Un-Reflowed Paste

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We are seeing un-Reflowed paste along the IC leads. There is... - Jul 26, 2004 by

How do you know that those specks of solder have not been re... - Jul 26, 2004 by davef

By looking at the solder balls they have not joined with the... - Jul 27, 2004 by

Hello , I agree with the solder ball theory, we used to hav... - Jul 27, 2004 by carterhoward

It would be uncontrolled reflow process. Solder paste smeare... - Jul 28, 2004 by

> We are seeing un-Reflowed paste along the IC > lea... - Jul 28, 2004 by

It would be uncontrolled reflow process. Solder paste smeare... - Jul 28, 2004 by

Both temperature and humidity can cause solder paste to beha... - Jul 28, 2004 by

Chris C

#29662

Un-Reflowed Paste | 26 July, 2004

We are seeing un-Reflowed paste along the IC leads. There is only a very small amount imbedded in the flux, typically there is about 10 beads per lead. But on most leads. We are using no-clean Kester 256 paste (Easy Profile)We have not encountered this until this summer. Any Ideas?

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davef

#29669

Un-Reflowed Paste | 26 July, 2004

How do you know that those specks of solder have not been reflowed? Could it be that what you are seeing is reflowed solder ejacta from a poorly controled reflow process?

While not as prevalent problem with NC as with water soluable, moisture in the air can lead to solder balling. Search the fine SMTnet Archives for other drivers to solder balling.

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Chris C

#29695

Un-Reflowed Paste | 27 July, 2004

By looking at the solder balls they have not joined with the other particles that are alongside them. suggesting that they did'nt reflow. But they could very well be as you suggested, reflowed and ejacta from the process.

We have been experiencing very high humidity, which is difficult to control.

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carterhoward

#29696

Un-Reflowed Paste | 27 July, 2004

Hello , I agree with the solder ball theory, we used to have an issue with high humidity and it produced the results you�re describing. Our solution to this since adding dehumidifiers was too costly was to increase the quantity of intake ducts for the A/C and spread them around the room, basically using the a/c to dehumidify. One thing I do suggest is to invest in a logging meter one that does temp and humidity OMEGA is a good source for these, it�s very helpful to track the temp/humd and cross check against the product.

Hope this helps

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NTV

#29709