another interesting link:
http://www.electronics.dit.ie/techprocs/p_c_b.htmTwo sections are very interesting:
An electric motor spins a shaft enclosed in a tubular barrel 18 inches long
containing holes perforated on the circumference from top to bottom. The
motor and tube are vertical from the top of the tank so as when switched
on, the motor spins the tube and stirs the solution. The effect is to
suction of the solution into the barrel and to spray the board being
etched.
>> (this is the rotrary sprayer we discussed before)
Tin-plating (optional)
This is done to provide a nice finish and to protect the copper from
oxidization; also soldering will appear neater and will flow better.
A solution made up of fine tin powder mixed with water is poured into a
basin. The copper is cleaned to a shiny finish be rubbing using a rubber
supplied with the kit. The board is placed in the solution for 10 minutes.
The board should then have a silver finish.
>> (What? tin powder in water? how does this work? really?)
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