I want a bunch of slots in my pcb, to separate out various experimental tiles. We'd assemble and then cut bits apart. I wonder if I can just say "slot out dumbbells with 50 mil router" instead of a mess of dimensioning.
Gotta ask some board houses.
Last board I did this way, I sawed it up after assembly. The saw vibration made the little EPC GaN fets jump off the board.
I like a combination of routed sots and V-grooves. You get smooth edges and snap-apart boards.
Not so much dimensioning since the V-grooves have to go edge-to-edge.
These sundry little boards tend to not fit conveniently into a rectangular cutout grid. When I plan to saw, it takes a bit of thinking about the cut sequence. The dumbbells would let me put slots anywhere.
Cutting out some residual corner webs wouldn't be a big deal for a few prototype circuits.
My next board proto will be 4 layer on Isola Tachion 100 microwave laminate. I'll include some test traces to measure risetimes and impedances.
Cut rates are better if the router bit is wider than the board thickness; 2mm, 3mm, or 0.125" are likely to be preferable. Thin cuts are slow ones with a router.
I wrote up a description of the board I want to do, including the dumbbells, the material (Isola Tachyon 100) and the stackup, and Bonnie is sending it to a few PCB houses to get their reaction.
We'll give them the option to use Isola on the L1-L2 dielectric, and Isola or FR4 on the others. But we have a warpage spec too.
I've done that, just leaving little corners to snap off.
2mm router is about the smallest that can cut at full-speed, so is cheaper than smaller sizes. Add a V-groove to make them snap well. Some folk drill a few small holes to delineate the snap line instead.
There's a risk of flexing the board and cracking MLCC capacitors too. They tend to invisibly fail short circuit, which can make things interesting when you power them up.
Clifford Heath.
For some reason 2.3mm comes to mind. Maybe that's the width of the path, not the bit diameter. At least in metals you don't want to just plow through, you want to keep the finished cut on one side of the cutter (conventional or climb).
I'm using pretty-good microwave-level edge-launch SMA connectors, so I need the board edge to be very smooth and accurate. So I can't v-score. Just 10 mils or so of connector to edge error affects the impedance.
Mixing the two reduces (but doesn't eliminate) the constraints:
I think 2.4mm (3/32ins) is a common default cutter size.
piglet
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