Thank you for answering! I am sorry if I did not explain it clearly, but it
was not advise on cleaning I asked for! My questions " What should I specify
to the PWB manufacturer as solder mask type?
> And yet could we optimize the process in some way to reduce or even avoid
> such problems?" were related to the cause of residues on/in the surface of
the solder mask after wave soldering! The residues are hard to clean because
they seem like embedded into the solder mask, and I am pretty sure it has to
do something either to the solder mask or the solder wave process. And as I
specified we use no-clean flux in wave soldering thus we did not plan
cleaning of the APCB unless forced to do so!

Yordan


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Brian Ellis
Sent: Wednesday, March 17, 2004 2:11 PM
To: [log in to unmask]
Subject: Re: [TN] Solder mask compatibility


Sorry to be patronising, but have you thought that a "no-clean" flux is
designed not to be cleaned? You don't say why and how you have attempted
the cleaning. It is not very clever to try and clean just one side.
Usually, all you do is partially clean it by removing the inactive
components and smearing the dangerous, active components all over the
place, probably reducing the reliability of your assembly. Changing the
mask to matt may give a cosmetically better result, but it will be still
just as bad, even if you can't see the residues as much: they will still
be there.

If you tell us the how and the why, we may be able to advise you better.

Brian

Yordan Venev wrote:
> Hi TechNetters!
>
> We face a problem with flux residues on the bottom (solder) side of the
PCB
> after wave-soldering. We have tried to clean only the bottom side since
> (usually) we do not clean the PCB after assembling, but it is very hard
and
> nearly impossible task! The PWB is FR4 substrate and the flux we use is
> alcohol based no-clean for foam. I cannot specify the solder mask as type,
> but what is obvious is the shining smooth surface. I have a strong feeling
> that for better performance in solder wave process the mask should have
math
> surface. What should I specify to the PWB manufacturer as solder mask
type?
> And yet could we optimize the process in some way to reduce or even avoid
> such problems? We try to follow the flux manufacturer's instruction about
> application, preheat and etc.
>
> Best regards,
> Yordan Venev
>
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