So I have just done a little reading. It seems a circuit itself cannot be copyrighted, but a visual representation of it can be. It can however be patented.
I think this means that sparkfuns files are copy-write with a CCSA license. However the circuit design itself is not.
You are correct. A circuit design cannot be copyrighted.
A PCB design can be, however. The PCB design is the actual layout of the copper traces on the board. In the industry, it is referred to as "artwork" and is copyrightable as such.
I think this means that sparkfuns files are copy-write with a CCSA license. However the circuit design itself is not.