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
formatting link
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.
snipped-for-privacy@isp.com 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 :-)