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Contamination of the cleaning agent

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Contamination of the cleaning agent | 5 May, 2016

Hello guys!

I have a question for you guys, we have been working with a cleaning agent call Safewash (SWAS) from electrolube, we use this safewash to clean the flux residue from the boards after wave soldering, since or customer doesn't like to have flux residues on their board, we use a water base flux (AIM NC270WR), we use a ultrasonic washer, first the boards are place in the safewash and then we rinse them with DI water on both process we leave them for 10 minutes each, after that we dry them up for 20min@190F, we have seeing problems with the plating of the board, since the board has a ENIG finish some TH's are coming out looking not golden but silver, the golden plating is gone,we think that the problem has to do with the safewash being to contaminated and is peeling the gold plating, this creates a problem for us, we normally change the safewash which is not diluted every 2 months, but now we think that probably we need to keep a close look at the safewash and we need to do a test to confirm that the safewash is working properly, my question to you guys is this: What type of test we can do in-house to determine if the safewash is ok or needs to be change?

Hope you guys can help me!!!

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Contamination of the cleaning agent | 9 May, 2016

From the SWA data sheet--"SWA is ideally suited for the removal of flux resides and many other cleaning applications that do not contain sensitive metals and substrates. Used for cleaning metals prior to plating operations to provide an extremely clean and slightly roughened surface, allowing excellent bonding of the plated material."

From the SWAS data sheet--"SWAS is ideally suited for the removal of very stubborn flux resides and no-clean fluxes, which can be extremely difficult to remove."

Based on the data sheet information, it appears you are using a far more aggressive cleaning solution than you need to. Water soluble fluxes clean off much easier than no-clean fluxes do. My guess would be that the Safewash is removing the gold plating.

We do a similar cleaning process for our water soluble fluxes after both SMT load and selective solder assembly steps. We use an ultrasonic tank filled with tap water and 1 ounce of cleaning agent per gallon. After 15-20 minutes in the ultrasonic tank at 35C the boards are rinsed by hand using DI water. The cleaning agent we use is from Omegasonics --> Omega Aqua Clean LPH. The flux we use in our selective solder process is Kester 2235.

Our process cleans water soluble flux very well if cleaned within 24 hours of the boards being processed. We have sent boards off for cleanliness testing per standards with passing results. It does not clean no-clean fluxes. Fresh water with cleaning agent needs to be put into ultrasonic tank every 2-4 days depending on volume of boards cleaned. I hope this information helps.

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Contamination of the cleaning agent | 9 May, 2016

I asked Randi Gates, Electrolube Marketing to join us to help with the conversation.

Taking a step back from the Electrolube question, I could envision a 10 minute soak in DI water stripping the gold from a an ENIG board, you know, depending on the resistivity of the DI water and thickness of the gold. Just to help prove the point, drop a penny into your DI water. After 10 minutes, take the penny out of the water and observe that the penny is free of oxidation.

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