| I am beginer in BGA assembly and am confused in selection of pick and place option. As per book on 'implementation of BGA Technology-by 1995 aeic inc. states that BGAs reflow is quite forgiving and you need only Mechanical centering of PBGAs. The IPC-STD-013 states that CPk for a typical 50 mil BGA 256 pin is .68 with mech centering and over 1.5 for BGA ball image alignment .I do not know if somebody is using mechanical centering as alignment method with high BGA yield.Jedec standard the true position of balls wrt edges shows +/-12 mils tolerance in addition to ball dia tolerance.
I've used mechanical centering with great success on my Mydata TP9-2U. The BGA was a ceramic package and the pads were on 50 mil centers.
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