We are a contract assembly house whose customer is in the process of
designing the MicroStar 144 package into one of their products and are
asking us if we can assemble it. This would be our first uBGA, so I would
also be interested in any assembly issues dealing with Frank's email. Also,
does anybody know of a good source of dummy components (at least similar to
the MicroStar 144) and practice boards for this package so that I can test
this with our surface mount machines.

Thanks,

Tim Stammely
Manufacturing Process Engineer
MSI
Manassas, VA
> -----Original Message-----
> From: Winiarski, Frank [SMTP:[log in to unmask]]
> Sent: Tuesday, October 13, 1998 1:31 PM
> To:   [log in to unmask]
> Subject:      [TN] Help with design and assembly of Micro BGA's TI
> "MicroStar"  and Tessera uBGA style
>
> We are in the process of designing a board with a large number of both
> "MicroStar" 144 ball packages from TI (.8mm ball spacing) and another
> part using the Tessera style uBGA (.75mm ball spacing) .
>
> There is a TI application note available which gives a few guidelines.
> Tessera has quite a bit more on their web site.
>
> In speaking to a current, high volume user of the TI part he indicated
> that it took quite an effort from design thru the test to develop their
> processes to accomodate this part.  He mentioned that the part was very
> "fragile" and that there were reliability issues to be concerned with.
> Unfortunately, most of this info was "proprietary" and he couldn't share
> the details.
>
> If any of you have had any experience with either of these packages, or
> micro BGA's in general and would be willing to share your knowledge, it
> would be greatly appreciated.  We know that it will require micro via
> technology in the PCB which will be a first for us.  Our contract
> assembly house has not had experience with micro BGA's yet, though they
> are willing and anxious to get the experience.  And our PCB design house
> is also learning how to design with micro via's.
>
> Thanks.
>
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