Doug 

Surely, if you had ants exuding acid that would be 'antacid' and therefore
neutral, wouldn't it? Or am I just a little mixed up here?:-)

 

Regards 

Mike 

 

  _____  

From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Wednesday, September 12, 2012 12:38 PM
To: [log in to unmask]
Cc: [log in to unmask]
Subject: Re: [TN] Source of IC Contamination Species

 

Speaking of formates, perhaps Rich has ants running around on his
assemblies.  We had an assembly come into a service center from Brazil
crawling with ants which we found exude high amounts of formic acid. 

Doug Pauls 



From:        Mike Fenner <[log in to unmask]> 
To:        <[log in to unmask]> 
Date:        09/11/2012 02:34 PM 
Subject:        Re: [TN] Source of IC Contamination Species 
Sent by:        TechNet <[log in to unmask]> 

  _____  




I think you have the answer from other posters, so for information to
complete the picture:
Some fluxless die attach in high power devices is done using formic acid.
The acid is injected into the (inert) furnace atmosphere at the beginning of
the reflow cycle. Formic is used because it breaks down completely at (from
memory) around 110C to H20 and CO2.  
This being the case formates are unlikely to be present after reflow, making
the probability high that they are being introduced later or generated
elsewhere as postulated.


Regards


Mike Fenner

Bonding Services & Products
M: +44 [0] 7810 526 317
T: +44 [0] 1865 522 663
E: [log in to unmask]




-----Original Message-----
From: TechNet [ <mailto:[log in to unmask]> mailto:[log in to unmask]] On Behalf
Of Richard Kraszewski
Sent: Tuesday, September 11, 2012 5:10 PM
To: [log in to unmask]
Subject: [TN] Source of IC Contamination Species

Occasionally, IC analyses are reported to have elevated levels of acetates
and formates.   Is it the general consensus that source of these
contamination is assumed to be the decomposition of larger molecular weight
weak organic acids found in soldering fluxes?  I can't imagine that any
manufacturer would actually be placing acetic or formic acids directly into
a flux formulation. These are much too volatile and aggressive. 

Thoughts?

Rich  Kraszewski 
Senior Process Engineer
PLEXUS 
 


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