PCB success!

[mark verbos]

jorgen.bergfors at idg.se wrote:

> Hi DIYers!
>
> Yesterday evening I managed to etch almost perfect circuit boards of my own
> design, at home in the kitchen.
> I have found a method that seems to give almost professional results every time.
>
> I design the boards in Corel Draw. The traces are in one layer, the component
> symbols in another. All traces are magenta, because it looks good together with
> the components when I print it on a colour printer.
>
> I print the board using color separation on transparencies. I tried both a
> Lexmark Optra Rx laser printer and a HP Deskjet 720C inkjet, with film material
> suitable for each. It turned out the inkjet gives better, more opaque traces,
> so that's what I used. It is important that the inkjet uses dye-based black
> ink. HP 720, 8xx and up, Lexmark 5700 and up are fine, but forget Epsons.
>
> I buy the boards pre-coated with positive photo resist (www.elfa.se).
> The film is put on top of the board, with the printed side down.
> A glass pane from a picture frame is put on top.
> Two lead weghts are placed on the glass (outside the board) to press it down.
> The boards are exposed to UV-light, using a tanning lamp that I bought at a
> flea market last weekend for SEK 15 ($2). A distance of 40 cm and 4 minutes
> exposure is ideal.
>
> The board is developed in NaOH (I think) for one minute.
>
> The etching is done in a ceramic heatproof container on the stove (normally
> used for baking food in the oven). That way the temperature can be kept around
> 50 degrees C, by turning the heat on now and then. Etching takes 20 - 30
> minutes. I don't remember the formula for the etching powder, but it is what is
> sold for PCB etching.
>
> The result is almost perfect. I didn't do too thin traces because I wasn't sure
> about the results, but traces between IC legs should be no problem at all.
> Seven point text looked perfectly clear on the board.
> This is the way to do one-off or a small series of boards I think. It's so
> quick and easy. An it uses no hard to get or expensive materials. Nothing seems
> to be particularly critical. There is no touching up or grinding to do to get
> functional boards.
>

this is how I have done all of mine. Not a problem yet! (I have done about 25
modules)
--
mark verbos

"I think the future of analog modulars is to build them yourself."

verbos at on-q.com
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