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May 2006

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Subject:
From:
"David D. Hillman" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Sat, 20 May 2006 13:20:42 -0500
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Hi Leo - Don Cullin of MacDermid just presented the "latest and greatest"
on the microvoiding phenomena associated with immersion silver finishes at
the CMAP Conference in Toronto. I recommend you contact Don for a copy of
his presentation. There were a significant number of very good technical
ppts and discussions at the CMAP Conference.

Dave Hillman
Rockwell Collins
[log in to unmask]




             Leo Higgins
             <Leo_Higgins@ASAT
             .COM>                                                      To
             Sent by: TechNet          [log in to unmask]
             <[log in to unmask]>                                          cc

                                                                   Subject
             05/16/2006 08:39          Re: [TN] Question about ENIG and
             PM                        other surface finishing


             Please respond to
              TechNet E-Mail
                   Forum
             <[log in to unmask]>
             ; Please respond
                    to
                Leo Higgins
             <Leo_Higgins@ASAT
                   .COM>






In my experience microvoids associated with leadframe soldering to PCB pads
are often associated with minor organic contamination of the leadframe
surface prior to leadframe plating.  This has been shown to result in
significant decreased drop test performance in hand-held electronics.

Based upon readings from a few sources it appears that microvoids
associated
with Immersion Silver are due to high organic level in a thick Ag deposit.
Cookson/Enthone provides an interesting presentation on their AlphaStar
ImmAg with a relatively thin deposit with low organic content (approx 1 -6
%, vs. a competitor level reported to be 22%).  In my past experience with
fluoroborate-based immersion Sn that produced a tin deposit about 0.2
micrometers thick, I never saw microvoids, but I did see degraded
solderability with time and temp due to the thin deposit and tin
consumption
with the creation of Sn-Cu IMCs.  While I have no direct experience with
this Enthone tin, the presentation shows it to be quite environmentally
robust even with a deposit about the same thickness.


Best regards,
Leo

Leo M. Higgins III, Ph.D.
Vice President, Technical Operations
ASAT, Inc.
3755 Capital of Texas Highway, Suite 100
Austin, Texas     78704

office phone   512-383-4593
mobile           512-423-2002
[log in to unmask]
www.asat.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier
Sent: Tuesday, May 16, 2006 4:05 PM
To: [log in to unmask]
Subject: Re: [TN] Question about ENIG and other surface finishing


Hi Kerry,
Here are pics of micro-voids.



Werner

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