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Deionized Water Standards

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#58013

Deionized Water Standards | 5 February, 2009

Can somebody help me to understand what standards are in place for deinozed water for cleaning circuit boards. I know they are supposed to be in acordance with J-STD-001D, but what does that entail? All I can find on the internet is that J-STD-001D allows a maximum of 1.56 micrograms/cm2 NaCl equivalent when tested in accordance with IPC-TM-650, Test Method 2.3.25 or 2.3.26.

Also, I am curious as to whether DI water removes non dissolved solids and not dissolved solids. Is that true?

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#58015

Deionized Water Standards | 5 February, 2009

There is no standard for deionzed water when used to clean boards. As you state, J-STD-001 defines a cleanliness requirement and a method for determining cleanliness. How you go about meeting that requirement is your decision, as it should be. Fresh tanks for creating DI water will have a resistivity starting at 18 megohm. As the tanks are used, the resistivity declines to ~50kohm, the resistivity of water from the tap.

Deionzed water is intended to aid with a cleaning machine in removing ionized materials. We'd expect that non-dissolved solids and not dissolved solids would be removed through the force of the water-jets of the cleaning machine.

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#58017

Deionized Water Standards | 5 February, 2009

So there is no "DI Water" standard, but what is max conductivity I should have coming from my water before I let it touch the boards? We just installed a DI system in our plant down in Mexico and our water analysis shows we now have HIGHER conductivity than if we were just pulling tap water. How bad is 1,566 uS/cm?

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#58021

Deionized Water Standards | 6 February, 2009

Conductivity is the recprical of resistivity. So, ... * 10 uS = 100k ohm * 5 uS = 200k ohm * 2 uS = 500k ohm

We're unsure of the units of your conductivity of "1,566 uS/cm". Also, is that one thousand, five hundred, sixty six?

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#58026

Deionized Water Standards | 6 February, 2009

Yes it is one thousand. I was hoping for 1.566 but no, that is a comma. From my understanding this unit of measuremeant would be a direct equivalent in megaOhms making this 1,566 megaohms in resistivity. I may be wrong.

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#58027

Deionized Water Standards | 7 February, 2009

We agree. 1,566 uS/cm doesn't make sense

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