Week 42, 2013 – PCB Process Revisited
So, as some of you know, I’ve had no end to trouble producing printed circuit boards (PCBs); there’s always some damn thing that isn’t quite right… Toner transfer is always a crapshoot, quality-wise. And photo-resist is iffy because my laser printer can print good high-density positives, but not negatives, and my CraftRobo can’t cut rubylith fine enough for the kind of PCBs I’m making…
I’m left with two options; Screen-printing resist to the board. (Since burning screens is a positive image process) Or! Using lithographic film in an emulsion-to-emulsion contact exposure with my laser printer transparencies to yield perfect high-contrast negative films to expose the dry film laminated photo-resist on the PCBs with. (I can also use lithographic ‘duplicating film’ to turn so-so positive transparencies into film positives with perfect contrast.)
Right now I’m just waiting on money for supplies. Like a hundred bucks in chemicals, film, and darkroom stuff.
In the meantime, here’s some YouTube links!
- Direct screen-printed etch resist method. Though these circuit board designs look like they’re from the 1970’s, the process is more than valid. I’d probably go with a ~300 mesh screen though.
- A company called EuroCircuits demonstrating 4+ layer PCB fabrication. This involves dry film laminated resist, and film negatives that are exposed with a laser. Pretty nifty.