Homebrew PCBs

Hi folks!

I am new to the group.  I very much want to use a milling machine 
approach to mechanically mill my circuits. I like the idea of being 
able to (perhaps) build part of a circuit...and then be able to add 
to it later.  Something completely impossible with any technique 
that relies upon chemical milling. So, I find myself trying to build 
a little cnc mill.  (I mean little. 3"x4"x3" of travel - the size of 
my linear slides...taken from a Reticon camera scan platform. I have 
some beautiful 12" ballscrews which will be sadly under-utilized 
driving it...:-)

Anyway, as you can imagine...I find I need to produce three 
identical PCBs for the three servo motor controllers.  So, I have a 
circuit laid out...but I find I cannot seem to get the Toner 
Transfer process to work.  I have tried all the recommended papers 
(i.e. Magazine paper, Staples "Picture Paper", etc...to no avail.)

Finally, thinking I would try a photographic method, I got my hands 
on some viewgraph transparencies.  I intended to make a "positive" 
for a contact photographic process.

But then I thought.  What the heck. I will try a Toner Transfer with 
the plastic viewgraph transparencies.  Lo and Behold!  It actually 
worked. 

In fact, I transferred so much toner...it was even smearing.  It 
seems to want LESS heat and pressure. 

I think I like this method (it isn't perfect, yet...but it's the 
most ink-on-copper that I have seen!)

A few things to note:

1. I printed on the "smooth" side of the transparencies...figuring I 
didn't WANT the toner to stick too well.
2. I used an iron on high heat.  This seemed to be too high. The 
toner was melted onto the copper in seconds. In fact, in areas it 
started to smear...probably from the combination of too much heat 
and my pressing down on it too hard. I will try a lower setting on 
the iron...and less pressure.
3. Clean-up is easy.  You peel it off like a giant piece of scotch 
tape. Hey, is this like dry Press-n-Peel?  :-) 

Anyone else have any good experiences with this method? Any hints?  
I didn't see this mentioned in the group...

Excuse the long post. It's my first. 

Jim

Jim, welcome to the list.

Hey, everyone, I think we need some FAQs! ;')

If you are printing on the "smooth side", then you are probably using
inkjet transparencies. I've tried using both sides, with the logic
that if I get it wet the inkjet coating will allow it to slide off.
Neither side was satisfactory using either an Okidata 400e or a
Lexmark 4029, using an iron. Some of the same problems with
smearing/spreading toner. Less heat or pressure ended up with
non-sticking toner.

Actually, PNP Blue is a dry peel. It has a coating that comes off with
the toner. In fact, someone has successfully printed directly onto the
back (bottom, non glossy) side of those laser foil transfers and used
it like PNP Blue. You must tape it to a sheet of paper or it's too
thin, use the heat resistant tape tabs that come with the laser foil
transfers.

Some other things various people have reported successful for toner
transfer carriers:

Left-over backing sheets from laser labels. Peel dry.

Glossy inkjet paper. Peel wet. Check out Tom Gootee's site and a few
others for tips on exactly which papers, they are -not- all the same.

Magazine pages. May need to be taped to a backing sheet for stiffness,
depending on the printer.

A general consensus seems to be that anything hard like transparency
film is doomed to suffer spreading/smearing because there is nowhere
for the toner to go but sideways. And that paper based toner transfer
is less prone as the toner is anchored to the paper and soaks up into
it if you press very hard.

That's what I've gleaned from discussions of toner transfer.

Steve

> 1. I printed on the "smooth" side of the transparencies...figuring I 
> didn't WANT the toner to stick too well.
> 2. I used an iron on high heat.  This seemed to be too high. The 
> toner was melted onto the copper in seconds. In fact, in areas it 
> started to smear...probably from the combination of too much heat 
> and my pressing down on it too hard. I will try a lower setting on 
> the iron...and less pressure.
> 3. Clean-up is easy.  You peel it off like a giant piece of scotch 
> tape. Hey, is this like dry Press-n-Peel?  :-) 
> 
> Anyone else have any good experiences with this method? Any hints?  
> I didn't see this mentioned in the group...
> 
> Excuse the long post. It's my first. 
> 
> Jim