>But soon after cleaning and drying with IPA, we find a white residue formation. A: IPA will not nothing to clean your board. The white residue is exactly what you should expect. Search the fine SMTnet Archives for background.
>How do we avoid this white residue? A: If you want to avoid the white residue, stop using IPA. Your IPA is probably 50% water. Water will turn the residues of most "low residue fluxes" a cloudy, white color.
>Is there any other cleanres available that doe snot affect the plastic casings of SMT LEDs? A: Can't talk to your LEDs, but many people cleaning low res flux residues from boards use a saponifier. Saponifiers convert the flux residue to a soap, which you can wash from the board with water. We think good saponifiers suppliers are: * Kyzen * Envirosense
Mike Konrad has commented on the saponifiers that he likes in previous SMTnet threads and he'll certainly join-in shortly.
Other saponifier suppliers are: * Prozone * Axarel
If you want to do this down and dirty, using Cascade in agitation with your ultrasonic cleaner will probably remove the NC flux residue. Continuing points on this are: * Cleaning the Cascade residue from your boards is another story. * Ultrasonic cleaning assembled boards could damage components on your board. Search the fine SMTnet Archives for background discussion.
How about taking a deep breath? Assuming your customer is certain that they don't want NC flux res on their boards, consider: * Sending this current batch of NC flux res boards to a contract cleaning shop * Converting the process for on-going product to water soluable flux residues
Finally, not all low residue fluxes are cleanable.
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