DISADVANTAGES OF LEAD-FREE WELDING
With the introduction of lead-free tin, we often receive reports that the tips turn black, last a short time, weld badly … and so on and so forth. Often it is an incorrect use of materials and in most cases the tips are still recoverable.
How to treat the soldering iron tips then?
The rules are few and simple. The tip should always be cleaned of flux residues and oxidation, but then it should be stagnated promptly. This is because leaving a layer of tin on the tip protects the tip surface when the stylus is stored.
At this point you will ask: How is the tip cleaned?
The traditional damp sponge can be used as long as it is not soaked with water; use only the double-layer sponges and the abrasive side (orange). The water used for moistening should be demineralized or deionized. Keep in mind, however, that the thermal shocks to which a tip meets when it is cleaned with a sponge cause delays in temperature recovery and greater wear and tear, shortening its life.
Instead, it is advisable to use the new type of brass straw hat, which replaces the steel wool pad. The choice of brass is linked to the fact that brass is a softer (less abrasive) alloy and does not risk removing even the galvanic layers of the tip, unlike the stainless steel one.
In addition to this it is important to switch off the welding station, or activate the standby / set back and auto off function, if work breaks are prolonged.
We have already said it but we repeat: “Promptly restore the tip after each cleaning with a sponge (or metal scouring pad) and at the end of the work, before putting it back in the holder. When the stylus does not work, the tip must be covered with a solder.”
It is possible to reduce the oxidation of the tips and the consequent non-wettability by using for example the Tip Activator while welding, if oxidations begin to form; you can protect the tip with the Tip Activator when placing the stylus in the holder.
Another important precaution is that of not exerting excessive pressure on the soldering tip during processing. Even over-tightening the tips in the toe tube can be detrimental in the long run. In both cases it is sufficient to apply a modest pressure to have an excellent result.
When the tip turns black …
If the tip has turned black, as if it were painted and no longer has affinity with tin, then it means that the flux contained in the tin burns and chars. This can mean several things. Whether we are using a tin with low quality flux or not suitable for our application, or that we are working at too high temperatures.