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74 SMT007 MAGAZINE I NOVEMBER 2020 Most tip cleaners contain highly aggressive chemicals and should be avoided, as buildup can lead to blackening of the tips and oxidation of the plating. Due to the numerous heat cycles and the many different coatings, fluxes, epox- ies, and other materials found in the rework area, cleaning may need to be on a more fre- quent basis compared to other areas of the manufacturing floor; thismaintains tip life and ensures solder joint integrity. Tip Tinning Once cleaned, one of the best ways to extend the life of your soldering iron tip is to apply solder so as to protect it from oxidation and premature failure. Tip tinning helps prevent oxidation, which hinders the tip from trans- ferring heat effectively. Simply flood the tip with solder before putting it into the holder. This layer of solder works to protect and seal the iron plating from the air, thereby inhibit- ing oxidation. The other benefit to tip tinning is that it creates a heat bridge, which can effec- tively transfer the heat from the soldering iron to the pad as well as the component leads. Storage and Handling In addition to cleaning and tinning of the tip, their life can be extended through proper han- dling and storage. It is recommended that tips be stored in a container to limit the effects of oxidation, corrosion, and debris accumulation. Never bang or drop the tip, as this can cause damage to the plating or heating cartridge. Through proper storage and handling, tip life can be extended. Understanding the Role of Flux Tip plating can be eroded and altered by flux as activators found therein can damage the plating of the tip through a chemical reaction. More aggressive fluxes such as rosin-based or water-soluble fluxes can act more aggres- sively in wearing the tip plating away. It is not advised to dip your soldering iron tip into the flux as it could prematurely damage the plat- ing. Instead, flux should be applied at the inter- connection point of where the solder is applied at the pad/lead interface and never directly to the tip itself to protect tip life. Maintaining the Right Tip Temperature Tip temperature has a big impact on the expected life of the soldering iron tip for a number of reasons. Fluxes and cleaning agents coming into contact with the soldering iron tip under increased temperature can accelerate the degradation of the tip coating. Oxidation of the tip increases under higher temperatures. Finally, the thermal stress on the tip increases with increased temperature, thereby inducing a greater rate of tip degradation. In some soldering stations, the soldering iron can go into a "sleep" mode to increase tip life, which greatly reduces the temperature of the tip while it is not in use. By understanding the impact of temperature on tip life, rework tech- nicians can prolong the life of their soldering iron tips. Conclusion By following these guidelines for soldering tip maintenance, more consistent and reliable hand soldering rework results can be obtained while reducing the consumable costs associ- ated with the purchasing of many tips. SMT007 Bob Wettermann is the principal of BEST Inc., a contract rework and repair facility in Chicago. For more information, contact info@solder.net. To read past columns or contact Wettermann, click here. Figure 2: Chisel tip plating erosion.