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BGA corners curling up during rework install...

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#44733

BGA corners curling up during rework install... | 27 October, 2006

Just wondering if anyone has seen this problem before. We are using a 456 ball FPGA and during installation on our BGA rework machine the corners curl up causing opens there. The part was profiled with our KIC and matches the paste MFG spec. Is this a case of slowing and cooling it down to avoid shocking it and causing curl?

Thanks in advance

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#44737

BGA corners curling up during rework install... | 27 October, 2006

Josh: Search the fine SMTnet Archives for background discussions. For further discussion on the "being hosed by the physics": http://www.cooksonsemi.com/tech_art/pdfs/Controlling%20Warpage.pdf

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RDR

#44738

BGA corners curling up during rework install... | 27 October, 2006

I thjink you should bake these parts for 24 hours at 125C

I used to have this problem and I even think it was the same package to be honest. Since we started baking all BGAs for rework process regardless of "condition of storage" we have increased success rate substantially.

Hope it helps

Russ

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#44739

BGA corners curling up during rework install... | 27 October, 2006

Thanks a lot for the suggestions. I will try baking and see what develops. For the record the parts are stored in nitrogen atmos. under 5% RH. Doesnt mean they werent overexposed when they got here however...

JD

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KEN

#44749

BGA corners curling up during rework install... | 27 October, 2006

slow your heating ramp down. You are "tater-chipping" the BGA.

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#44750

BGA corners curling up during rework install... | 28 October, 2006

Agree!! Where is Your thermocouple-probes attacded and can we get the info from this? Delta-T of the comp. is very, very important! The single most important smt-process step is the profiling/recipy and as a result of this, this poor package will correspond accordingly. Yes, this sucker will cause You problems, but You can minimize those with a minimum of effort. The problem is not to get this package right alone on a pcba (which I think is somewhat easy), rather than get it right on a complex multi layer pcba with a lot of other component packages such as: chips, soic:s, tqfp:s, bga:s, dc/dc:s, connectors, etc.

Start to attach 3 probes; one on top of the comp. & one underneath thhe component, right on the solder ball snd one from the bottom (you need to drill thgrough.

We face this very same problem and our company's solution? Fix it and we don't want to hear about it! Haha, that is also a solution... /

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