Hi Stephen!

When you say elongated BGA's, do you mean the spheres are elongated? Is it
all the spheres, or just in a certain area? Are they elongated in the "Z" axis?
Or more "squished" looking? Was the assembly built using a double-sided reflow?

If they're elongated in the "Z" axis, that is a good thing. An increase in
stand-off height has been shown in many studies to increase solder joint
reliabilty in BGA's.

-Steve Gregory-
I have been asked recently about the presence of elongated BGAs after card
assembly of a module to a PCB.

I am struggling with what reliability impact, if any, that they represent.
In addition I am looking for a list of reasons the condition can occur.

The ones that I can think of are:

- excessive warping in module when exposed to reflow temperature
- excessive moisture in module due to improper storage
- incorrect reflow parameters

Are there others?

Thanks.

Stephen Ayotte, IMD Manufacturing Quality Senior Engineer
Dept. N62V, Bldg. 966-2, Office 2J1309,   Mail Drop 967A

Phone (802) 769-4775,    t/l 446-4775,  Fax (802) 769-4139
Pager (802) 878-5386 Pin #4685 - external,    74685 - internal

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