James,

Most MMIC devices are low power enough to mount with Ag epoxy, however,
unlike bipolar or CMOS devices, they typically are made of very thin
(.004-.006) GaAs and contain air bridges. This means they are brittle and
you cannot contact the top side of the die. Hence die attach must be done
with tweezers for very low volume or a custom die collet for higher volumes.
Epoxy amount is critical to maintain a thin (.001), uniform interface
thickness for RF performance and prevent epoxy from coming over the top of
the die or contaminating the collet... typical epoxy fillets will not be
maintained.

Wire bonding is atypical as well.  Ultrasonics tend to create microcracks or
worse and should be minimized. You can compensate for this through higher
substrate and/or bond tool temperatures.

Also be prepared for removing them from Gel Paks. You will probably need a
Gel Pak release station. Contact me off line if you need more help.

Best of Luck, they're a challenge,

Bruce Misner

> ----------
> From:         Terveen, James @
> NARDAEAST[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Terveen, James @ NARDAEAST
> Sent:         Thursday, March 30, 2000 9:27 AM
> To:   [log in to unmask]
> Subject:      [TN] MMIC attach
>
> I need a little help on a new design that Eng.in coming up with.  They
> would like to take an Alumina substrate and attach a MMIC to it.  The
> substrate is a MicroBGA.  We have a clean room operation in our facility
> and do wire bonding but I do not have enough knowledge on how this would
> be done.  Whether to solder it or use epoxy.  and it either then what
> would the material be.  So if anyone can help with how the mmic should
> be attached to the substrate or direct me to some good literature it
> would be greatly appreciated.
>
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