More LED's - Again

To All:

The steady decline in the cost of ultra-bright green LED's (now about
two-bits each for a 100-piece baggie) has generated renewed interest in
the bug-eyed LED nav lights I described on this Newsgroup a couple of
years ago.

Unfortunately, that renewed interest has lead to some renewed problems,
one having to do with the lay-out of the circuit board, the other with
its fabrication. But the most serious problem has to do with the fact
that ham radio operators learn to solder shortly after birth, or even
before... according to some. Along with the ability to solder is the
companion knowledge of how to make a circuit board out of a bit of
substrate and a piece of string about... that long. But the main
stumbling block for non-hams appears to be how to make all those
teenie-tiny holes in the circuit board.

MAKING HOLES

It's pretty easy. You need a tiny drill -- somewhere between #70 and
#75. Then you need to spin it about 12,000 rpm. And you need to keep
it perfectly vertical as you make the hole.

The drill bits are no problem. Harbor Freight will sell you a
selection of solid carbide bits suitable for the task; simply pick a
size to suit the components you're using, such as the wire legs of an
LED or quarter-watt resister.

A Dremel tool (or similar) is the handiest means of chucking the tiny
drill, most of which have a shank diameter of 1/8".

To hold it perfectly vertical you don't 'hold' it at all -- you make up
a 90 degree bracket and clamp, wire or glue the tool to the vertical
leg. On the horizontal leg you drill a 1/4" hole to accept a bolt
which you then chuck into your DRILL PRESS. There's a few picky-bits
to this method, such as using a bracket that is a true 90, and thick
enough so as not to deflect as you run the quill of your drill press up
& down. You need some method of preventing the quill from rotating of
course -- I use a simple wedge between the quill pulley and the frame
of the drill press head (big, old Craftsman floor model. Your mileage
may vary...) To keep from ruining the chuck in your drill press (which
was not designed to grab hold of threaded bolts) you put a barrel-nut
on the bolt.

Deal with all the tricky bits and the result is a shake-free,
carbide-tipped hole-maker that will give you a life-time of accurate
service (and already has, in my case... I used it to make the boards
for my first computer back in the mid-70's).

ELEVATION vs AZIMUTH

Azimuth is relative to the horizontal. Elevation means over-head. In
laying out the circuit board, asimuth is taken care of by orienting the
legs of the LED's. Since the LED's have an average viewing angle of 25
degrees, to provide adequate coverage the azimuth angle starts at 10
degrees and progresses in 20 degree increments. Of course, when you're
trying to provide full coverage across a segment of a sphere, your
LED's must be accurately oriented in TWO dimensions.

The key point here is that I chose to build the aximuth angle into the
circuit board.

The elevation angle is bent into the legs of the LED's using a simple
form-block, accurately printed via DeltaCAD, glued to a bit of plywood
and sanded to the line. To keep things simple, I abandoned the
variable height arrangement as described in my original post, other
than allowing a bit of overlap between one row of LED's to the next so
as to keep down the circuit board, which comes out about two by two
inches.

As a further simplification, I eliminated the left vs right bending
angles used in my original (2002) lights. Now all of the LED's get the
same set of bends relative to their positive lead. To accommodate the
change from left- to right-facing, I re-drew the circuit board.

MAKING THE CIRCUIT BOARD

The Old Fashioned Way was to start with a drawing then go to litho
film, then to a fine-meshed silk screen. Once you had the silk screen
you could whip out a hundred circuit boards in an afternoon... after
spending a month to arrive at that point.

Nowadays I simply print the circuit board mask onto cheap
glossy-finished color photo paper using a monochrome laser printer.
Here's why it works:

Laser printer media is a finely divided thermo-plastic -- a powder so
fine it is attracted to the electrostatic charge created by the laser.
The thermo-plastic material is transferred to the paper by heat.

This lends itself to making circuit boards because once the
thermo-plastic material has been transferred to the paper, it may be
RE-TRANSFERRED to the clean copper surface of a blank circuit board by
the application of ADDITIIONAL heat. In effect, you literally iron-on
the mask, solidly gluing the paper to the circuit board.

Now the trick is to get rid of the paper, which I'll get to in a
minute. But before I do, you should know that while using plain paper
is possible, the resulting transfer will show a lot of voids; plain
paper simply isn't a very good substrait for the thermo-plastic
material. But cheap color copier paper is. Color copier paper is
typically coated, giving it a denser, more uniform surface than regular
#20 bond. That slicker surface attracts a more uniform layer of the
thermo-plastic material; you end up with a dense, dark, void-free
pattern.

