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No-clean SMT process and water wash (Clean) repair

Fluxed_State_of mind

#34487

No-clean SMT process and water wash (Clean) repair | 25 May, 2005

Need some input here.....

The fear is that the if we use water soluble flux at the repair operation, that the no-clean encapsulation will capture some of the organic material as it cools down and goes to its original state. The organic material will not be able to be washed off. I am thinking that between the flux and the additional heat cycle, that there will be very little of the remaining encapsulation material left - if any at all.

Any thoughts? Has anyone done any SIR tesing?

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RDR

#34489

No-clean SMT process and water wash (Clean) repair | 25 May, 2005

We have passed testing using this process, I would consider it on a case by case basis however. We are very careful about the quantity of the O.A. that we use. The water soluble flux is gone after cleaning unless it was/could be encapsulated or trapped somewhere where it cannot be exposed to the water sufficiently.

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#34590

No-clean SMT process and water wash (Clean) repair | 27 May, 2005

You do want to be very careful with potentially entrapped organic materials as they are prone to causing electrical leakage failures particularly around sensitive devices. There is a new clenliness testing tool available that tests a localized area of circuitry such as a site prone to entrapment to see if there are organic acids present as well as other ions that could cause potential problems. The tool also extracts a sample to use in an ion chromatograph if it's findings are considered dirty. You can find out about this tool: http://www.residues.com/C3.html

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