Homebrew PCBs

On Tue, 30 Jul 2013 10:26:26 +0100, you wrote:

>On 30/07/2013 04:29, Robin Whittle wrote:
>> Hi Dave,
>>
>> Thanks for this information.
>>
>> I think your attempt to laser print onto copper is doomed to failure.
>> As far as I know there is no way of transferring the toner from the drum
>> to any conductive surface.
>
>When I worked for Rank-Xerox in the 1960s, Xerox had a technique using 
>their original 1385 flat-plate system for direct printing onto copper. 
>They had some documentation for using it for making PCBs.
>
>Leon

Around 1969 Bell Labs, and maybe Xerox, was experimenting
with using a process camera with the photographic plate replaced
with a photoreceptor plate to reduce big engineering drawings
for archival storage.

The image was formed on the photoreceptor, a dark slide was
inserted into the "film" holder. The holder was slid into the side
of a box containing toner. The slide was pulled and the box
flipped over several times to allow toner to stick to the plate.

The plate was then placed in a charge transfer station and the
toner deposited on a sheet of mylar or paper.  I never heard
what voltage they were using. The image was then "fixed"
on the paper/mylar using a very fine mist of trichloroethelene.

I got them to add a step to the process. They used the transfer
station to transfer the image of a PCB drawing from the paper/mylar
to a sheet of copper. They then misted the copper to "fix" the toner
to the copper. Worked really well with IIRC amonimum persulfate
etchant.

Last I heard of the project they were waiting for a new toner formulation
from Xerox. Shortly thereafter we moved out of that building to a monster
complex shared with Western Electric and I lost touch.

Back in the early days of laser printers fuser failures weren't uncommon
and the images were in good shape when they came out of the printer
(assuming they came face up out the back and didn't get turned over and smeared
after the fuser station).

I've thought for years it would be interesting to try disabling the fuser on
a laser printer and trying to transfer the toner from the paper to a PCB
using a homebrew electrostatic transfer station and mister. 

Yet another project that will probably stay in the arena of thought.
Keith Bowers WB4LSJ- Thomasville, NC