How to clean, tin, and maintain soldering iron tip

[chris_dillman]

In this post I will talk about soldering irons and how to clean, tin, and maintain soldering iron tip

What is a Soldering Iron?
A soldering iron is a hand tool used in soldering. It is composed of a heated metal tip and an insulated handle. It supplies heat to melt solder so that it can flow into the joint between two work pieces to make a physical bond to component to component, component to board, or component to wire.

In doing so the tip gets hot enough to oxidize quickly, which will become dirty or contaminated just sitting in the soldering iron holder.

The oxidation will then act as an insulator which is not good for heat transfer when working on your project.
The ability for the soldering iron tip to transfer heat is drastically reduced when it gets covered in oxides and burnt flux residues. Not only does heat not transfer as well through this debris, but the contaminants also prevent solder from wetting or sticking to the tip. Most heat transfer goes through a fluid solder “heat bridge” that lies between the iron tip and components, so an iron tip that repels solder will be very ineffective.

The longer oxides and charcoaled flux residues remain on the tip, the harder they become to remove, so it’s a good idea to clean the tip every time you use your iron.

Above are some examples of tips that have not been properly cleaned and tipped.

Cleaning Options
Wiping the iron tip on a damp sponge can help to remove oxides easier, and allows waste to fall away. A Dry Cleaner (special brass wool) can also be used. It consists of soft metal shavings that are coated with flux. You clean the tip by thrusting the iron into the shaving a few times. By avoiding the thermal shock of touching a damp sponge, these cleaners help to increase tip life, and in my opinion, do a better, faster job. But both are better than not cleaning a tip at all.

Regular cleaning = easier soldering and longer tip life:

After cleaning the tip apply flux core solder to the tip to give it a new coat of solder.

Repeat this step before starting and every few minutes after, apply small amount of fresh solder to the tip. Usually touching the tip with rosin-cored solder will supply enough flux so that oxides can be removed with a damp sponge or dry cleaner.
If this isn’t sufficient, you can purchase "tip tinner, cleaner or also called Heavy Oxidation Removal Paste that are a mixture of solder paste and flux. The flux is oftentimes stronger (more activated) to help remove oxides.

Thrust the iron tip into the tip cleaner a few times till it has an even coat of solder.
If that doesn’t work, a special cleaning polishing bar can be used to salvage extremely bad tips.

Another last resort is to gently rub the oxides off with an emery cloth or soft steel brush. Cover the tip immediately with solder after cleaning to prevent further oxidation.

Never file the tip to clean it or form a different shape. The tips are mostly copper with a protective iron plating, and once that plating is pierced, the tip will die quickly. Copper is used because it’s an excellent heat conductor, but if exposed to solder, it will quickly dissolve into the solder

In Conclusion:

What the causes of detinning are:

• Failure to keep the working end of the tip covered with solder during idling periods.

• Operating at high temperatures, which speeds oxidation. Maintain the temperature of
  800°F (427°C), or less, whenever possible.

• Use of very small solder wire. Its small diameter carries inadequate flux to keep the tip
  tinned.

• Lack of flux in the soldering operation. Use of no clean fluxes and low-residue fluxes.

• Use of solder with low tin content.

• Repair and touch-up, and the use of wick.

• Wiping of tips on dry sponges, man-made sponges, rags, paper towels, or metal wool in lieu of a wet cellulose sponge.

To maintain the performance of any soldering iron tip, a simple maintenance procedure is recommended:

• Operate at the lowest possible temperature (800°F (427°C) or lower. Operating at
  temperatures exceeding 850°F dramatically increases the formation of iron oxides, which
  is one of the major causes of detinning.

For tip wiping: use a dry cleaner brass wool or only (sulfur-free) pure cellulose sponges; damp to the touch.

Add rosin core solder of adequate diameter (.032", .80 mm, or larger) to the working end
of the tip regularly.

If your soldering tip becomes detinned (oxidized), it can be restored in a
number of ways:

• With the iron tip cold use a polishing bar. A polyurethane foam bar with embedded abrasives which is used to polish the working end of the tip to remove surface oxides; then immediately re-tin the tip with rosin core solder.

