When it comes to soldering irons, “the tip is the tool”. The rest of the iron holds and heats the tip and controls its performance. But the tip is the critical component that must transfer heat efficiently and reliably to the connection point. Inadequate or improper tip maintenance is a leading cause of soldering problems.
What’s the best way to avoid trouble? The key to good tip maintenance is to keep the tip tinned with a thin coating of solder at all times.
Tinning makes soldering easier
This solder coating also forms a heat bridge between the tip and the parts being soldered. It’s difficult to heat parts efficiently with a point contact alone, as occurs with a “dry” (untinned) tip. With a tinned tip, the coating tends to flatten out as the tip touches the connection, creating a larger surface contact area – which in turn forms a more efficient heat path.
Tinning gives longer tip life
Proper tinning also optimizes tip life. Most tips consist of a copper base material, plated with iron to prevent erosion. Iron, however, tends to oxidize rapidly. When oxidation occurs, the tip becomes covered with a black or brown scale, which will not wet with solder – greatly reducing heat transfer. This is commonly known as “burn-out”. Burned out tips are usually discarded, though they may often be cleaned carefully with a fine abrasive and retinned.
Don't get burned bywater-soluble and "no-clean" fluxes
Water-soluble flux and high temperatures don't mix
Be aware that the water-soluble fluxes, which are corrosive at high temperatures, can be especially damaging to tips. Many companies use water-soluble fluxes only during wave soldering followed by thorough aqueous cleaning to reduce flux residue on the circuit board. The use of wire solder cored with water soluble flux during touch-up and rework operations will still result in very rapid tip failure.
No-clean flux just for soldering very clean parts
The use of “no-clean” fluxes is increasing worldwide. “No-cleans” are designed to be used for soldering very clean parts where minimal cleaning action is needed. This very mild cleaning action is usually insufficient to clean normal oxides off soldering iron tips. After a short amount of use the tip becomes badly oxidized, will not wet with solder and exhibits the “burn-out” appearance of black or brown scale coating the working surface.
Cleaning your oxidized tips
To clean tips oxidized due to using water soluble and “no-clean” fluxes, it is best to flush the tip several times with a rosin-activated, flux-cored solder. This should remove the oxides, unless the oxidation has been allowed to build up excessively. Once cleaned, the tip surface should be covered with a thick coating of solder.