HI Joseph,

can you shear us some information about reliability of such BGA or CSP
compared with standard TSOP packages soldered on board?

It will interessting to get a feling about the advantages of this
technology.

Greetings
Achim

Joseph Fjelstad wrote:

> Hello Bev,
>
> You had a very complete set of options for Sven-Erik but there is
> another
> option that is also making its way in as an alternative, the µBGA®
> CSP. It
> offers a compliant structure that mitigates the stresses resulting
> from the
> CTE mismatch between the silicon and FR-4 that Werner Englemaier has
> been so
> long warning us all about. In addition, it has a coarser lead pitch, a
>
> smaller proilfe and a can be placed using a chip shooter at rates up
> to
> 20,000 uph at near 100% yields. While presently aimed primarily at
> packaging
> flash memory, it is being targeted to replace the existing TSOP
> packages by
> a number of IC manufacturers around the world based on the demands of
> their
> users.
>
> Cheers!
> J. Fjelstad
>
> >Sven-Eric,
> >TSOPs on FR-4 with a high daily temperature swing are not reliable.
> >There are many papers out in the open literature that substantiate
> this.
>  >Recently Jean Paul Clech (hope I spleed that right) had a little
> >article in the SMT newsletter saying as much, also.  I am also sure
> that
> >Werner Englemaier, another reliability expert, would also agree.
> >
> >You have several options
> >1) ignore the problem and hope that your product becomes obsolete or
> >breaks for another reason
> >2) go to Thermount (aramid) or Ceracom (ceramic) boards
> >3) lower the temperature swings of your product (eg don't sell you
> >portable phone in Minneapolis)
> >4) use a different part type (eg SSOP)
> >5) embed the leads in a underfill material (so far not reworkable,
> >although rumors have it that we should see something in this area in
> >1998)
> >6) get TSOPs with the longest, thinnest leads possible
> >7) wait for the new TSOPs with copper lead frames which are going to
> >replace the Alloy-42 currently used in most of them today.
>
> Good luck!
>
> Bev Christian
> Nortel
> Tessera ...System Building Blocks for the Next Generation of
> Electronics
>  3099 Orchard Drive
>  San Jose, CA 95134
>  Phone 408 894-0700
>  Fax   408 894-0768
>
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