High current connector options for PCB 4

[SolarTrap]

Hi All,

I am looking for an alternative to these cable lugs
On my current PCB design I am using 10 of these in a row (rating of 30V DC with max 50A)

Unfortunately these lugs makes if very hard to design an enclosure and I came across the 'Powerpole PP75' connectors from Anderson Power.

Has anyone experience using them? I am in particular interested in the usage of the 'BusBar' type (rightmost pair):

Can they be directly screwed into the PCB?

Markus

 

[ScottyUK]

This type of connector is popular for battery connectors on small commercial UPS designs. It's a decent connector but the mating force required is likely to be too high for a standard PCB to withstand. I guess you could use a much thicker laminate and provide a lot of mechanical support local to the connector area, although I'm still not convinced it is a good solution.

 

[MacGyverS2000]

Any time a bus connection is made, you should assume there will be mechanical strengthening elements designed into the surrounding area of PCB. PCBs are not designed to handle the mechanical forces, that's the job of the case and support it's attached to.

Does this need to be quickly removed (either by the user or repair technician), or is this a more semi-permanent job? If it's the latter, the lugs are "okay", but I wouldn't trust them long-term due to heat cycling potentially causing loosening (though you can always use Loctite, or similar). If the former, plenty of solutions out there... look at computer servers, for example. Another would be hot-swap power supplies. Fat traces, often PCB-based, and connectors that allow for easy insertion yet high current.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[mcgyvr]

Do you really need 50A or is that just the rating of that block?

 

[ScottyUK]

"...you should assume..."

And that is the root of so many problems!

 

[mcgyvr]

Anderson power..
TE Rapid Lock/Crown Line/
or these

http://www.te.com/catalog/cinf/en/c/11410/1204

Harting Han-Fast
Amphenol Radsok
Molex Extreme BBC
FCI Barklip

and more..

More details on the intended use will help.. like one time or serviceable/multiple insertion.. wire or bus bar?,etc...

 

[SolarTrap]

@ScottyUK: Anderson Power is also offering the PCB mount type but that is only rated for 25A

@MacGyverS2000: the purpose is more a 'semi-permanent job'. Ideally this is setup once and never unplugged.

@mcgyvr: I really need 50A at 24VDC - at least this is what I want my unit to be rated for.

 

[VEBill]

50A is getting close to the point where you'd build up the high current circuits using (mechanical) bus bars, and the PCB would be like a daughter card holding only the low current circuitry. Maybe 50A is still within the range of PCB current carrying capabilities, but you're getting close. I'm not sure where the transition point is; somebody on here will know.

If you look inside really high current power supplies, you'll see a lot of bus bar construction, with a little PCB off in the corner.

 

[SolarTrap]

I am using 2oz copper on both sides of the board and I was told that is OK - can someone confirm that?

 

[VEBill]

http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/

You should triple check such on-line resources against other sources. And spot check some results against first principles.

50A -> 33 mm wide traces. Oops.

 

[VEBill]

Note.

Same URL: "The original graphs that this tool is based on (published in IPC-D-275) only cover up to 35 Amps..."

 

[MacGyverS2000]

VE, it would take 5oz copper to get down to 33(ish)mm traces.

Some of the better shops will do 4oz, but frankly, I think that's irrelevant. You are working at 50A, which means busbar.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Comcokid]

Actually, there are PCB places that specialize only in heavy copper plating, even up to 40 Oz. I am presently using a 10 Oz double sided that also contains SMT caps and resistors (nothing smaller than 1206). This PCB carries 70+ amps and forms the backbone of a 1800 Watt full-bridge converter, 24 volt input. Attachment to it is swaged-and-soldered 5/16 hex standoffs for #10 screws.

mcgyvr listed some connector series. I can add to this:
Hirose DF 60 series, listed as rated for 40 Amps, but designed for 12 to 8 AWG wire to PCB.
Molex Mini-Fit Sr. family rated 50 Amp.

 

[SolarTrap]

@VE1BLL: thanks for the link, I measured 11mm in parallel on both sides: 22mm with 2oz.

@Comcokid: can you share the information about the place you use for the high Oz copper?

Also can someone recommend places that have experience with bus-bars?

 

[MacGyverS2000]

Comco,

Do those places actually etch/plate? Seems like at that thickness, it would be laser-cut (or mechanical) copper shim glued to a substrate.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[mcgyvr]

I run "high currents" (up to 100A+) in circuit board traces all the time.. Most of my boards are 3 or 4oz clad plated up to 4 or 5oz or so after through hole plating with nice wide traces (1" W double sided or so as needed)
Many PCB houses can "plate" up to 10oz total thickness (but they must be UL approved to do so also)..
I also include thermal reliefs to aid in soldering,etc... As well as thermal vias to help spread the heat out between each side/plane..

We attach 8 AWG wire to PCB's all the time too but like the OP I had trouble finding an off the shelf terminal that fit our needs (and most importantly budget..whats out there is high dollar).. So we just make our own and have enough volume to justify it.. (which doesn't take much as you don't need to get it approved if used in your products only and when compared to whats out there already you can save quite a bit in the long run)

For bus bar attachments to PCB's I prefer to use PCB pem studs and leave a nice "pad" on the PCB to land the bus bar surface on.. Works great.. Sometimes I even use a pattern of vias spread far enough around the pem studs through hole radially to ensure that the plane to plane integrity is not compromised. I've also simply used "swage" standoffs in the PCB and attach a terminal/bus bar to that.

 

[itsmoked]

Interest discussion here!

mcgyvr; Are you saying you use various swagged/soldered standoffs (very short I imagine) then screw down essentially just flat copper with holes drilled to match the standoff placement? In other words home-fabbed busbar?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Comcokid]

I will post info on vendors who do heavy plated PCBs when I get to work on Monday.

I have seen designs where heavy currents were handled on a PCB by leaving the mask off the trace, manually soldering a tin plated bus wire down the trace. If you look at far east made DC/AC inverters, they tend to leave the mask off the trace so during wave solder a thick solder buildup is made on the trace. Commercial grade inverters tend to use bus bars that are vertical to the PCB that solder-in at the high-currnet places.

SolarTrap - who makes the screw lug you are using?

 

[MacGyverS2000]

Using solder buildup for high-current applications is bad bad bad. It would certainly never pass a UL/CE approval. There's no consistency in thickness, you can't guarantee a specific thickness, it has a higher resistance to current flow, etc.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[itsmoked]

I once saw in some magazine, the vertical, with leg pins, off-the-shelf, busbar being advertized. Of course when I finally needed some I couldn't remember the detail of who made it. All I can ever seem to find now is custom made-to-order only, shocking price busbar.

Keith Cress
kcress -

http://www.flaminsystems.com