I reworked the SiPM carrier boards a little in terms of the layout and also used the opportunity to make a board for the 3mm MicroFC SiPM from onsemi. This will definitely come in handy if someone wants to play around with these little LYSO sticks (4x4x20mm or so). The files for the 3mm carrier board can be found on GitHub: https://github.com/OpenGammaProject/Tiny-3mm-MicroFC-Carrier-Board

At 6x6mm, the board is slightly larger than a 4x4mm LYSO scintillator face, but it really couldn't be much smaller and it should work reasonably well regardless.

Overall, the layout of all boards is now tidier and, above all, the important connections are all a lot more clear better marked. I also reduced the distance between the individual SiPMs a little in the 2x2 array. The circuit is otherwise identical.

Here are the latest PCBs: