If you are looking to go to a film there is a very nice product sold by
M&R Marking. It is a negative film system that has extremely easy to use
water based chemistry. To produce a film you print a positive image
using a standard printer (I have always done it on a laser, but an
inkjet would likely work). You then do a contact print using standard
black light bulbs onto the negative film. Now to develop it you just
spray on a water based fluid from a squirt bottle and wait 90 seconds
then rinse and scrub the film under cool water with a paper towel. The
result is a completely negative film that is as opaque as the films I
have had done by a commercial photo plotter. Product info at:
Tim
[Denver ,CO]
toggle quoted message
Show quoted text
While it plots to film, I think you can get a few ideas from
it. And there are advantages if you can generate a good
film, such as exposing as many boards as you want from it.
|
Hey John,
Thank you for the kind words. A router is still the path for me but I think
you've come up with an excellent idea for people who want to use plotters
for resist work.
Just as a little follow-up:
A light pressure scribe line produced an isolation area .006" wide. At this
width it's very important to make sure etchant doesn't leave behind any
tiny hair width bridges across the isolation. Brushing the surface with a
soft brush during etching to make sure all these small areas "wet" worked
well and eliminated the hair size bridges.
A slightly heavier scribe, or going over the same area lightly twice with
the point, produced an isolation area .011" wide. No bridges across the
isolation lines were found.
Again, this was etching with sodium persulfate at 120 degrees F.and using
Dykem Steel Blue layout fluid as a resist.
Denny
toggle quoted message
Show quoted text
At 07:24 PM 04/06/2002 -0000, you wrote: Denny,
Great job! When the idea hit me I was working on a 4 axis
4 wire controller board. I try to be innovative. Like I said in
my first message. I am here to help out! I goofed by sending
people to a picture of an etched board I did. The problem was
I used the location of a page on my website instead of the
picture. I only wanted people to know I really mill circuit
boards for a living using a Dremel. I also use cheap 1/4-20 threaded
rod for all my machines. In the right hands Scratch and Etch will
be lots of fun! A cheap plotter and some isolation software.
Good work Denny!
John
--- In Homebrew_PCBs@y..., milwiron@t... wrote:
Hello Steve, John and All,
I had to run a sample of a redesigned board Saturday morning so I
tried a
simple Scratch and Etch test of John's idea.
Here are some fast notes:
I coated a small piece of 1 oz. single sided board stock with Dykem metal
layout fluid. (I did clean the board first with 320 wet or dry and a quick
wipe with lacquer thinner. Scribing lines through layout fluid coating
produces very clean marks with no chipping
A metal-scriber's weight alone is not quite enough to get a line down to
the copper, a little extra weight was needed. A light spring loading on the
plotter would probably be fine.
I also scribed some thicker lines with a 1/16" inch wide tool I had laying
on my bench.
The board was etched in Sodium Persulfate at 120 degrees F.
The Dykem layout fluid had no problem as a resist, in fact I'll probably
fill a pen and start using it to repair bad resist areas on proto boards.
Bottom line: The resulting etched scribe lines came out beautifully and the
Dykem cleans off easily with Scotch Brite or some light wet or dry sanding.
My only minor concern is the narrowness of the isolations produced by a
pointed scriber and soldering using a set of eyes that ain't what they were
10 years ago.
Denny
Very interesting idea.
You could use layout fluid for metal working. Most are a lacquer
type base
and scratch very cleanly since that's exactly what they're
designed for.
Dykem is one manufacturer, it's available in a couple of colors,
spray or
brush.
Denny Great idea. Anyone here have some and some etchant and want to try
it and report back here? Nothing fancy, just coat a scrap of board
and then scratch the surface with the scratching device held at 90
degrees with only its own weight holding it down.
Steve Greenfield
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@y...
Your use of Yahoo! Groups is subject to
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
|
Re: Acid Etching and getting rid of the fumes
Steve Greenfield wrote: A friend of mine long ago claimed he used a week solution of nitric
acid for etching PCBs.
Has anyone here tried this?
I'm thinking I need an exhaust hood in my basement. I figured if I
use a fan then I have to worry about the fan being eaten by acid
fumes, so thought maybe I'd use my air compressor with a simple
homemade venturi pump made out of plastic pipe.
Whatdya think?
