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Another Wacky Idea for Making Circuit Boards Part 2

D

D from BC

Jan 1, 1970
0
How about this for exposing PCB's?

1) Take a LCD monitor apart and replace its backlight with UV tubes.
2) Display a black and white image on the monitor.
3) The presensitized PCB is placed on the monitor for exposure..

I don't know too much about LCD displays. Could something like this
work?

It might very useful for a PCB fab house..
D from BC
 
J

John Larkin

Jan 1, 1970
0
How about this for exposing PCB's?

1) Take a LCD monitor apart and replace its backlight with UV tubes.
2) Display a black and white image on the monitor.
3) The presensitized PCB is placed on the monitor for exposure..

I don't know too much about LCD displays. Could something like this
work?

I suspect the resolution would be very poor. Put a thin piece of
frosty mylar or paper on your monitor... the image is pretty blurry.
And the LCD polarizers and such may not work for UV.

John
 
F

Fred Bartoli

Jan 1, 1970
0
John Larkin a écrit :
I suspect the resolution would be very poor. Put a thin piece of
frosty mylar or paper on your monitor... the image is pretty blurry.
And the LCD polarizers and such may not work for UV.

UVs will toast them pretty quickly.

D, why so much energy wasted in wacking ideas when today you just have
to provide some low cost PCB mfr with gerbers and let them work. Just
get real.
Oh, I can see some thread about a wacky idea on how to glue excel to
some video player and hack your own CAD program.
Then you just have to build a CNC drill, hacking an old sewing machine
with some old printer stepper motors...
 
D

D from BC

Jan 1, 1970
0
John Larkin a écrit :

UVs will toast them pretty quickly.

Oh bummer :(
D, why so much energy wasted in wacking ideas when today you just have
to provide some low cost PCB mfr with gerbers and let them work. Just
get real.
Oh, I can see some thread about a wacky idea on how to glue excel to
some video player and hack your own CAD program.
Then you just have to build a CNC drill, hacking an old sewing machine
with some old printer stepper motors...

It's just that I'm always changing my designs (f*ck ups) and my PCB
volume is like 20 boards/year..
I think I've never duplicated a PCB yet..
I have one PCB where I did so many design changes that if someone
copies the design ..that's a laughable amount of useless electronics
that I just isolated instead of removing..

So I don't mind DIY PCB fab for now.. Let's me get stuff done on the
weekend when PCB fab houses are closed. :)

By the way..
I've ordered dry film photoresist to play with for the 1st time. :)
D from BC
 
J

Jasen

Jan 1, 1970
0
How about this for exposing PCB's?

1) Take a LCD monitor apart and replace its backlight with UV tubes.
2) Display a black and white image on the monitor.
3) The presensitized PCB is placed on the monitor for exposure..

I don't know too much about LCD displays. Could something like this
work?

prolly not... maybe you could use the optics from a laser printer
instead... dunno what wavelength they use or if visible light
photoresist is available.


Bye.
Jasen
 
R

Rene Tschaggelar

Jan 1, 1970
0
D said:
How about this for exposing PCB's?

1) Take a LCD monitor apart and replace its backlight with UV tubes.
2) Display a black and white image on the monitor.
3) The presensitized PCB is placed on the monitor for exposure..

I don't know too much about LCD displays. Could something like this
work?

It might very useful for a PCB fab house..
D from BC

I'd expect the liquid cristals to absorb
ultraviolet at which the chemical bonds
may even break. As Fred put it : The UV
will toast the liquid cristals.

A simple solution is to use an polyester
foil in the printer. I prefer the laser,
but a colleague successfully applied an
ink jet too. Just make sure to have the
top layer mirrored, such that the ink is
right on the photosensitive copper surface.

Rene
 
J

Jim Yanik

Jan 1, 1970
0
How about this for exposing PCB's?

1) Take a LCD monitor apart and replace its backlight with UV tubes.
2) Display a black and white image on the monitor.
3) The presensitized PCB is placed on the monitor for exposure..

I don't know too much about LCD displays. Could something like this
work?

It might very useful for a PCB fab house..
D from BC

You can BUY cheap battery powered small fluorescents at Lowes,WalMart,Home
Depot,for ~$10,some also use 12V AC adapters. (I use them for emergency
lighting in blackouts)

Then get a UV sterilizing tube for it,leave the cover off.
I used to use one for erasing EPROMs.
 
J

John Larkin

Jan 1, 1970
0
Oh bummer :(


It's just that I'm always changing my designs (f*ck ups) and my PCB
volume is like 20 boards/year..
I think I've never duplicated a PCB yet..
I have one PCB where I did so many design changes that if someone
copies the design ..that's a laughable amount of useless electronics
that I just isolated instead of removing..

