kaniagostyn *UKS Kania Gostyń

PCBs in 15 minutes. Tankless etching. Panel art. Vacuum moulding.. See http://groups.yahoo..../Homebrew_PCBs/ for detailed discussion of this stuff.  I've tried it and got mediocre to bad results.  Maybe it was my technique.  The above-mentioned group also has info on using inkjet photo paper in a laser printer for toner-transfer.  Some people get better results that way than with Pulsar's special paper.

Low cost DIY PCB Etcher & Exposer.
You done anything big with the sponge, I did an 8x10 inch board using the sponge method, no problems related to the board size.

or anything with lots of small traces or hatch patterns? hehe, everything I etch has lots of small traces!  :)
Seriously though I always use a 16mil wide trace if it has to go between IC pads, and I never design anything through-hole with anything smaller.  6mil traces are possible (I have done some surface mount stuff unrelated to the MIDIbox) but there are a lot of other variables in your process that will dictate the smallest possible trace width.
Yet another cool thing about the sponge method is that it's so fast you get nice clean edges, unlike a warm bubble bath that can seep a little under the edge of an "under-bonded" (is that a word?) resist and give you a case of the jaggies.


Seems like it would also be good for doing double sided boards, if it doesn't put much slop around the edges of the current side. Yes.  The key to this is leaving a "gripper edge" to handle the board with, so you can hold onto it during the etch without touching resist areas with anything but the sponge.  Etch first, cut second.

I've also recently seen that the TRF is supposed to stick to Sharpie touch-ups as well. :) No.  Dunno who says that, but it's just plain wrong....They might be talking about filling in pinholes, and some of the foils will cover a smaller hole (due to a stiffer than needed formulation/carrier)...but the green TRF does not stick to sharpie ink.  It also won't stick very well to pnp blue transfer paper resists...but transfers using the Pulsar paper or inkjet photo paper (which wants to ruin the fuser rollers in your laser printer!) work fine.

While we are on this subject, the best toner transfers are done with a photo mounting press and a timer, followed closely by a modified laminator.  No clue how well the baby laminator Pulsar sells now works, and I'll never know since it won't do standard thickness boards.  But the suggested large GBC laminator (TIA?) and modification guide he has there on his site work great, and are more consistant than anything I know save directly silkscreening the solder mask to the bare copper.

One of my best tricks for DS protos is to drill the bare/uncleaned/un-etched laminate on the NC drill, then lay a sheet of 1200 grit aluminum oxide sandpaper face up on a granite block (or well leveled concrete floor), then dry sand the board until it's all shiny, moving the board not the sandpaper.  This removes any copper tearout from the drilling and levels the board out.  Makes it really easy to get the placement of the transfer papers dead-on accurate.  :)  Same method can be used without the NC drill, just make two transfers for one side (one to mark the alignment holes, then clean it off after drilling/sanding then apply both transfers)
Always wear a mask when using aluminum oxide sandpaper, two breaths of that dust is equal to years of sucking on lead in terms of memory loss.  :o

Best Regards

Smash