A solder pot or wave soldering machine may have solder that forms a color. The gold or purple-blue color is called “dross” or the tin oxide of solder. When the surface of the molten solder is exposed to air it oxidizes and changes color. This is normal and can only be prevented by using an anti-oxidant powder or pellet. Otherwise, the use of a dross skimmer will help solder performance by removing the oxide layer before soldering.
Dross is considered an impurity, and is especially noticeable when solder is still or resting such as in a solder pot. Kester offers the #5744 Dross Eliminator for this purpose, which reduces tin oxide back to tin metal which will greatly reduce dross scrap, reduce maintenance cleaning downtime or possible solder defects, and will help keep the soldering pot surface clear of residues.
Other Tips
- Avoid constant removal of oxides, dross layers prevents further oxidation
- Keep solder pot full, avoid excessive cascading of the solder
- Keep a turbulent free wave; use slower pump speeds
- Using a slightly lower solder temperature can reduce this oxide formation
- Keep impurities low
- Avoid high copper dissolution
- Use dross reducer, as a last resort
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Related Topics:
Source - Kester: FAQ
Source - Kester: Reliability with SnCu Based Solders
(60/40) vs. (63/37) Solder Alloy Comparison
Easily Remove Solder Joints: SMD Removal / Desoldering Solder - What is Removal Alloy?
Tin Whiskers in Pure Tin Surface
Nickel Advantages in Tin-Plated Terminals: Surface Contact, Soldering, & Tin Whisker Growth
Fluxing and Cleaning Consideration in Soldering
Good health practices when using Flux
Best Practices for Tinning and Maintaining Your Soldering Iron
Overcoming Challenges When Soldering to Gold and Gold-Plated Surfaces
Applicable Part Numbers
56-0005-5744-ND
56-0025-5744-ND
56-0005-5744
56-0025-5744