Blanchet,Richard wrote:
>
> Hello,
>
> As we hear more and more about BGAs, my perception is that there's some
> issues to be improved. From a military/high-end commercial application stand
> point, I have the following questions:
>
> 1- Do people put a lot of vias under BGAs to perform ICT or do they just
> perform functional tests ?
>
        Our normal approach is to be using plugged/tented vias,
        usually one per ball pad (full fanouts).

        For ICT we add a one-sided test pad on 2ndary side as in
        directly under the ball pad.  Of course we prefer to dis-
        tribute the testpoints across the board, but when we must
        probe at the BGA package that is how we do it.

--

      Jeff Seeger                             Applied CAD Knowledge Inc
      Chief Technical Officer                      Tyngsboro, MA  01879
      jseeger "at" appliedcad "dot" com                    978 649 9800

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