But it's gotta be CHEAP color copier paper because you want the stuff
to dissolve in warm, soapy water. High quality color copier paper is
some very tough stuff; it doesn't like to come apart. But the paper
HAS to come apart if we want to leave ONLY the thermo-plastic material
bonded to our circuit board. So use the cheap stuff. And soak it in
warm soapy water. Then scrub it with a tooth brush or whatever -- get
ALL of the paper off of the thermo-plastic.

Now you can etch the board in the usual way. And having etched it, you
gotta drill those zillion holes. Once etched & drilled, remove the
thermo-plastic, which you can do with MEK or other kidney-killer
solvent and a bit of steel wool.

The result is a bright copper circuit board, ready to accept components
and easy to solder. Once things are soldered and checked and and all
the errors corrected, give the thing a coating of clear finger-nail
polish (!) and you're all done -- a super bright nav light that will
never burn out (at least, not in your life time) that draws about a
quarter of an amp, meaning the wiring can be slightly smaller than a
starter cable.

-R.S.Hoover
-(KA6HZF)

PS -- Yes, you may have a copy of the circuit boards, if you wish. But
you could probably do better yourself -- except for the stern-light,
they're just rectangular 5x9 arrays. I don't have a web site and I
already get more email than I want so I'll try to find somewhere to
hang them. When I do, I post the information here... for all 385
subscribers of r.a.h. to read :-)

But the most serious problem has to do with the fact
that ham radio operators learn to solder shortly after birth, or even
before... according to some.

So that's what my mom was screaming about two months before I was born --
internal solder splashes {;-)



MAKING THE CIRCUIT BOARD

WEll, you just blew my August Kitplanes article out of the water.



The Old Fashioned Way was to start with a drawing then go to litho
film, then to a fine-meshed silk screen. Once you had the silk screen
you could whip out a hundred circuit boards in an afternoon... after
spending a month to arrive at that point.

Nowadays I simply print the circuit board mask onto cheap
glossy-finished color photo paper using a monochrome laser printer.

And after many experiments, Staples Photo Basic Gloss (#471861) is my
candidate for the best.


But the paper
HAS to come apart if we want to leave ONLY the thermo-plastic material
bonded to our circuit board. So use the cheap stuff. And soak it in
warm soapy water. Then scrub it with a tooth brush or whatever -- get
ALL of the paper off of the thermo-plastic.

One of those green kitchen pot scrubbers does a pretty fair job getting the
paper off while leaving the toner on the board.



Now you can etch the board in the usual way.

Or you can use the new, improved way without that nasty ferric chloride.
Plain old swimming pool etchant (muriatic acid -- 28% HCl) from the home
store plus plain old hydrogen peroxide (3%) from the drug store mixed 2:1
respectively does an admirable job at room temperature. Plus, when you get
done, you have metallic copper (not a hazmat), hydrochloric acid (not a
hazmat), and the hydrogen peroxide which, within half an hour, has broken
down into oxygen (which has escaped into the air) and water. If you want to
be totally environmentally friendly, you can neutralize the HCl with baking
soda ($5.99 for ten pounds at the Charlie's Club places) before pouring it
down the sink.

If you wanna get fancy, go down to the discount pet store and get a 5 gallon
aquarium, a small aquarium pump, and a long stone bubbler. Bubbling around
the board cuts the etch time in half.



And having etched it, you
gotta drill those zillion holes. Once etched & drilled, remove the
thermo-plastic, which you can do with MEK or other kidney-killer
solvent and a bit of steel wool.

Please don't use steel wool. It embeds into the copper and helps
galvanically corrode the board. Let the board soak in the MEK for an hour
and it will wash off with the aforementioned green pot scrubber.



The result is a bright copper circuit board

Made even brighter if you use Copper-Brite from the supermarket and the
aforementioned green pot scrubber.

You might also google on "Tinnit", which is a surface tin plating solution
that quite a few mail order houses sell. Copper will corrode over time; tin
will not. You toss the board in the Tinnit solution and it will plate the
copper with tin in a matter of ten minutes.

