Extreme copper p.c.b.s

Can they do 5/5 mil traces and spaces?

://dc.ee.ubm-us.com/i/112771

I wonder what sort of copper to insulator ratio's they can get in printed transformer windings? They might be able to do better than round enamelled copper wire for low resistance windings.

They say they can make 200oz (which is over 7mm/0.28" thick)! That's a fairly hefty bus bar, and might be challenging to solder.

No online pricing over a few oz.

This presentation has more information, including the limits on spacing etc..

Starting with 1-oz and going to 20oz (28 mils) final they recommend

a bit hard to do both at the same time ;)

I think the guide I've seem the limit is already something like 6/6 for 2oz, 12/12 for 4oz

-Lasse

Interesting stuff. The article does talk explicitily about plated windings for transformers, but the web-site doesn't seem to, though I'd imagine it to be an appreciable fraction of their business.

The point that extra-thick copper is a lot more resistant to thermal cycling came as a surprise - presumably it's thick enough to accommodate differential expansion by deformation, rather than cracking.

What's the cost comparison against just using your classic PCB-style bus-bar? ...Jim Thompson

Advanced (4pcb.com) is also offering it. They got a new factory up in MN that does it, I think. I've heard of UPE before, too (owned by Methode, who make buses the conventional way).

The aspect ratios are pretty much the same, so don't count on making a 20 mil copper layer with 5 mil gaps and 5 mil prepreg. You might be able to get a 20 mil core between 10-20 mil copper, with 10-20 mil design rules.

Vias are similarly inflated, AFAIK, which probably means smaller ones are filled (or nearly so; probably want to check with them first to make sure it doesn't, say, trap electrolyte and corrode later on).

Tim

tp://dc.ee.ubm-us.com/i/112771

I'm not sure. I wonder about the skin effect losses in thick plated copper. As another factor, the rectangular cross-section gives a good fill factor, but not if the multilayer construction adds too much space between windings.

So, could be pretty interesting, but I'm not sure. Somehow I suspect it's too pricey for casual uses.

Yes, depending on who "they" is, and what "do" means. :-)

I don't know. I looked hard last year for bus bars and couldn't find any suitable standard products--they seem to have faded away. Lots of companies make custom, laminated, multi-conductor buss bars to your spec, but I couldn't find a simple, thru-hole part with 0.xxx"-spaced terminals.

I had to pass 1kA peak. Total resistance budget was 2 milliohms, with

Here's what it wound up looking like:

bolt / washer crimp _ /_ / wire / _|_\/_|_/ ring terminal ______ |__|--|__| /

------| |------- |--| ---. copper bus bar, soldered to FR-4 .'.'.'| | \ \ \ \|--| \ \| /

------|_____|------- |--| ---'______________________. FR-4 | @ @ @|--|@ @ @ @ @ @ @ @ @ @ @ @ @ @| / |__@_@_|--|_@_@_@_@_@_@_@_@_@_@_@_@_@_|_____/ /________ |x| |__|--|__| |x x x x x x x x x x x x x / /x x x x x| | | /| |--| | | x x x x x x x x x x x x / /x x x x x | |x|/ |_|--|_| |x_x_x_x_x_x_x_x_x_x_x_x_/ /x_x_x_x_x_x| / '--' \ / / split nut . washer . . ||

That in turn depends on what the meaning of "is" is.

It might be more economical to bolt [1] a PC board to hunks of copper or aluminum, in only the areas where you need a lot of current.

That's right, not clamping the board. FR4 will cold flow over time, especially if it warms up. The contact pressure will fall, resistance will increase, and you can get thermal runaway.

Somebody makes a huge stamped metal tapped lug landing thing that solders to a PCB through a bunch of holes.

-4

-4

/ /________

/ /x x x x x|

/ /x x x x x |

/x_x_x_x_x_x|

ially

and

to a

look at something like this:

claims hundreds of amps and it is press fit not soldered

-Lasse

I was thinking copper sheet etched or laser cut to the shape of the traces needed, might even be possible to place and solder with a more or less standard smd process

-Lasse

especially

Yeah. There's also a stamped inverted U shape with a bunch of pins formed into the bottom, tapped on the flat top part. That solders.

The problem then becomes to get the current distribution right on the board, and not have some of the pins hog most of the current. That needs a finite-element-analysis program to do right, but you can cheat with a big sheet matrix of resistors in Spice.

Should work if you give it some compliance, eg. a Belleville washer.

I like wavy washers; they don't chew up the board as much.

Even better, solder in a bunch of fastons or a multipin Molex connector, and run a number of relatively smaller gage wires. It's more flexible, easier to handle, and the separate wire resistances tend to equalize the pin currents.

Ugh! What about soldering it? Would you use an acetylene torch? Even a 2 Oz board gives me a headache with a good soldering iron.

Jon

That's what ovens are for. It gets to be a pain with RoHS but do-able.