Eric,

I would have a hard time accepting that also.

But one needs to know if you will flux or add solder paste.

Since the ball dia has a tolerance on it, this affects ball volume and
resultant total solder in the final ball solder joint.

Also the attachment pad on PWB has a process tolerance at manufacturer which
will very likely be not much better than +.000" and -.003" which equates to
approx 20% range in area variation. This also contributes to the final
height dimension.

Collapsed height will very likely be more like +/- 0.004"  or  +/- 0.005"


R. Kubes
Honeywell  DAS  Albq

> ----------
> From:         Eric Christison[SMTP:[log in to unmask]]
> Sent:         Tuesday, October 13, 1998 8:55 AM
> To:   [log in to unmask]
> Subject:      [TN] Tolerance on Collapsed height of BGA Balls
>
> I am having difficulty in believing something a packaging engineer is
> telling me.
>
> We have a design of sensor which is now BGA packaged. The balls are 0.030"
> diameter and 0.023" high.
> After reflow I am assured that the collapsed height will be 0.019"
> +/-0.001"(given a correctly
> dimensioned footprint) . I have no problem with the 0.019", it's the
> +/-0.001" that stretches my
> credibility threshold.
>
> Is there anyone out there that can confirm or deny this tolerance?
>
> Regards,
>
>
>
>
> Eric Christison
>
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