Chapter 10. Precautions For Using Lead-Free Solder - Sharp R-890SLM Service Manual

R-890SLM

CHAPTER 10. PRECAUTIONS FOR USING LEAD-FREE SOLDER

1. Employing lead-free solder
The "Main PWB" of 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
2. Using lead-free wire 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 40°C higher than tin/lead alloy solder, it is recommend that a dedicated bit is
used, and that the iron temperature is adjusted accordingly.
3. 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.
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