Bob,
I've seen several tutorials on the laser engraving approach, which seems to
work very reproducibly. Naturally, these all came from shops that had
access to an industrial laser engraver for other reasons.
small-shop laser engraving machines have started to emerge on the market in
the past few years - I've seen one as low as US$4,000. Well outside of my
budget, but compared to some of the CNC milling approaches that I've seen
discussed here, it's actually very viable.
I've not specifically seen any of these low-end machines used for PCB
etching, though I wouldn't imagine there would be a problem.
-Andrew
On Mon, May 3, 2010 at 2:10 PM, Bob Butcher <bbutcher85@...> wrote:
>
>
> I have used several similar ideas, some with more success than others. One
> technique I use sometimes is to polish the copper board with a Schotch Brite
> pae, then spray paint the entire board with spray can enamel (Krylon or
> similar). Then I locate the holes and use my cad program to draw outlines
> around the traces that are connected together, making each net an "island".
> I use a scribe to remove the paint in thin lines between islands, then etch
> only the copper exposed in the thin lines. This uses very little etchant
> since it leaves nearly all the copper on the board. This technique is quite
> time consuming drawing the lines to isolate the islands, but on a fairly
> simple board it works well. I will post a sample file online to help clarify
> the technique.
>
> Years ago I had access to a CNC laser system that could be programmed to
> burn off the paint between traces, and that worked well, but the average
> hobbyist won't have that luxury!
>
> I have also used paint pens rather than the Sharpie ink pens to draw traces
> on the board. These can be purchased from graphic art stores, such as Aaron
> Brothers, and are good for drawing fine lines. The paint resists etchant
> well, but takes a while to dry, so it takes longer to draw the lines on the
> PCB.
>
> I have not had much luck with toner transfer and usually cannot get it to
> release from the dry transfer sheet. This is probably due to my Brother
> laser printer which others have reported does not work well. I think the
> toner used in Brother printers has too high a melting point or something
> similar. I had problems with an HP laser printer drawing lines made up of
> tiny dots that were not quite touching each other, resulting in a circuit
> board trace that looked like a screen, usually with breaks at numerous
> locations.
>
> Bob
>
>
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