I realize some people are against x-ray (personal preferences!), but I
for one am for it.  The one thing that must be remember though, is that
I am unaware of any x-ray system that has the capabilities to detect an
open.  Even the most expensive does not support any algorithm that
checks for an open solder joint, the most it can do is check for
insufficient amount of solder (even that is not necessarily an "open").
both laminographic and transmissive x-ray cannot define the area where
the solder meets the pads well enough to determine opens.

For the time being, electrical testing is the best way to detect opens
(my opinion)

Sean M. Heffernan
Quadrus Manufacturing
[log in to unmask]


> -----Original Message-----
> From: Paul M. Quintin Jr [SMTP:[log in to unmask]]
> Sent: Monday, September 14, 1998 2:48 AM
> To:   [log in to unmask]
> Subject:      [TN] BGA opens.
>
>      I would have to say you are correct, the testing for opens on
> BGAs is difficult, even with the HP 5DX machine we have here. I can't
> recall having seen a single open joint on a properly reflowed
> collapsible BGA, but we have seen them on non-collapsible.
>      How would you attempt to verify that the package is parallel to
> the board surface? I know some of the OMPAC plastic packages that we
> use will occasionally be lower in the center than the edges, although
> not by very much.
>      I look forward to other comments from Xray users about this
> subject.
>      Paul Quintin
>      Data General
>
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