Richard - I should stop but...
Nickel oxide is a totally different issue, boards would be clearly
rejectable by jstd-003 solderability testing and nickel oxide is clearly
reproducible by increasing rinse time post Ni prior to Au. In addition XPS
will clearly detect this. Reflow profiles cannot be ignored but I agree they
are not the be all and end of ENIG assembly issues.
Thanks for the ref at Alpha's Web site
Regards
Gerard
-----Original Message-----
From: Stadem, Richard [mailto:[log in to unmask]]
Sent: Thursday, October 13, 2005 10:14 AM
To: TechNet E-Mail Forum; Gerard O'Brien
Subject: RE: [TN] Hasl
Increasing the time and temperature have no effect if the plating
problem is there. It may help some, but I know from experience that you
cannot overcome the basic problem of trying to solder to the nickel if
the nickel is covered by a nickel oxide layer under the gold.
Many times, many times I have heard a board fabricator tell me that the
reason we could not get good solder results when trying to solder to his
ENIG was because we did not have the proper reflow profile. In nearly
every case, we had qualified the reflow profile with a thermal profile
of the actual solder temperature of the ball, by visually verifying the
solder joint characteristics, by microsectioning to verify the IMF
formation, and by life-cycling to establish the reliability levels.
Then, after building several hundred boards with no problems whatsoever,
we start having problems. All of the problems are traced and confined to
a single lot of fabricated boards. How then is this the reflow profile?
Have you read the article written by the Alpha Metals folks that was
referenced elsewhere on the forum today? The title is "The 'Black Pad'
Failure Mechanism-From Beginning to End". It was published in Global SMT
and Packaging. It is also located at Alpha Metal's website. Get it. Read
it. It is very informative.
I have not seen the Easter Bunny, so I cannot say for sure that it
exists. I have seen nickel oxides in ENIG, and believe me, they exist.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerard O'Brien
Sent: Thursday, October 13, 2005 9:23 AM
To: [log in to unmask]
Subject: Re: [TN] Hasl
Jason - not saying a defect does not exist, but the litany of possible
causes has made the search for root cause very difficult, possibly
similar to tin whiskers. We know many factors that potentially aid in
growing whiskers but as of now we cannot use them to produce a whisker
upon demand.
If I review all the items that have changed over the years with ENIG -
reformulation of the Ni bath for PWB loading instead of using a GMF Ni
bath, the use of on line controllers instead of massive over the side
adds, the reduction in Au thickness ( its has been some time since I saw
a requirement for 8 to 10 micro inches Au on a fab drawing) and the
education of the assembler to increase temperatures - all have combined
to reduce the defect from one of epidemic proportions to one governed by
Caveat Emptor.
Regards
Gerard O'Brien
Photocircuits Corporation
-----Original Message-----
From: Jason Gregory [mailto:[log in to unmask]]
Sent: Thursday, October 13, 2005 8:57 AM
To: 'TechNet E-Mail Forum'; 'Gerard O'Brien'
Subject: RE: [TN] Hasl
Hmmmm. Just because one can't produce a defect-at-will doesn't mean it
cannot exist. And yes, you are right, if we could produce black pad at
the snap of a finger, it could be fixed (but I, for one, DO believe it
exists - but not the Easter bunny)
Jason Gregory
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerard O'Brien
Sent: Thursday, October 13, 2005 7:04 AM
To: [log in to unmask]
Subject: Re: [TN] Hasl
Lee - the 4552 committee only works in the truth. We would be delighted
to report a final root cause of black pad if it could be demonstrated by
the "turn it on at will" method. Then the industry would be able to fix
it! I am still waiting to see such a thing. Bruce was a member of the
4552 committee
- he did not bring up any method to turn black pad on, he also endorsed
ENIG's use as defined by the specification. If ENIG is such a bad finish
then it would not have the market share that it does. Any surface finish
that would produce such poor performance and reliability that you seem
to indicate ENIG suffers from would not be found in the highest levels
of technology offered today. Perhaps you remember the very short lived
Immersion Bismuth surface finish - went the way of the Dodo because of
poor performance, based on the last market analysis for ENIG use world
wide, I have to say it is alive and well.
Best regards
Gerard O'Brien
-----Original Message-----
From: Lee parker [mailto:[log in to unmask]]
Sent: Wednesday, October 12, 2005 10:34 AM
To: TechNet E-Mail Forum; Gerard O'Brien
Subject: Re: [TN] Hasl
Gerard
It is unfortunate that you are offended by the truth. As you must be
aware there are several large OEMs that share my concerns with ENIG, you
need to put them into the same category you include me; there must be a
reason for their reluctance to use this product. I suggest that together
we begin counting the future instances reported by ENIG users in this
forum. You say
that:
"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."
I suggest you go back and look at the report of the original IPC study
chaired by Bruce Houghton (who is legendary in this industry) on black
pad and you will find several text book photographs of the defect. Based
upon this work and the statement below by Mr. Stadem, I rest my case.
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: Gerard <mailto:[log in to unmask]> O'Brien
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Wednesday, October 12, 2005 10:00 AM
Subject: Re: [TN] Hasl
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] <mailto:[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] <mailto:[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] <mailto:[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] <mailto:[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]
<mailto:[log in to unmask]> >
To: [log in to unmask] <mailto:[log in to unmask]:[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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