How to Solder with Flux

(Image source: MG Chemicals)

Flux is a substance created for cleaning mildly dirty or oxidized surfaces while soldering. Some solder has a flux core. The flux has a lower melting point than the solder itself to allow it to flow over the surface and clean it to remove contaminants from the surface. Now this may be all the flux needed, but sometimes solder doesn’t have a flux core, and oftentimes more flux is still required.

If flux is needed, apply a small amount onto the solder pad before soldering. This should be enough to provide a clean surface. Once the solder joint is made, clean the flux off following manufacturer instructions. This will be dependent on what type of flux is used.

Flux comes in many different compositions. There are the self-explanatory no-clean, water soluble, and rosin activated. The no-clean version uses an additive that will burn off during the soldering process to leave little to no residue behind. Water soluble has an additive that is easily cleaned by using just a little bit of water. Rosin activated has an additive that leaves a sticky residue behind that will require a cleaning solvent, such as flux remover or rubbing alcohol, to clean. It is important to clean the residue off to prevent corrosion over time.

When soldering, if the solder isn’t flowing as it should or making good, clean joints, give flux a try. Sometimes this is all that’s needed to make the process a lot faster and easier.


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Ashley Awalt 是一名应用工程技术人员,自 2011 年以来一直在 Digi-Key Electronics 工作。她通过 Digi-Key 奖学金计划获得了北国社区技术学院电子技术和自动化系的应用科学副学士学位。其目前的职责是协助创建独特的技术项目,记录流程并最终参与项目视频媒体报道的制作。在业余时间,Ashley 喜欢——哦哦,等等,当要照顾孩子的时候,还有空闲时间吗?

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