[chbot] Anyone making PCBs?

[Richard Jones]

Kind of you to post the details Andrew,

I've made several attempts at the toner transfer method using .020 inch
tracks and 0.020 inch gaps and failed miserably. I don't recall how I did
the cleaning, stainless steel cleaning pads I think, so maybe the additional
detail is in the acetone. What size tracks and gaps are you using? I finally
gave up and used photo sensitive PCBs instead. With your encouragement it
deserves another try :-)

Richard

On Tue, May 31, 2011 at 5:35 PM, Andrew Errington <
a.errington at lancaster.ac.uk> wrote:

> Hi everyone,
>
> Have you ever wondered if the 'toner transfer' method of making PCBs
> actually works?  Have you ever wondered how you can get the chemicals
> needed for etching at home?
>
> I am pleased to report the answer to the first question is yes!  And the
> second one is easy.
>
> Sorry to those of you who have blazed a trail and done this already, but
> I've always wanted to try for myself.  For a long time.  This weekend I
> got started and last night I successfully etched my first board!
>
> There are hundreds of websites describing the process in detail, but in
> case anyone is interested I'll summarise how I did it.  Sometimes it is
> necessary that 'someone you know' has done it to be the catalyst for you
> to try it yourself.
>
> Anyway, here are my key points:
>
> 1) I used KiCAD to draw a schematic and design my own PCB.  I'm making a
> simple voltage detector which lights a warning LED when the voltage on a
> battery pack drops below a threshold.  All the components are SMD.
> 2) Print a mirror image of the artwork on a laser printer.  There are two
> key points here (three, if you count mirror-imaging).
> 2a) Print onto cheap glossy paper.  I am using a supermarket flyer.  The
> paper is thin and flimsy, but has a shiny surface.
> 2b) In the printer driver set the toner density as high as possible (this
> might be set by a 'contrast' or other setting).
> 3) Clean the copper-clad board really well.  *Really* well.  I am using
> the green pan scouring pads (without sponges).  After that, I clean the
> board with acetone (I am using nail-varnish remover).  Make sure it's
> really clean!
> 4) I use a clothes iron to transfer the toner onto the surface of the PCB.
> 5) I let the board cool, and put some warm water in a bowl with a drop of
> washing up liquid.  I drop the PCB into the water and wait.  After a while
> the toner paper will come away.  After that I soak and rub the rest of the
> paper away.  The toner should remain stuck to the board.
> 6) If all is well you will have toner adhered strongly to your board.
> Touch up any small problems with a Sharpie permanent marker or a needle.
>
> You are ready to etch.
>
> It works for me!  But, it's very tedious to get it right, so persevere
> (step 4 is deliberately glib).  If you get a poor result you can wipe the
> toner off with acetone and start again.
>
> For etching I am using Hydrochloric Acid 12% (also called Muriatic Acid)
> and Hydrogen Peroxide 3%.  I am mixing 50/50, but this will change for
> different concentrations.  (Do this in a well-ventilated area, and wear
> gloves and safety goggles, and read up on handling precautions).  It takes
> about 20 minutes to etch the copper away.
>
> After etching you can use acetone to remove the toner before soldering.
>
> I take no responsibility for damage to your laser printer or anything else
> you own, or for injuries sustained playing with nasty chemicals.  I have
> skimmed over a lot of detail, so please check the web for more in-depth
> info.
>
> Today I will try and solder the components and see if it actually works.
>
> Best wishes.
>
> Andrew
>
>
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