Extreme copper p.c.b.s

[[email protected]]

These guys can make pcbs with selective 30oz. copper on FR4...very
cool. I possibly could've used this last year on my 500A switch.

I couldn't find a direct link or any decent equivalent articles on the
web...load the digital version here, then search on "extreme copper":
http://dc.ee.ubm-us.com/i/112771

See fig. 2, pg. M6.

 

[Bill Sloman]

These guys can make pcbs with selective 30oz. copper on FR4...very
cool.  I possibly could've used this last year on my 500A switch.

I couldn't find a direct link or any decent equivalent articles on the
web...load the digital version here, then search on "extreme copper":http://dc.ee.ubm-us.com/i/112771

See fig. 2, pg. M6.

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.

 

[Spehro Pefhany]

These guys can make pcbs with selective 30oz. copper on FR4...very
cool. I possibly could've used this last year on my 500A switch.

I couldn't find a direct link or any decent equivalent articles on the
web...load the digital version here, then search on "extreme copper":
http://dc.ee.ubm-us.com/i/112771

See fig. 2, pg. M6.

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..
http://www.upe-inc.com/heavy-copper-pcb/UPE PWB Presentation 20070222.pdf

Starting with 1-oz and going to 20oz (28 mils) final they recommend
0.04" minimum width and spacing minimum 0.029".

 

[[email protected]]

Can they do 5/5 mil traces and spaces?

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

40oz would be something like ~100 I guess


-Lasse

 

[Bill Sloman]

These guys can make pcbs with selective 30oz. copper on FR4...very
cool.  I possibly could've used this last year on my 500A switch.

I couldn't find a direct link or any decent equivalent articles on the
web..

http://www.epectec.com/

http://www.epectec.com/pcb/extreme-copper/index.html

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.

 

[Tim Williams]

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

 

[[email protected]]

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.

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.

 

[[email protected]]

Can they do 5/5 mil traces and spaces?

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

 

[[email protected]]

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

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
1 milliohm allocated for the switch. Rather than mess around I spec'd
a 3mm copper bar part, 12.5x30mm, surface-mounted. That served as
conductor and connector, as posted here in sed. Commanded "closed,"
the proto measured 450e-6 ohms, terminal-to-terminal.

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 .

 

[[email protected]]

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 soldersto a
PCB through a bunch of holes.

look at something like this: http://www.broxing.com/Catalogue/b13_en.pdf

claims hundreds of amps and it is press fit not soldered

-Lasse

 

[[email protected]]

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

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.

[1] very, very carefully.

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

 

[Spehro Pefhany]

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.

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

 

[[email protected]]

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.

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

 

[Jasen Betts]

Ugh! What about soldering it? Would you use an acetylene torch?
Reflow.

Even a 2 Oz board gives me a headache with a good soldering iron.

? A 60W Hakko works ok here for through-hole, perhaps the 2oz I
ordered isn't?

 

[[email protected]]

? A 60W Hakko works ok here for through-hole, perhaps the 2oz I
ordered isn't?

One of the boards I'm working on now has four layers of 4oz and two
2oz. There are a few places that it takes a huge iron but not too
bad. Of course the devices (e.g SON power FETs) that are really using
the planes for dissipation are a PITA to remove. It's mostly SMT, so
normal devices are no problem.

 

[[email protected]]

Reflow.

Yep.

 

[[email protected]]

dagmargood... wrote:



Ugh!

Ugh? Copper is beautiful, especially moving big amps. Not ugh(ly)!

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

I reflowed the custom 3x12x30mm bus bar onto the proto with an ordinary Hakko--it was easy. I tinned both surfaces, then warmed up the bar. The heat spread wonderfully well. Copper's magic. I even moved it a few times with the same technique.

Now had the parts been soldered on the bar, that would've been tricky.

 

[[email protected]]

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.

High current modules, such as 6 pulse rectifier stacks usually have
screw terminals.

I guess that you might save something in the assembly work, by
connecting the device with a few screws to a PCB, instead of manually
preparing some wire harnesses and then install these to the device.