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I've been reading up on distilled and deionized water and I've come across conflicting information.

If compared to regular tap water there are little to no minerals, is this the reason they're used because they're "hungry" for ions so they actually strip away any corrosion caused by mineral deposits? (If it's being used a cleaning agent)

That's my take on it and it got me wondering if that then makes distilled/di water corrosive if it's accidentally used on electronics when not intended to as a cleaning agent?

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  • \$\begingroup\$ One thing I could note, pure H2O is not conductive. If it has minerals, the water separates the compounds. So salt dissolved into water is chlorine and sodium split up in the water. Since the salt is separated, the water conducts. But when they are out of the water, they reunite. \$\endgroup\$ – Bradman175 May 31 '16 at 1:08
  • \$\begingroup\$ electronics.stackexchange.com/q/24428/104462 \$\endgroup\$ – Bradman175 May 31 '16 at 1:09
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No, deionized water does not "strip" corrosion.

Ordinary water contains ions that are the result of dissociating various salt compounds. If you were to wash a board with this water, some of those salts would be left behind as residue as the water evaporates. Over time, these salts will react with atmospheric humidity and cause corrosion in metal surfaces.

Therefore, boards are rinsed with deionized water to prevent such residues and the resulting long-term reliability problems.

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  • \$\begingroup\$ Yeah that's the knowledge I had about it too until I read more into it as in this following quote I pulled from a site detailing the use of distilled/deionized water: "Ultrasonic cleaning tanks – deionized water is extremely active cleaner and will pull ions from any surrounding metal, including stainless steel. As deionized water contains no ions of its own, it will always look to draw from its immediate surroundings and even the atmosphere" \$\endgroup\$ – ohmmy May 31 '16 at 1:14
  • \$\begingroup\$ So it makes it sound like its stripping metals clean? \$\endgroup\$ – ohmmy May 31 '16 at 1:19
  • \$\begingroup\$ That's bogus. "deionized water contains no ions of its own" is true but silly, since tap water is just as aggressive for attacking soluble solids. They don't get it: any solvent that's well below saturation is aggressive (for example, when tap water is dissolving NaCl.) Using distilled water, or even making the saturation zero, doesn't get you much benefit over tap water. Better to add detergent, so it removes surface grease films which prevent contact with water. Also: DDW is electrically insulating, so may have less electrolysis damage to copper/steel/tin/aluminum. \$\endgroup\$ – wbeaty May 31 '16 at 5:38
  • \$\begingroup\$ Yeah I've been reading a lot of conflicting information. Even came across an article stating that distilled water is MORE corrosive than tap due to its hunger for ions. So idk what to think \$\endgroup\$ – ohmmy May 31 '16 at 12:00

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