A project that has bounced around in my head for decades has been a desktop PCB printer. A recent post here has ressurected that project in my mind. I have of course made PCBs before using the toner transfer method, but it is a pain and messy.
What I would ideally want is a finished PCB board to just pop out of the printer. What I could sacrifice for is one that is ready to etch. I know many others have pondered this and I am would like to collect some brainstorming bits and ideas that you have come up with.
I have had several back-of-the-napkin ideas such as: Using a focused UV source to print directly to a photosensitized board (do UV lasers exist?) Using an LCD as a UV mask Using a DLP set up with a UV source Direct milling (with either a micro-engraver pen or an adapted vinyl cutter/plotter) Dye Sublimation printers to print a wax mask (I wish I had kept my old Commodore Okidata Thermal printer!)
What would be ideal is the ability to print accurate and small enough to place SMD parts and tracks between pads. And accurate enough to have perfectly registered double-sided boards. For that later part, I think that could be handled by having some type of system that can measure the inserted board and ensure it is aligned perfectly to one corner.
Some systems I have thought of for that:
An XY movable bracket that will find a corner of the PCB and apply some pressure against an immovable opposite corner. It would then know the distance between those two points and have the dimension of the board. A set of contacts on the print head that would run along the board mesauring continuity. Once the pins dropped off the board, the circuit would be open and it would have found the edge. Also some type of optical system could also detect the size of the board similar to how a scanner does it. Maybe even something that runs along with the printhead and reflects a light on the copper. Have a black background to sense the edges.
For double-sided boards, either the above system would allow accurate registration of the board once it is flipped, or just duplicate the same system used to handle the top for the bottom (added cost, but hey we are brainstorming here!)
The print head could also switch in a drill and possibly different drill bits (easier with the direct milling/micro-engraver) or perhaps even a laser cutter capable of cutting through the board. The cutting laser would also be great for creating a shaped PCB.
Hmm... a laser in general may be able to do all things needed if the amount of cutting can be controlled. Not sure how practical that is since copper would conduct heat really well. Perhaps preheating the board would help?
So, any thoughts?