Regards, Graham
Naisbitt
[log in to unmask]
http://www.concoat.co.uk
In the beginning the Universe was created. This has made a lot of people
very angry and been widely regarded as a bad move. Douglas Adams
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Joyce Koo
Sent: Thursday, August 23, 2001 08:07
To: [log in to unmask]
Subject: Re: [TN] Cleanliness evaluation! Definition of an Expert (Xspurt)
Graham,
Please let me know where I can
obtain a copy of draft (I think I'll pay 1.55 cents if it is possible)
IEC Draft
61189-5
Many Thanks.
jk
-----Original Message-----
From: Graham Naisbitt [mailto:[log in to unmask]]
Sent: August 17, 2001 6:56 AM
To:
[log in to unmask]
Subject: Re: [TN] Cleanliness
evaluation! Definition of an Expert
(Xspurt)
Doug and others,
What DO they put into that Mountain Dew?
I am compelled to correct Doug's kind but blatant advert for
me - call me a
member of the lunatic fringe if you
will...
The EU project we are referring to, involved a definitive
scientific
investigation of those "debatable" issues
viz: Field strength; Effects of
different voltages;
Coupon design; Measurement frequency etc.. However, the
second part of the project, based upon the results obtained from the
first
part, involved the development of a possible
process standard, and to see if
this would - forgive
the comment - "Hold water".
In this element of the project, 3 partners: Siemens, Berlin;
NPL, London and
NMRC, Cork; each tested the proposed
specification using different test
instruments!
NMRC used a system they developed themselves, as did Siemens
using a system
they built some 20 years ago. Only NPL
used our Auto-SIR.
The results of this (published) proved that the specification
is entirely
workable, as all 3 generated virtually
identical results - hence the attempt
to have this
developed into a global industrial standard - IEC Draft
61189-5.
For everyone's benefit, here are some links to follow:
The NPL has recently completed a 3-year project examining
exactly these
SIR issues for no-clean and other
pastes.
Take a look at:
http://www.npl.co.uk/npl/ei/publications/abstracts.html#5
http://www.npl.co.uk/npl/ei/publications/abstracts.html#6
http://www.npl.co.uk/npl/ei/publications/abstracts.html#21
http://www.npl.co.uk/npl/ei/publications/abstracts.html#22
The conclusions from this work highlight important issues with
the
current standards.
...and for all you fellow techies out there, do you know what
is the
definition of an expert?
X is an unknown quantity - a Spurt is a drip under pressure!!
Regards, Graham Naisbitt
[log in to unmask]
http:// www.concoat.co.uk <http://www.concoat.co.uk>
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-----Original Message-----
From:
TechNet [mailto:[log in to unmask]]On Behalf
Of
[log in to unmask]
Sent: Wednesday, August 15, 2001 02:35
To:
[log in to unmask]
Subject: Re: [TN] Cleanliness
evaluation!
Whilst I wholeheartedly concur with what Doug stated, I do not
agree for
the
need for Ion
Chromatography (IC) testing.
*WHAT?!!!! LIGHT THE TORCHES, BURN THE
HERETIC....... (he turned me into
a newt....I
got better...)
I must disagree with your
disagreement.
Iain, if you run a correct SIR test regime on your proper
proposed
production process, and you have acceptable
results, then you can feel
comfortable that you will
have a reliable end product. If you have failures
in
this test, then you need IC to find out precisely what is present on
the
surface that may be causing your problem. Yes you
should then use ionic
extract testing (SEC/ROSE) to
keep an eye on your process conditions - but
make no
attempt to correlate SIR with SEC/ROSE results.
*Graham brings up a valid point that there is more than one
tool for
assessing cleanliness or quality, but I don't
know that SIR would be any
better than IC at this
point. For both tests, you need someone to help you
interpret the numbers. Having the information that your
assemblies have
2.7 ppm of chloride doesn't do much
good unless you know if that is a good
or bad
number. Having the information that your process yields a mean
SIR
level of 283 megohms on a B-24 doesn't mean much
unless you can relate to
product. The advantage
of SIR is that of these two tests, it is better at
showing if residues have a propensity for electrochemical
failures
(leakage, corrosion, metal migration), but
you still have to do more
extensive correlation
studies on actual product to know whether the values
from that lab test relate to product life in the field. Then you
have to
also do a correlation study with ROSE/SEC to
see what levels to use as a
target and upper control
limit. An additional disadvantage of SIR is that
it is a long test. Brian Ellis wrote a paper a few years ago that
long
term SIR testing could be cut down to an 8 hour
test, but that is still
much longer than a 2 hour IC
test. Difficult to do as a process control
measure. I have found it easier to correlate IC results with SEC/ROSE
than
with SIR.
*You know, I find it really weird that after being and SIR
champion for so
long, I argue against it here. I
guess the point being that if you are
going to use
ROSE/SEC as a process monitoring tool, which several companies
do successfully, you have to do extensive correlation studies
between
product life testing (dozens of ways to do it)
and any quality control
measures you implement.
You have to know what your monitoring signal means
in
order to properly set the target and upper control limits. Most
existing ROSE/SEC levels in specifications are both
antiquated and bogus.
I would suggest that you retain the use of SIR equipment as
a
process/quality monitor. Taking sample coupons at
each stage of the
production process and running short
tests will (probably) give you the
necessary
indicators if the process or process materials are changing.
*This is possible, but I would say that you need a more
focused test coupon
than the B-24 and one that is
fabricated with your set of materials.
Additional cost
in doing this, but the data is more relevant. Maybe use
the **fanfare** CONCOAT TEST COUPON!!!! (Look, up in the sky, its
a bird,
its a plane...)
To ensure that you have used the correct test protocol, I
assume that you
took on board the recommendations as
published by the EU project partners
NPL, Siemens,
NMRC and Lares Cozzi. If anyone wants a copy of this work,
let
me know.
*What a clever way to do some academic spamming <grin>.
Sayyyyyyy, wasn't
that the work where the particpants
used **fanfare** THE CONCOAT AUTOSIR?
(Notice how I
very slyly slip in some gratuitous advertising for my friend
across the pond. Ain't I clever?).
*Graham refers to a consortia activity going on for the last
three years or
so looking at continous monitoring SIR
vs. various flux and processing
conditions. I
wasn't aware that this was a published report yet. I have
invited Dr. Chris Hunt of NPL in the UK to give a
presentation on this work
at the SIR task group
meeting at the Fall IPC meeting.
By the way, running IPC-TM-650 did they test to Appendix D of
J-STD001 (or
is it now B? Doug??) or did they run to
6.2.3. or 6.2.3.3? What was the
coupon they used? What
was the pitch/width they used? What was the test
voltage used?
*I'm sure Graham means methods 2.6.3 (cyclical environment)
and 2.6.3.3
(static environment). The SIR
protocol that Graham refers to was found in
Appendix D
of J-STD-001, Revisions A and B. Revision C is now the current
version and the protocol is now Appendix B (lost two
appendices somewhere).
*Graham, in his last two sentences brings up another good
point - there are
so many possible choices in an SIR
test (or IC test for that matter), that
you really
need a guide in selecting the best factors for any particular
situation. And where would you FIND such experts? Why, at
the upcoming
Fall IPC meeting in Orlando,
Florida. (notice the sly advertising for the
IPC...) Usually you can get a few of them to guide you along if ya buy
the
beer (well, at least ONE such expert I know
of...).
Doug Pauls
Rockwell Collins
(Well into his third Mountain Dew of the day)
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