20200903: Layout for T-Board (v3.1) are improved and updated. 

Modification:  1.remove the jumper (J1). 2.move the large capacitance (C5 & C7) to the other layer to solve the conflict between T-Board and Mechanical structure. 3.add two ground holes (W30 & W31) with 1 mm diameter. 4.improve the routing near the fixed holes of Nicomatic connectors. 5. remove four fixed holes for purple cable. 6. reduce 2mm along with y axis for the four corner holes to compensate the global shift of T-Board, and increase the diameter from 2 mm to 3 mm.

Reason: based on the experience of the prototype assembly  

Status: The layout for v3.1 T-Board is improved and updated.
             
             The latest output files included schematic, assembly drawings, CAD, BOM, and gerber files can be found in the attachment.