Ultrasonic wash for BGA

Now you are putting your assembly to vibrate with frequency of 30-60kHz. What kind of flux/paste are you using? If it is NC there is no reason to clean. If it is water wash, you should consider a proper way of cleaning it according to your paste/flux manufacturer(I don't know if the ultrasonic that will be).

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Consider ...

* National Physical Laboratory (NPL) [http://www.npl.co.uk] did an extensive amount of research on proper frequencies and power levels for ultrasonic cleaning, maybe in late 1980s or early 1990s. That report might help you sort through your questions.

* Many component suppliers comment on ultrasonic cleaning in there part description and application sheet.

* Ultrasonic cleaner equipment suppliers often provide user instructions on how best to use their equipment.

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Thank you for your replies. We use No-Clean Paste and some customers do not want any residue left around solder joint even so, so little. They want the residue washed completely. If we use water-soluble flux, we still need to wash, anyway. Their concern is the residue could cause failures later in future in some certain application conditions. We use de-fluxer/ flux-remover solution with ultrsonic washer. We already did some tests, no failure found after wash, physically and functionally. We still wonder ultrasonic wash could cause any harm to the product and the part?

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We did some tests with good result. No failure physically and functionally. Is there report/study/documents about this procedure so we can convince customer to approve our process using ultrasonic wash. Thank you, Dave

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