16 Jun
2006
16 Jun
'06
9:57 a.m.
Rumor has it that Brent Hilpert may have mentioned these words:
Scott Quinn wrote:
It's entirely possible - but *getting* that resolution is damn tough... see
below:
A while ago (late '80s, early '90s) I
heard a suggestion for using
copier toner as PCB etch resist
(draw on paper, copy onto overhead
transparencies, iron onto the PCB).
Now that PCB layout software is available easily, as are laser
printers, has
anyone here tried
it? I'm wondering how well it would resolve
for finer-pitch DIP/SIP
packages, or if the etchant would eat
through the traces.
One of the last of the local component retailers around here sells this
system:
http://www.pulsar.gs/PCB/a_Pages/1_Menu/overview.html
It *claims* to have good pitch resolution... I've been thinking about trying it, but have yet to
do so. It would be worth
it if it works, but it's in the category of "ya spends y'r money and takes
y'r chances".
In this case, it's "ya spends y'r money, then ya gots no more money." I
spent my money. I spent it again on a photo-resist kit. ;-)
From what I understand, you can make it work very well, with 3 things to
keep in mind:
1) the stuff was designed a *long* time ago - it does *not* work well with
newer laser printers (If it says "MicroFine Toner" beware - AFICT, this
toner needs a higher fusing temp. and the media's not able to handle that
well.) and certainly not with any color lasers that use fuser oil (read:
most of 'em). Use an old LaserJet II at 300DPI, and it should work OK..... if:
2) you keep in mind it's a one-shot-wonder. You can't print a half-page,
then save the other half-page for later - once it's been heated by the
toner, it's done for. It either gets expensive, or you have to save up your
projects for one go.
3) You can precisely control the temperature, pressure & humidity of the
heat transfer. The last time I tried it, it took four sheets of the stuff
to build a (really basic) 3x3 inch board, and I still had to touch up a few
of the traces before etching and one piece of kynar afterwards where the
paper bubbled "just a touch" in just the wrong spot due to uneven heating
(I'm guessing).
Personally, I'd point-to-point solder with fishing line before using the
stuff again...
As a kid in the 70s I made PCBs using the photo-resist
technique, but I can't
find supplies for that anymore, at least not locally (and it was a tedious
process).
This place has a kit, and a *really* good beginners book for it:
http://www.circuitspecialists.com/
[[ more specifically:
http://www.circuitspecialists.com/prod.itml/icOid/7783 (the book)
http://www.circuitspecialists.com/level.itml/icOid/7156 (the hardware)
]]
I'd suggest spending a bit more money for the better etchant tank &
aquarium heater, and the better exposure lamp.
They do sell some toner-transfer paper stuff, but even in the book they say
that the product doesn't work well... ;-)
They've got about the best prices for presensitized boards I've found, too.
[[ No affiliation except a satisfied customer... ]]
HTH,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger -- SysAdmin, Iceberg Computers
zmerch at 30below.com
What do you do when Life gives you lemons,
and you don't *like* lemonade?????????????