Hi Parag,
I can't answer your questions about the differences, but can tell you
what did and didn't work for me.
I've had good success with HP Inkjet transparencies. They have
several grades; I can give the exact part number if you're
interested. I'm using a Lexmark Optra E+ printer with toner refills;
I haven't found toner to be a significant variable. I've used the OEM
toner and any brand of refill and haven't noticed a difference.
Nothing else worked very well. Some CompUSA inkjet transparencies
looked like they'd do well (better toner coverage), but I couldn't get
a good transfer. May need to work on ironing time. Also tried laser
transparencies and transparencies used for color wax printers (Phaser
type). Nothing worked as well as the HP inkjet transparencies.
With all inkjet transparencies, I get virtually 100% of the toner
transferred. Laser transparencies appear to have a greater affinity
for toner; but I was doing a "hot" remove back then. With inkjet, I
do a "cool" remove.
Since I'm not using the laminator technique, I find that the
transparencies allow me to apply heat/pressure where needed. You need
to cover the transparency with a paper towel to protect the carrier
from melting. This will also help for double sided applications
because you can see through the carrier to line things up. To date,
the only double sided boards I've done were for card edge connectors
and I did the layout so that I only needed the fingers to line up --
basically 2 single sided layouts on the same board.
The paper towel will take a pass or two to shed excess fibers; then
sticking to the transparency will lessen.
I typically have some pin holes, but nothing that's more than cosmetic
and I've never noticed any etching all the way through the copper. If
you remove all of the toner (I used to leave it to prevent oxidation),
you could scrub the copper to remove any oxidized spots. Copper fills
are more problematic, but they can be touched up with an etch resist
(I use fine point black Sharpies, ultra-fine and industrial chisel
tips don't work). But that's purely cosmetic. If you're worried
about conductors being compromised by the pitting, you could make them
wider or tin the traces with solder. I tried using a solder pot for
tinning, but temperature appears to be important and I need to perfect
my technique. I've only had traces from an inkjet transparency
transfer that were "bad" enough for me to want to go over it with a
Sharpie once; I was too lazy to clean the board and try again. That
board was 100mmX160mm (posted with my photos).
An upside to my inkjet transparency method is that once ironing is
done and the board has cooled to the touch, I'm almost ready to etch.
No soaking/rubbing or dealing with paper fibers.
I use a toothbrush scrub with some liquid soap to remove any traces of
the coating from the transparencies. Then I do any touch-up before
etching.
One last thing. Since the carrier is transparent, I can see how much
traces are spreading. I can also see how small the pad/via holes are
getting. I like to have them almost closed to use as a pilot hole for
drilling. I choose the smallest hole diameter for all holes. For
library components, I put a via on them (there are times when Eagle
complains). I usually end up cutting and pasting the metal/vias to a
different board, replacing library pads with vias, and arraying the
pattern to fill an 8.5x11 sheet for printing.
I have some pictures posted for an inkjet transfer.
Regards,
Dennis
--- In Homebrew_PCBs@yahoogroups.com, Mr Crazy <crazymr420@...> wrote:
>
> Does any one know if OHP film, Transperancy and Acetate Films are
the same or all are different?
>
> Which is the best for Toner Transfer?
>
> Parag