Richard,
"no-clean myth"? Come on Richard, do you work for a solvent company!?
It is NOT a myth - if you know what you are doing.
Companies like Nortel, Lucent, Westinghouse, IBM and RIM have been
successfully using no-clean fluxes and solder pastes successfully since
at least the early 1990's. And I am not talking about just two year
life portable electronics - some of these companies made/make servers
and telephone switches that are just shy of having to be Class III and
have expected lifetimes in the order of 20 years.
This of course does not preclude the necessity to clean for certain
types of products or for when certain chemicals are used in your
soldering processes.
You'll scare the crap out of the young'uns. :)
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Tuesday, January 09, 2007 3:43 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning
There are many articles, some of which I posted here about a month ago,
that showed that many of the no-clean flux residues are very active
(reactive), sometimes even more so than water soluble (ORH0) fluxes.
Just because it says no-clean does not mean it is always safe to leave
on. One thing you should never do, and that is to mix no-clean liquid
fluxes with other no-clean flux-cored wire solder chemistries.
Read the following link:
http://www.aimsolder.com/techarticles/Incompatibilities.pdf#search=%22no
-clean%20Flux%3A%20the%20use%20of%20multiple%20vendors%20can%20produce%2
0a%20reliability%20time%20bomb%22.
Here are articles written by Terry Munson.
http://www.residues.com/pdf/FailureOfACircuit.pdf#search=%22The%20failur
e%20of%20a%20circuit%3A%20reliability%20effects%20of%20process%20residue
s%22.
The best solution is to get rid of all residues. This approach is
prescribed by Terry Munson, Jenny Hwang, and Les Hymes.
http://www.speedlinetech.com/docs/1714.pdf#search=%22detecting%20flux%20
residue%22
The most authoritive article on this subject is written by Ken Lei. He
fully exposed the no-clean myth for what it really is.
http://www.emeraldinsight.com/Insight/viewContentItem.do?contentType=Art
icle&contentId=1455640
http://circuitsassembly.com/cms/content/view/4229/95/
Doug Pauls also has written many excellent articles on no-clean fluxes,
and on cleaning in general. Check 'em out!
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: Tuesday, January 09, 2007 11:18 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning
So Bev,
LF residues really are more reactive? You seem to have done some
measurements.
Thanks,
Ioan
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian
Sent: Tuesday, January 09, 2007 12:12 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning
John,
Not if they do their homework and do the proper testing to show that the
tweak in reactivity won't put them on dangerous ground. That is why
there are tests like copper mirror, halide ion, British corrosion test,
SIR and electrochemical migration.
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: January 9, 2007 12:02 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning
That's what I was thinking Brian...................8-)
With the change to lead free and the various "wetting" issues a lot of
people are using a more active flux if only to make the joints "look"
more
like 63/37 and as a result are having to use cleaning systems to remove
the flux.
Of course the ones that do not remove the flux will find out eventually
why they should have done!!
John
John Burke
(408) 515 4992
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