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Grey Solder After Cleaning

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#85793

Grey Solder After Cleaning | 19 October, 2020

I have seen a post or two about this but I haven't found a definite answer. My company recently has had random batches coming out of the Aqueous Wash with grey/dull solder. This has been an ongoing issue, we have replaced basically everything in the machine that we are able (filters), and cleaned as much as we can. We did find that it seemed pretty dirty inside but it is basically spotless now and still giving us grey solder. Again, this is not like every job coming out of the machine has grey solder, everything will be fine and then at one point in the day, one job will come out dull or sometimes a bad grey/black. I have heard wash time could be an issue, we have been typically running our wash for between 20-30 minutes with our concentration at 13%. The owners of the company wanted us to check the PH levels but I am unsure of what we are looking for exactly in terms of PH. From what I was reading, the level should be about 10-11? I want to confirm if I am looking at this right. Any help would be greatly appreciated.

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#85796

Grey Solder After Cleaning | 20 October, 2020

Most often, dull solder joints (post cleaning) is a result of the cleaning chemical. Most (not all) modern cleaning chemicals are equipped with corrosion inhibition agents which prevent dulling. Check with your chemical supplier to see if your specific chemical is equipped with corrosion inhibitors. Most chemical suppliers offer a corrosion inhibitor as a sump-side additive as well. Also, evaluate how long your assemblies are subjected to the wash cycle. In an inline cleaner, that's a function of conveyor speed. In a batch cleaning system, it's a function of the programmed wash time. Your wash cycle may to too long. Dulling may be exacerbated if the wash temperature is too high. Contact your chemical supplier for more advice.

Mike Konrad

Aqueous Technologies

konrad@aqueoustech.com

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#85797

Grey Solder After Cleaning | 20 October, 2020

That makes sense, I am actually talking to the chemical supplier as we speak. I heard a couple of times about the time of the wash cycle, so I will also tweak that and see if we can resolve this. Thanks for your help.

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#85798

Grey Solder After Cleaning | 20 October, 2020

I think temperature is the most under appreciated parameter. I'm not saying that it is the most important parameter, Just that a lot people do not give it the consideration it needs. I don't think it mattered as much in the old days of saponifiers and simple solvents. (it still mattered just not as much as today) Now the chemicals are blends of chemicals with different functions not just making soap and dissolving stuff.

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#85799

Grey Solder After Cleaning | 20 October, 2020

I believe we are running most jobs at around 140°F on the wash cycle (which seems to be average from what I hear). We did find one job that we were running very hot at 160° F (at customers request) that could be an issue.

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SMTA-64386500

#85810

Grey Solder After Cleaning | 22 October, 2020

Hi John - send me an email (david.hillman@collins.com) and I can send you a few photos of what Mike K. was describing in terms of the solder joint surface being "etched" by the cleaning solution. The dull appearance is due to the abundance of lead oxide on the surface as the tin oxide, which is usually what we see, has been etched away.

This message was posted via the Electronics Forum @ SMTASMTA

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#85814

Grey Solder After Cleaning | 23 October, 2020

John & SMTA-64386500 ... Please post your photos here on SMTnet. So that we all benefit.

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#85828

Grey Solder After Cleaning | 23 October, 2020

We may have resolved this issue (fingers crossed) We had someone come out and they informed us that our refractometer was broken. Our measurement of 13% was actually closer to 18-20%. Since making the adjustments our solder has been running much cleaner. I attached a photo for an example of the "dirty" solder we were seeing. This particular picture was likely our worst case. For the most part it was just dull/grey on the solder. I unfortunately cannot find a picture of the normal situation that we were having.

Attachments:

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 Reflow System

water-based, pH neutral electronics cleaning agent