Homebrew PCBs

Don Perry wrote:
>>backup roll.  The hot toner melts into the paper.   What us home pc 
>>makers are trying to do is keep the toner from sticking to the paper 
>>so well.   Fuser oil or coatings on the paper  keep the toner from 
>>locking down.

   While this was my original thinking on toner transfer as well, actually far 
better tranfer results from having the toner *more* locked into the paper 
coating, and having the coating tear at the edge of the toner.  The 
toner/coating mix transfers heat better and sticks better, and tears at the edge 
easily once stuck.  Works much better than trying to have the toner not stick to 
the paper but still heat through and get on the board.




    Getting that  drum  image  transfered to a  sheet of
>>copper will be a feat.  The copper has to be moving at the same speed 
>>as the paper would be.

   That part is no problem with thinner copper board, it will easily be moving 
as the paper.

   The electrostatics for image transfer are
>>critical for focus.  The sheet of copper will be like a brick wall to 
>>the corona wire charge.

   That is why the charge needs to be put directly on the copper, still easy 
enough.  The voltage may take some tweaking, it has to be enough to pull the 
toner off the drum well on contact, but not so much as to pull it off before it 
is touching the toner thus smearing the image.  Will take some tweaking but 
shouldn't be hard to do.

   After transfer takes place  the left over
>>toner and charge have to be removed.  Sometimes another corona wire 
>>with a diffrent charge is in the drums path, some times a cleaner 
>>station to brush the left overs of the image off the drum.  Then the 
>>drum is ready for a repeat for the next scan from the laser.   While I 
>>don't know how to get that image on to a pc blank, I do know that is 
>>won't be easy or quick. 

   After looking at the specifics better today, I don't think it is going to be 
as difficult as most sources I'd read previously make it out to be.  It'll take 
specific changes that many people just trying some board through a printer may 
not think to do off hand.  But it's just adapting the process for a different 
material and getting the right charges in the right places, it doesn't look like 
it'll require any major re-engineering of the process, just some adaptation to 
make the normal things happen as with paper.

Alan