I want a PCB I am creating (in Eagle) to break apart like the new ProtoSnap boards do with ‘mouse bites’. I was hoping that this was a part in the SF Library (somehow), but it doesn’t seem to be.
Assuming I haven’t overlooked a part,… (or post)…
Does anyone know the dimensions of what the ProtoSnap is (hole size, distance between holes, trace width, trace to hole-edge separation)? Will BatchPCB accept a design with this on it? Are there better ways to do this?
After I am done with this particular project, I want to break off some individual parts for use in new projects.
If you look closely at the images, what makes them ‘snappable’ is just a bunch of tiny drill holes, spaced closed together.
I’ve used this in a design myself - not so much for being able to snap, but in order to keep 3 different boards within a single area together until we machine them out ourselves.
PCB fabs are fine with this as long as you obey their hole-hole distance rules, which I think are part of the DRC.
Edit: and there’s actually an Eagle file for the ProtoSnap Pro Mini, so you can just peek at that to see what drill size and distances they use
The Proto-Snap board would not work with V-groove scoring. Most PCB fabs will requires that V-scores go all the way across a board in a straight line. This is easy when panelizing a lot of the same board. You can see the Proto-Snap has breaks on lines with other parts of the PCB, so routing and mousebites are the way to go.
The ideal way to do this is to route most of the outline away, leaving the small mousebite sections with the drills and no copper for easy breakaway. That’s much better than trying to put drills along the whole outline of the board; you’ll get complaints from PCB fabs and an edge that is hard to smooth after breaking.
Good point macegr! Indeed that is the trick that makes all the protosnap products work. I did some of my initial prototyping for the protosnap products through BatchPCB, and one thing I’d like to mention to you, Matt, is that the PCBs form BatchPCB are standard thickness (which is a little thicker than our Protosnap PCBs). This means that if you would like to match the “snap-ability”, you may want to tighten up the distance between each drill hit.
SFE protosnap: 15 mil drill hits, with a spacing of 30 mil between center points.
Suggested spacing for standard thickness PCB: 15 mil drill hits, with a spacing of 20-25 mil between center points.
But even if you do it exactly the same spacing as the protosnap line, it will break apart - but it will need a little more force.
I might also like to add: you may want to keep your spacing between center points to 30 mil for the spaces that you route traces.
