Homebrew PCBs

Hi Dave,

I added some distinctive text to this subject line so your message would
be easier to find in the archives.

Can you tell us what type of laser printer you use?

Also, exactly what is your source of paper.  I think the backing paper
for adhesive labels is paper infused or coated with polyethylene, rather
than wax.  Wax would melt and stick in the laser printer's fuser roller.
 I am surprised that the toner sticks well enough to the paper you use
in order to bond to that rather than sticking on the fuser roller.

I developed some DIY transfer paper using thin card (120gsm I recall)
coated with a water soluble glue.  I wrote a series of messages about
this in July 2012.  I was using this to transfer toner onto some
laminating film which I would then bond to a self-adhesive mylar label
material to make robust self-adhesive labels.  However, it should work
for transfer to copper too.  The advantage of these glues, which are
based on Poly Vinyl Alcohol (not to be confused with PVA Poly Vinyl
Acetate emulsions used for wood glue) is that they dissolve in water, so
as soon as the water soaks through the paper, the whole sheet can be
peeled off and the remaining glue gently washed away.  This paper or
thin card feeds well through laser printers, if it is not to stiff.  The
toner sticks to it well.  The trick is to make it consistently without
bubbles.

I had some success and I think this could be improved upon, but I gave
up this process of making labels in favour of injket printing onto a
difficult-to-obtain matte silvery Japanese self-adhesive inkjet label
material (A-One 29283) followed by baking this at ~120C to drive out all
water from the ink (I am using pigment ink from an Epson Stylus Pro
3800) and then laminating it.

Fax paper is very thin and I find it hard to imagine it going through
the laser printer well.

Also, what sort of laminator do you use?  I think there are difficulties
finding a laminator which will accept 1.6mm PCB material in terms of
thickness and also in terms of the board being stiff and requiring a
straight-through path.

What kind of etchant do you use?

I have not experimented with toner transfer onto copper since there are
so many reports of difficulties, and since toner is probably not a good
etch resist.  I am happy so far with using laser printed phototools to
expose Riston negative photoresist.  My messages in the archives
describe my techniques so far.

Nonetheless, if there is a reliable combination of techniques, laser
printer, heating technique (you use a laminator) and etchant for direct
toner transfer, I might give it a go.

  - Robin