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SMT electronics assembly manufacturing forum.

pcba cleaning

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pcba cleaning | 29 October, 2019

how long i can keep pcba after bottom reflow soldering to top side reflow soldering. like 12 hours or 24 hour or 48 hours........Enig board. leadfree soldering with 10% flux

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pcba cleaning | 29 October, 2019

It depends on the flux type. If it's water soluble, it should be cleaned soon after reflow because OA flux remains active after reflow. If it's rosin or no-clean (low-residue), then the only concern is the longer wait time, the more difficult it will be to clean. The second reflow process will further polymerize the flux, making it more difficult to clean. We have experience cleaning assemblies days after reflow. It's just more difficult. It really depends on the cleaning machine/method, and the chemical additives used.

I hope this helps.

Mike Konrad

Aqueous Technologies

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pcba cleaning | 30 October, 2019

yes and thanks for this feedback.

we clean with degreaser ( strong) and flux is rosin with 10% in the paste (koki). we clean after second reflow . the gap time from bottom to topside completion is 10 hours. cleans with this time.

my even after 20 hour cleaning is good but after 30 hours i found flux residue ( hard flux).

once again my thanks to u bro.

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pcba cleaning | 4 November, 2019

There are multiple methods where you can perform top and bottom reflow soldering simultaneously. With this method, you might not worry about the type of flux there is. Each part is covered and baked as per the requirement, while making sure there are no cold spots around the region.

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