Hi Group
This is my first time post here, so please forgive me in case this is
already known. However, there is a small german company selling very
low priced spray etchers which are not that bad. There is a model that
etches one side, and also one that etches two sides at once. However,
the single sided model can also be used for double sided PCB's by
simply turning the PCB once one side is etched. The signle sided one
goes for ~117 Euro (about the same in USD), the double sided one goes
for ~178 Euro. I have the single sided one and I'm pretty satisfied
with the results. The advantage of this etcher is that the device is
"always" ready, there is no mess with etchant since it's a closed box
and etching goes fairly quick also (3 minutes per side). The principle
is simple. There is a rotating tube that delves on the bottom of the
box into the etchant. Since the tube is having fine holes, the etchant
is forced out of these holes due to the rotational speed of the tube,
this results in a fine spray of etchant going over the PCB. Even
though the device is simple I would find it hard to build the same
device on my own for the same price. Let me stress that I'm not at all
related to this firm. I'm simply a happy user of one of their
products.
Here's the link, search for "Sprühätzer".
http://www.radixgmbh.deA word of warning though. The guy running this site aparently is
having a problem with the foreign politics of the US governement. Let
me stress that because of this I really thought twice to publish this
link here but then the etcher is simply too good to be ignored.
Markus
>Some ideas I haven't tried:
>
>Use a stainless steel stirrer such as is used for making milk shakes.
>
>Make some stirrer vanes out of suitable plastic, drive them with small DC
>motors (so you can adjust speed by adjusting the voltage).
>
>Make a centrifugal pump out of plastic. It doesn't have to be terribly
>efficient, just needs to direct a stream of etchant across the board to be
>etched.
>
>Use an oscillating room fan, or a windshield wiper mechanism to move the
>board around in the etchant solution.
>
>Chemical supply houses have a combination hotplate/stirrer. The stirrer
>works by having a rotating magnet underneath the beaker, and inside the
>beaker you put another magnet that is coated with some inert material. You
>might be able to use a "cow magnet" as the coated magnet. These are fed to
>cows to attract iron nails and stuff in the cow's digestive system and get
>them out of the system. (That's no bull :-) I just called a veterinary
>supply company and they sell a 2-inch coated cow magnet for $2.65.)
>
>You might not even need the cow magnet. Since the etchant is conductive, it
>will try to stay stationary with respect to any magnetic field. So, if you
>rotate a strong magnet adjacent to the tank, the solution may rotate in the
>same direction. This is the principle that makes induction motors work.
>
>Use a peristaltic pump, such as from scrapped medical equipment.
>
>Cheers,
>- Jan
>
>
>
>
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