I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin plate,
dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should I
direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin plate,
dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should I
direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

http://en.wikipedia.org/wiki/Photochemical_machining
http://www.fotofab.com/about.php

jsw

On Wed, 08 Feb 2012 17:14:35 -0500, Jim Wilkins wrote:

"Tim Wescott" wrote in message
...
I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin
plate, dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should
I direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

http://en.wikipedia.org/wiki/Photochemical_machining
http://www.fotofab.com/about.php

Thanks for the link. That's exactly the process I was looking for, and
if they don't have enough search terms then I'm just not looking hard
enough!

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin plate,
dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should I
direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

Hi Tim,

The usual process is as you described and called variously photo etching,
photo-chemical machining, photo-chemical milling, chemical machining. There
are a bunch of places that do this if you search with those terms.
Tolerances depend on the metal thickness and can be as small as a couple of
microns. The price per square inch is pretty low, but the tooling charges
can be several thousand. The usual materials are stainless and berylium
copper, but they can do others as well.

There is another company called Metrigraphics
(http://www.metrigraphicsllc.com/) that does electroforming
(electrochemical deposition on a mandrel). They get very nice edge surface
finish and edge roughness and can do very small apertures repeatably. I
think the tooling and per part cost is more though.

If you are looking just for small pinholes or slits, National Aperture has
them off the shelf (http://www.nationalaperture.com/)

Tim Wescott wrote:

I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin plate,
dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should I
direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

This stuff isn't that hard to do yourself, even, if you have a way to
make the master films. I make solder paste stencils this way. I use
..003" brass shim stock, and laminate dry film photoresist to both sides.
I make mirror-image films with a photoplotter and align them to each other.
I then slip the sensitized brass between the films and expose both sides
to UV from the filtered black light bulbs. Develop the photoresist in
sodium carbonate and then etch with ferric chloride in a double-sided
spray etcher. I've gotten down to .010" apertures or thereabouts.

positional accuracy of the apertures can be quite high, easily to
..001", maybe better. SIZE accuracy depends on how well-controlled their
process is. Mine isn't so great, I get a lot of undercutting where
the etchant gets between the resist layers and opens up the apertures,
even with short etch times. But, I guess a professional vendor of
such work can hold tighter tolerances.

There are outfits that will make "solder stencils" for $50 each, up to
maybe a foot square. If you can get them the artwork in Gerber file
format they do it pretty much by the process I described above, or
by laser-cutting the apertures. This is done for the printed circuit
assembly industry, you should get a million hits googling for
"solder stencil".

Jon

Tim Wescott wrote:

I have seen (held in my hands, actually), metal parts that are made by
etching thin steel with acid (presumably after printing on a resist).
It's great stuff for making optical stops, encoder wheels, and other
things where the worst that the metal has to resist is a stream of
photons smacking into it.

The steel in question appears to be either stainless steel or tin plate,
dead soft, and is maybe 5 or 10 mils thick.

What's the processing called in the industry? What sort of shop should I
direct someone to look for in their yellow pages or their Thomas
Register? What sort accuracies can one expect, and setup costs, and
fabrication costs?

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

I recall seeing a kit for photo-etching model parts in I think it was
the Micromark catalog.

Jon Elson wrote:
This stuff isn't that hard to do yourself, even, if you have a way to
make the master films. I make solder paste stencils this way. I use
.003" brass shim stock, and laminate dry film photoresist to both sides.
I make mirror-image films with a photoplotter and align them to each other.
I then slip the sensitized brass between the films and expose both sides
to UV from the filtered black light bulbs. Develop the photoresist in
sodium carbonate and then etch with ferric chloride in a double-sided
spray etcher. I've gotten down to .010" apertures or thereabouts.
--This sounds fascinating. I'd looove to see a photo essay of you
doing this. Got any links??


