In a message dated 02/22/2000 12:30:42 PM Central Standard Time,
[log in to unmask] writes:

<< Has anyone used square apertures for micro-BGA ?  What are the advantages
 over round apertures ?

 Thanks.

 Gener Arciaga
 Manufacturing Engineer
 Aimtronics Corporation (Delta, BC)
 Direct (604) 940-5751
 Pager (604) 296-8632
 [log in to unmask] <mailto:[log in to unmask]> >>

Hi Gener!

Yep, I do...that's all I use. You get a few things; 1). Better paste release
from the stencil. 2). A teeny bit more volume for the joints (make the square
dimension the same diameter as your pads) 3). A little bit of "slop-factor"
for placement, as long as the balls are in the paste, the part will
self-center during reflow.

I originally got this from Tessera's web page (http://www.tessera.com) and
tried it, had so much good results with squares I use it everytime now...

-Steve Gregory-

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