gurus have spoken!  Brian and Doug... OK, I am in the lake... just need to
dry out a bit...concentrate... may be...(non-standard of course)... I am
freezing here..low blood pressure too.  Thanks.
                               jk


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Douglas O. Pauls
Sent: Friday, October 01, 2004 11:35 AM
To: [log in to unmask]
Subject: Re: [TN] how clean is clean


Weeeelllll, it depends.   Yes, I know, you are all shocked at my response.

To answer your question, thee are no standards for how clean, ionically,
CSPs, or flip chips, or BGAs, need to be.  When the Ionographs and
Omegameters were first made, CSPs or flip chips weren't even envisioned.
There are many reasons why the bulk ionic cleanliness will not work to
answer this question.  Too much solution, not enough signal, not enough
sensitivity, not enough accuracy.

Since you are expecting it, go jump in a lake.  While you are in the lake
(hopefully not in northern Minnesota right now), try to find the single
minnow in that lake.  That is analogous to what you are asking.  Using a
bulk ionic tester to find flip chip contamination levels is like looking
for the minnow in the lake.  Too much lake, not enough minnow.  Ion
chromatography would be a better tool since you can shrink the size of your
lake down to a mud puddle.

It still comes down to signal to noise ratio.

Doug Pauls
Rockwell Collins




                      Joyce Koo
                      <[log in to unmask]        To:       [log in to unmask]
                      com>                     cc:
                      Sent by: TechNet         Subject:  [TN] how clean is
clean
                      <[log in to unmask]>


                      10/01/2004 09:24
                      AM
                      Please respond to
                      jkoo






Gurus,
for a device, (fine pitch, like CSP, flip chip), how clean is clean (in
terms of extractable ionics using omega meter or ionograph).  I want as low
as 4.5 ug/sq inch (usd to be 6.45 ug/sq inch).  I think someone may tell me
to jump the lake....  What is the standard for CSP/flip chip or direct chip
attach?  Thanks.
Best regards,
                                           jk

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