From Cricut to Circuit - Making your own Printed Circuit Boards

[deadastronaut]

yep sharpies work fine for missing bits.......just draw!....a few layers to be sure though!...

i drew a wah circuit with just a sharpie and it came out ok...

[edvard]

I read a posting that enamel paint for models (like Testors) can be effective as an etch-resist if applied properly.

That's how I did all my boards for a few years.
I thinned the Testors down to almost ink consistency and used an old-fashioned dip pen to draw the traces on.
A 13EF cartographer's nib or Speedball B-6 for regular traces, a Speedball B-5 or B-3 for fatter traces and pads.

I scratched a sharpie across it to mark it out, and the sharpie ink had apparently filled the space between the vinyl and the copper.  There was no undercutting whatsoever across those points where the ink intersected the vinyl

That may also be due to solvents in the ink tacking down the vinyl edges.
I used to work in a shop that did vinyl banners and signs, and one of the things available in the catalogs was a solvent pen for sealing the edges of the cutouts.
Sometimes if a sign was in the sun for a long time, the vinyl would shrink a bit and peel up just enough to catch dirt and whatnot.
Sealing the edges stopped that whole business, but was time consuming so we never offered it.

Something else you could try is something called heat press or heat transfer vinyl for t-shirts.
It's just like adhesive vinyl, but is heat-transferred instead of adhesive (we had a big flat heat press for this).
The vinyl is much thinner and comes backed by a thin plastic substrate, so no transfer taping is required and it can hold LOTS more detail.
The only drawback is you have to print your design in reverse, but that shouldn't be a big deal.

[BlueJay]

I will look into the solvent pen, but I am concerned that the acrylic base in it could get messy if over-applied and will act as an unwanted etch-resist of it's own.  Another thing I am thinking of now is just touching the joint between the vinyl/copper with a fine-tip sharpie along the edges, and try to get some flow going to fill the gap.  I may get a little bit of extra ink on the board itself, but it should be easier to clean up with some alcohol and a sharpened q-tip, which shouldn't dissolve the ink in the joint too much.

The circuit designs are simple enough at this point in testing this manufacturing process, in that I don't need to etch a whole lot of detail..yet.  If I get to the point that I need lots of fine detail, I will look into more traditional methods of etching suited for that purpose (ie. photoetching).

I am also looking into a temporary solution to mitigate any undercutting issue I had on this test board by just tinning the copper traces.  Looking back on Freekmagnet's design, I realized that he designed the layout for bass by omitting C1.  So the next board I etch will probably be a layout of my own design, because this board was just a trial run to check the viability of this process...

...And it certainly has potential!

[BlueJay]

Yesterday, the guy at Vetco Electronics was very impressed with the results of the etching, and also recommended I tin it to protect the copper from any corrosion or oxidation.  He sold me a small spool of copper solder wick, and a small jar of Orange-based paste flux, which I spread across one of the circuits last night.  I also picked up a couple more copper-clad boards while there to further experiment on.

I then melted a little bit of lead-solder on the wick, and wiped the tinned wick across the copper traces, it made a nice and shiny thin layer on the copper, and should eliminate any electrical issue that may have risen from the undercut I experienced on this board.

I am now working with the DIY Layout Creator from another thread, and trying to wrap my head around turning a one-dimensional schematics into two-dimensional layouts. 
Or should I just continue using a layout that someone else made, even though it may have a larger footprint?

[BlueJay]

I took a different layout this time, the Pepper Shredder layout that Jimmy-H posted on Page 23 of the ValveCaster thread (http://www.diystompboxes.com/smfforum/index.php?topic=63479.440), and tried it out since it was a lot more intricate than the earlier test.

Retraced it into InkScape, to convert into SVG format:

Etched another board, with the same results of more dramatic 1mm undercutting (I didn't press this one with a warm iron this time)
Decided to follow earlier advice and mark out large sections of blank copper to conserve FeCl.  And discovered by accident again, that where the sharpie had touched the vinyl, it almost formed a perfect edge to the trace with no undercutting.  I knew I was on to something here...

So the moment of truth!  Can a Sharpie applied across all edges of the vinyl really make a difference in eliminating the undercutting of the FeCl?
I printed out another few 4x6 copies on the Cricut, took one, applied it to another Copper board, and this time dabbed a wet sharpie marker along all the edges of the vinyl, and wiped off with a bit too much alcohol.

Etched another board, to compare against...

Without sharpie:


With sharpie:


Conclusion,  I got beautiful results with liberal use of the sharpie on the vinyl.  But be sure to get ALL the excess sharpie off, otherwise you may end up with shorts on the etching!

[potul]

[EDIT] Silly post...