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minimum solder ball (bead) size

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#41941

minimum solder ball (bead) size | 1 June, 2006

Just wondering if anyone knows this off the top of there head. I might be able to figure out the math based on surface tension (this is 63/37 so the data is out there) but I REALLY do not want to put that kind of effort into this. :/

Editing to clarify that I'm looking for what is physically possible, not what is allowed/typical/problematic.

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Chunks

#41986

minimum solder ball (bead) size | 6 June, 2006

IPC 610 says acceptable Class 1 (Class 2, 3 indicator) if they are entrapped/encpsulated balls within 0.13mm of lands or pads. or exceed 0.13mm in diameter.

Defect Class 1,2,3: Solder ball violates min electrical clearance.

Solder balls not entrapped/encapsulated or not attached to a metal surface. (?)

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#41992

minimum solder ball (bead) size | 6 June, 2006

Yep. What I'm really looking for is the minimum radius of curvature for 63/37, which is a function of it's surface tension. It's physical properties issue, not an agency issue.

I've seen some references that I have interpreted to mean that it's somewhere in the neighborhood of 2.2mm but I'm not quite sure. Missing parentheses sure put a damper on formulaic interpretations.

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Chunks

#42003

minimum solder ball (bead) size | 7 June, 2006

In the past, I would normally tell out highly talented inspectors to leave the balls there. The were trapped in the flux residue and were hard to remove. Never caused a problem. But then there was an incident where someone had the bright idea to use a pick and knock the solder balls off. Unfortunately we had a bin of another product under this table and those little solder balls managed to find their way onto the product in the bin, causing a field return. That sparked a reorder of home plate style stencils to eliminate the balls all together. Now we're ball free.

Wow, a jwob where no balls is better than small ones! Go figure.

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#42008

minimum solder ball (bead) size | 7 June, 2006

We do not understand the question. Take a deep breath, remember not all of us are trained as geologists.

The smallest solder ball we've seen is a little less than 5 nm.

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#42009

minimum solder ball (bead) size | 7 June, 2006

Ha ha! davef finishes you guys off again!

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#42012

minimum solder ball (bead) size | 7 June, 2006

Similarly, we have eliminated solder balls by using an aqueous washer.

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#42026

minimum solder ball (bead) size | 8 June, 2006

Awwww, man.

I was looking for something a little less on the anecdotal side for our local municipality's environmental stewards.

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