Steve
They make much finer screens out of synthetics and metals that are
used for the PCB business.
I don't know squat about it other then what the Dow rep told me about
the conductive ink. The
spec says not for use on anything finer than 150um (micrometers)
thread/openings sizes for the
silver ink, about 1/170 inch per thread or hole, or 85 dpi of ink (0.117
inch hole to hole, 0.0058
inch hole size). I think that is fine enough for circuit board
printing, though I'm not sure, that's
why I'm on this list, I don't do it professionally <G>.
The copper ink can use screens down to 125 um thread/opening size.
The spec says the largest particle size is 29 um in the silver ink and
20 um in the copper.
The rep said it was too big for inkjet nozzles, because of the particle
size. Does anyone know
what the inkjet nozzle sizes are?
From what (little) I've read, the way they make flexible circuits is
screen printing the
conductive inks onto the flexible substrates.
The reason I'm interested in printing onto screens is that I'm
interested in screen printing PCBs
in entirety. I'd still like to be able to (best case) run a blank piece
of fiberglass or flexible
substrate through my printer and get a complete, multi-layer, pcb out
the other.
My ideal would be UV hardening inks, with high power UV LEDs on the
print head so that
as soon as it prints, it starts getting cured. Then be able to multi
pass print, where the ink
reservoirs are filled with conductive ink, insulating ink, solder mask
and component marking ink.
Print conductors, print insulating layer for crossovers, print
crossovers, repeat as needed,
print ground layer, you get the idea.
Problem is, they don't make UV curable conductive inks, since the
metal in the inks
blocks the UV penetration into the epoxy matrix, they only make heat
cure and VOC based.
So to give a short answer, if I can't print like I would really like,
the next step back is doing
it by directly printing the layers onto the screens, then using the
screens to print the different
conductive and insulative layers, drying between layers, then curing it
all together.
I don't want to mess with exposing the screens and developing them
anymore than I want
to expose, develop and etch the copper ;)
I'm basically lazy and cheap.
I want it, I want it now, I want it free and I don't want to work to
get it.
I will work real so that I can be lazy about something later. I could
make pcbs the 'old
fashioned' way, but I'd rather just have the pcb already. If I'm doing
a design, that's what
I'm concerned with, and interested in doing. At that point making a PCB
is just a means to
an end.
Right now I'm in interested on how to make one off pcbs the cheap and
lazy way, so it's
got my attention. Later on, I'll just want the darn pcb, so I have to
help figure out a real quick
and fairly easy way to do it, now, so I can be lazy about it later.
Take the last three or four paragraphs with grains of salt and smileys
after every line.
Except the cheap and easy one. Damn, I meant cheap and lazy. :(
RM
>Why would you print onto the screen? A screen has to be exposed just
>like photosensitive PCBs so you print a transparency then expose and
>develop the screen.
>
>It's been discussed here quite a bit, that fabric printing screens are
>just not fine enough mesh to screenprint etch resist.
>
>If you mean can the screenprint inks be fed into an inkjet printer,
>no, they are way too thick.
>
>I am going to try the pigmented inks I use directly onto a PCB. I am
>assuming I'll have problems with puddling, so I'm going to start out
>with a hot board and lay down very little ink for a start. I have some
>thin PCB about the thickness of a business card, that should feed fine
>in my printer.
>
>Steve
>
>
>