Richard - great come back - perhaps you have missed all the champagne
voiding issues with silver! Ask Cisco, et al, the great proponents of Ag
what their finish de jour is - it is no longer Ag. All surface finishes come
with a price if not applied correctly. You correctly pointed out that the
formation of NiSn IMCs requires more time and temperature - something that
is taught in soldering 101 but something that the industry has seemed to
ignore and in some cases continues to ignore. It is clearly stated in 4552!
I am not naive enough to think there is no problems with ENIG, you pays your
money and you get what you pay for. We have run ENIG here for 8 years with
no black pad related issues, sure some mis calls due to mask on pad. It is
amazing that there are so many experts on black pad but yet the extensive
work by the IPC could not produce ONE single incidence of black pad, perhaps
all these new experts would like to revisit the subject.
While you bring up all these labs working on these defects - when will the
industry realize that EDX is NOT the tool for surface analysis and that the
scans produced confuses the situation even more. Correct analysis by XPS
will produce at the fractured interface data to show if any IMC was ever
formed - back to your point of correct temperature and time necessary for
correct IMC formation - without this the solder joint has the reliability of
snot.
Has anyone shared with purchasing the cost of all these
returns/failures/liabilities and compared to the "massive savings" they have
achieved by outsourcing?
Regards
Gerard O'Brien
Also co-chairman of 4553 and a supplier of all surface finishes.
-----Original Message-----
From: Stadem, Richard [mailto:[log in to unmask]]
Sent: Wednesday, October 12, 2005 8:53 AM
To: TechNet E-Mail Forum; Gerard O'Brien
Subject: RE: [TN] Hasl
Gerard,
So, the days of Black Pad are over, eh?
Tell that to XXX Analytical Services in Minneapolis. I know they have
more than one analysis going on to confirm the presence of ENIG plating
issues. The symptoms are the classic "cracked mud" appearance of the
nickel under the gold.
Tell that to YYY Labs. They have been doing analysis on several ENIG
issues in the past few weeks.
Tell that to the folks at many other fabricators struggling to fix ENIG
plating issues. They may not all admit it, but there are many who are
still struggling with the reliability problems inherent to ENIG.
One of the reasons two different fabricators closed down in the Twin
Cities area last year was due to liability issues with ENIG plating. Not
the only reasons, but definitely a big factor.
Sorry to be so negative. But I have to tell you that what I see and what
you are saying are two completely different things.
Mr. Parker has company. Lots of it.
You may not be aware of it. That does not mean the problems don't exist.
The problems are beginning to be better understood. And once again I
state that ENIG is a good finish, if done properly.
And once again, for sure, it is not the best finish to use with area
array packages such as BGAs, interposed components, and CSPs. You cannot
deny that nickel's dissolution into the IMF is much more difficult to
achieve, requires higher reflow temperatures at a longer time. This is
exacerbated by the fact that array packages induce an insulating affect
to the solder joints underneath.
Yes, to all of you who will respond that you never have had a problem
with it. That is good, you have a good supplier. Stick with it.
But too often it is not, and the results are absolutely devastating to
the end customer who ships his product everywhere, only to see their
product fail in the field. It has happened to more than one company that
I have worked at. No matter what anyone tells me, it presents a risk I
would rather not take.
I have pushed many other companies other than the ones I worked for
directly to switch to immersion silver, if the finish is the proper one
for the service environment. They all have, with good results.
I am sorry, but I have not a single problem to report with immersion
silver. None. I can think of over 20 major programs I was involved with
that are using it. Military programs are using it.
High-frequency/high-impedance telecommunications companies are using it.
Medical programs are using it. They have all been using it for more than
4 years now.
And as long as I continue to hear of the ENIG horror stories elsewhere,
I will try to stay away from it.
