Inge,
You might want to try putting a layer of electroless Ni over Au plating
(The solution is widely available). It is an easy thing and would
provide you a few microns thick layer of E-Ni over soft Au. Once it's
done, cross-sectioning is almost a piece of cake :-)
Regards,
Vladimir
Vladimir Igoshev, Ph.D.
Physical FA Laboratory Manager
ATI Technologies Inc.
Ph: 905-882-2600, x 6611
Fax: 905-882-5536
Cell: 416-300-4203
E-mail: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar Hernefjord
(KC/EMW)
Sent: Friday, October 20, 2006 8:19 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG problem
Zlatko,
Right. Preparation is extremly difficult for such thin gold platings. I
modified the preparation by means of acrylic, gold sputter and liquidous
nitrogen, and succeeded to take several SEM images of the Immersion
Gold. My earlier foundings were misleading, instead the gold is too
thin!!!
I estimate the thickness to some 10-20 nanometers, while we want minimum
50 nanometers and medium 100 nanometers. See photo sent to Steve. The
'foil' in the middle is the Immersion Gold. Bottom on picture is nickel
plating and uppermost is a "special" that helped me to define the
Immersion Gold unquestionably.
Too thin a Immersion Gold is not a very negative factor for aluminum
heavy wire bonding, because you are in fact bonding on the nickel.
So...the problem is apparently not the gold, but something else.
Possibly the very hard and rough nickel. I was expected to deliver a
certain and specific recommendation today, but I'm not ready yet.
The case continues...
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of ZLATKO BIJEDIC
Sent: den 20 oktober 2006 13:15
To: [log in to unmask]
Subject: Re: [TN] ENIG problem
I believe that there was Ni skipped; micro-section of gold (up to 5 mic
inch) is not accurate because of smearing during polishing.
ZB
----- Original Message ----
From: George Milad <[log in to unmask]>
To: [log in to unmask]
Sent: Tuesday, October 17, 2006 12:48:12 PM
Subject: Re: [TN] ENIG problem
Ingemar,
One thing attracted my attention when I read your posting. You stated
that the gold was very thick (>1um)
As a supplier of ENIG Chemicals and the chairman of the plating
committee that specified ENIG as surface finish, I can tell you that the
process is not capable of depositing that thickness of gold on nickel.
The only time this gold thickness may be encountered is when the nickel
plating skips the pad (does not or fails to plate) and the gold is
deposited directly on a copper pad.
Verify the Ni thickness on that specific pad that had the very high gold
deposit thickness. this may give us a clue as to what is behind the
failure.
Regards
George Milad
George Milad
National Accounts Manager for Technology Uyemura International Corp
(UIC)
249 Town Line Rd
Southington CT 06489
[log in to unmask]
Cell: (516) 901 3874
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