On Tue, 26 Jan 2010, James wrote:
>> I've thought of the photo process, but the price of pre-coated boards
>> scares me off. I'd like to be able to cut a piece of board for what I'm
>> up to and not have to waste an entire larger board for that. How about
>> spray-on resist?
>
> A friend of mine experimented quite extensively and came to the
> conclusion that the spray on resist is garbage, which is probably why
> hardly anyone carries it anymore. If you try that, you will wish you
> spent a bit more for the pre-coated boards. The trick with this method
> is to plan ahead and either keep a stock of the sizes you most often
> use, or combine several layouts onto a single piece. You can cut it too
> if you're careful, but you need to be sure you store the unused portion
> in an opaque container. Another tip with this stuff is print on vellum
> instead of transparency, and place the print ink side down on the blank,
> and use a piece of reasonably thick glass to press against it so that
> the whole thing stays absolutely flat.
I suppose a scroll saw with an appropriate blade would do the trick for
trimming boards. Half-inch glass slabs seem easy enough to come by, but I
wonder about their UV transparency. I suppose it would be transparent
enough if I calibrate how long it takes to get a good exposure.
>> I had a modified GBC laminator of the sort that Pulsar advocated. I
>> haven't a clue where it wound up. Pulsar suggests that the laminator
>> works with their product, but not with Press-n-Peel. I used an iron last
>> night with Press-n-Peel and absolutely nothing transferred.
>
> How did you prep the board prior to attempting the transfer? I've had
> great luck using plain glossy paper I cut out of catalogs that come in
> the mail. I was even able to get usable boards with an ancient Okidata
> LED printer I had, but the 600 dpi Xerox I have now works FAR better.
> You might try a different laser printer and see if that works better, a
> lot of people report good results with the HP Laserjet series using OEM
> toner, you should be able to find one of those pretty cheap.
I pulled the board out of the package, then washed with 93% isopropyl,
then with acetone. I have access to an HP Laserjet 2600n that I might
try. Another thing that bugged me is that Press-n-Peel seems a lot harder
to get taped down to the paper. My first attempt curled up in the
printer.
> I'm wanting to try the inkjet method in order to do fine pitch SMT
> stuff, but toner transfer is by far the easiest method I've come across
> so far, you really ought to give it another go.
One of the things that is driving me to the photo process is that I'd like
to do double-sided boards sometime. It seems a bit easier to get the two
layers registered properly by taping two stencils together to make a
pouch.
--
David Griffith
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