Jim

I also used the laser printer toner transfer method for my LED design
which I posted a couple of weeks ago. I originally discovered the
technique from http://www.fullnet.com/u/tomg/gooteepc.htm
The paper came off easily in water and a gentle scrub. One problem I
noticed is that the gloss sticks to the ink more than the paper. So
when the paper peels off, the gloss stays on the ink. This may not be a
problem where the ink is supposed to be, but the gloss also bridges
across small openings like drill hole location markers. I tried
scratching these areas with a needle to remove the gloss, but it did
not come off easily. Also, this is very hard to see because the gloss
is transparent. Only after the etch you realize that the location
markers are missing. But this was not a big problem for me because the
location markers were simply an aid for centering the drill bit.But it
could be a problem if the bridging is between closely spaced tracks.

Also, regarding the #70 drill bits, are you sure you got them at Harbor
Freight? They did not have anything smaller than 1/16". If you have a
product number or a URL that would be helpful.




wrote:
To All:

The steady decline in the cost of ultra-bright green LED's (now about
two-bits each for a 100-piece baggie) has generated renewed interest in
the bug-eyed LED nav lights I described on this Newsgroup a couple of
years ago.

Unfortunately, that renewed interest has lead to some renewed problems,
one having to do with the lay-out of the circuit board, the other with
its fabrication. But the most serious problem has to do with the fact
that ham radio operators learn to solder shortly after birth, or even
before... according to some. Along with the ability to solder is the
companion knowledge of how to make a circuit board out of a bit of
substrate and a piece of string about... that long. But the main
stumbling block for non-hams appears to be how to make all those
teenie-tiny holes in the circuit board.

MAKING HOLES

It's pretty easy. You need a tiny drill -- somewhere between #70 and
#75. Then you need to spin it about 12,000 rpm. And you need to keep
it perfectly vertical as you make the hole.

The drill bits are no problem. Harbor Freight will sell you a
selection of solid carbide bits suitable for the task; simply pick a
size to suit the components you're using, such as the wire legs of an
LED or quarter-watt resister.

A Dremel tool (or similar) is the handiest means of chucking the tiny
drill, most of which have a shank diameter of 1/8".

To hold it perfectly vertical you don't 'hold' it at all -- you make up
a 90 degree bracket and clamp, wire or glue the tool to the vertical
leg. On the horizontal leg you drill a 1/4" hole to accept a bolt
which you then chuck into your DRILL PRESS. There's a few picky-bits
to this method, such as using a bracket that is a true 90, and thick
enough so as not to deflect as you run the quill of your drill press up
& down. You need some method of preventing the quill from rotating of
course -- I use a simple wedge between the quill pulley and the frame
of the drill press head (big, old Craftsman floor model. Your mileage
may vary...) To keep from ruining the chuck in your drill press (which
was not designed to grab hold of threaded bolts) you put a barrel-nut
on the bolt.

Deal with all the tricky bits and the result is a shake-free,
carbide-tipped hole-maker that will give you a life-time of accurate
service (and already has, in my case... I used it to make the boards
for my first computer back in the mid-70's).

ELEVATION vs AZIMUTH

Azimuth is relative to the horizontal. Elevation means over-head. In
laying out the circuit board, asimuth is taken care of by orienting the
legs of the LED's. Since the LED's have an average viewing angle of 25
degrees, to provide adequate coverage the azimuth angle starts at 10
degrees and progresses in 20 degree increments. Of course, when you're
trying to provide full coverage across a segment of a sphere, your
LED's must be accurately oriented in TWO dimensions.

The key point here is that I chose to build the aximuth angle into the
circuit board.

The elevation angle is bent into the legs of the LED's using a simple
form-block, accurately printed via DeltaCAD, glued to a bit of plywood
and sanded to the line. To keep things simple, I abandoned the
variable height arrangement as described in my original post, other
than allowing a bit of overlap between one row of LED's to the next so
as to keep down the circuit board, which comes out about two by two
inches.

As a further simplification, I eliminated the left vs right bending
angles used in my original (2002) lights. Now all of the LED's get the
same set of bends relative to their positive lead. To accommodate the
change from left- to right-facing, I re-drew the circuit board.

MAKING THE CIRCUIT BOARD

The Old Fashioned Way was to start with a drawing then go to litho
film, then to a fine-meshed silk screen. Once you had the silk screen
you could whip out a hundred circuit boards in an afternoon... after
spending a month to arrive at that point.