Steve Greenfield Nitric acid is a controlled substance in Australia. Its not something I would like to have around the house or garage. Do you know the byproducts from copper and nitric acid ? There are many safer and much more usable etchants around. If you are having troubles with a particular etchant then it could be that your etching equipment/process needs improving. The chemistry is only half the story.
|
Hi Alan, I think Denny nailed it! Yes I am talking isolation. You only etch a thin line between traces. Or you can have the point go around a second time and make the isolation wider. Second option is a wider tool. The coating Denny is using does not need burnishing. If you have worked sheet metal, there is a coating you put on the metal. Then you scribe you layout lines. The lines show up against the dark coating. This is methode can be used to make very precise parts. John --- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...> wrote: Hi John,
I recall the JFax, and AEA's fax. Milling PCB's is quite a challenge, and even more interesting!
I didn't quite get the "scratch and etch". This is for isolation, like milling? Just enough to remove resist?
What about a burnishing bit, perhaps abrasive, to scrub off resist? It would have to be quite small dia. Just mill through the resist.
Alan KM6VV
crankorgan wrote:
Alan,
Ralph had a BBS that I used to visit. I drew up his
ZipZap antenna as a ZIP package. Fax Dahl was software
that would turn Fax audio from my R71a to VGA images.
Later on there was a German Freeware program that would
work through the serial port with only a few resistors
and an opamp. If you do a search for Kleinfax on the net
you may find my diagram for turning a serial board into
a radio fax board. JFax killed my design off! I think
later versions of HamCom did fax too! That was a long time
ago.
After using steppers to spin my drum, I made a spinning
mirror camera like the ones the satellites use. Now I use
steppers to run my PCBMill. I mill circuit boards as part of
my business. There is no cheap way to make a 4" x 6" board. I
stick with the milling process because it works best for me.
John
--- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...>
wrote: Hi John,
Yes! I have Taggert's book, and I played around with weather fax's, but
AFTER CRT's were common. what is FAX_Dhals? A software
package?
73's,
Alan KM6VV
|
Denny, Great job! When the idea hit me I was working on a 4 axis 4 wire controller board. I try to be innovative. Like I said in my first message. I am here to help out! I goofed by sending people to a picture of an etched board I did. The problem was I used the location of a page on my website instead of the picture. I only wanted people to know I really mill circuit boards for a living using a Dremel. I also use cheap 1/4-20 threaded rod for all my machines. In the right hands Scratch and Etch will be lots of fun! A cheap plotter and some isolation software. Good work Denny! John --- In Homebrew_PCBs@y..., milwiron@t... wrote:
Hello Steve, John and All,
I had to run a sample of a redesigned board Saturday morning so I
tried a simple Scratch and Etch test of John's idea.
Here are some fast notes:
I coated a small piece of 1 oz. single sided board stock with Dykem metal layout fluid. (I did clean the board first with 320 wet or dry and a quick wipe with lacquer thinner. Scribing lines through layout fluid coating produces very clean marks with no chipping
A metal-scriber's weight alone is not quite enough to get a line down to the copper, a little extra weight was needed. A light spring loading on the plotter would probably be fine.
I also scribed some thicker lines with a 1/16" inch wide tool I had laying on my bench.
The board was etched in Sodium Persulfate at 120 degrees F.
The Dykem layout fluid had no problem as a resist, in fact I'll probably fill a pen and start using it to repair bad resist areas on proto boards. Bottom line: The resulting etched scribe lines came out beautifully and the Dykem cleans off easily with Scotch Brite or some light wet or dry sanding. My only minor concern is the narrowness of the isolations produced by a pointed scriber and soldering using a set of eyes that ain't what they were 10 years ago.
Denny
Very interesting idea.
You could use layout fluid for metal working. Most are a lacquer
type base
and scratch very cleanly since that's exactly what they're
designed for.
Dykem is one manufacturer, it's available in a couple of colors,
spray or
brush.
Denny Great idea. Anyone here have some and some etchant and want to try
it and report back here? Nothing fancy, just coat a scrap of board
and then scratch the surface with the scratching device held at 90
degrees with only its own weight holding it down.
Steve Greenfield
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@y...
Your use of Yahoo! Groups is subject to
|
Hi John,
I recall the JFax, and AEA's fax. Milling PCB's is quite a challenge,
and even more interesting!
