Bubbles after coating

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Hi all, I need some pro help me with issue bubbles after c... - Sep 20, 2018 by Hai Nguyen

Hello Hai, The first step is to determine where in the pr... - Sep 21, 2018 by Michael Szuch

This chart is from ... - Sep 22, 2018 by davef

Hai Nguyen

#81076

Bubbles after coating | 20 September, 2018

Hi all, I need some pro help me with issue bubbles after coating. some information for some pro: Machine: Asymtek Chemical: Achime AVR80 Oven: IA 4 zoon4 ( setting 100 100 90 80 conveyor speed: 0.6 m/min). I had happened before and after the oven. We had trouble shooting: - Clean the nozzle, - Adjust nozzle height dispensing on PCB - Replace new fluid filter - Adjust fluid pressure - Removed coating material in the tank, and replace with new material. - Put the PCBA at conveyor 2-5 minutes before though IR Oven machine. but the issue still happens.

I think profile had a problem but I don't have experience about profile coating.

Now I don't have any idea troubleshooting for this care please help me. Thanks pro.

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Michael Szuch

#81090

Bubbles after coating | 21 September, 2018

Hello Hai,

The first step is to determine where in the process the bubbles are being generated - either during coating or during curing. You can easily check this by letting a few boards air dry (no oven) and comparing them to the oven-cured ones. If you only see bubbles after oven cure and no bubbles with air cure then the most likely root causes are 1) not enough solvent in the coating mixture, 2) wrong type of solvent in the coating mixture, 3) improper oven profile, 4) moisture contamination within the PCB itself.

What applicator are you using on the Asymtek coater? Are you using the recommended DVA thinner? What is your mix ratio?

Best regards,

Michael Szuch Senior Process Engineer Nordson Asymtek

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davef

#81091

Bubbles after coating | 22 September, 2018

This chart is from http://www.nordson.com/-/media/Files/Nordson/asymtek/Papers/Process%20Control%20and%20Traceability%20in%20Automated%20Conformal%20Coating.pdf?la=en

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