--- In
Homebrew_PCBs@yahoogroups.com, "d1camero" <a8723@...> wrote:
>
> Hi gang. This is my first time trying this method and I am having
> some troubles.
>
> First of all I am using photo paper and an iron to transfer component
> artwork to a PC board. The boards are thick 1/8" and big 4" x 12".
...
My next attempt was trying 5 minutes with the iron -
> but again, little stuck.
>
> Any suggestions?
>
Hmmm, after poor results with TT years ago, I've been trying it again
and it's working quite well. My biggest probelm is with ironing by
hand, the trace width varies slightly. I can get 12/12 in small areas
but I pretty much feel 16mil/16mil is the lower limit (stuff above
20mils wide looks great.
Stephan T. seems to really have this down but here's my process
Best paper for me right now is Hammermill OfficeOne Glossy Paper
#229030 - I get mine at Sam's Club (online only). Thisn is also
inkjet paper but works just fine in Lasers. I think the Hammermill
Color Laser Gloss Paper #292253 might also be worth a shot but I
haven't tried it yet.
I clean my board with just a Scotch Brite sponge & some drops of Dawn
dish soap with a little water, scrubbing both directions and little
circles, ect. Just a minute or so of cleaning is plenty. If the
appears to be any residue or I get a fingerprint on it, then I wipe it
with 99% alcohol (most drug stores have or can order the 95 or 99% stuff).
One important tip, I take a small file and file the ridge off the edge
of the board. Sometimes there's one left from the shear process and it
can keep the image from being pressed well.
I pre-heat the board for only about 30 seconds (if I'm doing single
sided, no preheat for double as the toner gets tacky and makes
alignment more difficult).
I place the image on the board and a plain sheet of printer paper over
that and then iron it with the irn on high (cotton). I place the iron
on the image and push just straight down to set it and then holding
the paper by the corner, slowly move the iron around the board. I've
found it best to push the iron away from the corner I hold so the
paper doesn't lift up (the sheet of printer paper helps here to, it
helps the iron slide better). I've been ironing the trace for 2
minutes on a pre-heated board, 2 1/2 to 3 if not pre-heated. A larger
board like yours is going to need a lot more time with an iron.
Probably about 2 minutes in each quadrant I would guess.
For double sided, I let the board cool, flip it over (image & transfer
paper still attached), align the second image (pre-driiled alignment
holes before transfers), and repeat the ironing process.
After ironing, I let the board cool, fill a sink with warm water
(couple of inches) and soak the board (usually 5 to 10 minutes because
I forget about it, couple is enough). I rub gently (sometimes scuffing
a spot with my nail to start it) and almost all of the paper falls
right off.I then soak the board a few more minutes and rub it again,
the rest of the paper removes easily. Rubbing gently with a foam Magic
Cleaning pad (not a scouring pad, a white foamy thing) removes any
residue between the small traces (ST says he uses plain foam rubber).
Then etch. I used HCL once. the mix was Muratic Acid (31% HCL) with
drug store Hydrogen Peroxide (3%). I 50/50 mix etched the board well
but gave off plenty of nasty fumes. In a tub of warm water below the
etch tank though, it did etch the board in a couple of minutes. Went
back to Ferric Chloride though, it's more user friendly and can be
used indoors. I'll probably use the Muratic acid when the weather is
better (outside on a sunny day).
One thing is some toners work better than others. Work machines are HP
Laserjet 8000 series with HP cartridges. They work good. My home
machine is an HP Laserjet 1200. I have a remanufactured cartridge in
it and it works really well, better than the machines at work (gotta
order a couple of spare cartridges from that place!)
I still like the photo process for fine images and truely professional
looking boards, but for pumping out a quick proto-type the Toner
Transfer is hard to beat. It's become my first choice for home boardz.
Phil
KA0HBG