I am referring to the development of ENIG and the early issues with
cleanliness levels. With improvements to the ENIF process, performance
for cleanliness is comparable to HASL. The issue with HASL are flux
related and poor cleaning coupled with HASL technique offer much
variability in testing results. Older vertical systems required a
different fluc chemistry that required a more aggressive post cleaning
process to achieve a result compliant with Bellcore. The fluxes/fusing
fluids used in the horizontal equipment process more affectively in post
cleaners using a chemistry designed to lower ionics. In our current
HASL process we are measuring levels below 1 ugm/inch2 consistently.
ENIG is also very close to this level given the improvements to that
process. I would conclude that either your supplier if not maintaining
a Robust process for low ionics or your requirement is too stringent.
Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302
Voice - 802.257.4571 ext 21
Fax - 802.257.0011
<http://www.vtcircuits.com/>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Ball
Sent: Friday, September 15, 2006 9:00 AM
To: [log in to unmask]
Subject: Re: [TN] bareboard cleanliness related to surface finish
Hello Jeffrey-
Yes, it's possible our requirement is more restrictive than need be.
We've
relaxed it a little for new designs (we also now spec ion chromatography
characterization). It was a reaction to a very specific problem. But
better
safe....
I'm slightly alarmed by your response since most previous responses
leaned
towards HASL finish being the slightly 'dirtier' of the two. Am I
missing
something or are there just two schools of thought here?
Thanls,
-Chris
"Jeffrey Bush"
<[log in to unmask] To: "TechNet
E-Mail Forum" <[log in to unmask]>, Chris
om>
BALL/AuburnHills/VSDS/VALEO@VALEO
cc:
09/14/2006 04:37 PM Subject: RE:
[TN] bareboard cleanliness related to
surface
finish
ENIG will in general terms return higher Ionic Contamination levels than
properly cleaned HASL products. Years ago early in the ENIG development
process, the contamination results - among a laundry list of disasters -
were poor with ENIG. The Reflow and early HASL processes had better
results, but this was a factor of much work done with post-process
cleaning to obtain levels required by Bellcore. With capabilities to 6
ugm NACL eq/inch2 on solder boards, the first ENIG parts processed at
15-20 were shocking. This issue was also related to the soldermask and
here also many improvements were made in mask chemistry as well.
Dryfilm mask for example had very poor results in testing, while some
flat liquids also had heightened levels.
With many improvements in processing and ENIG chemistries, we have been
able to maintain all products to a standard level, which for us still
remains the fairly low some where in the 2 ugm area for all parts ready
to ship.
Is it possible you requirement is to low?
Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302
Voice - 802.257.4571 ext 21
Fax - 802.257.0011
<http://www.vtcircuits.com/>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Ball
Sent: Thursday, September 14, 2006 8:16 AM
To: [log in to unmask]
Subject: Re: [TN] bareboard cleanliness related to surface finish
Hello Inge-
I asked because we are changing over to a new bareboard supplier for
several different products. Actually, several different divisions within
the company are moving a single product each to the new supplier. These
are
all mature, already in production parts. The previous shops either had
no
problem meeting the spec., or didn't meet it but we didn't know. The new
shop is asking for exceptions to the requirement, and all the requests
funnel back here.
I see that they request different levels for different products.
Sometimes
different levels for the same product on different days, but that's
another
email....
When I showed them an earlier request for a lower level they told me it
was
due to the different surface finish. That was a new thing to me, so I
checked with the experts.
So, not trying to split a whisker, and not even a psuedo-academic. Some
of
the other questions, concerns, and exceptions from the shop have made me
generally suspicious. Maybe these are delay tactics. Just checking. And
trying to get a little smarter at the same time. Reading this forum is
pretty educational, IMHO. I appreciate the responses and apologize for
not
taking the time to research the archives first, but as a
not-even-psuedo-academic, I usually follow the easiest path to
enlightenment. ;-/
Best Regards,
-Chris
"Ingemar Hernefjord
\(KC/EMW\)" To: "TechNet
E-Mail Forum" <[log in to unmask]>, Chris
<ingemar.hernefjord@ericss
BALL/AuburnHills/VSDS/VALEO@VALEO
on.com> cc:
Subject: RE:
[TN] bareboard cleanliness related to
09/14/2006 02:52 AM surface
finish
Chris,
Why do youi put the question? I've never heard about practical
in-field-use problems based on ionic level diff between the two
treatments. Never. Academics can always find hair cleaving topics, but
we working with design production and marketing are more interested in
the question "do they work?"
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Ball
Sent: den 12 september 2006 20:19
To: [log in to unmask]
Subject: [TN] bareboard cleanliness related to surface finish
Hello Gurus-
Is it fair to expect a higher contamination on a HASL finished bareboard
than, say ENIG? I would have expected the same level of cleanliness when
receiving the bareboards, but new supplier says they have different
levels for different finishes.
We specify tighter than std. IPC levels and never varied the spec due to
surface finish. Requests for exceptions have been rare and not related
to surface finish.
Any comments appreciated,
-Chris
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