RE: PCB Etching (Was : Phono Faceplate - Photos)

[Keith Doxey <keith.doxey@xxxxxxx>]

Hi Ian,

I use photo etching.

Way way back in 1980 I bought a UV Lightbox and used to use drafting film
and stick on templates and track tape. A bit fiddly to do but it gives
excellent results. The track tape is TOTALLY impervious to the UV light so
you get perfect exposures.

Develop the pre-sensitised board in Developer (weak Sodium Hydroxide) and
then etch in Ferric Chloride.

I now have an excellent PCB/Schematic package called Proteus
http://www.labcenter.co.uk
for which thee is a shareware version available as well.

My biggest problem at the moment is lack of a Laser Printer although this
will hopefully be resolved very soon. I used to use the laser printer at
work but since changing offices we have a crappy printer that has a habit
of
depositing black lines on the image. I think it needs a damn good overhaul.
My inkjet printer gives less than perfect results. The image is clear but
the black is nowhere near dense enough. This means I have to be EXTREMELY
careful with the exposure times or I remove all the photoresist :-(

If you do opt for the Photo etch method BUY THE PRE-SENSITISED BOARDS.
I had a load of plain copperclad board bought as part of a bargain pack and
decided to spray it myself. I bought the special spray, cleaned the boards
carefully, sprayed them in near darkness (not an easy or pleasant task) and
then scrapped the lot. The surface of the boards was covered in "fish
eyes"
with a totally uneven covering of resist and after working out the
difference between pre-sensitised board vs plain board + spray + time
p***ing about, the pre-sensitised board won hands down.

I did invest in a bubble etch tank last year along with aquarium pump and
the results are amazing. The quickest etch times ever with all areas of the
board evenly etched.
You do need to cover anything in a 1 metre radius with old newspaper though
because the little bubbles pop and spash ferric chloride everywhere.

Remember, EYESHIELDS, GLOVES, VENTILATION.

Be careful

Keith

> -----Original Message-----
> From: Ian [mailto:I.Bird@xxxxxxx]
> Sent: 17 November 2000 09:36
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Phono Faceplate - Photos
>
>
> Keith
>
> I am making a PCB for the IR circuit at the moment and am
> just about ready
> to etch this weekend. If all goes well I should have two
> pairs by Sunday. I
> was wondering - your circuit is much more complicated than
> the IR one, how
> do you get it onto the copper. I have used the iorn on
> thingys that are
> printed with a laser and then touched it up with a pen. This
> has not been
> altogether successful. How do you prototype?
>
> Thanks for the forthcoming words of wisdom.
>
> Ian
>


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