Power Distribution Board
This Power Distribution Board (PDB) is specifically designed for Phoenix Solar Racing's Phoenix solar car and hopefully future solar cars.
-Got from PCBWAY.com for 74$ & 22$ shipping, That's for Ten, 175mm x 120mm boards with 2-once copper. Please excuse me as I shill, but I am really impressed with the quality and price of PCBway as well as their advanced website that shows the status of your PCBs on the assembly line. A real person makes sure your Gerber files are not screwy, and the boards are tested with flying probes before they are shipped, but that might be for protecting their own reputation. >facebook post ;)
I tried to keep power traces on one side, and signals on the other. Power-traces had to jump up to the top to connect to surface-mount current sensors. Lots of vias were use
>small PCB photo with Google photos link >micro scope photo?
I simulated the input protection in Multisim and experimented and tested many different Zener Diodes. The diode I chose is a special type of Zenar called a TVS diode. Unlike normal zeners, TVS diodes can conduct thousands of Amps when in breakdown (for a few micro seconds). The simple cheap automotive fuses used on the board take relatively a long time to break. The TVS diodes "burn up" and fail closed by the time the fuse breaks. if the PDB experiences an Over-voltage situation, one or more TVS diodes will need to be desoldered and replaced. I chose this input protection circuit because of its simplicity, low cost, and feature-set.
I added 5.1V zener diodes on the 5V rail just in case a high voltage tries to find it way onto it.
I designed the board to handle 10 Amps of current. This is probably more than we will ever use, even in peak situations. To design the trace sizes I used simple geometric calculations of trace thickness and length, to get 0.01ohms from farthest-input to farthest-output. At 10A that's 1W of power dissipation and 0.1V drop. I used 2-once copper PCBs and removed the solder mask on the ground traces around the outside of the board, just in case I needed to increase the current handling by piling on solder.
>Flir photo >In tests, 10A of current showed no clear signs warm traces. Only fuses and input diode are warm >temperature resolution is very fine so if the traces were dissipating