--- In
Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
> I don't think flux will ever evaporate, no matter in what it is
dissolved.
Well, I'm not a chemist (didn't pay much attention to chemistry - I
was an EE major). But I can tell you what I'm seeing. If I clean
flux from an area with 70% IPA and compare it to an area cleaned
with 98% IPA, the 98% IPA area is cleaner; has less residue. This
is without allowing it to run off the edge of the board or blowing
off the residue with compressed air. I'm pretty sure some amount of
flux will be carried off when a volatile solvent evaporates.
Did you ever think about what's going on when you smell some dog
crap? You're actually breathing molecules of dog crap...
> Maybe the water is doing something bad, i sure don't understand
it. Flux
> will not solve in water, maybe that's causing the dusturbance.
It's the water that's cauing the problem. I talked to several
Pharmacists when I was searching for a source of anhydrous IPA.
They all said that rubbing alcohol was 70% IPA and 30% water.
> What does the good IPA cost in comparision?
98% IPA is costing me $4/pint vs. $1 for drug store variety rubbing
alcohol.
> In general i noticed IPA seems to leave more residue than
denatured
> alcohol.
The more volatile the solvent, the less residue it will leave. I
attribute that to how quickly it evaporates. But I'm not a chemist.
> I do know what you mean by the snagging wires problem, that's why
i rarely
> clean the flux off.
I'm somewhat of a Perfectionist. I started working as a technician
before I became an engineer. I prided myself on quality of
workmanship. When I was an R&D Tech at HP Labs, I used to gold
plate my prototypes and black annodize my heatsinks. I got a lot of
compliments on my work. Back then, I used an endmill to layout my
boards (a manual CNC if you will). Even though I could have sent
them out to have boards made. Since I never did more than one of
each design, I did it manually. It was less work in the end. I did
more than a few calculations to determine the proper width for 50
ohm transmission lines.
Once flux has done it's job of preparing materials for good solder
joints, it needs to be removed or deactivated so it doesn't cause
problems. I was always taught to remove the flux. Every single
person who worked on the line where I built computers removed flux.
But, I've seen commercial equipment that was hand soldered and no
attempt was made to remove the flux. Whenever I open up a piece of
equipment and see that, I remove it; at least from the area where I
make repairs. Even if it didn't have the potential to cause
problems, it still looks better without it.
If I were buying two similar products and one looked like there was
more quality in workmanship, I'd probably buy the one that had
better workmanship; even if it cost more. Maybe that's just me.
Regards,
Dennis