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Water wash flux and cleaning

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Water wash flux and cleaning | 19 June, 2017


I am planning to use a water wash flux. As this is new to me, would you guys share what should I be aware of? I know cleaning PCBs itself presents issues. If you can share your experience so I can prepare better, it would be great.

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Water wash flux and cleaning | 19 June, 2017

You have a lot to think about! What does the flux manufacturer recommend as far as specifics like water temp or pressure? Do they recommend high temp di-water a detergent or saponifier?

Do you currently have a cleaning machine, batch cleaner or inline? Do you have a water filtration system?

Your flux manufacturer knows their flux chemistry better than anyone and they should be able to give you all the information you need regarding cleaning their product.

If you have cleaning equipment in your facility such as a batch cleaner or an inline aqueous cleaner you need to make sure the equipment is capable of meeting the cleaning parameters or requirements, water temp/pressure/drying. If you need to use a detergent or saponifier the cleaner needs a chamber capable of applying the chemistry in a controlled method as directed by the cleaner/flux manufacturer.

Careful when using detergents or saponifiers they can remove ink, component markings, labels and in some cases they can change the color of material like plastics or connector bodies. There is a suggested % rate of cleaning chemicals to water that needs controlling.

Filtration is another concern, in most cases you need to use hot, clean deionized water. Testing your water annually helps assure purity. You need to make sure you do not have chlorides, bromides, salts or other contaminates in your water. You may need to change out your filtration tanks or filters more often.

Another thing to think about is testing your products cleanliness after it is cleaned. Using an outside source is an option, purchasing equipment is another.

Are your products components/layout washing safe? Are all of the components on or in your assembly moisture/water safe? Is the component layout very tight? In some cases components such as switches, LED’s and moisture sensitive components are not able to be cleaned in automated cleaning processes due to the fact that they are not hermetically sealed or are too sensitive for such an aggressive process. Assuring all of the components are safe to be cleaned under high water pressure and high water temperature and dried under high heated air pressure is another thing to think about. Low standoff height components such as LGA’s, BGA’s, QFN’s or some connectors sit tight to the boards surface cleaning under them is a challenge. What about the people hand soldering in a post operation? They will be soldering components that are moisture sensitive and cannot process through the cleaner so you will need a simple cleaning process for them as well. Let us not forget that you cannot just dump the waste water down the drain. Maybe you will need an evaporator to burn off any waste water from your process?

There are companies like Zestron or Aqueous Technologies who can help guide you in the right direction. Please remember, your flux manufacturer knows their flux chemistry better than anyone.

I hope this helps ;)

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Water wash flux and cleaning | 20 June, 2017

Thank you for the detailed input. That gave me material to think on.

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