Homebrew PCBs

Short version:  More details of making this transfer paper, including
using a globally available Elmer's glue.  Also, no success using
"wash-away" Poly Vinyl Alcohol embroidery stabilizer film.


I bought some "Elmer's Washable Clear School Glue" and used it to make
laser transfer paper.  It appears to be identical in all important
respects to the Poly Vinyl Alcohol glue I originally used:

. http://www.miyartcrafts.com.au/Craft-Smart-Paper-Gum.html

This Elmer's glue is widely available in the USA and I assume in other
countries.  The 5 Fl.Oz (147ml) bottle I bought was made in the USA.

. http://m.elmers.com/product/detail/E305

The MSDS doesn't list ingredients, but it indicates that the glue
contains nothing of interest regarding health concerns.  This is
consistent with it being based on Poly Vinyl Alcohol, which can be used
as a coating on snack bars.

Searching for:

"Elmers Clear School Glue"
"Elmer's Clear School Glue"

turns up many online retailers from various countries.

Judging by the MSDSs, I think "Gloo Clear Gum" would be identical to the
CraftSmart Paper Gum:

  http://www.miyartcrafts.com.au/view/1509
  http://www.craftsmart.com.au/data/craftsmart_catalogue.pdf

This is available in 1 litre bottles from Officeworks (though not my
closest store) and is also sold (I am not sure where) in 5 litre
bottles, for less than $8 a litre.

So I think this Poly Vinyl Alcohol glue is relatively easy to obtain.


I found greatest success so far with somewhat thicker paper, such as the
very smooth and dense Mondi "Color Copy" 160gsm:

http://www.mondigroup.com/paper_new/EN/color_copy_professional/Products/Color%20Copy/Product%20description/about_color_copy.aspx

This is widely available all over the world.  140gsm would probably be
fine too - I could only get 160gsm.  Two other papers which might be
worth trying are "HP Color Laser 120gsm" and "Mondi Color Copy 120gsm",
both of which I can purchase here at Officeworks.

The thinner the paper, the more curling and potentially sogginess.
However, if there was a way of getting a coating onto thinner paper,
this would probably work better in a laser printer than something
thicker - at least beyond 160gsm.

The paper needs to be smooth and even, and these high-density papers for
colour laser work are ideal.  These are not coated or glossy.  A coating
or gloss layer might be helpful for reducing curling of the paper when I
make it, but I am concerned it would reduce the flow of water through
the paper when I need to release it.

I made an 80/20 glue/water mix and added a few drops of food dye so I
can see more clearly how it is spreading over the paper.  I used a thin,
broad, squeegee to spread a film of glue over the paper.  Then I dried
it with a hot air gun.

I haven't figured out a non-messy way of doing this.  The paper still
curls.  Also, even if it was relatively flat going into the laser
printer, it curls inside the printer after going through the fuser roller.

I tried dampening the sheet in steam (on a wire tray immediately above a
tray of simmering water) before applying the glue mixture.  This may
reduce the curling when applying the mix.  I haven't tried the acetone /
kerosene mixture technique again.  I think it reduces curling, but it is
an extra step with volatile compounds.

I will try using a compressed air sprayer to make a future batch.  It is
possible that by quickly spraying and drying both sides of a sheet I
will get less curl, including less curl in the laser printer.  Coating
both sides may lengthen the release time, but the back layer coating
could be scrubbed off quickly, so this impact could probably be reduced
or eliminated.

The transfer paper I make with 160gsm Mondi Color Copy releases very
well, but it takes about 5 minutes for the water to soak through the
paper and soften the Poly Vinyl Alcohol layer.  I think this can be
accelerated somewhat by one or more of the following techniques: using
warm water; by agitating the water or rubbing it into the back of the
paper; by adding a little detergent; or by putting it in an ultrasonic
cleaner.  When it releases, the Poly Vinyl Alcohol layer remains with
the paper and comes away cleanly.  There's no visible residue of glue on
the surface which now holds the laser toner.  (I am using this for
purposes other than toner transfer to copper - I will write about these
techniques in the future.)


I purchased some Poly Vinyl Alcohol film which is intended to be used as
an embroidery stabilizer.  I got it by the metre from Spotlight and
don't remember exactly which type it was - but it was one of this series:

http://threads.madeira.de/threads/stabilizers-and-non-wovens/wash-away-stabilizers.html

It is far too soft and flimsy to put through a laser printer.  Even
taping one edge to a sheet of card or paper would not work, since it is
soft and prone to wrinkling.

I couldn't find a way of bonding this to paper to make a transfer film.
 There seems to be no solvent other than water, and water rapidly
dissolves it.  I used a ~150C laminator (an unmodified Lowell LOOL28)
and it only slightly attached itself to the paper.  Perhaps with a
higher temperature this might work.  However, I think coating paper with
a liquid glue is a better approach.

  - Robin  http://www.firstpr.com.au/pcb-diy/