Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


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Cleaning "No-Clean" in a Non-Aqueous Process | 22 August, 2011

I am looking for a methods to clean boards built with a "No-Clean" flux but the boards have non-hermetically sealed parts on them, therefore they cannot be exposed to an semi-aqueous process (what I typically use). These boards will be built in large enough volumes that manual cleaning is out of the question.

I have heard of vapor degreasing and am familiar with it in regards to metal fabrication but have never used it or seen it in an electronics manufacturing facility although I know it has been used. Is this the way to go? Or am I missing something? Any suggestions, knowledge, etc would be greatly appreciated.


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Cleaning | 22 August, 2011

How many non-hermetically sealed parts does each board have? If it is only 1 or 2, could you attach them AFTER an aqueous cleaning process?

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Cleaning | 23 August, 2011

There are only two (2), but the qty and size do not really prohibit hand soldering and we would still need to clean around their leads manually to meet the cleanliness spec.

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Cleaning | 23 August, 2011

vapor degreaseing has two main flavors mono solvent and co-solvent. the later being the best performance

Yes can clean PCB and in many ways is best in cycle time and cleaning quality.

Is batch machine based usually or automated batch if budgets allow.

Used solvents can be vacuum distilled and some material recovered for re-use.

Also uses less energy than water based systems.

So yes can clean electronics in vapor degreasing but have to do home work on plastics compatibility with target chemistries etc

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Cleaning | 25 August, 2011

Ryan, Another option to look at would be ultrasonic cleaning if your boards/process would allow it. Automated multi-tank models with wash, rinse and dry capability are available for larger throughput. Typically both wash and rinse tanks have ultrasonic and heating capability. No-clean fluxes respond better to slight alkalinity and any solvents with alkaline components would work better in removing the no-clean contamination. This would necessitate rinsing however. For a water-free process, you could rinse with IPA which will also enable faster drying.

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Cleaning | 31 August, 2011

Vapor phase or vapor degreasing cleaning for electronics is simple technology that holds merit on process situations like you described. Easy and quick to set up and process with today's modern equipment you can be up and running in no time once the machine is on your floor. The hard part comes from matching the flux to the cleaning solvent. Many of the newer flux and solder paste formulas used today are very resistant to vapor phase cleaning. OA flux formulas are out as they do not clean with vapor phase cleaners. To compound this flux selection process the number of available vapor degreasing solvents available today has boiled down to just two major chemical choices. This will make flux selection critical to insure that it can be removed using a solvent. The cleaner must match the solvent to insure a 100% clean part. Ryan if you would like more details please contact me off-line.

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Cleaning | 31 August, 2011

My company is reviewing cleaning methods and I read your blog and was left wondering. What is Non-Hermetically Sealed Parts mean exactly. If this is something I need to know moving forward with clean solutions can someone tell me what these types of parts are.

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Cleaning | 31 August, 2011

I am quite busy currently, but expect a message from me next week on this topic. Thank you very much for you help.

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Cleaning | 31 August, 2011

Non-Hermetically sealed parts are parts are not air tight and gasses and liquids will pass into the package of the part and come in contact with the electrical or other components within the package (i.e. some switches, relays, transformers, etc.)

Def: A hermetic seal is the quality of being airtight. In common usage, the term often implies being impervious to air or gas.

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