High current connectors

Yeah, but are the PCB mount?

The forklift we had in our back shop had a nice high current connector, but it was cable to cable, rather than cable to PCB.

Chris

I sometimes use a regular nylon-shell Amp or Molex connector at, say,

5-10 amps per pin. Inter-board cables are run with one modestly-sized wire per pin pair; that's cheap, easy to fab, flexible, and the wire resistance equalizes pin currents if you plan it right.

Somewhere north of 50 amps RMS, current crowding and power dissipation in the PCB traces becomes a problem. A big connector with lots of smallish pins helps here, by spreading out the current footprint.

John

Look up the Fork-lift servicing people in the phone book . They have standard Connectors for wheel-chairs to Industrial Fork-lifts !

Yukio YANO

Why solder/unsolder/resolder?

Yup, did that whan I was young and foolish. Lots of trouble.

The problem isn't so much the connector as it is the current distribution and heating in the PCB traces. It's fairly easy to get most of the current squeezed into a relatively small part of where you expected it to be. The Amp block-o-pins thing has such a low resistance that the pcb pad/trace geometry is going to determine the current sharing. I like the multi-wire thing because it can be made to force a nearly equal current on each pcb pad, and can spread out that current over a wide area. Plus, the octipus of wires just above the shell housing provides much better air cooling than you'd get from a single equivalent fat wire.

John

I have used wire-mounted "Singlepole" and "Multipole" Anderson connectors

for DC (150 V, 150 A) and AC (300 V, 70 A) connections and they seem to work well. It looks like they do a PC-mount version of some of their connectors (which I haven't used) for up to 55 A.

Big copper land on PCB, big bolt, ring terminal...

Thinking out loud: do you know about the lugs that are used to terminate larger stranded wires to fuse holders, etc? Like

. Maybe you could use a lug like this, bolt the thin part to your board permanently, and have the user insert a stranded wire into the hole and tighten the screw. Essentially it's a DIY high-current terminal strip.

Standard disclaimers apply; I don't get money from any of the companies mentioned.

Matt Roberds

AMP now make them, but we designed our own. Make a big fat (red) cross, out of 1mm Cu, with fingers on each of the protrusions, and a hole in the middle. Fold the protrusions down, to make a little box, and drop into a suitable PCB footprint (fingers thru holes get soldered). Then unsolder it, and pop a suitable sized nut underneath (appropriate hole on PCB) then re-solder, and voila - a nice high-current connector you can bolt too. After you forget the nut once, you wont forget again :)

careful choice of dimensions mean the nut is contained but cannot spin freely. poor choice of dimensions renders the idea useless.

Others just bolt big fat lugs directly to PCBs, but beware the Z-axis CTE of FR4 is about 10x worse than X- and Y-axis CTE, and that near Tg it'll happily flow. Still, thats what Mithras invented Schnorr washers for :)

Cheers Terry

And less impact from skin effect. ;-)

Cheers! Rich

just a cheeky comment. And because most people do that, at least once.

oh yes. a terrible idea.

and a split-washer (cheap shit spring washer) exacerbates the problem, by heavily loading one point.

Cheers Terry