BGA underfill

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My company is looking for an IPC expert consultant in BGA un... - Sep 20, 2011 by Justin

You might find a lot of experience in the forum here, but ma... - Sep 22, 2011 by Hegemon

Underfilling BGA is an uncommon practice. We'd start looking... - Sep 22, 2011 by davef

Justin

#65062

BGA underfill | 20 September, 2011

My company is looking for an IPC expert consultant in BGA underfilling to support an important contract that is being prepared. We are looking for someone with hands-on experience with large (~2"x2", with as much as 1800 pin, 1mm pitch, 0.5mm ball diameter) BGA underfill that knows how to avoid creating any voids and can help us develop a process capability that is full-proof, production friendly and associated with a comprehensive validation/demonstration program.

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Hegemon

#65077

BGA underfill | 22 September, 2011

You might find a lot of experience in the forum here, but maybe not so many consultants for this niche.

BGA underfill is not rocket science, and in my opinion, the key items are the material chracteristics, and the dispensing method and pattern.

For an example: A particular underfill material is dispensed with the PCB surface temperature maintained at 80C. At that temperature, the material stays thin, and will be pulled beneath the BGA by capillary action. The trick is in dispensing a line on two consecutive sides of the BGA, and replenishing those 2 lines as the material is pulled beneath the BGA, without allowing any air to be pulled in as well.

Truly, unless you are working with automated dispensing, this is more of a trial and error until you find the correct material, use the correct associated temperatures, dispensing timing, needle diameter.

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