I didn't quite get the "scratch and etch". This is for isolation, like
milling? Just enough to remove resist?
What about a burnishing bit, perhaps abrasive, to scrub off resist? It
would have to be quite small dia. Just mill through the resist.
Alan KM6VV
crankorgan wrote:
toggle quoted message
Show quoted text
Alan,
Ralph had a BBS that I used to visit. I drew up his
ZipZap antenna as a ZIP package. Fax Dahl was software
that would turn Fax audio from my R71a to VGA images.
Later on there was a German Freeware program that would
work through the serial port with only a few resistors
and an opamp. If you do a search for Kleinfax on the net
you may find my diagram for turning a serial board into
a radio fax board. JFax killed my design off! I think
later versions of HamCom did fax too! That was a long time
ago.
After using steppers to spin my drum, I made a spinning
mirror camera like the ones the satellites use. Now I use
steppers to run my PCBMill. I mill circuit boards as part of
my business. There is no cheap way to make a 4" x 6" board. I
stick with the milling process because it works best for me.
John
--- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
Hi John,
Yes! I have Taggert's book, and I played around with weather fax's, but
AFTER CRT's were common. what is FAX_Dhals? A software package?
73's,
Alan KM6VV
|
Hello Steve, John and All,
I had to run a sample of a redesigned board Saturday morning so I tried a
simple Scratch and Etch test of John's idea.
Here are some fast notes:
I coated a small piece of 1 oz. single sided board stock with Dykem metal
layout fluid. (I did clean the board first with 320 wet or dry and a quick
wipe with lacquer thinner. Scribing lines through layout fluid coating
produces very clean marks with no chipping
A metal-scriber's weight alone is not quite enough to get a line down to
the copper, a little extra weight was needed. A light spring loading on the
plotter would probably be fine.
I also scribed some thicker lines with a 1/16" inch wide tool I had laying
on my bench.
The board was etched in Sodium Persulfate at 120 degrees F.
The Dykem layout fluid had no problem as a resist, in fact I'll probably
fill a pen and start using it to repair bad resist areas on proto boards.
Bottom line: The resulting etched scribe lines came out beautifully and the
Dykem cleans off easily with Scotch Brite or some light wet or dry sanding.
My only minor concern is the narrowness of the isolations produced by a
pointed scriber and soldering using a set of eyes that ain't what they were
10 years ago.
Denny
toggle quoted message
Show quoted text
Very interesting idea.
You could use layout fluid for metal working. Most are a lacquer
type base
and scratch very cleanly since that's exactly what they're
designed for.
Dykem is one manufacturer, it's available in a couple of colors,
spray or
brush.
Denny Great idea. Anyone here have some and some etchant and want to try
it and report back here? Nothing fancy, just coat a scrap of board
and then scratch the surface with the scratching device held at 90
degrees with only its own weight holding it down.
Steve Greenfield
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
|
I have agree with Tom on the plain mercury vapor street lamps. they are
cheap, readily available and work great. I use 400W, no reflectors, 400 mm
distance and get 90 seconds exposure on dry film resist. I have heard from
several people about using quartz halogen lamps. Quartz halogen run hot and
put out significant UVA and even some UVC (if not shielded by normal glass),
the UV level depends on the operating temperature. Bulbs that run extra hot
and short lived are better, such as a photographic lamp. You could try
running one of those 12V 80W quartz halogen ceiling lights at say 15V.
Here is some info on dry-film photoresist spectral sensitivity,
,2133,3647,00.html
Standard 'soda' glass (windows) stops pretty much everything shorter than 350
nm. The sensitivity of dry film resists starts dropping off past this anyhow.
You won't loose much from the glass, Even a thick sheet, say 8 mm.
I tested the effect of glass by doing a 10 step exposure on a sample of dry
film. The effect of 4 mm glass sheet was virtually unmeasurable (passes
greater than 80% of light). probably somewhere around 90% - 95%.
Good work Steve on setting up this forum.
Adam.
Steve Greenfield wrote:
toggle quoted message
Show quoted text
Don't stop! It is good to have you here.
So can you tell us, is my memory faulty or does it only require
near UV to expose PCB photoresist?
