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Cleaning a No Clean

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Cleaning a No Clean | 13 January, 2011

We have a customer whom we have built boards for. They want a "cleaner no clean look".

The process uses a no clean Kester 256 SN63 solder paste. After reflow the "residue" noted by the client is too much. We have tried a few things. We are a small shop with a closed acqueous cleaner. We have gone over the myriad of reasons why the customer is asking for something the materials were not designed to deliver. The customer is always right so.....

What do we do given that we do not have a cleaner that can take a saponifier? We could hand clea or we have a small sonic bath..


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Cleaning a No Clean | 13 January, 2011

Not sure this would be of some help, but in the past I worked in the OEM industry in a fully No Clean process using A*M NC Solder.

If customer expectations cannot be tempered, you're stuck cleaning the No Clean.

To remove the NC residue, (which we did for no other reason than our customers wanted it that way), we used a combination of a Dupont Vertrel (or an analogue thereof ) soak for 10 minutes followed by an DI water wash with a saponifier and 'sonics for 10 minutes, followed by a DI water rinse and blow dry, and then a bake for 20 minutes at 100C. Watch the rating of your sonics, there are some frequencies that can be harmful to some devices. Using this method worked great and left the assemblies looking very nice.

Ultimately we went to a Vapor based system for the Vertrel portion, and stayed with our 'sonic DI wash and rinse.

I feel your pain...customer expectations. The customer wants quality! What is quality? Quality - it is the sum of the customer expectations, really. Anything that is a reduction of the customer expectations is not quality. Literally in most cases.

Best of luck `hege has no affiliation with any company mentioned above.

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Cleaning a No Clean | 14 January, 2011

isopropyl alcohol and a toothbrush! =)) seriously. If you do not have a washing machine - no problem. Incidentally, both military and medical equipment are always clean no clean paste - This process greatly improves reliability.

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Cleaning a No Clean | 14 January, 2011

There is a lot of information available about cleaning no-cleans. Takes chemical, mechanical and thermal energy. Find the right chemistry for the flux (not something like IPA that will most likely just smear the residues around and cause problems later.) Then, find a manual or mechanized approach to apply some physical energy and maybe some heat to the chemistry or board to help with cleaning.

Regarding the posted suggestion for the definition of quality, 'sum of the customer expectations', I suggest a definition of quality equaling the expectations of the seller.

Shean Dalton

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Cleaning a No Clean | 14 January, 2011

Contact Zestron. We have cleaned many different solder pastes, including 256, over the years using Zestrons products. They will steer you in the right direction using the equipment you have.

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Cleaning a No Clean | 14 January, 2011

I much prefer your definition of quality SheanDalton. LOL

But customer expectation is King. They expect a certain thing, be it good looking solder, lack of NC residue, perfect FAI documentation, and of course the old silk purse out of the sow's ear. (Here's a bag of parts... build me a class III flight mechanism) Anything less than their expectations brings them quickly to our QA Group!


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