Vinyl cut PCB resist
Recently, we are working in class on a variation of the Rock and Roll Speakers from Fashioning Technology. Rather than using perfboard for the circuit, we’ll be burning our own circuit board. The chips are through hole LM386’s, but I don’t think it is realistic to have the students drill 8 aligned holes on the circuit board. There is an excellent primer on printed circuit board etching in MAKE, Volume 02. After thinking this through a bit, I came up with an idea to turn the through-hole component into a smd component. The technique is a bit like the design of the Broadcast Your Podcast FM transmitter circuit, which just has you solder the components together in pools of solder on chips of board.
When the chips finally arrived from Electronic Goldmine, I looked up the datasheet for the LM386 to get the measurements. In Open Office Draw, I drew out a design that would match up with the pins. With the help of Pat, who is doing an independent study on CNC tools this year, I sent the file to the machine with the vinyl cutter. He cut the file, then we weeded it to see if it matched the chip. The file matched the pin locations of the chip, so we made a few more iterations to get the process down and the layout right. When we got it right, we cut three copies of the file for boardmaking.