Nowadays I simply print the circuit board mask onto cheap
glossy-finished color photo paper using a monochrome laser printer.
Here's why it works:

Laser printer media is a finely divided thermo-plastic -- a powder so
fine it is attracted to the electrostatic charge created by the laser.
The thermo-plastic material is transferred to the paper by heat.

This lends itself to making circuit boards because once the
thermo-plastic material has been transferred to the paper, it may be
RE-TRANSFERRED to the clean copper surface of a blank circuit board by
the application of ADDITIIONAL heat. In effect, you literally iron-on
the mask, solidly gluing the paper to the circuit board.

Now the trick is to get rid of the paper, which I'll get to in a
minute. But before I do, you should know that while using plain paper
is possible, the resulting transfer will show a lot of voids; plain
paper simply isn't a very good substrait for the thermo-plastic
material. But cheap color copier paper is. Color copier paper is
typically coated, giving it a denser, more uniform surface than regular
#20 bond. That slicker surface attracts a more uniform layer of the
thermo-plastic material; you end up with a dense, dark, void-free
pattern.

But it's gotta be CHEAP color copier paper because you want the stuff
to dissolve in warm, soapy water. High quality color copier paper is
some very tough stuff; it doesn't like to come apart. But the paper
HAS to come apart if we want to leave ONLY the thermo-plastic material
bonded to our circuit board. So use the cheap stuff. And soak it in
warm soapy water. Then scrub it with a tooth brush or whatever -- get
ALL of the paper off of the thermo-plastic.

Now you can etch the board in the usual way. And having etched it, you
gotta drill those zillion holes. Once etched & drilled, remove the
thermo-plastic, which you can do with MEK or other kidney-killer
solvent and a bit of steel wool.

The result is a bright copper circuit board, ready to accept components
and easy to solder. Once things are soldered and checked and and all
the errors corrected, give the thing a coating of clear finger-nail
polish (!) and you're all done -- a super bright nav light that will
never burn out (at least, not in your life time) that draws about a
quarter of an amp, meaning the wiring can be slightly smaller than a
starter cable.

-R.S.Hoover
-(KA6HZF)

PS -- Yes, you may have a copy of the circuit boards, if you wish. But
you could probably do better yourself -- except for the stern-light,
they're just rectangular 5x9 arrays. I don't have a web site and I
already get more email than I want so I'll try to find somewhere to
hang them. When I do, I post the information here... for all 385
subscribers of r.a.h. to read :-)

On 12 Mar 2006 09:31:42 -0800 in sci.electronics.design, "Andrew
Sarangan" wrote,
I also used the laser printer toner transfer method for my LED design
which I posted a couple of weeks ago. I originally discovered the
technique from http://www.fullnet.com/u/tomg/gooteepc.htm
The paper came off easily in water and a gentle scrub. One problem I
noticed is that the gloss sticks to the ink more than the paper. So
when the paper peels off, the gloss stays on the ink.

I find it easy to remove the residue by scrubbing the board with a
dishwashing brush with soft plastic bristles while the board is wet.

Andrew Sarangan wrote:

snip

Also, regarding the #70 drill bits, are you sure you got them at Harbor
Freight? They did not have anything smaller than 1/16". If you have a
product number or a URL that would be helpful.

McMaster has numbered sizes to #80. They are good people.

I won't do business with Harbor Freight. They have the worst parts
and tech help departments I ever dealt with. They still haven't sent me
a part I was promised in early December.

Dan, U.S. Air Force, retired

On the faceplate legend thing-does it change the color of the aluminium
and to what, black?

John

It simply transfers the black toner to the aluminum surface. I haven't
tried painting the surface before transferring, but if I'm careful I can
probably get away with it without scorching the paint.

Anybody got a cheap and dirty way of coloring aluminum without paint? I
haven't seen a good cheap way of using dye nor a good anodizing method. I
can get gold by using alodine, but the coating is rather subject to
scuffing.

Jim


"John T" wrote in message
...
On the faceplate legend thing-does it change the color of the aluminium
and to what, black?

John

RST Engineering wrote:


MAKING THE CIRCUIT BOARD

WEll, you just blew my August Kitplanes article out of the water.

