Since the move from lead to lead-free solders, a common complaint has been short tip life. The higher heat needed for lead-free solders and flux, with greater activity, all lead to faster tip burn-out. Often the tips turn black, which results in the solder beading. This is also sometimes referred to as a ‘cold tip’.
Soldering tips have a copper core that transfers heat from the heating element to the working tip. Because copper is very soft and easily corroded, other metals are used to plate over the copper, including an outer layer of iron. Although iron is very hard, it will still corrode eventually. In addition, it can be coated with flux and other soils, which can cause dewetting (the tip losing its protective coating of solder). Corrosion and dewetting will slow down soldering and eventually necessitate replacing the tip. Although all tips will have their day in the trash bin, there are several steps an operator can take to increase tip life.
Step 1: Turn down the heat
In soldering, like everything else, speed is king. Operators will turn up the soldering temperature to speed up heat throughput. This allows them to go from one solder joint to the next, faster. However, there is a catch – the higher the heat, the shorter the tip life. Many solder stations may go up to 450°C, but 380°C is usually the highest temperature needed for most lead-free wire. Plato soldering tips – tips constructed from highly conductive premium grade copper – are designed for optimised heat recovery, which will help maintain soldering efficiency.
When leaving the solder station for anything over five minutes, it should be turned off. When the station is left on, the tip remains at soldering temperature, further reducing tip life. Modern soldering equipment heats up to soldering temperature in seconds, so the time saved is not worth the reduction in tip life.
Step 2: Properly clean the tip
Solder stations normally come with a sponge and/or brass ‘brillo pad’. The purpose is to remove excess flux and solder from the tip. If too much flux builds up and burns onto the soldering tip, it will eventually dewet and be unusable (but not necessarily unrecoverable as shown in step 4). Unless the tip cleaning tools are used properly, they can do more harm than good. When choosing a sponge, make sure it is made of natural cellulose. Synthetic sponges will melt onto the soldering tip and can shorten tip life.
Use clean deionised water. Tap water may include minerals that can build-up on the tip. If the sponge is saturated, it should be wrung out. Too much water can increase thermal stress of the tip and slow down tip recovery.
Brass ‘brillo pad’ type tip cleaners should be used sparingly. While brass is softer than iron, it is certainly more abrasive than a sponge.
Step 3: Tin the soldering tip
It is a common practice to wipe down the soldering tip before putting it back into its holder. This exposes the raw iron on the working end of the tip, which will rust in the open air. Add any residual flux to the mix, and you have a prematurely pitted soldering tip. Once soldering is complete, residual flux and solder should be wiped off the tip and the tip should then be re-tinned by applying fresh solder.
Step 4: Use special cleaning tools
When the soldering tip has turned black from baked-on fluxes, and no longer wets properly, it is time for the last-resort cleaning tools. Tip tinner (Plato #TT-95) is a combination of lead-free solder and cleaner. While the soldering iron is at full temperature, the tip is rolled in the tip tinner. As it is rolled, it should change from black to shiny silver as the baked flux is cleaned off. The excess tip tinner is then wiped from the soldering tip, which can then be re-tinned using wire solder. Tip tinner is not intended to be left on the tip.
Polishing bars are also available and are used to scrub the tip clean of flux residues. However, a polishing bar should be used only as a last resort, because iron along, with the burnt flux ,will be removed. Once a tip shows pitting (holes in the iron), it is time to replace it.
If these steps are carefully followed, a 30 to 100% increase in tip life may be expected. However, there is no substitute for a quality manufactured soldering tip. Plato tips contain proprietary plating technology which can provide a superior life span.
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