Charles Barker@I-O INC
12/16/97 10:01 AM

     I know some questions have been asked and some comments returned to
the 'net, but I still don't have clear in my mind whether of not or the
best way  to try to close up via's under BGA's. Many folks said "Don't do
this or that," but few have said "Do THIS!"
     We are using LPI for our main mask. Board will have smd top and
bottom, some thru-hole parts on top too. Process will be:  Screen Solder
Paste-Place-Reflow-Clean on top. Screen adhesive-Place-Heat Cure-Stuff
TH-Wave-Clean the bottom.
     Our Engineering is putting the finishiong touches on this board with a
352-BGA with "dog-bone" pads on topside under the BGA. Should the vias be
tented or plugged? Some time ago, someone on the 'net said they had found a
new way to plug the vias without trapping contaminents. I requested more
info from them, but have not heard back and have lost their address.  This
particular board will NOT be run through an ATE. Future boards with higher
run numbers will go thru ATE, so we need to have our house in order from
the beginning.
     Input will be greatly appreciated.
TIA
Charlie B.

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