It sounds like you'd do better investing energy in getting it right
the first time, instead of finding a speedier way to iterate mistakes.

Most of the things we design are sellable as Rev A, the first board,
and we don't prototype. As complexity and density and board layers go
up, time spent checking really starts to pay off.

John
 
G

Gary Tait

Jan 1, 1970
0
How about this for exposing PCB's?

1) Take a LCD monitor apart and replace its backlight with UV tubes.
2) Display a black and white image on the monitor.
3) The presensitized PCB is placed on the monitor for exposure..

I don't know too much about LCD displays. Could something like this
work?

It might very useful for a PCB fab house..
D from BC

Might not work.

If a fab house were to do it optically, they'd use mylar sheets with the
pattern printed on to do a silkscreen, which they'd use to screen etch
resist or powered/liquid conductors on a PCB.

For one off optical, they could use the mylar sheet, or a transparency
from laser or a plotter.
 
J

John Larkin

Jan 1, 1970
0
Might not work.

If a fab house were to do it optically, they'd use mylar sheets with the
pattern printed on to do a silkscreen, which they'd use to screen etch
resist or powered/liquid conductors on a PCB.

Nobody I know of screens boards these days. The bare copperclad board
is cleaned and roller-laminated with a dry resist. The board is
sandwiched with the artwork film and exposed to UV, which sensitizes
(actually polymerizes) the resist. The resist is then "developed",
which removes the unpolymerized areas of resist. Then the copper is
etched.

I suppose some people still use liquid/baked-on resist, but the
process is pretty much the same.

Silkscreens have very bad resolution, so could be used only for very
crude boards.

I wonder if any direct laser-scan exposure is being done, to eliminate
the film.

John
 
D

D from BC

Jan 1, 1970
0
Nobody I know of screens boards these days. The bare copperclad board
is cleaned and roller-laminated with a dry resist. The board is
sandwiched with the artwork film and exposed to UV, which sensitizes
(actually polymerizes) the resist. The resist is then "developed",
which removes the unpolymerized areas of resist. Then the copper is
etched.

I suppose some people still use liquid/baked-on resist, but the
process is pretty much the same.

Silkscreens have very bad resolution, so could be used only for very
crude boards.

I wonder if any direct laser-scan exposure is being done, to eliminate
the film.

John

I think I've seen UV lasers in my internet travels.

I'd be happy with a slow moving low power laser on an XY plotter or
CNC :)

My optics are crappy..but I think it'll work. The PCB copper might
need to be buffed to a mirror finish before the photoresist is put on.
D from BC
 
J

John Bordynuik

Jan 1, 1970
0
Selected by John Bordynuik "Nobody I know of screens boards these days. The
bare copperclad board
is cleaned and roller-laminated with a dry resist. The board is
sandwiched with the artwork film and exposed to UV, which sensitizes
(actually polymerizes) the resist. The resist is then "developed",
which removes the unpolymerized areas of resist. Then the copper is
etched."

I see many automotive single and double-sided board manufacturers still use
silk-screening. In fact, a shop I was at a couple of weeks ago is continuing
to use it on flex circuits. Screening has improved much....

P.S. I wouldn't use it - photo is better but more expensive.

Regards,

John Bordynuik
CPU Architect
JBI
http://www.johnbordynuik.com
 
D

D from BC

Jan 1, 1970
0
Selected by John Bordynuik "Nobody I know of screens boards these days. The
bare copperclad board
is cleaned and roller-laminated with a dry resist. The board is
sandwiched with the artwork film and exposed to UV, which sensitizes
(actually polymerizes) the resist. The resist is then "developed",
which removes the unpolymerized areas of resist. Then the copper is
etched."

I see many automotive single and double-sided board manufacturers still use
silk-screening. In fact, a shop I was at a couple of weeks ago is continuing
to use it on flex circuits. Screening has improved much....

P.S. I wouldn't use it - photo is better but more expensive.

Regards,

John Bordynuik
CPU Architect
JBI
http://www.johnbordynuik.com

Long ago I tried to find silk screen...screen material...another
GoogleFu battle that I lost.. :(
D from BC
 
D

D from BC

Jan 1, 1970
0
?? You just have to know that silk screens are not made from silk.

;-)


Best regards,
Spehro Pefhany

doh! :eek:

What's some good keywords to find that stuff?
silk screen screen?
printing screen?
screen for printing?

"I scream for silk screen" :p
D from BC
 
S

Spehro Pefhany

Jan 1, 1970
0
Long ago I tried to find silk screen...screen material...another
GoogleFu battle that I lost.. :(
D from BC

?? You just have to know that silk screens are not made from silk.

;-)


Best regards,
Spehro Pefhany
 
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