after each use.
PRECAUTIONS FOR USING LEAD-FREE SOLDER
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