I used to use a plant grow light incandescent floodlight bulb,
150W. I don't recall the exposure times but they weren't terribly
long or terribly short. IE, somewhere between 30 seconds and 5
minutes is the closest I can remember, with the bulb about 1 foot
away and the film/PCB held under glass. The film was mylar with a
variety of things on it, drafting tape, those rub-on pads from
Radio Shack, paint, copier toner, and anything else opaque.
What about those inexpensive 150W quartz halogen shoplights? Or are
they built to block too much of the UV?
An idea I had long ago but never tried out- use a bare xenon
flashtube, calibrate by number of flashes. Use one of the larger
tubes rather than the tiny ones in modern cameras. Easy to power it
with AC and to set up a programmable counter circuit to flash it. A
PIC or even just a 555 timer that enables flashing.
It is my understanding (could be wrong) that a fair amount of UV
(low UV, anyway) gets through the tube and that the plastic cover
on the flash serves two purposes, color balance and UV block.
Someone said standard window glass blocks some UV. What types of
glass block less UV? What percentage is blocked? Is it just a
matter of using a thinner sheet of glass to hold the artwork to the
PCB?
Steve Greenfield
--- twb8899 <twb8899@...> wrote:
I'm new here but find this list very interesting. A good UV
lighting
system is the plain old mercury vapor lamps. -snip lots of good stuff-
I do enjoy the hobby side of this technology and would be willing
to
help out with ideas and maybe some equipment projects that could
be
posted on this list. If there is any interest let me know. Sorry
about the long post... sometimes I get going and don't know when
to
stop!!! Hope I can help out.
Tom __________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
|
Steve Greenfield wrote:
Yep, far too long to expose, and the problem of "blooming". UV
laser, anyone?
That sounds do-able! It would just require modifying a pen with one
of those carbide point marking pens. I think you could probably
just spray something like one coat of black fast drying laquer to
scratch through.
And one of the things I've always liked doing to boards I make is
sign them. Couldn't do that when I made some with the vinyl cutter.
So the only issues are paint that will scratch away cleanly and
that it leaves a wide enough opening after etching.
Steve Greenfield
--- crankorgan <john@...> wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would take
way to long. Ok, I use Mechanical Etching bits myself. But what
if you coated the whole board with resist. Then you put a sharp
point in the plotter. Have the plotter do isolation paths. Then
the board goes to the acid.
You could have a fibre-optic cable close to the pcb resist putting out high power. Could also try lens focusing with enough power to speed the exposure.
|
Alan, Ralph had a BBS that I used to visit. I drew up his ZipZap antenna as a ZIP package. Fax Dahl was software that would turn Fax audio from my R71a to VGA images. Later on there was a German Freeware program that would work through the serial port with only a few resistors and an opamp. If you do a search for Kleinfax on the net you may find my diagram for turning a serial board into a radio fax board. JFax killed my design off! I think later versions of HamCom did fax too! That was a long time ago. After using steppers to spin my drum, I made a spinning mirror camera like the ones the satellites use. Now I use steppers to run my PCBMill. I mill circuit boards as part of my business. There is no cheap way to make a 4" x 6" board. I stick with the milling process because it works best for me. John --- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...> wrote: Hi John,
Yes! I have Taggert's book, and I played around with weather fax's, but AFTER CRT's were common. what is FAX_Dhals? A software package?
73's,
Alan KM6VV
crankorgan wrote:
Hi Alan,
I built a similar unit for receiving Radio Faxes
from around the world VIA a shortwave radio. My unit used
stepping motors from a floppy. That's 20 years ago! Here
is a picture of the unit. I used some of Ralph Taggerts
circuits and some of my own. I went on to design a circuit
board that goes in the computer. I used FAX_Dhals.
see machine at:
73s
John
--- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...>
wrote: Hi Steve, John, list,
check out Jon E's photo plotter:
While it plots to film, I think you can get a few ideas from it. And
there are advantages if you can generate a good film, such as exposing
as many boards as you want from it.
But yes, I DO like the concept of mechanical etching! And the software
to do the isolation tool paths is very interesting to me (programmer).
As well as the controller it's self!
I don't know the linear speed of Jon's photo plotter (perhaps
it's that
the film is faster then the photo resist), but I'm surprised it couldn't
be made to work. A laser out of an HP laser printer? Then
you'd need a
mirror to get the light over to the "pen lens" and down to the board.
Put the hole laser thing on the XY carriage? Yeah, that could
work!
Perhaps we'll get a little more info on the HP, and someone can
try some
experiments on exposing the resist on a board with a laser!