---------------------------------------------------------------------
Dear Jim,

Not a problem. No one actually READS these posts to rah :-)
-------------------------------------------------------------------

But the paper
HAS to come apart if we want to leave ONLY the thermo-plastic material
bonded to our circuit board. So use the cheap stuff. And soak it in
warm soapy water. Then scrub it with a tooth brush or whatever -- get
ALL of the paper off of the thermo-plastic.

One of those green kitchen pot scrubbers does a pretty fair job getting the
paper off while leaving the toner on the board.

--------------------------------------------------------------------

Agree.

Initially, I went at the paper in a very tentative way, worried that
any amount of scrubbing would remove the toner. Which is something of
a joke. If you've used enough heat, the toner STAYS, despite scrubbing
with everything that came to hand.

---------------------------------------------------------------------

Now you can etch the board in the usual way.

Or you can use the new, improved way without that nasty ferric chloride.
Plain old swimming pool etchant (muriatic acid -- 28% HCl) from the home
store plus plain old hydrogen peroxide (3%) from the drug store mixed 2:1
respectively does an admirable job at room temperature.

----------------------------------------------------------------------

Having several jugs of ferric chloride on-hand (plus a heated, rocking,
etching tank), I'll stick with what I know.

If you use acid, make sure it's compatible with the substrait; some
phenolics are not. And be sure to neutralize the BOARD after etching.

-------------------------------------------------------------------------------------

The result is a bright copper circuit board

Made even brighter if you use Copper-Brite from the supermarket and the
aforementioned green pot scrubber.

You might also google on "Tinnit"....
-------------------------------------------------------------------------------------

....or simply paint the exposed copper with clear fingernail polish,
dilute epoxy or whatever.

I've found the main advantage of 'Tinnit' and other circuit board
plating schemes is that they prevent corrosion BEFORE the board is
populated & soldered. Once the board is finished, anything that serves
to seal the surface from the air will prevent corrosion, assuming the
original etchant and solder flux was not. Plated boards make good
sense when you run up a batch then dole them out over a period of years
-- the plating keeps the exposed copper from corroding, especially if
you've kitted the board with other components, some of which may
produce corrosive fumes (ie, certain types of capacitors, some
plastics, etc).

The LED nav lights are a continuation of the series of articles about
Flying on the Cheap. I assumed the folks who make them would populate
& solder the board immediately after etching, hence no mention of
'Tinnit' or other plating. In fact, I've assumed folks would want to
keep the cost down, using whatever etchant they could pick up from
their local Radio Shack (probably ferric chloride) and sealing the
board with clear fingernail polish, for which a suitable REMOVER is
commonly available. (Seal a board with epoxy, if you need to work it
in the future, you're pretty well screwed :-)

In closing, someone else has already mentioned an excellent article on
the subject of generating circuit board masks using a laser printer. I
arrived at the process by a slightly different route in that I was
making faux 'antique' astrolabes and needed a method of etching Arabic
and Chinese characters onto brass plates. In developing that method I
also used it to do nomenclature on instrument panels and rivet-on data
plates, which I feel deserves mention.

Not only does this method allow you to make near-perfect reproductions
of data plates and the like, it allows you to etch logos, names and so
forth onto aluminum tool boxes, prepare 'engraved' plates for
presentations, and so on. The tricky bit here is that you are
typically etching in the positive sense rather than the negative. I
found the best way to do this was to make individual masks -- OIL
PRESSURE -- 10 A -- TACHOMETER ...or whatever. The characters
themselves are left clear and the mask is cut to leave a border of
toner. These masks are then ironed on to the panel, plate or whatever
in the usual manner. (Large pieces, such as a tool box or instrument
panel, will benefit from being pre-heated.) Once the masks have been
transferred to the work-piece all of the open areas are sealed with
something that will resist the etchant; regular enamel paint works
okay.

This is a case where acid has a definite advantage, since the object is
to remove a signficant amount of metal.

Once the piece is finished, the etched areas may be filled with a
contrasting paint.

