[chbot] Anyone making PCBs?

[Charles Manning]

I've even had some success using regular photocopy for the toner transfer 
medium. The trick with this is to soak it for a couple of minutes and then 
slowly rub it really gently so that the paper slowly rubs away, leaving the 
toner in place.

If some of the track comes away you can fix this by using a waterproof marker 
pen.

As for etchant? What's wrong with Ferric chloride? Or does the Nanny State 
only allow us to use organic lemon juice? 

sicom.co.nz  sells Ammonium Persulphate.

In the Good Old Days you could buy HCl as Spirits of Salts. It was commonly 
sold in hardware shops for cleaning. Works well at cleaning up those odd bits 
of cement left behind after grouting etc.


On Tuesday 31 May 2011 17:35:06 Andrew Errington 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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