Homebrew_PCBs

Has anyone ever tried using silk screen printing emulsion as a cheap photo resist for PCB fabrication? I have an order in with my neighbor for some from his shop. I'm going to give it a try, just want some input from anyone with experiance with emulsion.
Dan


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On 20/11/06, Dan Pickard <dlpwebmail@...> wrote:

>
>
>
>
>
>
> Has anyone ever tried using silk screen printing emulsion as a cheap photo resist for PCB fabrication? I have an order in with my neighbor for some from his shop. I'm going to give it a try, just want some input from anyone with experiance with emulsion.
> Dan
>
>

How do you plan to get it on the board?
Lez

Are you talking about using the silkscreen process itself or just the inks? A friend of mine silkscreens a tar through the screen and etches away. Don't know if he ever tried the ink/paint itself. Some of that stuff is pretty rubbery might just work.
Dave


-----Original Message-----

From: Dan Pickard <dlpwebmail@...>
Subj: [Homebrew_PCBs] Screen printing emulsion
Date: Mon Nov 20, 2006 2:13 pm
Size: 1K
To: Homebrew_PCBs@yahoogroups.com

Has anyone ever tried using silk screen printing emulsion as a cheap photo resist for PCB fabrication? I have an order in with my neighbor for some from his shop. I'm going to give it a try, just want some input from anyone with experiance with emulsion.
Dan


---------------------------------
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--- In Homebrew_PCBs@yahoogroups.com, Dan Pickard <dlpwebmail@...> wrote:

>
> Has anyone ever tried using silk screen printing emulsion as a cheap

photo resist for PCB fabrication? I have an order in with my neighbor
for some from his shop. I'm going to give it a try, just want some
input from anyone with experiance with emulsion.

> Dan

Searching the archives for "silk screen emulsion" (no quotes) brings
up some useful matches.

I just cropped and removed extraneous images from a file someone had
uploaded previously of his tests using silk screen emulsion as photo
etch resist. He just brushed it on. However, as per his later
messages, which emulsion you use is very important. Not all will stick
to copper.

Steve Greenfield

I just cropped and removed extraneous images from a file someone had
uploaded previously of his tests using silk screen emulsion as photo
etch resist. He just brushed it on. However, as per his later
messages, which emulsion you use is very important. Not all will stick
to copper.

Thanks, Steve
I'm new to the group thing. I found it, Thanks.
As for the other posts: the screen printing of PCB works out perfect for high-run production but it's way to costly for one-off boards. The ink holds up under etchant for hours. I had a few boards screen printed for the lab at $100 for two. You have to pay that set-up fee :-(




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--- In Homebrew_PCBs@yahoogroups.com, Dan Pickard <dlpwebmail@...> wrote:

>
>
>
> I just cropped and removed extraneous images from a file someone had
> uploaded previously of his tests using silk screen emulsion as photo
> etch resist. He just brushed it on. However, as per his later
> messages, which emulsion you use is very important. Not all will stick
> to copper.
>
> Thanks, Steve
> I'm new to the group thing. I found it, Thanks.
> As for the other posts: the screen printing of PCB works out

perfect for high-run production but it's way to costly for one-off
boards. The ink holds up under etchant for hours. I had a few boards
screen printed for the lab at $100 for two. You have to pay that
set-up fee :-(

>

Dan, I can't tell what you wrote and what was quoted.

You'd probably not have found those pictures on your own, the
gentleman who uploaded them didn't label them very well.

Yes, screen printing setup charges are spendy. $35 to $75, and in
order to have a screen good enough for a PCB the screen must be a much
finer mesh than those normally used for Tshirts.

The pictures I "fixed", however, are of using the photo emulsion that
normally goes on the screen, right on the board as the etch resist. I
think the idea is that it is supposed to be a lot cheaper than normal
PCB photosensitive etch resist. Not having priced the two, I don't
know. In that particular case, the gentleman involved I think was
unable to find conventional photosensitive PCBs or coating in his country.

Steve Greenfield

We used to use it all the time in high school. The Graphics Arts lab
was right next to the Electronics lab. The GA guys would whip up a
silk screen and frame it for us. We'd set it in a jig over the pcb,
press it down tight, and squeegee some ink over it. Set it to dry
(under a heat lamp to dry it faster) and etch.

Worked really well with professional looking results. I'm not sure of
the ink we used though (20 years ago now). It was thick and gooey and
blue.

Bert

> Steve wrote:
>
> The pictures I "fixed", however, are of using the
> photo emulsion that normally goes on the screen,
> right on the board as the etch resist. I think
> the idea is that it is supposed to be a lot cheaper
> than normal PCB photosensitive etch resist. Not
> having priced the two, I don't know. In that
> particular case, the gentleman involved I think was
> unable to find conventional photosensitive PCBs or
> coating in his country.

If you have a brother in law that works in a screen
printing shop then the diazo stuff might be cheaper.

If you are comparing the price of diazo stuff with
something like kodak KPR then screen printing is
cheaper.

If you are comparing prices of buying small bottles
of diazo screen printing emulsion from your local
art/hobby shop with pre sesitised boards then it
looses.

I have to pay $60 (AUD) for a little bottle of the
diazo stuff from an art shop. I pay $3 (AUD) for
a 100 x 150mm PCB with dry film already on it.

That said - I might try it just to see how good a
result can be acheived. That is when I have spare
time :(

--- In Homebrew_PCBs@yahoogroups.com, Dan Pickard <dlpwebmail@...> wrote:

>
> Has anyone ever tried using silk screen printing emulsion as a cheap

photo resist for PCB fabrication? I have an order in with my neighbor
for some from his shop. I'm going to give it a try, just want some
input from anyone with experiance with emulsion.

