Graham,
One of the most important words you used in your reply was the word "might".
FTIR is a great tool, but not the ultimate tool, in fact I would go so far
to say that there is no ultimate chemical analytic tool, which drove bean
counters crazy when I would ask for yet another piece of lab equipment.  :)

The issue with conventional FTIR is that it CANNOT detect something like
sodium chloride (NaCl). NaCl is an ionic compound and has no covalent bonds
with a changing dipole moment that can interact with the infra-red beam of
the equipment. Now a good FTIR can detect something like ammonium (NH4+),
sulfate (SO4-2), nitrate (NO3-) ions because these polyatomic ions do have
covalent bonds that exhibit asymmetric bends and stretches.

So if you do suspect SIR or ECM failure and only use FTIR you are not going
to detect, for instance, alkali and alkaline earth halides, often the main
bad actors for ionic contamination.

If the issue is weak organic acid reside contamination, FTIR may be helpful.
However, the issue may then be that there are so many compounds present that
the spectrum is so complicated (crowded with peaks) that you and/or any
automatic program may not be able to make any sense out of it. 

To finish off on FTIR, why did I use the word "conventional"? A nitrogen
purged FTIR with Mylar optics can "see" down to double digit wave numbers
and you could detect what are called lattice vibrations of purely ionic
salts.  But these pieces of equipment are still not common and very
expensive.

Ion chromatography is great if you know what you are looking for.  It is
great for separating out soluble materials.  But what do you do with peaks
that don't match the retention times of your reference compounds?  Or what
if you had an ionic material that is not very soluble?

I could come up with similar failings of something like Raman spectroscopy
or SEM/EDX.  Every technique has its advantages - and disadvantages.  There
is no one size fits all piece of analytical equipment.

Hope that helps.

Regards,
Bev

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Naisbitt
Sent: Tuesday, August 02, 2016 6:06 AM
To: [log in to unmask]
Subject: Re: [TN] FTIR and Assembly Process Control

Hi Bev and Stuart and all Techies,

I guess I need to elaborate on the reason for my earlier question.

I am engaged, with many others, on a project with both IPC and IEC to
consider a protocol for characterising and controlling an electronics
assembly process.

As it stands today, we have both CAF (2.6.25) and SIR (2.6.3.7) testing that
can be used to characterise a material set. The beauty of SIR is that it can
be used as a predictor of electro-chemical reliability, but it cannot tell
you what is present causing any problems so..

.You could employ Ion Chromatography (2.3.28) that would be able to inform
what is present that might be causing a problem identified in SIR tests.

Alternatively or in addition, the user could use FTIR (2.3.39C - which, as
Bev points out, has been cancelled) for the same determination.

In essence, IC and/or FTIR can tell the user what is present causing a
problem but neither test can determine if the intended end-product might be
electro-chemically reliable. Contrariwise, that is the role of SIR.
 
Once this examination has been completed and the user is satisfied that they
have reasonable evidence of electro-chemical reliability for the intended
end-product, they would use Process Ionic Contamination Testing (PICT) to
monitor their process in respect to ionic contamination. This was the
original intention of what today has become known as ROSE testing. The
significant problem that exists today is that the industry believes this to
be a "Cleanliness Test" which it, most certainly, is not.

Have I missed some other test that could be used in place of, or
supplementary to, IC / FTIR?

Graham Naisbitt

> On 1 Aug 2016, at 17:08, Bev Christian <[log in to unmask]> wrote:
> 
> Graham
> 2.3.39C CANCELLED.  This is the only one that I am familiar with.  What is
> your problem/issue you are trying to solve?
> Regards,
> Bev
> 
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Naisbitt
> Sent: Monday, August 01, 2016 11:57 AM
> To: [log in to unmask]
> Subject: [TN] FTIR
> 
> Hello fellow Techies,
> 
> Do any of you know if there is a test method in IPC for FTIR?
> 
> Thanks in advance
> 
> Graham Naisbitt