The Hackaday community offline password keeper is slowly coming together. A few days ago we received the top PCB for Olivier’s design (shown above). If you look at the picture below, you may see the problem we discovered when opening our package: the soldermask was the wrong color! Given the board is meant to be placed behind a tinted acrylic panel, this was quite a problem…
After using some spray paint, we managed to get to the point shown in the bottom left of the picture. The next task was to find the best way to illuminate the input interface with reverse mount LEDs. Using a CNC mill we machined openings (top right PCB) but also removed some epoxy on both PCB’s sides, thinking it would provide a better light diffusion. We then wrote part of the Mooltipass PWM code and took these pictures:
We hope you agree that the ‘FR4 version’ looks better. The other version, which has the cut openings, illuminates unevenly because the smartcard isn’t under all of the LEDs. This raises several questions that we hope our dear Hackaday readers can answer:
- Can this kind of machining be done in standard PCB fabs?
- Instead of leaving the bare FR4 on top, should we cover it with white soldermask?
- Instead of leaving the bare FR4 on top, should we cover it with white silkscreen?
Keep in mind that we would only need to machine one PCB’s side.
Another concern is the top panel. As previously mentioned we’re currently using a tinted acrylic panel, which may not be the best solution to prevent scratches. We’re thinking to use glass in the future (corning gorilla glass?) so we may also hide everything around the display’s active area. Do you guys have any experience with this? Would it be expensive in relatively small quantities?
As you can see, we still need to find the best compromises and we hope you can help us. Please post a quick message in the comment section below or contact the team in the official Mooltipass Google Group.