> Dan
>
>
> ---------------------------------
> Sponsored Link
>
> Mortgage rates near 39yr lows. $310,000 Mortgage for $999/mo -

Calculate new house payment

>
> [Non-text portions of this message have been removed]
>

One way to coat the bare copper board is to use a blank silkscreen.
Tape off an area slightly smaller than the size of the board and use a
squeege to flood coat the copper panel with the screen emulsion. This
method will print an even coating of emulsion. Let it dry and expose
it with a UV lamp. Keep in mind most screen printing emulsions are
negative acting. Any areas exposed to the UV lamp will remain after
development. This would probably work good if the adhesion to copper
is sufficient. Diazo type screen emulsions can be stripped after use
with chlorine bleach. Diazo screen emulsions also have a short shelf
life (about 30 to 45 days) once the two parts are mixed.

Coating boards with a bare screen is one way to apply photoimageable
soldermask. I used to apply Taiyo photoimage soldermask this way by
using a 110 mesh polyester screen. Finer screen meshes will result in
a thinner coating on the board. This coating method works but the only
question is how well it will adhere to bare copper.

Several years ago I tested a sample of screenable photo resist. It was
made by a company in Germany but I can't remember their name. This
screened photo resist worked great but was expensive. The main
application for this product was for imaging inner layers for
multilayer boards. If I can find the information on this product and
company I'll post it later. This type of product would be excellent
for making print and etch boards.

Tom

http://www.cbridge.com/howtos/printedcircuitboard.shtml

StencilPro. I have thought of using this for pcb, silkscreen and
solder mask.

On 27/11/06, john80014 <jhewatt@...> wrote:

>
>
>
>
>
>
> http://www.cbridge.com/howtos/printedcircuitboard.shtml
>
> StencilPro. I have thought of using this for pcb, silkscreen and
> solder mask.
>
>

Anyone used this, I'm puzzled as to how it works, I can see that its
light sensitive, but how does that make it allow the etch resist to
pass through???

I think I'm missing understanding part of the process.

Looks like an answer to my prayers though, I can make one stencil, and
from that produce more boards whenever I need them (of the same design
of course)


Lez

I have never used this but assume its like normal silkscreening.
Basically think of like womens stockings stretched tight over
something.

Then coat it with the stuff, what gets light hardens and plugs the
netting/holes and the rest washes out leaving fine holes to press
the resist through.

The holes are much finer and so on this is just a quick visual.

--- In Homebrew_PCBs@yahoogroups.com, Lez <lez.briddon@...> wrote:
>
> On 27/11/06, john80014 <jhewatt@...> wrote:
> >
> >
> >
> >
> >
> >
> > http://www.cbridge.com/howtos/printedcircuitboard.shtml
> >
> > StencilPro. I have thought of using this for pcb, silkscreen
and
> > solder mask.
> >
> >
>
> Anyone used this, I'm puzzled as to how it works, I can see that
its
> light sensitive, but how does that make it allow the etch resist to
> pass through???
>
> I think I'm missing understanding part of the process.
>
> Looks like an answer to my prayers though, I can make one stencil,
and
> from that produce more boards whenever I need them (of the same
design
> of course)
>
>
> Lez
>

StencilPro looks like it might be very useful for creating silkscreens and
solder masks. I can see using regular white enamel from a spray can for the
silkscreen but what would people suggest applying through the stencil for
the solder mask?



_____

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of john80014
Sent: Monday, November 27, 2006 2:28 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Screen printing emulsion



http://www.cbridge
<http://www.cbridge.com/howtos/printedcircuitboard.shtml>
com/howtos/printedcircuitboard.shtml

StencilPro. I have thought of using this for pcb, silkscreen and
solder mask.





[Non-text portions of this message have been removed]

At 5:20 pm ((PST)) Mon Nov 27, 2006, Lez wrote:

>On 27/11/06, john80014 <jhewatt@...> wrote:
> > http://www.cbridge.com/howtos/printedcircuitboard.shtml
> >
> > StencilPro. I have thought of using this for pcb, silkscreen and
> > solder mask.
>
>Anyone used this, I'm puzzled as to how it works, I can see that its
>light sensitive, but how does that make it allow the etch resist to
>pass through???
>
>I think I'm missing understanding part of the process.

The part you are missing is development in water. This is
steps 7 & 8 in the illustrated stencil production process at
http://www.cbridge.com/howtos/createstencil.shtml


Regards, LenW

I can now see how it works, some of the photo-reactive material washes
away, leaving the mesh behind, does the mesh not create problems when
the resist is pressed through? I would have expected a checkerboard
pattern in the resist, so tracks dont conduct end to end ect.

It sounds a great may to make a stencil for a small 'run'.


Lez

They are really rather fine holes and threads. Most mass production
T Shirts with graphics are done this way along with snowboards,
skateboards, and most any flat surface mass production item that
needs a nice graphic on it.

If you have ever seen some of the amazing graphics on the bottoms of
skateboards you can see just how high quality it can get.

Again I have never tried this product but I can see how it would
totally work and not leave a checkerboard behind.

--- In Homebrew_PCBs@yahoogroups.com, Lez <lez.briddon@...> wrote:
>
> I can now see how it works, some of the photo-reactive material
washes
> away, leaving the mesh behind, does the mesh not create problems
when
> the resist is pressed through? I would have expected a checkerboard
> pattern in the resist, so tracks dont conduct end to end ect.
>
> It sounds a great may to make a stencil for a small 'run'.
>
>
> Lez
>

They make two products. 1) general use and 2) a super wich i think is
1200dpi.

They actually give a short step by step for pvb track layout.

For solder mask i bet you could even use a poly plastic paint or maybe
clear for that mater.

John