Your experience sounds much like mine, and this is why I think this
new method is likely superior, but I do have a suggestion for you.
Note that I HAVE NOT TRIED THIS, but the idea was triggered by one of
the steps in the new method.  Every heat transfer technique I've seen
tells you to polish the copper blank, then roughen it with sandpaper
to give the toner something to adhere to, but I have never found this
to be a satisfactory solution.  One of the techniques used in this new
method is probably applicable to the heat transfer method as well.

The trick here is to polish the board as usual, but then instead of
using sandpaper to roughen the surface, dip the blank in etchant
instead.  After some small percentage of the total etching time (by
trial and error), remove the board and rinse thoroughly under running
water.  Dry the board with warm air (even a lint free cloth might snag
some debris in the rough surface), then transfer the toner to the
board with heat as normal (the surface will probably look terrible,
but that's the idea).  After etching, remove the toner, with solvent
preferably, then use steel wool or rubbing compound to polish the
remaining copper.

As I said, I have not tried this, but the copper surface should be far
more porous this way than with the sandpaper method, and the toner
should have much more luck adhering to it.  If this works for you,
please let the PICLIST know with a short message describing your
results.

CIAO - Martin.

On Wed, 28 Jan 1998 11:35:15 -0500, Sean Breheny <shb7@CORNELL.EDU>
wrote:

>Hello all,
>
>I have a question regarding this whole thread: I have tried using the
>special paper that you print onto using a laser printer and then "iron" on
>to the board, and I have had very little luck (this is NOT the copper foil
>paper, which I have never seen). What I did was to print my patter using a
>laser printer. I baked the paper slightly in an oven (I also tried not
>doing this). Then I thorouly cleaned and even lightly sanded the board,
>placed the paper on it, and then applied heat and pressure. To apply the
>heat and pressure I tried both an iron and a commercial t-shirt press on
>max. heat and on medium heat. I then within 20 seconds placed the
>board/paper combination into  water until the paper separated. I ALWAYS got
>an unsatisfactory result, some of the toner would fall off in the water and
>I would be left with a spotty board. I even called the manufacturer and
>tried his suggestions. Nothing worked. I even tried several different
>batches of paper. To no avail. Any idea what I was doing wrong?
>
>Thanks,
>
>Sean
>
>
>At 11:04 AM 1/28/98 +0000, you wrote:
>>Is there a web site where I can purchase necessary components to try
>>the copper foil technique on my own?
>>TIA
>>AY
>>
>>> Actually, the copper foil technique was developed precisely because it
>>> is easier than the heat transfer method, and produces vastly superior
>>> results.  It is very dificult for most people to get consistent
>>> results with the TEC sheets (and similar products), and the very fact
>>> that the toner is transferred twice limits the minimum reliable trace
>>> width.  This new method promises high quality prototype PCB's with a
>>> minimum of fuss.
>>>
>>>
>>> CIAO - Martin.
>>
>+--------------------------------+
>| Sean Breheny                   |
>| Amateur Radio Callsign: KA3YXM |
>| Electrical Engineering Student |
>+--------------------------------+
>http://www.people.cornell.edu/pages/shb7
>mailto:shb7@cornell.edu
>Phone(USA): (607) 253-0315


Martin R. Green
elimar@NOSPAMbigfoot.com

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