Looking for suggestions as to designing the ground layer of a PCB. 

Effectively the board is a LED driver. It has a number of TLC5940 shift register ICs and their signal paths coming from an Arduino, as well as a sensor input or two. Specifically, I’m trying to make sure that all of the grounds have a clean return path through the bottom copper layer. I’ve routed any and all GNDs (power, ICs, Arduino, Sensors) through vias to this bottom copper ground layer. As I understand it though, that is only half the battle.

I’ve had this full circuit with sixteen TLC5940s working on a breadboard, but as of yet can’t get the PCB version running correctly. My problems could be the board design itself or they could be my inability to solder those tiny little SMD components. Either way, I want to get the power/ground design checked/fixed before I send away for yet another set of boards, this time with Pick and Place. 

BTW, I realize that this is a very inelegant solution for a LED driver, but it is the solution that I need nonetheless. It’s for an art installation that is already built, coded, so I have to make the circuits work as such. 

**Power** - three 5V lines from a single 5V 40A Meanwell DC power supply. 5V line for the Sensors, 5V line for the Nano and ICs, and 5V line for the LEDs, separated and decoupled (I think)

**IC’s** - TLC5940 Shift Registers - TI Datasheet -  https://www.ti.com/document-viewer/TLC5940/datasheet/pin_configuration_and_functions#SLVS5159151

**Arduino Nano**

**Sensors** - Using three different sensors to bring signals in and out of the Arduino via screw terminals. Per Sensors: The terminals and traces are close to the Nano.

[![Front PCB][1]][1]
[![Back Ground Copper Layer][2]][2]
[![Schematic - works on a breadboard][3]][3]

The schematic for this circuit board on EasyEDA - https://easyeda.com/adlib33/cloudpongschematic11_21
The PCB - https://easyeda.com/adlib33/cloudpongpcb


  [1]: https://i.sstatic.net/B3kkc.png
  [2]: https://i.sstatic.net/Ziy09.png
  [3]: https://i.sstatic.net/6y3vP.png