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Date: | Tue, 11 Sep 2012 20:31:52 +0100 |
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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]] 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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