Hi All,

I've been one of the lucky ones who hasn't had to deal with high ball count
BGA's (1900+ balls) until now. I have a 1936-ball BGA that we are looking
to assemble. I was able to get a couple of mechanical samples so that I
could use them to dial my reflow profile in. When I got them, if I said I
was surprised, that would be an understatement. This thing weighs close to
an ounce with the heat spreader (23.133-grams):

http://stevezeva.homestead.com/1936_Ball_BGA_with_Heat_Spreader.jpg

So I remember reading threads on the Technet about shimming heavy, high
ball count BGA's in the corners with something to keep the weight from
squishing the balls out and causing shorts, I know that can happen because
I have seen it on 1152-ball CBGA's from Xilinx.

Is there anybody willing to share some tips about assembling these beasts?
At least I have a couple of mechanical samples I can play with before I
dive in with live product....these are spendy.

Steve

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