Choose Well When Soldering

Based on an original publication by Hakko

Molten Metal

Soldering can be described as gluing with molten metal. Two or more metal objects are joined together by heating them and then applying solder. The solder melts onto the joint (wetting) then, cools and bonds them together.

Flux Can

As technicians know, “flux is your friend” and removes oxides and prevents new build-up. Oxidation occurs when oxygen in the air reacts with the hot metal and forms a covering layer over the metal that keeps solder from sticking.

Flux can -

  • Remove greasy dirt, dust and oxidized film
  • Prevent re-oxidization
  • Help to cause solder wetting
  • Decrease solder trension to help solder "wet" to metal

What's in Flux

When choosing a flux, how and what it will be used on must be considered. Choosing between a low-corrosive or high-corrosive flux is imperative when working with certain applications and metals to be joined. Certain fluxes can be harmful to components and others work best with, for example, chrome-plated or stainless steel components.

Some metals are easier to solder than others and range from excellent to poor, with tin being the easiest to solder and stainless steel the most difficult. Silver, gold, copper, lead and zinc can also be soldered. Depending on the type of flux, joints can be created between metals that would not normally be possible.

As with many areas of manufacturing, fluxes have advanced to meet regulatory requirements. Today you’ll find halogen-free flux, halogen-free solder and solder paste, as well as, some of the support equipment like the Lead Free Compatible Digital Solder Pot with Auto Shutoff Timer by Hakko.

Note: The mixture of heat, solder and flux causes toxic fumes that should be dissipated in some manner. Depending on the job, fume extractors like the Volume Fume Extraction Unit with Pre-HEPA by Hakko, may be a good solution.


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