And who cares if it takes a long time? Controlling the size of the laser "dot"
on the board with an aperture would be the tough part. I'm told that
commercial photo plotters use an aperture disk, which is a set
of "films" with an appropriate mask.
Alan KM6VV
Steve Greenfield wrote:
Yep, far too long to expose, and the problem of "blooming". UV
laser, anyone?
That sounds do-able! It would just require modifying a pen
with one
of those carbide point marking pens. I think you could
probably just spray something like one coat of black fast drying
laquer to scratch through.
And one of the things I've always liked doing to boards I
make is sign them. Couldn't do that when I made some with the vinyl
cutter.
So the only issues are paint that will scratch away cleanly
and that it leaves a wide enough opening after etching.
Steve Greenfield
--- crankorgan <john@k...> wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would
take way to long. Ok, I use Mechanical Etching bits myself. But
what if you coated the whole board with resist. Then you put a
sharp point in the plotter. Have the plotter do isolation paths.
Then the board goes to the acid.
John
|
Hi John,
Yes! I have Taggert's book, and I played around with weather fax's, but
AFTER CRT's were common. what is FAX_Dhals? A software package?
73's,
Alan KM6VV
crankorgan wrote:
toggle quoted message
Show quoted text
Hi Alan,
I built a similar unit for receiving Radio Faxes
from around the world VIA a shortwave radio. My unit used
stepping motors from a floppy. That's 20 years ago! Here
is a picture of the unit. I used some of Ralph Taggerts
circuits and some of my own. I went on to design a circuit
board that goes in the computer. I used FAX_Dhals.
see machine at:
73s
John
--- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
Hi Steve, John, list,
check out Jon E's photo plotter:
While it plots to film, I think you can get a few ideas from it. And
there are advantages if you can generate a good film, such as exposing
as many boards as you want from it.
But yes, I DO like the concept of mechanical etching! And the software
to do the isolation tool paths is very interesting to me (programmer).
As well as the controller it's self!
I don't know the linear speed of Jon's photo plotter (perhaps it's that
the film is faster then the photo resist), but I'm surprised it couldn't
be made to work. A laser out of an HP laser printer? Then you'd need a
mirror to get the light over to the "pen lens" and down to the board.
Put the hole laser thing on the XY carriage? Yeah, that could work!
Perhaps we'll get a little more info on the HP, and someone can try some
experiments on exposing the resist on a board with a laser! And who
cares if it takes a long time? Controlling the size of the laser "dot"
on the board with an aperture would be the tough part. I'm told that
commercial photo plotters use an aperture disk, which is a set of
"films" with an appropriate mask.
Alan KM6VV
Steve Greenfield wrote:
Yep, far too long to expose, and the problem of "blooming". UV
laser, anyone?
That sounds do-able! It would just require modifying a pen with
one
of those carbide point marking pens. I think you could probably
just spray something like one coat of black fast drying laquer to
scratch through.
And one of the things I've always liked doing to boards I make is
sign them. Couldn't do that when I made some with the vinyl
cutter.
So the only issues are paint that will scratch away cleanly and
that it leaves a wide enough opening after etching.
Steve Greenfield
--- crankorgan <john@k...> wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would take
way to long. Ok, I use Mechanical Etching bits myself. But what
if you coated the whole board with resist. Then you put a sharp
point in the plotter. Have the plotter do isolation paths. Then
the board goes to the acid.
John
|
Hi Steve and the group,
Most of the dry film photo resist used for printed circuits requires
lamps to have the peak spectral output at 365 nanometers. They will
respond to other wavelengths but more power will be required. A
quartz lamp will probably work because many years ago we accidently
exposed some dry film with stray light from a quartz tube. The way to
test this is to laminate some copper panels with photo resist and use
a Stouffer 21 step wedge. This step wedge is nothing more than a
calibrated piece of film that starts out clear and progresses to
opaque black in 21 steps. I think we ran our exposure to retain a
step 8 during development. This is probably an overkill for homebrew
circuits but some may want to try this out because it will give you
the absolute final word on exposure performance. These test strips
are very inexpensive. The old fashion trial and error method will
also work.
More info is located here.
Best results will be obtained by using a higher power lamp and
INCREASE the distance from the lamp to the board being exposed. This
allows the light beam to become collimated or "staightened" out. If
you have ever had undercutting problems try this out as it may help.
