> Good evening Kelly,
> (you must be working near the east coast, arent you?)
>
> Top 1:
> are these major effects on the soldering process still true, if this the
> insert is only about 2x3 mm2 ?
>
> Your new process, how does it deal with the huge tolerances? Can you tell
> more about it?
> In my processes, I can not allow to get large forces on my IC-package
> during mountig of the heat sink. Thats the reason why i think of having
> the insert preassembled before SMT Placement and reflow.
>
> Using an adhesive (even with l=8W/mK) is a "week" solution compare to
> copper.
>
> Top 2:
> why not use copper? the PCB is adjusted to lie somewhere between copper
> and silicon
> how expensive is the assembly, any estimate compared to standard FR4
> double side?
>
> who does manufacters such things?
>
> BTW: what does SCI manufactures?
>
> Regards - Wolfgang
>
>
>
>       ----------
>       Von:
> [log in to unmask][SMTP:[log in to unmask]]
>       Gesendet:       Montag, 12. Oktober 1998 14:57
>       An:     [log in to unmask]
>       Betreff:        RE:[TN] Inserts into PWB
>
>
>       Good morning Wolfgang -
>
>       Yes, quite a few of us use "thermal cores" with our circuit boards.
> We have
>       at various times used aluminum, alumina, copper and graphite.  All
> of these
>       items can be very efficient heat sinks.   A few words of caution, in
> a
>       practical sense:
>
>       1] Addition of an efficient heatsink, can and will have a major
> effect on your
>       soldering process.  Accordingly, we try to design a structure that
> will allow
>       addition of the heatsink AFTER the soldering process has been
> completed;
>       2] Bonding the heat sink to a circuit board will make the circuit
> board try to
>        emulate the expansion of the heat sink UNLESS a compliant adhesive
> is used to
>       mechanically decouple the two.
>       3] Be careful to ensure that the bond line provides sufficient
> dielectric
>       spacing to prevent shorting from the cirucuit board to thermal core.
>
>       While it is possible to laminate a predrilled, filled sheet of
> aluminum or
>       copper into the basic circuit board, I do not recommend this
> practice for the
>       reasons noted above.
>
>       Regards - Kelly
>
>

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