The joke here is that I spent a couple of years making instrument
faces, 'antique' compases and the like before I realized the method
could also be used to make circuit boards :-)

-R.S.Hoover

Andrew Sarangan wrote:
I also used the laser printer toner transfer method for my LED design
which I posted a couple of weeks ago. I originally discovered the
technique from http://www.fullnet.com/u/tomg/gooteepc.htm
The paper came off easily in water and a gentle scrub. One problem I
noticed is that the gloss sticks to the ink more than the paper. So
when the paper peels off, the gloss stays on the ink. This may not be a
problem where the ink is supposed to be, but the gloss also bridges
across small openings like drill hole location markers. I tried
scratching these areas with a needle to remove the gloss, but it did
not come off easily. Also, this is very hard to see because the gloss
is transparent. Only after the etch you realize that the location
markers are missing. But this was not a big problem for me because the
location markers were simply an aid for centering the drill bit.But it
could be a problem if the bridging is between closely spaced tracks.

Also, regarding the #70 drill bits, are you sure you got them at Harbor
Freight? They did not have anything smaller than 1/16". If you have a
product number or a URL that would be helpful.




wrote:

To All:

The steady decline in the cost of ultra-bright green LED's (now about
two-bits each for a 100-piece baggie) has generated renewed interest in
the bug-eyed LED nav lights I described on this Newsgroup a couple of
years ago.

Unfortunately, that renewed interest has lead to some renewed problems,
one having to do with the lay-out of the circuit board, the other with
its fabrication. But the most serious problem has to do with the fact
that ham radio operators learn to solder shortly after birth, or even
before... according to some. Along with the ability to solder is the
companion knowledge of how to make a circuit board out of a bit of
substrate and a piece of string about... that long. But the main
stumbling block for non-hams appears to be how to make all those
teenie-tiny holes in the circuit board.

MAKING HOLES

It's pretty easy. You need a tiny drill -- somewhere between #70 and
#75. Then you need to spin it about 12,000 rpm. And you need to keep
it perfectly vertical as you make the hole.

The drill bits are no problem. Harbor Freight will sell you a
selection of solid carbide bits suitable for the task; simply pick a
size to suit the components you're using, such as the wire legs of an
LED or quarter-watt resister.

A Dremel tool (or similar) is the handiest means of chucking the tiny
drill, most of which have a shank diameter of 1/8".

To hold it perfectly vertical you don't 'hold' it at all -- you make up
a 90 degree bracket and clamp, wire or glue the tool to the vertical
leg. On the horizontal leg you drill a 1/4" hole to accept a bolt
which you then chuck into your DRILL PRESS. There's a few picky-bits
to this method, such as using a bracket that is a true 90, and thick
enough so as not to deflect as you run the quill of your drill press up
& down. You need some method of preventing the quill from rotating of
course -- I use a simple wedge between the quill pulley and the frame
of the drill press head (big, old Craftsman floor model. Your mileage
may vary...) To keep from ruining the chuck in your drill press (which
was not designed to grab hold of threaded bolts) you put a barrel-nut
on the bolt.

Deal with all the tricky bits and the result is a shake-free,
carbide-tipped hole-maker that will give you a life-time of accurate
service (and already has, in my case... I used it to make the boards
for my first computer back in the mid-70's).

ELEVATION vs AZIMUTH

Azimuth is relative to the horizontal. Elevation means over-head. In
laying out the circuit board, asimuth is taken care of by orienting the
legs of the LED's. Since the LED's have an average viewing angle of 25
degrees, to provide adequate coverage the azimuth angle starts at 10
degrees and progresses in 20 degree increments. Of course, when you're
trying to provide full coverage across a segment of a sphere, your
LED's must be accurately oriented in TWO dimensions.

The key point here is that I chose to build the aximuth angle into the
circuit board.

The elevation angle is bent into the legs of the LED's using a simple
form-block, accurately printed via DeltaCAD, glued to a bit of plywood
and sanded to the line. To keep things simple, I abandoned the
variable height arrangement as described in my original post, other
than allowing a bit of overlap between one row of LED's to the next so
as to keep down the circuit board, which comes out about two by two
inches.

As a further simplification, I eliminated the left vs right bending
angles used in my original (2002) lights. Now all of the LED's get the
same set of bends relative to their positive lead. To accommodate the
change from left- to right-facing, I re-drew the circuit board.

MAKING THE CIRCUIT BOARD

The Old Fashioned Way was to start with a drawing then go to litho
film, then to a fine-meshed silk screen. Once you had the silk screen
you could whip out a hundred circuit boards in an afternoon... after
spending a month to arrive at that point.

Nowadays I simply print the circuit board mask onto cheap
glossy-finished color photo paper using a monochrome laser printer.
Here's why it works:

Laser printer media is a finely divided thermo-plastic -- a powder so
fine it is attracted to the electrostatic charge created by the laser.
The thermo-plastic material is transferred to the paper by heat.

