Having been involved with packaging ICs, the caps have silicon that
melts at a certain temperature and seals the cap to the body of the chip. So
after the ICs have been wire bonded to the body( carrier) of the chip, a cap
is placed on each chip carrier before they are run through an oven.  When
they come out the other side, the silicon has cooled enough to solidify and
hermetically seal the cap to the carrier. So a packaging company will be a
good source to obtain caps from.
        Regards,
        Ramon

> -----Original Message-----
> From: Mike Kuczynski [SMTP:[log in to unmask]]
> Sent: Monday, December 09, 2002 9:40 AM
> To:   [log in to unmask]
> Subject:      [TN] Mounting Modified BGA
>
>
> I need some information in mounting a BGA asic, that has been modified.
> The top is cut-off, modifications to the wirebonds to the die are made.
> Then it's sealed w/ this black gunk and covered
> by this yellowish film. The problem is that this black gunk is melting and
> shorting out the whole die, when the BGA is being mounted on the PCB.
>
> Is there a different sealant (black gunk) we should be using to close up
> this BGA? Could it be exceeding the temp. when mounting the BGA? Is there
> another process we should look at?
>
>
>
>  << File: ATT876367.gif >>

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