If the no-clean hand soldering wire is classified as "Rosin based, low
residue (<0.5% solids)", is it safe to "not clean" the assemblies? What
if the amount of flux residue is a concern?

If everything unchanged, how would one choose between a low residue
(ROL1 as per J std-004) solder wire as supposed to "no residue" (ROL0)?


Peter



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kathy Kuhlow
Sent: September 6, 2001 9:04 AM
To: [log in to unmask]
Subject: Re: [TN] Removal of No-Clean Flux residue

It depends on the reason why you are cleaning no-clean.  As you stated
the reason you are using a no-clean is to add components that are
sensitive to water.  You  also use a water washable in other process
steps.  I have seen issues were the hand cleaning operations have
damaged many components that are sensitive mainly due to washing.

I have also been involved with chemistry issues due to mixing
fluxes/solders.

In past lives I have seen disclaimers added to all contracts that use
moisture sensitive components where the customer has made a no residue
requirement even from no-clean solders.  This way the customer has to
acknowledge that this is not an acceptable practice for no-cleans.  You
can also get paid for the hand wash process.

Recently I know of an issue where a battery was installed in a hand
soldering operation and the customer had a no-residue requirment (due to
end user perception) was being hand washed after using a no-clean.  When
the operators were cleaning the two leads and got both leads  wet the
battery started to discharge because of the water conductivity.

I was trying to find a study that I had read about a year ago talking
about the reliability issues when some no-cleans are cleaned.  I thought
it was on EMPF but I looked through the archives and couldn't locate it.
It talked about possible contaminate entrapement if all of the residues
aren't removed completely but more smeared around.  It also discussed
reduced life due to chemistry mismatches.

I will continue looking and if I find it I will send it to you.

Kathy


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