This lends itself to making circuit boards because once the
thermo-plastic material has been transferred to the paper, it may be
RE-TRANSFERRED to the clean copper surface of a blank circuit board by
the application of ADDITIIONAL heat. In effect, you literally iron-on
the mask, solidly gluing the paper to the circuit board.

Now the trick is to get rid of the paper, which I'll get to in a
minute. But before I do, you should know that while using plain paper
is possible, the resulting transfer will show a lot of voids; plain
paper simply isn't a very good substrait for the thermo-plastic
material. But cheap color copier paper is. Color copier paper is
typically coated, giving it a denser, more uniform surface than regular
#20 bond. That slicker surface attracts a more uniform layer of the
thermo-plastic material; you end up with a dense, dark, void-free
pattern.

But it's gotta be CHEAP color copier paper because you want the stuff
to dissolve in warm, soapy water. High quality color copier paper is
some very tough stuff; it doesn't like to come apart. But the paper
HAS to come apart if we want to leave ONLY the thermo-plastic material
bonded to our circuit board. So use the cheap stuff. And soak it in
warm soapy water. Then scrub it with a tooth brush or whatever -- get
ALL of the paper off of the thermo-plastic.

Now you can etch the board in the usual way. And having etched it, you
gotta drill those zillion holes. Once etched & drilled, remove the
thermo-plastic, which you can do with MEK or other kidney-killer
solvent and a bit of steel wool.

The result is a bright copper circuit board, ready to accept components
and easy to solder. Once things are soldered and checked and and all
the errors corrected, give the thing a coating of clear finger-nail
polish (!) and you're all done -- a super bright nav light that will
never burn out (at least, not in your life time) that draws about a
quarter of an amp, meaning the wiring can be slightly smaller than a
starter cable.

-R.S.Hoover
-(KA6HZF)

PS -- Yes, you may have a copy of the circuit boards, if you wish. But
you could probably do better yourself -- except for the stern-light,
they're just rectangular 5x9 arrays. I don't have a web site and I
already get more email than I want so I'll try to find somewhere to
hang them. When I do, I post the information here... for all 385
subscribers of r.a.h. to read :-)



Don't use drill bits. They break too easily, and don't
give you much "mileage". Use dental burs, instead.
Far better.
http://www.prevent.dentsply.com/cata...hor-Round-5677

Ed

wrote in message oups.com...
RST Engineering wrote:



But the paper
HAS to come apart if we want to leave ONLY the thermo-plastic material
bonded to our circuit board. So use the cheap stuff. And soak it in
warm soapy water. Then scrub it with a tooth brush or whatever -- get
ALL of the paper off of the thermo-plastic.

One of those green kitchen pot scrubbers does a pretty fair job getting the
paper off while leaving the toner on the board.

--------------------------------------------------------------------

Agree.

Initially, I went at the paper in a very tentative way, worried that
any amount of scrubbing would remove the toner. Which is something of
a joke. If you've used enough heat, the toner STAYS, despite scrubbing
with everything that came to hand.

---------------------------------------------------------------------


Not only does this method allow you to make near-perfect reproductions
of data plates and the like, it allows you to etch logos, names and so
forth onto aluminum tool boxes, prepare 'engraved' plates for
presentations, and so on. The tricky bit here is that you are
typically etching in the positive sense rather than the negative. I
found the best way to do this was to make individual masks -- OIL
PRESSURE -- 10 A -- TACHOMETER ...or whatever. The characters
themselves are left clear and the mask is cut to leave a border of
toner. These masks are then ironed on to the panel, plate or whatever
in the usual manner. (Large pieces, such as a tool box or instrument
panel, will benefit from being pre-heated.) Once the masks have been
transferred to the work-piece all of the open areas are sealed with
something that will resist the etchant; regular enamel paint works
okay.

This is a case where acid has a definite advantage, since the object is
to remove a signficant amount of metal.

Once the piece is finished, the etched areas may be filled with a
contrasting paint.

The joke here is that I spent a couple of years making instrument
faces, 'antique' compases and the like before I realized the method
could also be used to make circuit boards :-)

-R.S.Hoover



Would a color copy (negative) transfer the same way? This way you could make labels and placards and then iron them on,
color and all...