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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