Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Ion exchanger

Irun

#30370

Ion exchanger | 2 September, 2004

Hi all I have a question about DI water for cleaning system. What water quality should ionic exchanger produce for assembly cleaning (SMD and THT components with BGA and microwave application). What is recommend water conduction and minimal level (0.1 uS/cm or 1 us/cm is enough?). What about PH and other contamination.? Question 2. Where i can find or you can recommend bench top DI station (small volume production about 18l/h DI water).

Thanks Irun

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#30376

Ion exchanger | 2 September, 2004

It depends. We've known cases where 10 mohm-cm was insufficient and others where 0.1 mohm-cm was more than sufficient. No standard exists.

Our final rinse is fed from a recycling unit that produces DI water. We use 0.5 mohm-cm resistivity as the low limit.

For low volume, spiratic use applications; you might find it economic just to use ion exchange tanks from your local supplier.

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KEN

#30379

Ion exchanger | 2 September, 2004

Not sure of what a bench top DI setup would look like. I use 3.5 Cubic foot tanks but have a special application that uses a 1 cubic foot tanks....even then its not a bench top setup.

What is clean. No one can tell you. YOu can use IPC TM650 or the old mil spec 2880 (???been a few years). Either way, these specs in no way can validate your performance vs. application criteria. Measure, test adjust, remeasure. Generally, 1meg ohm / cm^3 will clean quite well. But, this can also be a function of your cleaner.

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Irun

#30391

Ion exchanger | 5 September, 2004

What do you think to use distilled water to rinsing?

Irun

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#30395

Ion exchanger | 6 September, 2004

There is distilled water and distilled water. It depends on the distallation process used. Using distilled water is fine, as long as it meets your standard. So, if you buy distilled water, get a written certification that conductivity is less than 1 uS-cm at the time of packing (it may rise to about 5 uS-cm if not consumed rapidly).

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