If anyone want to try out the quartz type of lamp start out at least
12" or more from the board being exposed and adjust the time to get
the correct exposure. It may take several minutes but I think it
should work. We never used these in a commercial setting because
exposure speed for production was important. I wouldn't worry about
this for hobby circuits... whats a few extra minutes if it works?
BTW, these quartz lamps were used for years in machines that would
melt solder plated boards and fuse the solder to the underlying
copper. Don't get too close to your film when using this type of
lamp!
Don't worry about glass types because the commercial exposure units
use regular window glass for the exposure tray with a mylar plastic
sheet over the top. The board is between these layers and a vacuum
pump removes the air for a very tight contact with the top and bottom
films. This tray slides into the exposure box for the proper amount
of time and then rolls back out automatically. The vacuum is
released, board removed and the process starts over. A hobby version
of this machine could be built at a very low cost. I have thought
about making these myself and selling them. Quartz glass is the
proper type to pass UV light but it just isn't required.
The photo resist we used was DuPont 4715 which is their 4700 series
and 1.5 mils thick. Here is a web site that might be of interest.
I hope this info helps.
Tom
|
Hi Alan, I built a similar unit for receiving Radio Faxes from around the world VIA a shortwave radio. My unit used stepping motors from a floppy. That's 20 years ago! Here is a picture of the unit. I used some of Ralph Taggerts circuits and some of my own. I went on to design a circuit board that goes in the computer. I used FAX_Dhals. see machine at: 73s John --- In Homebrew_PCBs@y..., Alan Marconett KM6VV <KM6VV@a...> wrote: Hi Steve, John, list,
check out Jon E's photo plotter:
While it plots to film, I think you can get a few ideas from it. And there are advantages if you can generate a good film, such as exposing as many boards as you want from it.
But yes, I DO like the concept of mechanical etching! And the software to do the isolation tool paths is very interesting to me (programmer). As well as the controller it's self!
I don't know the linear speed of Jon's photo plotter (perhaps it's that the film is faster then the photo resist), but I'm surprised it couldn't be made to work. A laser out of an HP laser printer? Then you'd need a mirror to get the light over to the "pen lens" and down to the board. Put the hole laser thing on the XY carriage? Yeah, that could work!
Perhaps we'll get a little more info on the HP, and someone can try some experiments on exposing the resist on a board with a laser! And who
cares if it takes a long time? Controlling the size of the laser "dot" on the board with an aperture would be the tough part. I'm told that commercial photo plotters use an aperture disk, which is a set of
"films" with an appropriate mask.
Alan KM6VV
Steve Greenfield wrote:
Yep, far too long to expose, and the problem of "blooming". UV
laser, anyone?
That sounds do-able! It would just require modifying a pen with
one of those carbide point marking pens. I think you could probably
just spray something like one coat of black fast drying laquer to
scratch through.
And one of the things I've always liked doing to boards I make is
sign them. Couldn't do that when I made some with the vinyl
cutter.
So the only issues are paint that will scratch away cleanly and
that it leaves a wide enough opening after etching.
Steve Greenfield
--- crankorgan <john@k...> wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would take
way to long. Ok, I use Mechanical Etching bits myself. But what
if you coated the whole board with resist. Then you put a sharp
point in the plotter. Have the plotter do isolation paths. Then
the board goes to the acid.
John
|
--- Alan Marconett KM6VV <KM6VV@...> wrote: Hi Steve, John, list,
check out Jon E's photo plotter:
His new website has more info on it: Check out "Machining", too, it has more info including the photo plotter. Steve Greenfield __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax
|
Yes, but that happens anyway. You'll only be etching out a narrow channel to start with, so I can't see it being any more of a problem than etching the "normal" way. Steve Greenfield --- Henrik Olsson <henrik-olsson@...> wrote: Denny, list,
Interesting idea, but.....
If you do scratch thru the coating and into the copper there will
be a big
chance of under-etching. That is when the acid starts to etch in
and under
the protective coating thus making the traces a lot thinner than
they should
be.
/Henrik Olsson.
----- Original Message -----
From: <milwiron@...>
To: <Homebrew_PCBs@...>
Sent: Friday, April 05, 2002 6:46 PM
Subject: Re: [Homebrew_PCBs] Scratch and Etch
I'm finding John's idea pretty intriguing.
