Hello W E,
I'm impressed by the width of questions that arise in this forum. By the
way, how many dared to mount chips acc to the description? And how many
got catastrofic results with cracked chips and electrons and holes
spread over the board? The bumble-bee should not be able to fly, but
does. Theoretically, such a mismatch (Al-Si)ought to lead to catastrofic
failures but sometimes crazy designs work despite scientific warnings.
Now, a more precise question: is there anyone out there who dared to
mount large GaAs MMIC chips on aluminium by means of DIEMAT (MULTIMAT)
materials. Except for excellent mechanical properties, these materials
are said to have lambda >50 W/mK!!
Ingemar Hernefjord
Ericsson Microwave Systems
---------------------------------------------------------------------
> Hi John,
> In a message dated 11/17/98 12:56:44, you wrote:
> >Does anyone have practical experience of the effects of thermal
expansion
> >mismatch on a thermally conductive glueline between a silicon die (in
our
> >case, Motorola MPC740 BGA Power PC processor) and an aluminium
heatsink?
> >
> >We have looked at several adhesives, some of which are much more
compliant
> >than others, and are looking for criteria on which to base the final
> decision.
>
> The answer to your question is: It depends (not meant to be funny).
> The higher the power dissipation, the more temp cycling (testing?),
the larger
> the silicon die, the more compliant your die attach needs to be.
> What are you electrically connecting these die to?
>
> Werner Engelmaier
> Engelmaier Associates, L.C.
> Electronic Packaging, Interconnection and Reliability Consulting
> 7 Jasmine Run
> Ormond Beach, FL 32174 USA
> Phone: 904-437-8747, Fax: 904-437-8737
> E-mail: [log in to unmask]
>
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