Jeffrey,
I will send you a document that I drew up about 12 years ago, together with
the late Dr. Bill Kenyon.  It talks about no-clean fluxes and why someone
would choose to clean a no-clean flux.  You might find it of benefit.

There are also a number of excellent papers by Dr. Mike Bixenman of Kyzen
on the nature of fluxes under QFNs that more addresses what can happen if
those low solids residues do not get to the proper temperature.

*Douglas Pauls *| Principal Materials and Process Engr | Advanced
Operations Engineering

*COLLINS AEROSPACE*

400 Collins Road NE, MS 108-101, Cedar Rapids, IA  52498  USA

*Tel:* +1 319 295 2109 | *Mobile: *+1 319 431 3773

[log in to unmask]

[log in to unmask] for all Export Compliant Items


On Thu, Feb 27, 2020 at 2:21 PM Jenkins, Jeffrey (US) <
[log in to unmask]> wrote:

> Fellow TechNetters,
>
> I apologize if this may seem like a newbie question and if so I apologize.
> I've used OR fluxes and RO fluxes and have always had them removed by the
> cleaning process as most of the products that I work on have an expected
> life of 10+ years.  We've typically validated the amount of WOA and
> Chlorides and set baselines for those.
>
> Someone posed me a question about cleaning no-cleans. Even though in a
> perfect world a no-clean flux should be 100% inactive after reflow, I'm
> betting that's never perfectly the case.   So my view and response was that
> based on the life span and end use environment, my concern would be
> humidity/moisture mixing with the residual material and in the long term
> increasing the risk of dendritic growth and other things.  Am I off the
> mark?
>
> Thanks,
>
> Jeffrey A. Jenkins, CID+
> Principal Engineering Designer
> Cubic Mission Solutions
>
> Note: This email and any attachments may contain confidential or
> proprietary information.
> If you are not the intended recipient, any use or distribution is
> prohibited; please notify the
> sender and delete from your system.
>