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Removal of No-Clean flux residue

Jeff Meier


Removal of No-Clean flux residue | 5 September, 2001

We have customers that are requiring no flux residue left on boards after soldering of non-water washable parts. We currently use Multicore Crystal 502 No-Clean to solder parts that are not washable. Has anyone come up with a good way to remove this flux residue other than trying to hand scrub with IPA and Flux-Off flux remover. It gets to be very labor intensive. Looking for ideas for ultrasonic or vapor degrease type cleaning methods. Thanks, Jeff Meier

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Sean D


Removal of No-Clean flux residue | 5 September, 2001

Hello Jeff,

If you have components on your board be careful of how low the frequency is that you will be applying to your board. Ultrasonics are great for cleaning stencils and bare boards at around 40kHz. These frequencies (and Lower)may however have negative repercussions to certain components. The last thing you want is clean but damaged components. You may raise your frequency for longer cleaning times at a less aggressive frequency or run multisonic cleaning with a combination of frequencies depending on the various products you are cleaning. A good contact for this application would be Steve Cramer (800-766-6606)at CAE Ultrasonics in Jamestown, NY ( I represent CAE in AZ and would be more than happy to help you locate your local representative for an application review.

Vapor degreasing can be affective depending on your residue yet the environmental setbacks lead alot of companies away from persuing the process. There are a number of cleaning methods that are more environmentally friendly than Vapor Degreasing. What's a little purging of the local fish population gonna hurt anyway?

There are a couple of other possibilities that also offer environmentally friendly cleaning options....

1. Centrifugal Cleaning: Speedline Technologies' Accel division provides the Microcel and Hydrocel centrifugal cleaners. These are capable of being configured for aqueous cleaning as well as with a cleaning chemistry of your choice. These modules will also dry their respective products once cleaned. A good contact to discuss this process per you application would be John Sanders at Accel (972-424-3525). For more information you can log on to

2. Jet Cleaning. For a lower cost batch cleaning module, the Aqua Jet by Speedline's Electrovert division operates as a programable batch jet cleaner for both boards and stencils. This unit is capable of handling various chemistries and I do have customers cleaning completed complex board assemblies with a great deal of success. The hurricane jet on this machine makes for an effective mechanism for propelling water along the surface of the board to remove contaminants. It also batch dries the boards as well. For questions regarding this platform you may want to call Bill Boyde of Electrovert (573-346-3341)For more information you can log on to

Each of these groups will run applications testing and quantify their results if you wish to provide samples. If you let the testing speak for itself these options should give you the results you're looking for.

Please feel free to contact me if you have any questions or concerns.

Best Regards, Sean D. 480-829-8170 ext. 14

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Kevin Facinelli


Removal of No-Clean flux residue | 6 September, 2001

This is a real problem. We have experimented with a number of off the shelf products as well as discussed the issue with a few solder manufacturers. As you are aware IPA or Flux off can make the product look worse. I would discuss with the customer the importance of the requirement...are they properly educated as to what is really left on the board after soldering. Please let me know what you come up with....especially if it is cost and labor effective.

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Removal of No-Clean flux residue | 6 September, 2001

Hi Jeff,

Sean is correct. Although ultrasonic technology will work in post-reflow de-fluxing applications, you will receive concerns regarding ultrasonic �damage� to wire bonded components. Much has been written to combat this belief but the concern remains alive and well.

Vapor degreasers are not much more than time machines set back about 13 years. They have their place in the manufacturing food chain but are not commonly used in your proposed application.

The most common approach to removing flux is with a spray-in-air system. This technology is available in batch-formats (clean a quantity of boards at once) or in an inline format (one board after another).

There are many manufacturers of these systems including:

Aqueous Technologies (batch and inline): Unit Design (batch): Technical Devices: (inline): EMC (batch and inline): Speedline (batch and inline): Austin America (batch and inline): Trek Industries (inline):

If you are planning on removing flux, it would be easier and less costly to remove water soluble flux. Although the removal of no-clean flux is common (our most common application), you will need to use a chemical additive in the wash water. If you are considering an inline system, this will raise the equipment price substantially as a chemical-compatible inline cleaner costs considerably more than a water-only system. Add to that the extra cost of chemicals and your overall cleaning costs skyrocket.

For batch format systems, the cost difference is less. Although it still costs more to clean no-clean boards compared to water soluble, the cost difference is not so alarming. One big question� What to you want to so with your used water? If you desire or require a closed-loop (zero-discharge) system, then it is less expensive to use water soluble flux.

Hope this helps!

Mike Konrad Aqueous Technologies

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Removal of No-Clean flux residue | 6 September, 2001

We're with Kevin.

First, there is hardly a worse cleaning solvent for fluxes than IPA. At the best, it will spread the soluble residue over a larger area, until it is thin enough to be invisible. This increases the surface area so that any dangerous contaminants, such as those ionic compounds that are soluble in IPA are more readily accessible to cause harm.

Next, IPA is VERY poor at dissolving the metal-organic salts formed by reaction between the flux and the oxides and will do so ONLY if it is virtually 100% pure => saturation occurs at ppm levels.

Remember, IPA is extremely flammable and its bulk use makes the plant liable to all sorts of quite repressive safety rules/regulations and so on. Ignoring these rules exposes the owner to fines and possible plant closure.

Using IPA for cleaning flux residues became popular because of: * Erroneous belief that what is used for formulating a liquid flux must be good for cleaning off the residues. * It improved cleaning capabilities of Freon and it was still on hand * Who knows?

... anyway, this forgets [ignores] that: * IPA can damage components and component marking. * SHeating to over 200�C modifies some flux constituents. * Chemical reactions occur during the fluxing process modify flux constituents.

Second, we too use nc wire solder for third ops soldering. Cleaning these nc flux residues is bad news. If the res can be cleaned at all, it requires a saponifier. Using a saponifier gets you into using an aqueous washer, which you don�t want to do with 3rd op components. You�re stuck.

Third, if your customer is not placated by chanting the �no benign residues of no-clean� mantra and this is a solid customer requirement, consider using a different flux in your wire solder that can be spot cleaned. Look at using a RMA and M.G. Chemicals [212-269-5533] "Safety Wash Cleaner Degreaser". We have no experience in this area. Check the fine SMTnet Archives for a contact of a SMTnetter [Genny] using Safety Wash to clean RMA. The thread is less than 6 months old.

Finally, using ultrasonic cleaners is not appropriate for some components. There is a thread on this in the fine SMTnet Archives. Continuing, usually people sink the board in a liquid when using ultrasonic cleaners. This gets you back to the not wanting to wash these components problem.

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Removal of No-Clean flux residue | 6 September, 2001

If I had to deal with this problem, I would switch to water soluble paste. It is a much more cost effective solution.

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Removal of No-Clean flux residue | 7 September, 2001


We use IPA and Prozone, if IPA is so drastically detrimental, to the pcba's.....what suggested alternative, can you please recommend, as IPA replacement?


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