1. Use period
The use of lead-free solder paste follows the principle of "first in, then out", first use the earlier production date of lead-free solder paste, and can not exceed the use period of 6 months (unopened).
2. Environmental standards
The indoor temperature should be controlled at 22-28℃ and the relative humidity RH40-60% is the best operating environment temperature.
3. Retemperature
Take the lead-free solder paste out of the refrigerator, place it in a cool place and let it warm up normally, at least for 4 hours, and do not open the seal when warming up.
4. Inspection
After warming up, the operator should check if there is any dry caking on the surface of the solder paste, if there is, inform the PE engineer to deal with it.
5. Stirring
In order to ensure the consistency and uniformity of the solder paste in the soldering process, the paste should also be stirred well before use, using a machine stirring time of 1-3 minutes and a manual stirring time of 3-5 minutes.
6. Printing
① When adding solder paste, use the "small amount, many times" method to make up the amount of solder paste on the stencil to ensure the quality of the solder paste.
② Different solder pastes should not be mixed. When replacing different types of solder paste, wash the stencil and scraper.
③ For the previous day's unused solder paste, it should be mixed with the newly opened solder paste in a ratio of 1:2
7. Wash
When the stencil is not in use, clean the surface with a rag moistened with alcohol, then brush the stencil mouth with a toothbrush and finally scrub both sides of the stencil with a fibre-free cloth and put it back into the corresponding stencil bit after checking that it is correct.
The above storage and use of lead-free solder paste specifications are more commonly used in the factory, in the SMT production process, resulting in the quality of lead-free solder paste will have a lot of problems, but also need operators to feel well, to maximize the quality of solder paste printing.
