I think it is critical to train in the basic fundamentals, as applicable. Handling after the wash is critical;



1. Ensure a good blow-off of any remaining water is performed, and explain that even after a good wash and rinse, CCAs should never be allowed to sit with standing water that can evaporate, leaving behind white residue in the form of suspended flux particles, minerals, etc. This is applicable to most in-line cleaners, perhaps not for many batch (non-conveyor) cleaners which typically perform a drying function within the chamber at the end of the final rinse. A good blow-off or drying cycle takes any remaining contamination off of most of the CCA with the leftover water.

2. Never package wet CCAs directly into closed ESD boxes, bags, or other packaging. This ensures creep corrosion, etc., etc,.

3. A section on saponifier mix verification, typically done with in-situ process analyzers, or whatever method the saponifier manufacturer recommends. Information on how the ventilation of the cleaner can cause changing mix ratio levels, etc

4. Matching of the cleaning process for the flux(s) used. Considerations to be given to using batch cleaning with an appropriate saponifier or solvent for non-water soluble fluxes, and perhaps an in-line conveyorized machine for soluble. Or vice-versa, dependent on the typical product mix.

5. Why the cleaning process should ONLY be used for cleaning fluxes and "normal" soils, and not for cleaning carburetors, smocks, removing of the wrong adhesive (uncured), cleaning of newly-machined shop fixtures/tools covered with silicone-bearing cutting grease or oils.

6. Prevention of silicone contamination in general. Nothing like an operator cleaning heatsink grease as part of a rework procedure to screw up your wash process permanently. Just try coating boards after they have been washed in a silicone-contaminated cleaner. Such fun!



I will think of more, whether you like it or not, LOL!



dean





-----Original Message-----

From: TechNet <[log in to unmask]> On Behalf Of Douglas Pauls

Sent: Wednesday, February 26, 2020 6:43 AM

To: [log in to unmask]

Subject: [TN] Cleaning Course of Study



Good morning Technetians



OK, so I have been thinking (and we know how dangerous that is) about developing a course of study for someone to become a "cleaning expert".

Something along the lines of starting with a new hire and educating the new hires up to my level. Courses would include things like flux chemistry, cleaning processes and chemistry, cleanliness measurement methods, SIR methods, etc.  What items would you suggest be added to the course of study?



*Douglas Pauls *| Principal Materials and Process Engr | Advanced Operations Engineering



*COLLINS AEROSPACE*



400 Collins Road NE, MS 108-101, Cedar Rapids, IA  52498  USA



*Tel:* +1 319 295 2109 | *Mobile: *+1 319 431 3773



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