Just to take the brainstorming another step:
One big problem with PCB routers is tool life and their cost.
But using a CNC router with a cutter to just cut through the
surface of
the
resist and a thou or two in to the copper would prolong the life of a
carbide tool immensely... and produce a board that should etch quickly and
cleanly.
Yes it would be better do away with etching all together but a marriage of
the two technologies for some applications could be useful.
Denny
At 02:35 PM 04/05/2002 -0000, you wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would take
way to long. Ok, I use Mechanical Etching bits myself. But what
if you coated the whole board with resist. Then you put a
sharp
point in the plotter. Have the plotter do isolation paths.
Then
the board goes to the acid.
John
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
------------------------ Yahoo! Groups Sponsor
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
===== Steve Greenfield // Digital photo scanning, retouching, Polymorph Digital Photography // and photomorphing to your specs. 253/318-2473 voice // We use the best little computer in polymorph@... // the world, the Amiga! // Based in Tacoma, WA, USA __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax
|
Denny, list,
Interesting idea, but.....
If you do scratch thru the coating and into the copper there will be a big
chance of under-etching. That is when the acid starts to etch in and under
the protective coating thus making the traces a lot thinner than they should
be.
/Henrik Olsson.
toggle quoted message
Show quoted text
----- Original Message ----- From: <milwiron@...> To: <Homebrew_PCBs@...> Sent: Friday, April 05, 2002 6:46 PM Subject: Re: [Homebrew_PCBs] Scratch and Etch
I'm finding John's idea pretty intriguing.
Just to take the brainstorming another step:
One big problem with PCB routers is tool life and their cost.
But using a CNC router with a cutter to just cut through the surface of
the resist and a thou or two in to the copper would prolong the life of a
carbide tool immensely... and produce a board that should etch quickly and
cleanly.
Yes it would be better do away with etching all together but a marriage of
the two technologies for some applications could be useful.
Denny
At 02:35 PM 04/05/2002 -0000, you wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would take
way to long. Ok, I use Mechanical Etching bits myself. But what
if you coated the whole board with resist. Then you put a sharp
point in the plotter. Have the plotter do isolation paths. Then
the board goes to the acid.
John
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
To unsubscribe from this group, send an email to:
Homebrew_PCBs-unsubscribe@...
Your use of Yahoo! Groups is subject to
|
Don't stop! It is good to have you here. So can you tell us, is my memory faulty or does it only require near UV to expose PCB photoresist? I used to use a plant grow light incandescent floodlight bulb, 150W. I don't recall the exposure times but they weren't terribly long or terribly short. IE, somewhere between 30 seconds and 5 minutes is the closest I can remember, with the bulb about 1 foot away and the film/PCB held under glass. The film was mylar with a variety of things on it, drafting tape, those rub-on pads from Radio Shack, paint, copier toner, and anything else opaque. What about those inexpensive 150W quartz halogen shoplights? Or are they built to block too much of the UV? An idea I had long ago but never tried out- use a bare xenon flashtube, calibrate by number of flashes. Use one of the larger tubes rather than the tiny ones in modern cameras. Easy to power it with AC and to set up a programmable counter circuit to flash it. A PIC or even just a 555 timer that enables flashing. It is my understanding (could be wrong) that a fair amount of UV (low UV, anyway) gets through the tube and that the plastic cover on the flash serves two purposes, color balance and UV block. Someone said standard window glass blocks some UV. What types of glass block less UV? What percentage is blocked? Is it just a matter of using a thinner sheet of glass to hold the artwork to the PCB? Steve Greenfield --- twb8899 <twb8899@...> wrote: I'm new here but find this list very interesting. A good UV
lighting
system is the plain old mercury vapor lamps. -snip lots of good stuff- I do enjoy the hobby side of this technology and would be willing
to
help out with ideas and maybe some equipment projects that could
be
posted on this list. If there is any interest let me know. Sorry
about the long post... sometimes I get going and don't know when
to
stop!!! Hope I can help out.
Tom __________________________________________________ Do You Yahoo!? Yahoo! Tax Center - online filing with TurboTax
|
Hi Steve, John, list,
check out Jon E's photo plotter:
While it plots to film, I think you can get a few ideas from it. And
there are advantages if you can generate a good film, such as exposing
as many boards as you want from it.
