>
> I'm stuffing compenents in all my boards for the first pass solder/wash.
I
> normally mount electrolytic capacitors firmly up against the PCB. After
> reading about the problems of organic flux residue, I am wondering how I
am
> going to clean under under them. Does it matter if I can't clean under
them?
> Or do I need to keep a centimeter or so space, so I can clean
Actually, the hole spacing is about 0.025 ∗wider∗ then 'spec' to make the
caps "stand up"
off the pcb about 1/32" so the water will flow under there. Note the "yellow
box caps"
have small cutouts for this purpose.
> Is the only reason we are not using good old rosin core 63/37 solder
because it leaves
> unsightly flux marks?
There are two reasons MOTM does not use rosin core solder (in fact, no one
has used rosin-core solder
∗in mass production∗ since about 1990).
#1 - rosin is designed to ∗attract moisture∗ (think of the rosin bag in
baseball, and in gymnastics). Attracting
moisture in ∗NOT∗ what we want in synths! Especially VCOs.
#2 - in order to ∗remove∗ the rosin off the boards, you need ∗horribly
messy∗ chemicals. Freon was the older
choice. There are spray cans of non-CFC rosin flux remover, but my
experience is that this makes a huge
mess because all you do is dissolve the flux and coat the whole pcb with it!
In production lines in the '70s/'80s
there were massive, high-power water jets that 'scrubbed' the flux off with
150 psi water nozzels after a good old Freon
bath (the boards were actually immersed in liquid Freon).
Today, ∗all∗ soldering is using "No Clean" flux.
So, a fair question is :"Why not use No Clean everywhere?"
The answer is that I felt that No Clean is harder to solder, and that
organic ∗still∗ has the best overall
joint construction. The only reason No Clean replaced organic is that the
manufacturers saved millions
of dollars on water bills (and floor space!).
Paul S.