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BGA bake out....

#29286

BGA bake out.... | 28 June, 2004

Morning all, we have been seeing some problems with the edges of some of our BGA's curling away from the PCB after reflow. Is this possibly a moisture problem? If so what would be a good time/temp to bake them at to rectify the problem?

Thanks in advance JD

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#29288

BGA bake out.... | 28 June, 2004

The answer is yes, it is possibly a moisture-related problem. You can confirm this by baking your parts at 125C for 48 hours (ref. J-STD-033A, table 4-1).

For more technical background on this issue I recommend you read the following paper :

Impact of Ingressed Moisture and High Temperature Warpage Behavior on the Robust Assembly Capability for Large Body PBGAs - ECTC 2003, Shook and Al., Agere Systems

I can send you a pdf copy of that paper if you are interested.

Francois Monette Cogiscan Inc. Tel : 450-534-2644 fmonette@cogiscan.com www.cogiscan.com

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#29290

BGA bake out.... | 28 June, 2004

Yes please send a copy of that paper as I dont have access to the 033 STD. That would be great, thanks a lot. jdumont@astromed.com

JD

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#29292

BGA bake out.... | 28 June, 2004

There multiple potental causes of BGA curling during reflow. One of them is moisture inclusion in the part, as Francois mentiones above in this thread. Another has to do with the construction of a BGA.

So, from our perspective, more often the moisture absorption, a materials mismatch in the fabrication of the BGA causes this potato chipping, that you are seeing. For more: * We've commented on this previously on SMTnet http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=27586

* For further discussion on the "being hosed by the physics": http://www.cooksonsemi.com/tech_art/pdfs/Controlling%20Warpage.pdf

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#29293

BGA bake out.... | 28 June, 2004

JDumont: In trying to find the paper that Francois referenced, poke around his site [ http://www.cogiscan.com ], where he's collected a bunch of papers on the control of moisture sensitivity in components.

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#29294

BGA bake out.... | 28 June, 2004

Yes i was looking around that site this morning and found everything i needed. Thanks to all. Basically what im trying to do is justify the expenditure of a new NO2 generator for our IC cabinets. Ours died a little while back and we have been using nothing since. I should be able to write something up now with all this new technical info.

Thanks a lot!

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#29295

BGA bake out.... | 28 June, 2004

If you dont mind me asking, what are you guys using to keep your IC's dry??

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#29296

BGA bake out.... | 28 June, 2004

McDry seems be a good unit to consider.

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#29297

BGA bake out.... | 28 June, 2004

Oh, you posted something about that a couple of weeks ago. Nice that you have the justification, too bad that's the way you needed to get it.

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#29490

BGA bake out.... | 14 July, 2004

Feel free to also take a look at http://www.drycabinet.com We provide Dry Cabinet and Dry box storage solutions to keep MSD 's below 5% RH. You can also reach us by visiting http://www.totechamerica.com

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