• Use Tip Tinner/Cleaner. This is a halide free, solid paste which
  provides quick and safe re-tinning and cleaning of oxidized tips.
  Just wipe the oxidized tip at normal soldering temperatures into the tip tinner for a few seconds until the bright tinning surrounds the working end of the tip. It’s fast acting, residue free.

• Use a conventional solder wire with rosin base flux of sufficient diameter .032" (.80 mm)
  or larger, (with a sufficient percentage of flux available) to re-tin the solder tips.
  Flood or coat the working end of the tip regularly with solder.

[daveca]

NEVER use sponges or sandpaper, especially on SMD irons.

The reason cannot be seen without a microscope or good magnifying glass, but wiping the tip on the sponge often brings away carbonized particles of sponge on the tip surface.

Sand paper is abrasive grit bonded to a paper backing with glue, The grit particles are far harder than the tip, so the sandpaper will abrade the tip surface away and leave particles of it on the tip. The tip can end up with metal and glue residues that are very difficult to see without magnifcation.

In both cases, the contaminant particles will find their way into the solder joints. On large heavy joints, its not so much of a problem, but in SMT it can be a disaster.

Basically speaking, if the tip is “dirty” then the tip is too hot, or , the materials being soldered are contaminated. A universal problem in soldering is too much temperature.

It is critical to realize that most belief and training in soldering comes from the 1930s - 40s, back in vacuum tube days. Back then cleanliness was not important, solder jointe were huge and there was no option but to have a very hot iron or gun as the joints were physically very large. The SMT world is radically different. This is especially critical if you work in a SMT manufacturing or repair operation. In those cases, education and training thru SMTA is important. In SMT soldering, little errors in soldering and manufacturing can cause severe quality problems that are difficult to diagnose.

www.smta.org

Remember, soldering is CHEMISTRY first, not mechanical. The process must be pure and clean, and we cant get that with the glue from the sandpaper contaminating the solder.

USe the copper wool and change it regularly. Dont reuse an old band aid!

“Operating at high temperatures, which speeds oxidation. Maintain the temperature of
800°F (427°C), or less, whenever possible.”

This is GROSS error. Eutectic solders melt around 380-400 degrees F. An iron tip need only be that, or slightly higher, temperature to do good solder work. 800F will incinerate a soldering iron tip.

This error is due to a lack of understanding ot thermodynamics. There is heat, there is temperature. They are different things. Heat is thermal energy in a mass. Temperature is the difference in heat between two masses, that results in heat transfer from the hotter to the colder.

If the temperature must be raised much above 400F (its useless to have the joint and tip any higher temperature if the solder melts at 380F) then the tip does not have enough heat (not enough thermal mass) which basically means a larger tip is required to transfer more heat (not temperature).

Such extreme high temperatures immediately oxidize the iron tip and disintegrate the flux, causing bad solder joints and tip destruction.

[tylerlockwood]

It was enough knowledge on soldering iron. Thanks a lot.

[Shutterbugs]

This is exactly the type of discussion that can help a hobbiest like myself to start out on the right foot and learn the basics. I will be searching for all the Tech Tips threads. Links to reference materials (ex. SMTA site from @daveca) are always appreciated Thanks!

[PCB_Greeks]

The flux in tip cleaner removes the oxidation and build up from the soldering iron tip, and then the solder re-tins the tip ready for use. This step will coat the iron in a mixture of flux and solder. Wipe the iron on a damp sponge to remove the excess. This should lead to a clean shiny tip, ready for use & for more info see this video

Kitronik

[Ryan_2724]

See also:

Hand Soldering Guidelines for Tip Longevity

Use quality solder iron with adjustable temperature, making sure the tip is tight before use. Adjust the temperature of the iron just above the melting temperature of the solder being used. Using excess heat can damage the circuit board, oxidize and damage the tip, and render flux useless in flux cored solder. Flux cored solder reduces tip oxidation and promotes quicker more solid solders, minimizing heat damage to parts on the board. Additional flux can also be used (pens, paste etc). …