Clad AL substrate - high current interconnect

Got any links to the clad Al substrates? Is this the Bergquist stuff? Is the Al always insulated from PCB traces?

I assume that, if it's a pc board bonded to an aluminum plate, you must use all surface-mount connectors.

Is this stuff cost-effective? You could just bolt a PC board onto a hunk of aluminum or a heat sink, but then you could provide clearance holes for serious thru-hole connector pins, and use the mounting bolts (with proper washers!) to connect to the substrate and use it as a conductive layer.

I like to use 0.25" faston blades on pc boards for high currents, with the female mate crimped onto harness wires. You can parallel these for higher currents, with the wires acting as current-balancing ballasts. But if you're limited to surface-mount, you'd have to be careful, use a *lot* of copper on the board, so that the connect/disconnect forces don't rip the tabs off the board.

How much current? How many circuits?

John

As John said, define high current. I've used several different methods. For low current, I've use 0.50sq posts, these provided control signal connections. For high current the easiest method was to simply sandwich Cu bar between the AL clad substrate and another FR4 PCB. Another method was custom clips shaped sort of like a U with a flat bottom and the top of the U pinched together. This was soldered on the metal clad and Cu 'legs' slid in. Similar to the clips used to hold EMI shield in place on a PCB, just heftier.

Robert

The requirement for SMD connectors is driven by application of the substrate.

I'd considered using faston pins, as there are methods of adapting the socket component for bottom entry.

SMD of the pin could be a bit hit and miss, particularly if it has to have any length.

Current is in the region of 40A/connection and subdivisions of same.

Although cost isn't currently the issue - this having been resolved before starting, so as not to waste the design effort - the processing of a troublesome interface could be an added cost that wasn't anticipated.

RL

How did you establish/maintain good contact/pressure in the sandwich?

RL

Bolts/nuts and belleville washers. Works quite well. Used it for PCB/PCB sandwich as well.

BTW on the small posts we didn't have much in the way of registration problems between boards, can't say as I'd want to fit together a large number of pins though. We were using a 4x2 IIRC.

Robert