How anyone can state that there are no more problems with ENIG in the
face of reams of articles, white papers, and reports in every single
major industrial magazine related to electronics assembly, and every
single major trade show, etc. in the past few years is mind-boggling.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerard O'Brien
Sent: Wednesday, October 12, 2005 7:51 AM
To: [log in to unmask]
Subject: Re: [TN] Hasl
Lee - as co-chairman of 4552 I have to take exception to your continuing
negative comments on ENIG. You may be the most unlucky individual on the
planet continuously finding the remaining bad ENIG suppliers, but ENIG
is a mature, high reliable surface finish. We created the 4552 document
to be used to weed out the bad suppliers as well as defining a realistic
deposit thickness to provide a reliable surface finish with excellent
solderability and shelf life. The days of "black pad", whatever the
true definition is, are over. Both myself and my committee would be
delighted to review your data that has the black pad phenomena tied
directly to a deposit over 4 micro inches, perhaps you could stop by the
4-14 meeting at Los Vegas.
Chemical suppliers, FAB houses and industry have worked to produce a
deposit that is multifunctional and world class. If you read the
technical paper in the back of 4552, you will see that a 1 micro inch
deposit was tested as the lowest deposit thickness, which I am still
testing in real time, unprotected going on for 42 months. We obviously
did not spec 1 micro inch minimum as it is not a practical deposit
thickness to maintain on a daily basis, but it proves the point that
thin I Au protects the underlying Ni very well, contrary to you own
experiences unfortunately.
Regards
Gerard O'Brien
Co-chairman 4-14
.
-----Original Message-----
From: Lee Parker [mailto:[log in to unmask]]
Sent: Tuesday, October 11, 2005 9:45 PM
To: [log in to unmask]
Subject: Re: [TN] Hasl
Joel
I am glad to here that you are successfully using ENIG boards;
unfortunately this has not been the case with some other OEMs and CMs.
Almost every week in this forum, I see a report of a problem with ENIG.
I myself spent this spring moving several clients from ENIG to other
solderability coatings. It has been my experience that if the gold
thickness is <2 microinches there is a serious risk of poor
solderability.
If the gold thickness is> 4 microinches black pad may become a problem.
The issue can also be elevated or diminished by the particular plating
chemistry and the ability of the fabricator to control the process.
Consequently, I often work with clients to evaluate and migrate too
other hard metal finishes such as immersion silver and flash gold. The
attributes of immersion silver have been discussed here at length many
times and I am an advocate. I installed the first immersion silver line
in North America at the AT&T plant in Richmond. I then worked with most
of the AT&T assembly locations to verify the process.
Flash gold is more recent and is found mostly in Chinese PCB shops where
it has been resurrected and improved upon. In fact, we used a similar
process at the AT&T facility in Richmond many years ago for "other" OEM
boards. Most Chinese shops have installed the process and have made
substantial improvements. The price is competitive. I along with others
will be giving a paper on this process at the IPC February meeting.
As an aside, this is probably the first novel technology innovation to
originate in the Chinese PCB industry and we should all take notice. I
believe we are seeing the same ingenuity in the Chinese PCB shops that
Marco Polo found on his first visit to China when he returned to Venice
with firecrackers and gun power.
Best regards
Lee
J. L. Parker Ph.D.
JLP Consultants LLC
(804) 779 3389
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Mearig
Sent: Tuesday, October 11, 2005 3:54 PM
To: [log in to unmask]
Subject: Re: [TN] Hasl
Lee,
Good input that I agree with. However, I was wondering if you could
further
discuss the "flash" vs. "ENIG" issue. I have been using ENIG on my
Pb-free
assemblies for about 7 years with very little problems. If I am missing
something further education would be extremely helpful. Thanks
Joel Mearig
Delta Tau Data Systems, Inc.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker
Sent: Tuesday, October 11, 2005 10:03 AM
To: [log in to unmask]
Subject: Re: [TN] Hasl
Ramon
After reflowing a soldered surface, you will form a meniscus which will
interfere with SMT component placement. To avoid the problem I suggest a
flat metal finish such as immersion silver or flash gold (not ENIG)
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: Dehoyos, Ramon<mailto:[log in to unmask]>
To: [log in to unmask]<mailto:[log in to unmask]>
Sent: Tuesday, October 11, 2005 12:52 PM
Subject: [TN] Hasl
Hi technetters:
Is there a fine pitch limit to the use of HASL board
plating
finish due to its variation in thickness? Does selective solder strip
and reflow plating, SSSR, have a significant advantage over HASL? Any
comments relating to platting finish would be greatly appreciated. I
thank you for your comments.
Ramon
ME
410.552.2210
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