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Eric,<br>
<br>
As I just noted in a response to Phil, the water based flux products
may be much better now that they were when my company tried them.<br>
<br>
My experience with water based flux does not inspire me to want to use
them again. The No Clean products I do recommend are very good for
people who are familiar with the rosin flux most of us learned to
solder with. The flux stays in the joint doing it's job of reducing
oxides all the way to flow temperatures of the alloy. The viscosity at
temperature is the same as rosin flux, and the only difference you
would see in using it is that it stays water clear to a much higher
temperature than rosin, and smokes less.<br>
<br>
Some of the failures were corrosion related in that the flux contained
acids that would attack metals if not completely removed from the
assembly. I think it is in fact more corrosive than rosin flux, and
careful cleaning is essential to prevent corrosion failures. The
formula of the No Clean products is completely inactive below solder
flow temperatures and will not cause corrosion if it is left on the
board.<br>
<br>
I do clean my boards after assembly even with the No Clean flux, but
only to remove excess flux to prevent it from migrating to areas of the
assembly where it might interfere with things like switch contacts,
sockets, and headers where it might insulate the contact surfaces.
Because the flux is not reactive, I am not concerned if there is a
slight residue left on the board, so long as it is not enough to flow
across the board surface. I use denatured alcohol as a cleanup solvent
when conditions require it.<br>
<br>
This is the inspection standard used in our production processes that
have been reviewed and approved by the FAA. The only cleaning required
is where there is excessive amounts of flux that might migrate or where
there is other debris such as solder balls trapped in the flux residue
that could break loose and migrate to other parts of the assembly.<br>
<br>
This HPSDR project is probably the best radio I ever expect to own, and
I want it to be the best it can be. Give me a print to follow and
parts and a board to assemble and I can do the assembly labor for just
about anything except BGA chips. I have worked with SMD caps that
looked like grains of sand under the microscope. I for one will enjoy
the assembly as much as using the finished product.<br>
<br>
These comments are my own experiences and opinions and do not represent
the official opinions of my employer.<br>
<br>
73 de AD5FU - John in Little Rock<br>
<br>
Eric Blossom wrote:
<blockquote cite="mid20060819134948.GA23186@comsec.com" type="cite">
<pre wrap="">On Sat, Aug 19, 2006 at 03:48:58AM -0500, John Nordlund wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi all,
I thought I might chime in and confuse all of you solder slingers just a
bit.
Water based fluxes do work to a point, but there are some other options
you might want to consider.
</pre>
</blockquote>
<pre wrap=""><!---->
Thanks for sharing your "real world" exerience. It's always good to
have hard numbers on failure rates ;)
73, Eric K7GNU
</pre>
</blockquote>
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