Creating a high-current bus on a PCB

Question

I'm planning a custom power-distribution / fuse-board for in-car application, but that requires carrying high currents (50A+ @12v*) on a PCB trace. Since I'd like to keep the board cost, and physical size down, can anyone suggest efficient (as in easy & inexpensive) methods for creating a power bus on a PCB?

Feed in would be from a chunky copper cable, most likely with a screw-terminal tag on the end.

My thoughts so far:

• Thick trace with thick coat of solder
• Same but with some thick copper wire soldered to it
• Same, but use a single strip of stripboard
• A length of copper or aluminium, either attached with screws through holes in the trace, or soldered down (obviously not soldering aluminium down!)

These are all OK but require special effort to populate the board, whereas something available off-the-shelf would make life easier.

Edit to add more info: The basic layout will be a bus up the board, with feeds off for each item, each of which may draw <30A (but most of them are <10A), so per-connection there can be a little thermal relief to make life easier.

* = Average of maybe 30-40A if the cooling fan's running and all the lights are on, ~10A if not, potentially 100A max although more headroom is better.

Answer 1

You might try searching for solderable bus bars. They come in various sizes and shapes. You can solder them down to the PCB, and they provide masses of current carrying capability.

Answer 2

I frequently have currents of that level entering PCBs. I typically use a solderable screw terminal. This, for example, is spec'd for 50A. I've used others rated for as high as 70A, and pushed them past that considerably without problem on a regular basis.

The biggest challenge is often soldering to a PCB designed to handle high currents. Thermal relief is a no-go because the copper needs to be there to handle the current, but then you have to heat up a thick and wide copper plane to get the solder to flow. Proper solder masking and a big iron is a must. We've also used a torch when all else fails.