Homebrew PCBs

dkesterline wrote:
> That's pretty good results for a first time!
> Did you do anything special for the large copper area? As I mentioned
> in a recent post, when I print the large area, the toner isn't dark
> enough and I have to go over it with a pen- or I get etch through
> and 'pitting'.

Sorry I've taken so long to reply, busy making things work :) I didn't do
anything special for the large copper area. I have the printer set on the
darkest setting with no toner save. I just looked up the MSDS for the toner
in my printer (OKI 4w LED printer) and it seems to have a lower melting
temperature than other toners, 110C. Wether this helps I don't know. The
paper I am using is ordinary magazine paper, Jameco/Time magazine style.
Transferring with an ordinary clothes iron set on the highest setting, it
has a nice flat Teflon coated base without too many holes, which might help.
I've found if the toner has stuck well the paper will bubble up nicely where
the is no tracks.

> I've been TT'ing component print layer for a while now. Somthng you
> might want to try is "Jet PRINT PHOTO Multi Project Paper Gloss

Thanks for that tip, I might try that. The magazine paper does leave a bit
of a mess for silkscreens but if you are careful you can scrub off the paper
with only minor damage to the toner.

> Two problems I havent been able to overcome:
> I can't get a good layout transfer to the copper side of the board-
> including the component side of a DS board. Seems the paper won't
> conform to the uneven surface.

Are you using a clothes iron? What kind of printer are you using? I am only
new to this but I have a feeling that the type of toner has quite an
influence on the consistency of the transfer as well as paper. I don't do
much surface prep at all, just a scrub with a cheap kitchen pad (which isn't
very rough) under some hot water and the toner still transfers perfectly
with no dropouts. Maybe I'm just lucky but using what I have here and not
even going to any special effort I've managed to etch a few perfect boards
without dramas.

Have fun,
Dean

> > Two problems I havent been able to overcome:
> > I can't get a good layout transfer to the copper side of the 
board-
> > including the component side of a DS board. Seems the paper won't
> > conform to the uneven surface.
> 
> Are you using a clothes iron? What kind of printer are you using? I 
am only
> new to this but I have a feeling that the type of toner has quite an
> influence on the consistency of the transfer as well as paper. I 
don't do

I'm using a HP Laserjet 5M, with what I beleive is the original 
cartridge (bought it used, not sure). I started with an iron, but 
recently bought a heavy laminator off e-bay. My TT etch resist 
improved significantly that day. Like others I've tried dozens of 
papers. The best I've found for resist layer is magazine (mine's 
a "Hobby People" catalog - www.hobbypeople.net) and for component 
print / front panels / general artwork I use the "JetPRINT PHOTO 
Multi-Project paper". It releases FAR easier than any other paper 
I've tried and leaves a very clean transfer. But it's not good for 
resist because it leaves some small pinholes that etch through.

My troubles only apply to the component print layer on the etched 
side of the board. I can get a nice clean print on an all copper 
area, and it works fine on a no-copper area, but near an area with 
traces it doesn't transfer well at all. I'm pretty sure this is due 
to the unevenness of the area preventing the toner from making 
contact evenly and I don't expect that it's "fixable".  

> much surface prep at all, just a scrub with a cheap kitchen pad 
(which isn't
> very rough) under some hot water and the toner still transfers 
perfectly
> with no dropouts. Maybe I'm just lucky but using what I have here 
and not
> even going to any special effort I've managed to etch a few perfect 
boards
> without dramas.
> 
> Have fun,
> Dean

My surface prep is about the same, green scotchbrite, a little IPA, 
dry with a clean paper towel. Sometimes I use a scotchbrite type 
wheel in my dremmel for realy oxidized board. I used to remove the 
toner with Lacuer thinner, it's fast but I found out it can attack 
the fiberglass and that's what was causing my dark streaking. Now I 
use a medical adhisive remover wipe with citrus oil. It's not as 
fast, but it works well and isn't as nasty as some of those other 
solvents.

-Denny

>
> My troubles only apply to the component print layer on the etched
> side of the board. I can get a nice clean print on an all copper
> area, and it works fine on a no-copper area, but near an area with
> traces it doesn't transfer well at all. I'm pretty sure this is due
> to the unevenness of the area preventing the toner from making
> contact evenly and I don't expect that it's "fixable".
>

try a soft material between the pcb and iron.
a big pad of silicone thermal conduction rubber would be perfect but i 
think
a piece of soft cloth would work too.
you propably need to heat ot longer.

if you have a clothes press (such a ugly big thing which you can use 
instead of a iron.)
(sorry, correction, this is only to be operated by a woman says the manual 
on the first page
so most likely you don't have one - ask around)

but these monsters have soft padding. maybe it would work.
i may try it some time.
probably you could get it very cheap, i can't imagine anyone wanting such 
a thing.

regards

st