Believe it or not, with care it is possible to directly print onto PCB stock with a (modified) laser printer. It's been done by a few people now on the Homebrew PCB Yahoo Group^. Mark Lerman has pioneered this method with his conversion of a Lexmark E260 which he has documented in pictures^
Jim KI6MZ says:
I modified (with Mark's guidance) the E260 printer to directly print an toner image to a PCB or other substrate. I will now describe how I fix (harden) the PCB pattern to the copper substrate.
When the PCB exits the printer with its pattern, the pattern is attached to the PCB by an electrostatic charge. You can BANG the PCB on the table and nothing comes off the PCB. But if you lightly touch the pattern, it will smear. The usual way to harden the pattern is to use heat (up to 400 degrees F). Here is a method that uses NO heat.
The toner consists of finely ground poly-ester resin. Acetone will dissolve this resin. In fact, Acetone solvent is the perfect way to remove the toner after etching. To FIX the toner to the PCB, without heat, in preparation to etch the board, take a table spoon of acetone and put it in a glass dish that can be covered and sealed. Put something in the bottom of the dish to place the PCB on face up. I use stainless steel bolts. Seal the dish with a glass pane or an acetone resistant plastic cover. Leave the PCB in the VAPOR of the acetone for at least 2 minutes. Remove the PCB and allow the acetone vapors to dissipate from the PCB (30 seconds). You can now touch the toner traces without damaging them and the PCB is ready to etch.
sentientnz says: {ed: paragraphs rearranged}
...found an old Laserjet 2200DN...Because the LJ2200 triggers imaging from the registration sensor, and the registration roller is before the sensor, once the board starts feeding through the registration roll the imaging is identical every time. I couldn't be bothered bypassing the fuser/thermistor but the LJ2200 has a transport assembly between the drum and fuser of about 6" so the PCB simple sits in this gap after imaging - I remove the drum {ed: toner cartridge?}, lift out the PCB, and reinstall the drum.
I had to remove a tin guide from between the regi roll and the drum to make the paper path straighter..
it was simply a case of reducing the pressure on the registration rollers and the transfer roll for the added thickness of the PCB (I only had 1/16" single-sided board floating around).
...with the transfer roll.. I removed the spring from underneath, and clipped them in half, then reinstalled. This reduces the pressure significantly and allows the regi rollers to 'push' the pcb through between the drum and transfer roll.
I don't use the bypass feed roll ... In figuring out how to make it work, I destroyed the bypass feed roll clutch, so I had to remove it.
I have printed some test patterns, down to 3mil traces with 3mil spacing. Under a magnifying glass the traces appear uniform and even.
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