Homebrew PCBs

> 
> it has not to hold the image i think.
> the electrostatic image is only at the drum.
> the paper is charged the whole surface the same, no matter if black or 
> white.
> then this charge attracts the toner from the drum (which is only present 
> where the black is).
> 

   Yes I was thinking more the direct draw method than what's going on in a 
laser printer.  There are printable foil sheets etc, but I'd assume they're 
coated to both protect the drum and cut the conduction.  It's still an evenly 
conductive surface coming into contact with a surface trying to hold a charged 
image, supposed to cause image smearing and other problems.  Still it was on my 
own list of things to try eventually too.  Be sure and try oxide layers etc on 
the PCB, may improve the image and or adhesion.

   As noted in the later messages, the fuser wasn't made for this and is much 
too cool to heat up the board fully.  Might be able to heat the board to say 
120F then pass it through, don't want to go over 140F or so though since that's 
headed towards the toner melt point and you also don't want to damage the drum, 
not sure what it's coating could handle.

   Can always bake the board for a few minutes later to get a better melt and 
adhesion.  Since it's much easier to control the temp and time after the fact it 
should be possible to melt it just enough to stick well without spreading.  Of 
course it may be good enough as is, or crank up the fuser heat just a tad.  You 
can't go too much higher without a hotter fuser assembly, fuser is just a 
lightbulb and will burn out not too far over intended power.

   Expect to ruin the drum etc in the short term, but find a cheap cartridge 
printer and it's only $60 or $80, so if it lasts well enough for 100 or 200 
boards with care it's still little more than a 50 cent paper etc.


   And note that there are plenty of older laser printers that at first glance 
look bad for this with wrap around paper paths, but then have a removable piece 
to get to jams and could then be fed straight manually.  And note that a copier 
would generally be acceptable too, this gives a much wider selection of units 
and path designs.  Plus they're equally cheap at yard sales these days.  I think 
the HP 1100 had this piece, can't quite remember though been a little while..

   Of course about the time this is all working perfectly, the solid inkjet 
printers will be done and you just print your conductive circuit directly on a 
sheet.

Alan