Brian,
Thanks for the data point. Concerning comments of the ramblings of an old
man, I would prefer to consider your ramblings coming from a wise man, but
who am I to judge... :)
Where can I get a copy of the European Space Agency report?
Lee Whiteman
Senior Manufacturing Engineer
ACI / EMPF
Telephone: (610) 362-1200; Ext. 208
FAX: (610) 362-1290
E-Mail: [log in to unmask] <mailto:[log in to unmask]>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Brian Ellis
> Sent: Thursday, December 14, 2000 11:49 AM
> To: [log in to unmask]
> Subject: Re: [TN] Ionic contamination Limit
>
>
> Lee
>
> I agree with you, but these equivalence figures may be very misleading
> as they were established using instruments which were relatively
> primitive, by today's standards, in the 1970s, using old process
> methods. The European Space Agency found that the equivalence between
> different instruments varied enormously with different flux/cleaning
> processes (see their published report). It could be dangerous or too
> easy to slavishly rely on these old data.
>
> I agree that ion chromatography is an excellent diagnostic tool, where
> ionic contamination testing is a good process control method. Believe it
> or not, I designed a combined instrument for both in the mid 1980s but
> never commercialised it as no-one would have paid the price, at that
> time. It worked on the principle of doing an ionic contamination test
> (computer controlled). While it was printing out the data from that, the
> computer commanded the extraction of two samples of the solution (one
> was a reserve, in case of problems. One sample was passed to the
> chromatograph which looked for halides as anions and Na, K, Cu and Sn as
> cations. The same computer then analysed the results from both tests,
> including the curve shape from the first and the ionic conductivities,
> to give known values of ions and to make a stab at guessing what the
> difference was between the two tests. It sometimes found a total of more
> ions with the Dionex than was found by the Contaminometer (ie the total
> of the the conductivity from the detected ions was > the conductivity of
> the solution!!!!). Such are empirical errors. However, it was spot on
> with known injections of reagents and mixtures of them. The software did
> a helluva lot of number crunching. Academically, that was one darn good
> instrument. Please excuse an old man rambling about his previous lives!
>
> Brian
>
> Lee Whiteman wrote:
> >
> > Ken Patel,
> >
> > I agree with Brian Ellis, but to give you some more insight on Ionic
> > Contamination limits, I pulled my old copy of MIl-STD 2000.
> Based on Table
> > VII, you find the following upper control limits:
> >
> > MIL-P-28809 Beckman / Markson: 10 micrograms NaCl / sq. in.
> > Omegameter: 14 micrograms
> NaCl / sq. in.
> > Ionograph: 20 micrograms
> NaCl / sq. in.
> > Ion Chaser: 32 micrograms
> NaCl / sq. in.
> >
> > What that means is that for different test methods, there are varying
> > degrees of sensitivity (ionograph is more sensitive than
> omegameter). If you
> > (or anyone else) is interested, I have a report that explains
> this to you.
> > It's rather lengthy (15 Mbytes in PDF format) to send via
> E-Mail so I will
> > need you address, etc., to FED-Ex to you.
> >
> > However, if you application requires a higher cleanliness
> standard, you can
> > (and should) reduce these upper control limits appropriately. I
> agree with
> > Brian that you should set the upper control limits for ionic
> contamination
> > found by the omegameter or ionograph.
> >
> > For additional information on the omegameter and ionograph, you
> may want to
> > check out the following website: http://www.scscookson.com/instruments/.
> >
> > If you are setting up a cleaning process, or have a problem with
> > cleanliness, your best bet would be to have the boards tested via Ion
> > Chromatography. That will tell you what ionic contamination is
> on the board,
> > and their respective quantities. We have this capability and
> you can call me
> > off-line about it.
> >
> > Good Luck.
> >
> > Lee Whiteman
> > Senior Manufacturing Engineer
> > ACI / EMPF
> > Telephone: (610) 362-1200; Ext. 208
> > FAX: (610) 362-1290
> > E-Mail: [log in to unmask] <mailto:[log in to unmask]>
> >
> > > -----Original Message-----
> > > From: TechNet [mailto:[log in to unmask]]On Behalf Of Ken Patel
> > > Sent: Wednesday, December 13, 2000 8:44 PM
> > > To: [log in to unmask]
> > > Subject: [TN] Ionic contamination Limit
> > >
> > >
> > > Guys,
> > > What is the acceptable Ionic contamination limit for
> Omegameter 600 and
> > > Inograph 500 both made by Alphametals?
> > >
> > > re,
> > > ken patel
> > >
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