[Robotgroup] Board etching experience/problem

[Gray Mack]

Using acetone with a tooth brush worked even better and finally got down all that board conductance.
Here is some info I found on the different kinds of flux relating to lead free soldering:

Journal of ELECTRONIC MATERIALS, Vol. 34, No. 7, 2005

Soldering with fluxes has been practiced for thousands
of years by artisans and metal workers, but
only began developing as a technology with the industry
revolution.5,6Aflux is considered as a catalyst
that lowers the surface tension between the molten
solder and a metal surface.7
There are three basic flux formulations: (1) no-clean,
(2) rosin, mildly activated (RMA), and (3) water-washable.
The “no-clean” formulations are mild activity
fluxes that produce postsoldering residue, which is
both nonconductive and noncorrosive. Therefore, the
residue can be safely left on the assembly with no corrosion
concern, and cleaning is not required. No-clean
flux residues can be removed after soldering if desired.
Cleaning procedures are generally similar to RMA flux
residue removal. The RMA formulations were the
precursor to no-clean formulations. However, the RMA
flux residues may be conductive or corrosive after
soldering. Removal of the flux residue is recommended.
The RMA flux residues, being rosin based
and organic in nature, are generally removed with a
solvent/saponifier. The “water-washable (soluble)”
fluxes are higher activity fluxes designed for removal
after soldering. The flux residue is cleanable using
water. The water is typically heated and used in a
pressurized spray. Water-washable flux residues are
corrosive and conductive after soldering; therefore,
removal is mandatory


 
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