But yes, I DO like the concept of mechanical etching! And the software
to do the isolation tool paths is very interesting to me (programmer).
As well as the controller it's self!
I don't know the linear speed of Jon's photo plotter (perhaps it's that
the film is faster then the photo resist), but I'm surprised it couldn't
be made to work. A laser out of an HP laser printer? Then you'd need a
mirror to get the light over to the "pen lens" and down to the board.
Put the hole laser thing on the XY carriage? Yeah, that could work!
Perhaps we'll get a little more info on the HP, and someone can try some
experiments on exposing the resist on a board with a laser! And who
cares if it takes a long time? Controlling the size of the laser "dot"
on the board with an aperture would be the tough part. I'm told that
commercial photo plotters use an aperture disk, which is a set of
"films" with an appropriate mask.
Alan KM6VV
Steve Greenfield wrote:
toggle quoted message
Show quoted text
Yep, far too long to expose, and the problem of "blooming". UV
laser, anyone?
That sounds do-able! It would just require modifying a pen with one
of those carbide point marking pens. I think you could probably
just spray something like one coat of black fast drying laquer to
scratch through.
And one of the things I've always liked doing to boards I make is
sign them. Couldn't do that when I made some with the vinyl cutter.
So the only issues are paint that will scratch away cleanly and
that it leaves a wide enough opening after etching.
Steve Greenfield
--- crankorgan <john@...> wrote:
Hi,
Nobody liked my light on a plotter idea. I was told the
light source would have to move too slow. The board would take
way to long. Ok, I use Mechanical Etching bits myself. But what
if you coated the whole board with resist. Then you put a sharp
point in the plotter. Have the plotter do isolation paths. Then
the board goes to the acid.
John
|
Acid Etching and getting rid of the fumes
A friend of mine long ago claimed he used a week solution of nitric
acid for etching PCBs.
Has anyone here tried this?
I'm thinking I need an exhaust hood in my basement. I figured if I
use a fan then I have to worry about the fan being eaten by acid
fumes, so thought maybe I'd use my air compressor with a simple
homemade venturi pump made out of plastic pipe.
Whatdya think?
Steve Greenfield
__________________________________________________
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
|
I'm new here but find this list very interesting. A good UV lighting
system is the plain old mercury vapor lamps. These are commonly used
for dusk-to-dawn lighting. The bulbs are available in several
wattages such as 175, 400 and 1000 watts. One of these bulbs and a
reflector makes a great UV exposure system. Visit any large warehouse
and check out the lighting system since these are very commonly used
in larger buildings.
I have a commercial exposure system that uses this type of bulb. It
is a Colight Model DMVL-930 with 1000 watt bulbs on the top and
bottom. The exposure time when using 1.5 mil dry film photoresist is
17 seconds. If there is any interest in this I can photograph the
"guts" of this machine next time I clean the reflectors and post the
photographs in the photo section of this list.
It really would not be hard to make this exposure unit. Polished
aluminum sheeting or aluminmum foil could be used to make the
reflector system. I have helped several of my ham buddys set this
type of unit up and they have all been amazed at how fast this can
expose the photo resist. You can also make silk screens with this
setup.
I made my first hobby circuit board in 1966 and owned a commercial
printed circuit business for 23 years. We closed that plant last year
due to foreign competition and rising costs. I did keep the best
"small" equipment for my own home shop. This still allows me to make
boards for the instruments I make as well as my ham radio projects.
We gave away the plating operation because it was really a drag
putting up with the evironmental issues etc. I kept one smaller
photoplotter, several semi-automatic drilling machines, silk
screening equipment and all of the tooling and setup stuff. The big
Excellon CNC drilling and routing equipment was all sold off.
I started my company on the kitchen table in the late 1970's and it
looks like I've gone full circle but this time ended up in the
basement! It's much more fun this way I might add. We made boards up
to ten layers back then but it was just way to much work and the
headaches just kept getting worse. Too much work, too many hours, too
little pay and no more fun !!
I do enjoy the hobby side of this technology and would be willing to
help out with ideas and maybe some equipment projects that could be
posted on this list. If there is any interest let me know. Sorry
about the long post... sometimes I get going and don't know when to
stop!!! Hope I can help out.
Tom
|
Steven Greenfield AE7HD