v0.8

NeuroBytes v0.8: the biggest thing since v0.4. These boards were the second round to be manufactured in pilot-scale quantities, and marked the first time we actually bought a stencil to help with solder paste application. They carried us through the UW-M and PHHS trials crucial to our SBIR Phase I grant, and taught us a ton about how students interact with the product.

One of things we wanted to lock down with v0.8 was the PCB shape. A running concern with previous iterations--all the way back to the first custom PCBs of v0.4--was the lack of organic shape. NeuroBytes are intended to emulate biological neurons and be used as a science teaching tool, so they shouldn't be square or angular. We also wanted to get the logo back on the boards, as the miniaturization efforts of v0.7 precluded this option.

Two v0.8 boards, showing the front and back of the design. Mode switches! Bottom mount LEDs! JST GH connectors! Crazy routed PCB design! So many changes.

An hour of fiddling around with Digi-Key's parametric search tool happened to turn up a unique part: a SunLED bottom-mount RGB LED. Some carefully scaled whiteboard sketching showed that all the parts would match nicely with our logo, so we decided to base the design around it. We actually ordered a few prototype boards to validate the design:

Sharp eyes will notice the UW-M logo near the axon terminal--these boards were the final iteration before our big classroom trial, so it felt appropriate for the prototypes.

Sharp eyes will notice the UW-M logo near the axon terminal--these boards were the final iteration before our big classroom trial, so it felt appropriate for the prototypes.

After confirming that the layout was sound, we pulled the trigger on our biggest PCB order yet: 210 NeuroBytes spread across 14 panels:

As suggested above, the stencil was crucial to success here; we were able to hit 10 boards/hr, including depanelization, 'mouse-bite' removal, paste application, manual component placement, reflow, and programming.

This 3 mil stencil from OSHstencils lasted the whole run without any problems.

This 3 mil stencil from OSHstencils lasted the whole run without any problems.

In addition to the two classroom trials, we managed to bring the v0.8 boards to two Maker Faires where they were a huge hit:

Many more pages could be written about v0.8 (I didn't cover mode switches or connector selection or... etc), but newer versions have already rendered the model obsolete. If you're interested in seeing it for yourself, we are selling some of the prototypes!