Ok, so here is a detailed description of how this process works
for the benefit of making repeatable, one-off cheap PCBs.
Again, this process makes high detail artwork survive the etch
process faithfully, and therefore is a perfectly viable cheap method.
Not to take anything away from the pioneers of the idea who are mentioned
at the start of this thread.
1: Happy with the artwork?...I printed it out on a laserjet HP -5P
model using Kodak Picture Paper (for inkjet printers) A4 75sheets
cat #835 0613 (PIC 1)
2: I prepared a bare PCB with a light brush of a kitchen scour pad
with gentle strokes. (not steel wool because that can leave harsh scratches
that let etchant seep under resist material.)
Then, as per the supplied links, I gave the raw PCB a quick wipe with
paint thinner( or acetone) to make it as clean as possible.
Then I placed the printout carefully face-down on the PCB ready to iron
it on. (PIC 2)
3. Iron on highest setting, no steam...carefully put pressure over entire
area without sideways motion to avoid moving artwork initially.
Then the artwork 'glues' itself to the PCB allowing sideways motion
with the iron.
I found I could work the artwork using the tip of the iron (the hottest point)
and actually see the artwork appear through the bubblejet paper slightly.
(Pic 2 shows the artwork appearing after about 1 minute of ironing)
4. The PCB is very hot now and I dropped it into the kitchen sink filled with
warm water. After about a minute the backing of the bubblejet paper
can be carefully peeled off and it leaves behind the thin printout layer
still stuck to the PCB (PIC 3)
5. After very carefully rolling the printout layer with your thumb under water
you can remove all of the paper remnants until the artwork (toner) is left
intact.
Carefully inspect you have 'rolled' all of the paper off especially between IC
pads etc because if you leave ANY paper behind at this stage the etchant
will also leave that copper behind.
The toner survives fairly rough rubbing as long as it isn't scratched by a
fingernail etc.
PIC 4 shows the board ready to etch, alongside the original artwork
and a fully tested board.
Note as the pre-etch board dries off the tracks/ artwork take on a greyish
appearance. That is paper left on the toner/tracks.
That is perfectly ok....as long as it is not left on copper you want removed.
5. Etching.....(PIC 5) shows my small etching tank, fed with regulated
compressed air to speed up the process.
Pre-heating Ferric Chloride to above 30-40C also speeds it up.
Etching is complete in about 2-3 mins with good fresh FeCl.
6. All done....washed down, ready to use
(PIC 6)
This method works!....bottom line is it works...reliably....minimal variables to
mess up success/failure....gotta be happy with that.
Steve
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