Best results with lead free solder
When using lead free (silver) solder for the first time, you are probably much disappointed. The solder joint looks not nice, looks unreliable, and badly done. Well, and that is probably just what it is. Lead-free soldering is not more difficult, but mostly it is ANOTHER process, and you probably don't know that. All you need to do is change the way you are soldering, and you can have very nice results. Lead-free soldering was always done to get solder joints of higher stability. So... what keeps you from doing it? .
Here is a typical problem situation:
What causes this problem?
Here is the difference. With lead solder, the moment it melts, and there is some flux, it will flow nicely. The flux is active from the very moment the solder has melted, and lead solder melts at such a "low" temperature, the flux will not burn away quickly, doing it's job all of the time.
Not so with lead-free solder. The flux is initially not working. You need to understand this. You have to heat up the joint, until the flux starts to burn away, which means really it is quite hot. It is this very moment, where the flux burns away, the solder suddenly flows nice, and after that is nti functional, and you have to remove the solder iron. However, this moment is short, since the burning flux is disappearing quickly. This makes the moment of good solder flow so short, and you can only make small solder joints, like solder two little wires together. The moment you need to do something larger, you simple need to apply extra flux, or even apply it a few times. I have tried everything, but I find this the only way. For best optical results, you can remove the flux residue with alcohol, and it will look very nice.
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This is a liquid flux, of highest possible concentration, so as much as possible will stay on the object. It looks like honey. If for some reason you find it too thick, you can use alcohol to make it thinner. You can also use it to prepare printed circuit boards before soldering. For this application, mix 1 part of the liquid solder flux with 1 part alcohol. Paint the PCB with this, let is dry on the air for one hour, or dry it with air from a hair dryer. When dry, solder the PCB the normal way. Don't bother how it looks afterwards, you can remove the residue nicely with 100% pure alcohol. Hint: Resin in a good glue. So keep the bottle clean before you close it. If in any case you glue the lid on, with spoiled residue, you can open it after warming the lid with very hot water, or leave the closed bottle in alcohol a few hours. |
How to apply extra flux?
The good old way, to dip the solder iron into some flux is not working with lead free solder. The flux is burning away already on the solder iron. The small residue that is left, will not spread over the solder joint insufficient, and you may just burn the components.
Process for larger solder joints:
Hint: For clean de soldering we sell an excellent, and low cost de soldering iron. (Check under "tools" in the menu)