--
"Steamboat Ed" Haas : Steel, Stainless, Titanium:
Hacking the Trailing Edge! : Guaranteed Uncertified Welding!
www.nmpproducts.com
---Decks a-wash in a sea of words---

steamer wrote:

Jon Elson wrote:
This stuff isn't that hard to do yourself, even, if you have a way to
make the master films. I make solder paste stencils this way. I use
.003" brass shim stock, and laminate dry film photoresist to both sides.
I make mirror-image films with a photoplotter and align them to each
other. I then slip the sensitized brass between the films and expose both
sides
to UV from the filtered black light bulbs. Develop the photoresist in
sodium carbonate and then etch with ferric chloride in a double-sided
spray etcher. I've gotten down to .010" apertures or thereabouts.
--This sounds fascinating. I'd looove to see a photo essay of you
doing this. Got any links??


Hmmm, well, not really. I do have some stuff on my web pages showing
some of the gear. Here's a poor picture of the laser photoplotter.
http://pico-systems.com/photoplot.html

I put litho film on the drum, it records the image in a raster
fashion, building up the image at .6 inches/minute. Develop
with usual photo chemistry.

I snagged a Kepro dry film laminator on eBay years ago. It
is made for laminating the resist to PC boards, but if you
put a shim of several sheets of heavy paper under the brass
shim stock, it laminates perfectly to thin shim stock, too.
You put the resist on both sides, and then expose with mirror-image
photo masters. The resist is developed and then put in a
Kepro spray etching machine that I got just before it hit the dumpster
at work.

I used to use this gear to make PC boards, but they make these so
cheap in China now that I rarely make my own. (I have scraps
left over from so many projects that I can usually find a board
that can be re-purposed for new experimental projects.)

I built the photoplotter myself. The machine wasn't too hard to
make, once diode lasers came out. The software was a lot
harder to do.

I've got some pics and story about getting the Philips pick
and place machine in my basement. That was an ORDEAL!

Jon

some other hobby uses and techniques for photochemical
electro etching, that are less tech intensive [i.e. less
expensive].

http://www.aardvark.co.nz/pjet/makevalves1.pdf

http://www.youtube.com/watch?v=jEnNMTMZadw

http://www.scribd.com/doc/80581475/1...emical-Etching



--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"

Jon Elson wrote:
steamer wrote:


Jon Elson wrote:

This stuff isn't that hard to do yourself, even, if you have a way to
make the master films. I make solder paste stencils this way. I use
.003" brass shim stock, and laminate dry film photoresist to both sides.
I make mirror-image films with a photoplotter and align them to each
other. I then slip the sensitized brass between the films and expose both
sides
to UV from the filtered black light bulbs. Develop the photoresist in
sodium carbonate and then etch with ferric chloride in a double-sided
spray etcher. I've gotten down to .010" apertures or thereabouts.

--This sounds fascinating. I'd looove to see a photo essay of you
doing this. Got any links??



Hmmm, well, not really. I do have some stuff on my web pages showing
some of the gear. Here's a poor picture of the laser photoplotter.
http://pico-systems.com/photoplot.html


A nice little project you have there. Do you get much trouble with
temperature stability. I ask as my local photo plotter mentioned that
they keep the plotter in a temperature controlled room and also that the
film itself is quite sensitive to temperature changes. IIRC their photo
plotter was 2000DPI for normal use but could go higher and the sheets
were about 2ft x 2ft.

I put litho film on the drum, it records the image in a raster
fashion, building up the image at .6 inches/minute. Develop
with usual photo chemistry.

I snagged a Kepro dry film laminator on eBay years ago. It
is made for laminating the resist to PC boards, but if you
put a shim of several sheets of heavy paper under the brass
shim stock, it laminates perfectly to thin shim stock, too.
You put the resist on both sides, and then expose with mirror-image
photo masters. The resist is developed and then put in a
Kepro spray etching machine that I got just before it hit the dumpster
at work.

I used to use this gear to make PC boards, but they make these so
cheap in China now that I rarely make my own. (I have scraps
left over from so many projects that I can usually find a board
that can be re-purposed for new experimental projects.)

I built the photoplotter myself. The machine wasn't too hard to
make, once diode lasers came out. The software was a lot
harder to do.

I've got some pics and story about getting the Philips pick
and place machine in my basement. That was an ORDEAL!

Jon