Hi Ingemar,
In a message dated 11/19/98 10:31:49, you wrote:
>We attach a 2x3" Alumina 0.25mm 99% on CuMo 1.0mm carrier by means of a
>thermoplastic from one of the big US companies in the game. It's a
>transfer, silverfilled product for automatic mounting. Max Tg approx. 75
>degrees C. The substrates contains some chips that develop several watts
>which has to be taken care of by the CuMo carrier. This is then mounted
>on a aluminium structure.
>
>Now, a pessimistic scientist thinks that, if vertically mounted, the
>alumina substrate will glide slowly from its position, especially at max
>operating temperature which may be 60 degrees C. The positioning is
>important in this case because of bond wires. His argument is that the
>thermoplastic is not crosslinked and stable as are thermosets.
>
>Anyone out there, who is more optimistic?
>
> //Ingemar Hernefjord
> Ericsson Microwave Systems
You sure come up with interesting questions.
You do not say what kind of thermoplastic you are using (polysulfone,
polyphenylene sulfide, polyether-imide, PES, PET, PBT) or what the glass
transition temperature is.
Thermoplastics are used for telephone housings, containers, even injection-
molded circuit boards. Have you seen trooping plastic housings lately? Even
glass is theoretically a liquid—ultimately (500 years plus?) your window panes
may wind up as puddles on the floor. I think your colleagues concern is far-
fetched; he should be worrying about more immediate things, like improving his
golf game.
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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