I think Guy got it right. Relooking at the recently posted board level
photos and comparing them with the CSP images, it seems clear the solder
balls were detached and became part of the board columns. Hence, the
following exchange:

How did you get those images? Looks like the image of a collapsed solder
ball with the BGA removed.
Were the CSPs installed using solder paste or tacky flux? Are we looking at
the bottom of the CSP or the board?


My dear friend,

I told you it was really exciting stuff. I got the images with my trusty
rusty Intel Play microscope after cutting the hell out of the printed circus
board.

You are looking at the PCB surface and what I believe to be solder paste,
but how can that be when adjacent component solder joints were formed but
cold. The solder balls never wetted or collapsed. The solder columns still
are visible with solder balls seemingly in suspension unless I don't know
about that which I'm talking.

As the device solder balls did detach, maybe we are looking at them and not
just solder paste. That's why I posted them so informed folks like you could
rationalize the situation.

Keep the information coming. Also, revisit the CSP photos taken from the
bottom of the device showing clearly they detached.

What's going on here?

MoonMan


Guy,

I just went back and looked again. You have to be right. The balls detached
from the device and are shown present on the board's solder termination
areas.

Thanks for the observation,

MoonMan

So, back to ground zero. How could those balls detached in such a way? TI
has promised the problem is solved though they admitted too thick an IMC
layer was to blame

MoonMan

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------