Our friend [Jeri] tipped us off about this cool video on youtube where the author makes his own “transparent” PCB’s using some nontraditional materials. One ounce copper foil is found online along with some clear glass microscope slides, from there it is just a matter of cementing the foil onto the glass slides with some thin UV curing glue. Once the 2 parts are mated the entire thing is popped into an eeprom eraser for its intense UV light, then excess is trimmed.
The normal routine of toner transfer is used to copy a circuit pattern onto the copper clad glass and it’s etched in standard ferric chloride. The copper is removed but the UV glue that was holding it is still left, some special care needs be followed as this stuff is pretty weak against even mild solvents, and you do not want your traces peeling up. Next no clean solder paste is applied and parts are soldered down with a heat gun, keeping the glass evenly heated to prevent it from cracking.
This leaves you with a board that looks like frosted glass, and in order to protect the glue while clearing up the frosted effect, some polyurethane is applied which fills in all the little bumps and smoothes the surface bout out to almost 100% clear.
The end application in this video is a touch sensitive board which works fine though the back side of the glass and presents a nice smooth interface for the user. Join us after the break for the video.