All this back and forth conversation is great regarding how to bond to Au.
Remember the first rule of thumb. GET TO THE ROOT CAUSE!!!!
A eraser is simply abrading the surface, removing "crud" but also removing
precious Au that you need for acceptable bonds. The eraser does not
miraculously act as a vacuum but a tool to smear the crud, not remove it.
If it is an organic problem that you have, plasma may work but plasma will
only remove ~200-300 angstroms, not a whole lot being removed. Plasma also
depends on the gas, flow, temp, electrode configuration, chamber size. You
just can't buy a plasma unit and plug it in.
Good Luck and if more help is needed, I can be reached at
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: Wednesday, April 21, 1999 2:45 AM
To: [log in to unmask]
Subject: Re: [TN] Wire Bonding On Gold
Hi, sorry to get in between. You seem to discuss what is hot also here
at our company to and from. My first question would be: please,
gentlemen, what are you from Chuck and pupil? I have got some good
advice from Dave at Rockwell, maybe we have something good to learn
from you too. I have tried for one year to buy an american plasma
cleaner, but when the economists ask "what is the payback time" , then
what can I answer? Oh, my adrenaline...! /Regards
Ingemar Hernefjord
Ericsson Microwave Systems
> >Date: Tue, 20 Apr 1999 19:09:41 -0400
> >To: [log in to unmask]
> >From: joyce <[log in to unmask]>
> >Subject: Re: [TN] Wire Bonding On Gold
> >
> >(1) If you have good plating, you don't need any physical abrasion.
> >(2) you can use eraser if the surface of Au is not clean, but make
sure it
> has no/low ionics (such as Sulphur- common additive for rubber).
> >(3) you can use brush
> >(4) depend on your process and product, you may be able to use plasma
> too...However, if your plating surface required eraser to remove the
top
> surface, the plasma normally would not do the trick.. Plasma is great
to
> remove MINOR oragnic residue.
> >(5) if your gold is too hard (impurity or voids concentration are
high),
> you will have problem to bond and have reliability problem. (eraser,
brush,
> plasma are not going to help you).
> >good luck.
> >jk
> >At 06:29 AM 4/20/99 EDT, you wrote:
> >>We are presently wire bonding aluminum wire to gold lands on circuit
boards.
> >>I have heard many times that wire bonding goes sour to clean them
with an
> >>eraser. This seems a little primitive. Is there any other way that
this can
> >>be accomplished.
> >>If the eraser works why hasn't someone designed something to take
care of
> >>this.
> >>Chuck Garth
> >>
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