Thanks Mike, All good advice. I'll get with IMAPS..If they're as helpful as
Technet, I'll be sure to get an answer.
Ron Vandendolder
Telaxis Communications
-----Original Message-----
From: Mike Fenner [mailto:[log in to unmask]]
Sent: Wednesday, February 14, 2001 5:12 PM
To: TechNet E-Mail Forum.; Vandendolder, Ron
Subject: Re: [TN] Potential of galvanic couple of dissimilar metals
Well I waited and waited for someone to answer this as I don't have a
definitive answer, but no one has so here is a definite 1/2 cents
worth..
The idea of using bonding tabs to ensure compatibility of bond wire to
surface is not novel. The semiconductor and to a lesser extent the
chip and wire hybrid people have been doing it for years. It may be
that you might be better off looking in those directions than this
forum. I believe that IMAPS has a similar forum to this, I don't know
if the semi conductor people do, but you could try SEMI. Another idea
you might be able to steal from them is a getter. These mop up
moisture in package cavities. It might also be worth looking at the
mono molecular or at least very thin coatings like Alpha's Paralene,
might not upset your values.
Mike
----- Original Message -----
From: "Vandendolder, Ron" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 12, 2001 10:23 PM
Subject: [TN] Potential of galvanic couple of dissimilar metals
> I've got a conundrum wrapped in riddle inside an enigma.
>
> We are planning to make an bondwire interconnection from a microwave
RF
> board that is copper/nickel gold plated to an epoxy PCB
> that is copper/ immersion silver plated using 1 mil aluminum wire.
Our
> plan is to silver epoxy a bimetallic copper/aluminum tab onto the
microwave
> RF board so that the aluminum faces up. Then we plan to solder
another
> bimetallic copper/aluminum tab onto the
> epoxy PCB by reflowing with solder paste, again, leaving the
aluminum side
> up. Now we have aluminum pads on both boards that we can aluminum
wire
> bond.
>
> My concern is whether the all the dissimilar metals are a galvanic
cell
> waiting to happen! I should mention that the end assembly is
mounted in a
> cast housing, which although leak tested, does not have either a
hermetic
> seal or an inert atmosphere.
> The product will be located outdoors and must last 10 years.
>
> Has anyone had past successes using a similar technique that they'd
care to
> share?
>
> Thanks in advance.
>
> Ron VandenDolder
> [log in to unmask]
>
> --------------------------------------------------------------------
-------------
> Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
> To unsubscribe, send a message to [log in to unmask] with following
text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send the following message:
SET Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
> information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
> --------------------------------------------------------------------
-------------
>
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
