Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Does any one know if LCDs are transparent to UV? Would it be possible
to replace the backlight on a LCD display (like a LCD computer monitor)
and do a contact exposure to a sensitized PCB with the PCB image
displayed on the LCD? A number of monitors have sufficient resolution
to do fine traces if when the LCD is clear UV is transmitted and the UV
is blocked when the LCD is dark (or visa versa if you have positive or
negative resist).
Having disassembled a LCD monitor it does not look like it would be too
difficult to replace the cold cathode lamp with UV LEDs. (Unfortunately
the LCD was cracked or I would have tried the experiment). This would
eliminate the need for photo-plotting, printing on Velum, or overhead
material. With a white light behind the LCD, you would get what you saw.